−---
−title: Storm Drainage
−category: Sitework
−toc_depth: 3
−description: >
− When to use: Site storm water collection and conveyance for commercial, institutional, and industrial building projects, including curb inlets, grate inlets, combination inlets, area drains, yard drains, storm sewer mains and laterals, manholes, junction structures, headwalls, flared end sections, outfalls, and connections to municipal storm systems or on-site detention and retention facilities. Covers gravity storm drainage piping on the site side of the building from the first structure downstream of any building roof drain leader connection out to the public right-of-way, including pipe materials (reinforced concrete, HDPE corrugated, PVC profile-wall, PVC SDR sewer, ductile iron), structures, castings, excavation and bedding, installation, connection to existing systems, testing, and acceptance.
− Not intended for: Roof drainage piping that runs vertically through the building (governed by the adopted plumbing code and outside the site utility scope); sanitary drain, waste, and vent piping inside the building or building sewer (see [[sync/sanitary-waste-and-vent-piping]]); building-perimeter foundation drainage and footing drains (see [[sync/foundation-drainage]]); subsurface agricultural drainage; storm water quality treatment devices and detention/retention basin earthwork and structural design (those are designed by the civil engineer of record and may reference this standard for the piping that connects to them); roadway pavement and aggregate base course (see [[sync/aggregate-base-course]]); culverts under state DOT roadways (governed by the state DOT standard specifications); and dewatering or temporary construction stormwater controls (see [[sync/earthwork]] and the project SWPPP).
−---
−
−# Scope
−
−This standard covers the materials, fabrication, installation, testing, and acceptance of site storm drainage systems that collect surface runoff from paved and unpaved site areas, convey it through gravity piping and structures, and discharge it either to a municipal storm sewer, to an on-site stormwater management facility, or to a permitted outfall. The scope begins at the throat of each curb inlet, the rim of each grate or area drain, and the first downstream structure or fitting receiving a roof drain leader from the building, and ends at the project-defined point of connection to the public storm system or to the inlet structure of the on-site stormwater facility.
−
−Storm drainage is the scope most directly responsible for the long-term flood performance of the site. Under-sized or poorly graded storm systems do not fail dramatically the way pressure piping fails — they fail by overtopping, by ponding, by surcharging back into adjacent properties, and by gradually filling with sediment until what was designed as a 10-year system performs at the 2-year level. Errors in alignment, invert elevations, bedding, and joint integrity propagate forward as settlement at pavement repairs, exfiltration into adjacent utility trenches, and infiltration of groundwater that consumes the design capacity. The civil drawings carry essentially all of the design-specific information for storm drainage — pipe sizes, slopes, invert elevations, structure rim and invert schedules, manhole types, and inlet types are drawing-driven for nearly every project. This standard governs the means and methods, the material requirements, and the installation and testing protocols within which the drawings operate.
−
−This standard does not include the hydrologic or hydraulic design of the storm drainage system. The civil engineer of record establishes the design storm, runoff calculation method (rational method, NRCS curve number method, or hydrograph-based methods such as HydroCAD or SWMM), pipe sizing, inlet capacities, and structure schedules. The Contractor shall install the system as designed and shall report to the Engineer of Record any condition that would prevent the designed system from being constructed as drawn — including conflicts with other utilities, inadequate cover, insufficient slope, or differing site conditions at the trench bottom. Coordinate work under this standard with [[sync/earthwork]] for trench excavation, dewatering, and backfill, with [[sync/foundation-drainage]] for the building-perimeter system that may discharge to storm structures, and with [[sync/aggregate-base-course]] for pavement structure that drains into curb inlets and area drains and that bears on completed storm trench backfill.
−
−# Referenced Standards
−
−Materials, manufacturing, installation, and testing shall comply with the latest adopted edition of the following standards. Where contract documents, adopted codes, or referenced standards conflict, the more stringent requirement shall govern unless the Engineer of Record directs otherwise in writing.
−
−| Standard | Title |
−|----------|-------|
−| ASTM C76 | Standard Specification for Reinforced Concrete Culvert, Storm Drain, and Sewer Pipe |
−| ASTM C361 | Standard Specification for Reinforced Concrete Low-Head Pressure Pipe |
−| ASTM C443 | Standard Specification for Joints for Concrete Pipe and Manholes, Using Rubber Gaskets |
−| ASTM C478 | Standard Specification for Circular Precast Reinforced Concrete Manhole Sections |
−| ASTM C923 | Standard Specification for Resilient Connectors Between Reinforced Concrete Manhole Structures, Pipes, and Laterals |
−| ASTM C990 | Standard Specification for Joints for Concrete Pipe, Manholes, and Precast Box Sections Using Preformed Flexible Joint Sealants |
−| ASTM D2321 | Standard Practice for Underground Installation of Thermoplastic Pipe for Sewers and Other Gravity-Flow Applications |
−| ASTM D3034 | Standard Specification for Type PSM Poly(Vinyl Chloride) (PVC) Sewer Pipe and Fittings |
−| ASTM D3212 | Standard Specification for Joints for Drain and Sewer Plastic Pipes Using Flexible Elastomeric Seals |
−| ASTM F477 | Standard Specification for Elastomeric Seals (Gaskets) for Joining Plastic Pipe |
−| ASTM F679 | Standard Specification for Poly(Vinyl Chloride) (PVC) Large-Diameter Plastic Gravity Sewer Pipe and Fittings |
−| ASTM F949 | Standard Specification for Poly(Vinyl Chloride) (PVC) Corrugated Sewer Pipe With a Smooth Interior and Fittings |
−| ASTM F1417 | Standard Practice for Installation Acceptance of Plastic Non-Pressure Sewer Lines Using Low-Pressure Air |
−| ASTM F2306 | Standard Specification for 12 in. to 60 in. Annular Corrugated Profile-Wall Polyethylene (PE) Pipe and Fittings for Gravity-Flow Storm Sewer and Subsurface Drainage Applications |
−| AASHTO M294 | Standard Specification for Corrugated Polyethylene Pipe, 300- to 1500-mm (12- to 60-in.) Diameter |
−| AASHTO M252 | Standard Specification for Corrugated Polyethylene Drainage Pipe (3 in. to 10 in.) |
−| AASHTO M306 | Standard Specification for Drainage, Sewer, Utility, and Related Castings |
−| ASTM A48/A48M | Standard Specification for Gray Iron Castings |
−| ASTM A536 | Standard Specification for Ductile Iron Castings |
−| AASHTO HS-20 / HS-25 | Standard Highway Loadings for Bridge and Culvert Design (referenced for casting and structure live load) |
−| ASTM C150 | Standard Specification for Portland Cement |
−| ASTM C913 | Standard Specification for Precast Concrete Water and Wastewater Structures |
−| EPA NPDES CGP | Construction General Permit (National Pollutant Discharge Elimination System) |
−
−State DOT standard specifications (e.g., FDOT, Caltrans, TxDOT, NJDOT) and local public works manuals are referenced as concept where work connects to public infrastructure; the specific governing edition shall be confirmed with the Authority Having Jurisdiction (AHJ) and the public works department or utility owner before work in the right-of-way begins. Local stormwater management permitting requirements — including any municipal separate storm sewer system (MS4) program requirements — shall be identified by the Contractor as part of pre-construction planning, and the SWPPP shall comply with the project's coverage under the EPA Construction General Permit or the state-equivalent NPDES permit.
−
−# Submittals
−
−## Action Submittals
−
−The Contractor shall submit the following for the Engineer of Record's review and acceptance prior to procurement, fabrication, or installation of any portion of the storm drainage system. Below-grade work for which submittals are pending shall not be installed.
−
−- Product data for all pipe and fitting materials, indicating the manufacturer, the applicable ASTM or AASHTO standard, the class or pipe stiffness (PS) where applicable, the wall thickness or SDR, the joint type, the gasket material and the applicable joint standard (ASTM C443, C990, D3212, or F477)
−- Product data and shop drawings for precast manholes, junction structures, inlets, and headwalls, including the manufacturer's standard sections and adjustments, eccentric/concentric cone configurations, base type (monolithic or separate), pipe connection details (cast-in resilient connectors per ASTM C923 or core-drilled with boot), reinforcement schedules, lift-and-set hardware, and AASHTO HS-20 or HS-25 load rating
−- Casting product data for all frames, grates, covers, and lids, indicating the casting standard (ASTM A48 for gray iron or ASTM A536 for ductile iron), the AASHTO M306 listing, the load rating, the clear opening dimensions, and any local public works pattern conformance where the casting is at or within the public right-of-way
−- Bedding and backfill material gradations conforming to ASTM D2321 Class I or Class II as specified, including sieve analyses for each source proposed
−- Trench excavation and dewatering plan where storm drainage trenches will exceed 5 feet in depth or where groundwater is anticipated; this submittal may reference and incorporate the project earthwork submittal under [[sync/earthwork]] for the same trench work
−- Pipe joint testing plan, including the proposed method (low-pressure air per ASTM F1417, hydrostatic, or joint-by-joint pressure test for large-diameter pipe), the test pressures and durations, the testing agency and equipment, and the sections to be tested
−- Deflection testing plan for all flexible pipe (HDPE and PVC), including the timing relative to backfill placement and the mandrel sizes for each pipe diameter being installed
−- Connection details and any required permits or utility owner approvals for connection to existing storm systems or to municipal infrastructure
−- Working storm drainage plan (record-set markup) that the Contractor maintains and updates daily, showing actual horizontal and vertical alignments of pipe and structures as installed
−
−```datasheet
−label: Action Submittals Required
−type: checkbox
−options:
− - "Pipe and fitting product data with applicable standard, class, and joint type"
− - "Precast manhole and structure shop drawings with load rating"
− - "Frame, grate, and cover casting product data with AASHTO M306 listing"
− - "Bedding and backfill material gradations (ASTM D2321 classification)"
− - "Trench excavation and dewatering plan"
− - "Pipe joint testing plan"
− - "Deflection testing plan (flexible pipe)"
− - "Existing-system connection details and utility owner approvals"
− - "Working record-set markup procedure"
−default: "Pipe and fitting product data with applicable standard, class, and joint type"
−```
−
−## Closeout Submittals
−
−Prior to substantial completion the Contractor shall provide:
−
−- As-built storm drainage record drawings showing the installed plan and profile of all pipe, including station and offset to permanent reference points, finished rim elevation and all pipe invert elevations at every structure, every casting model number installed, every pipe size and material installed by reach, and any deviations from the contract documents
−- Field test reports for all pressure or air tests, leakage tests, deflection tests, and structure vacuum tests, signed by the testing technician, with pass/fail determination for each pipe reach and structure
−- Manufacturer warranties for castings, precast structures, and any specialty products
−- Final cleanout / flushing certification confirming that pipe and structures have been cleared of debris, sediment, and construction materials before turnover to the Owner or to the AHJ
−- AHJ acceptance documentation where the system connects to public storm infrastructure or where the local jurisdiction issues a separate acceptance for the on-site storm system
−
−# Quality Assurance
−
−## Installer Qualifications
−
−Storm drainage piping and structures shall be installed by a contractor with verifiable experience on at least three projects of comparable size and complexity within the preceding five years. Personnel installing gasketed joints (concrete, HDPE, or PVC) shall be familiar with the manufacturer's recommended joint assembly procedure, including gasket installation, lubricant application, and home-mark verification.
−
−Installation of large-diameter reinforced concrete pipe — 36 inches and larger — shall be performed by personnel experienced with the rigging, jointing, and bell-and-spigot home requirements of that pipe size. Pipe installation crews working on RCP for the first time on a project shall demonstrate joint assembly on the first three sections in the presence of the Engineer's inspector before proceeding with production work.
−
−## Listing and Marking
−
−All pipe, fittings, gaskets, castings, and precast structures shall bear the manufacturer's identification, the applicable standard designation, and the production date or batch number sufficient to trace each item to its certification documents. Unmarked pipe or structures shall be rejected and removed from the project regardless of supplier documentation.
−
−Castings used at or within the public right-of-way shall bear the AASHTO M306 mark, the foundry identification, and any local public works pattern number required by the utility owner. Castings without the M306 mark shall not be installed in vehicular areas.
−
−## Pre-Installation Conference
−
−Prior to beginning storm drainage installation the Contractor shall participate in a pre-installation conference attended by the Contractor's superintendent for site utilities, the Owner's geotechnical engineer of record, the civil engineer of record, the AHJ inspector (where required), and the testing agency. The conference shall review the pipe materials and joint types, the bedding and backfill requirements, the testing program, the inspection hold points, the procedures for connection to existing systems, and the protocols for dealing with differing site conditions.
−
−## Inspection Hold Points
−
−The Contractor shall provide the Engineer of Record and the AHJ inspector with not less than 24 hours' notice before each of the following inspection hold points. No work past a hold point shall proceed until the inspection is completed and released.
−
−- Trench bottom and bedding placement, before pipe installation
−- Pipe alignment, slope, and joint assembly, before initial backfill
−- Structure base placement, before structure sections are stacked
−- Structure pipe penetrations and resilient connector seating, before grouting or sealing
−- Backfill compaction in the pipe zone, before pavement subgrade preparation
−- Final pipe testing (air, hydrostatic, or joint test) and deflection testing for flexible pipe
−- Casting setting and grade, before final pavement placement
−
−# Pipe Materials
−
−## Primary Material Selection
−
−The pipe material for each reach shall be as indicated on the storm drainage plan, profile, and pipe schedule. Where the drawings permit more than one material for a given reach, the Contractor shall submit the proposed material for that reach for the Engineer's acceptance and shall not mix materials within a continuous reach between structures without an approved transition fitting. Different materials may be used in different reaches of the same system where the drawings so indicate.
−
−```datasheet
−label: Primary Storm Sewer Pipe Material
−type: select
−drawing_ref: true
−options:
− - "Reinforced concrete pipe (RCP) per ASTM C76, gasketed bell-and-spigot joints per ASTM C443"
− - "HDPE dual-wall corrugated pipe per AASHTO M294 Type S / ASTM F2306, gasketed joints per ASTM D3212"
− - "PVC profile-wall pipe per ASTM F949, gasketed joints per ASTM D3212"
− - "PVC SDR 35 sewer pipe per ASTM D3034, gasketed joints per ASTM D3212"
− - "PVC large-diameter sewer pipe per ASTM F679, gasketed joints per ASTM D3212"
− - "Ductile iron pipe (specialty applications, see drawings)"
− - "Per drawings"
−default: "Per drawings"
−```
−
−Material selection is a civil engineering decision, not a means-and-methods decision, and is established by the civil drawings. The narrative that follows describes the conditions under which each material is appropriate so that the Contractor can recognize and report mismatches between drawn material and field condition.
−
−## Reinforced Concrete Pipe (RCP)
−
−Reinforced concrete pipe conforming to ASTM C76 is the long-standing standard for large-diameter storm sewers, public storm mains, and any reach where high structural strength, long service life, and tolerance to heavy live loads with shallow cover are required. RCP is available in five classes (Class I through Class V) reflecting increasing strength designations under the three-edge bearing test; the class for each reach shall be as indicated on the pipe schedule and shall be chosen by the civil engineer based on cover depth, live load, trench width, and bedding class.
−
−```datasheet
−label: RCP Strength Class
−type: select
−drawing_ref: true
−options:
− - "Class II (0.01-in. crack 1000-D, ultimate 1500-D)"
− - "Class III (0.01-in. crack 1350-D, ultimate 2000-D)"
− - "Class IV (0.01-in. crack 2000-D, ultimate 3000-D)"
− - "Class V (0.01-in. crack 3000-D, ultimate 3750-D)"
− - "Per pipe schedule"
−default: "Class III (0.01-in. crack 1350-D, ultimate 2000-D)"
−```
−
−Class III RCP is the most commonly specified class for typical commercial site storm drainage with cover depths of approximately 3 to 12 feet and HS-20 live loading. Class IV and Class V are used where cover is shallow, where trench widths exceed the standard installation envelope, or where unusually heavy live loading is anticipated. The Contractor shall not substitute a lower class than indicated under any circumstances; the class designation reflects the structural design assumption of the civil engineer.
−
−RCP joints shall be gasketed bell-and-spigot or single-offset joints with confined O-ring or profile gaskets conforming to ASTM C443. Mortar-only joints, mastic-only joints, and "tongue and groove" joints without a gasket are not acceptable for new storm drainage construction. The gasket creates the watertight seal; any mortar or external sealant is supplemental and does not substitute for the gasket. The Contractor shall verify that the gasket has been seated correctly in its groove before stabbing the joint, shall apply lubricant per the manufacturer's instructions, and shall confirm that the joint is fully home — typically verified by a paint mark or stencil on the spigot indicating the design home depth.
−
−## HDPE Corrugated Dual-Wall Pipe
−
−High-density polyethylene corrugated dual-wall pipe conforming to AASHTO M294 Type S (12 in. and larger) or AASHTO M252 (3 in. through 10 in.), and to ASTM F2306 for the 12-in. through 60-in. size range, is widely used for site storm drainage in private development where cover depth, live load, and pipe size are within the range supported by the AASHTO design specifications. HDPE is a flexible pipe — its performance depends on the soil envelope around it, and proper bedding and haunching are critical to long-term shape stability.
−
−```datasheet
−label: HDPE Pipe Stiffness (PS) Minimum
−type: radio
−unit: psi at 5 percent deflection
−options:
− - "46 psi (AASHTO M294 / ASTM F2306 minimum, Type S)"
− - "Higher PS as specified by civil engineer for deep cover or surcharge"
−default: "46 psi (AASHTO M294 / ASTM F2306 minimum, Type S)"
−```
−
−HDPE joints shall be bell-and-spigot joints with elastomeric gaskets conforming to ASTM F477 and meeting the watertight performance requirements of ASTM D3212. The gasket shall be factory-installed in the bell. Joints relying solely on a slip-fit or on a snap-ring without a continuous gasket are not acceptable for storm drainage applications connected to permanent infrastructure. The Contractor shall confirm the joint type and gasket configuration against the product submittal and shall use only the manufacturer's recommended lubricant.
−
−HDPE pipe shall be installed in accordance with ASTM D2321 with embedment material conforming to ASTM D2321 Class I or Class II crushed stone or gravel placed to the depths specified in the Bedding and Pipe Zone Backfill section of this standard. The maximum allowable installed deflection shall be 5 percent of the nominal inside diameter, measured by mandrel pull-through not earlier than 30 days after final backfill and final cover load have been placed.
−
−## PVC Sewer and Profile-Wall Pipe
−
−Polyvinyl chloride pipe is acceptable for storm drainage in the configurations indicated on the drawings, in any of the following standards:
−
−- ASTM D3034 SDR 35 (4-in. through 15-in. nominal), solid-wall gasketed sewer pipe
−- ASTM F679 (18-in. and larger), solid-wall gasketed large-diameter sewer pipe
−- ASTM F949 (4-in. through 36-in.), corrugated/profile-wall PVC pipe with smooth interior
−
−```datasheet
−label: PVC Pipe Type for Storm Drainage
−type: select
−drawing_ref: true
−options:
− - "SDR 35 solid wall (ASTM D3034) — 4 in. through 15 in."
− - "Large-diameter solid wall (ASTM F679) — 18 in. and larger"
− - "Profile-wall (ASTM F949) — 4 in. through 36 in."
− - "Per drawings"
−default: "Per drawings"
−```
−
−PVC pipe joints shall be bell-and-spigot integral gasketed joints conforming to ASTM D3212, with gaskets conforming to ASTM F477. Solvent cement joints are not permitted for buried storm sewer service; the storm system is subject to differential thermal and ground movement that solvent-cement joints do not accommodate, and the gasketed joint is the recognized standard for buried gravity sewer. The Contractor shall verify that all PVC pipe delivered to the site is rated for the storm sewer service (the pipe shall be marked with the applicable ASTM standard and shall not be DWV or Schedule 40 pressure pipe re-purposed as a sewer material).
−
−PVC pipe is, like HDPE, a flexible pipe and is subject to the same maximum installed deflection limit of 5 percent. PVC pipe shall be installed in accordance with ASTM D2321 with the same bedding and pipe-zone embedment requirements as HDPE.
−
−## Ductile Iron Pipe — Specialty Applications
−
−Ductile iron pipe is occasionally used for storm drainage in specialty locations: under heavy equipment foundations, under building footings where structural drawings require it, in seismic regions where high joint deflection tolerance is needed, or where the storm system crosses sanitary or pressure utilities at constrained vertical separation. Where ductile iron is specified, the pipe material, joint type, lining, and class shall be as indicated on the drawings; the requirements of this standard for bedding, jointing, testing, and structure connection apply.
−
−# Structures
−
−## Manholes and Junction Structures
−
−Storm drainage manholes shall be circular precast reinforced concrete structures conforming to ASTM C478. Cast-in-place concrete structures may be used where indicated on the drawings, typically for unusual geometries (junction structures with multiple inlet pipes at varying elevations, energy dissipation structures, or weir structures within the storm system). Brick or masonry block manholes shall not be used for new storm drainage construction unless specifically required to match existing infrastructure under a renovation scope.
−
−```datasheet
−label: Manhole Type
−type: select
−drawing_ref: true
−options:
− - "Precast circular concrete (ASTM C478), monolithic base"
− - "Precast circular concrete (ASTM C478), separate precast base"
− - "Cast-in-place concrete structure per drawings"
− - "Per structure schedule"
−default: "Precast circular concrete (ASTM C478), monolithic base"
−```
−
−Manhole barrel diameter, riser sections, eccentric or concentric cone, top slab type, and adjustment ring stack shall be as indicated on [[drawing: the structure schedule and manhole details]]. Standard interior barrel diameters for storm drainage manholes are 48 inches and 60 inches; larger diameters (72-inch, 84-inch, 96-inch) are used at junction structures, at structures with large incoming pipes, or where personnel access for cleaning and inspection requires it.
−
−```datasheet
−label: Minimum Manhole Inside Diameter — by Largest Pipe Connection
−type: select
−drawing_ref: true
−options:
− - "48-in. manhole — pipes up to 24 in."
− - "60-in. manhole — pipes 27 in. through 36 in."
− - "72-in. manhole — pipes 42 in. through 48 in."
− - "84-in. manhole or larger — pipes 54 in. and larger"
− - "Per structure schedule"
−default: "Per structure schedule"
−```
−
−Manhole sizing is a function of the largest pipe entering or leaving the structure, the angle between pipes at the junction, and the maintenance access required. Under-sized manholes cannot accommodate the bench shaping required to direct flow smoothly between inlet and outlet pipes; the result is hydraulic loss at the structure and accelerated sediment deposition. The Contractor shall verify the structure size on the schedule against the pipe sizes converging at that structure before fabricating or ordering precast components.
−
−## Pipe Connections to Structures
−
−Every pipe entering or leaving a precast manhole or junction structure shall be connected by either a cast-in-place resilient connector conforming to ASTM C923, or by a core-drilled opening fitted with a boot-type resilient connector also conforming to ASTM C923. Direct mortared pipe penetrations through a precast structure wall without a resilient connector are not acceptable; the dissimilar thermal and mechanical movement of pipe and structure cracks rigid mortar seals and causes both exfiltration of storm flow and infiltration of groundwater.
−
−```datasheet
−label: Pipe-to-Structure Connection
−type: radio
−options:
− - "Cast-in resilient connector (ASTM C923) at precast fabrication"
− - "Field-cored opening with boot-type resilient connector (ASTM C923)"
− - "Cast-in-place structure with rigid penetration and flexible gasket sleeve"
− - "Per drawings"
−default: "Cast-in resilient connector (ASTM C923) at precast fabrication"
−```
−
−The cast-in resilient connector is the preferred method because it provides factory quality control on the seal-to-structure interface; the core-drilled-and-boot method is acceptable for field connections that were not anticipated at precast fabrication, provided the core hole is drilled cleanly with a diamond core barrel and the boot is sized correctly for the pipe outside diameter.
−
−## Manhole Joints
−
−Joints between precast manhole sections (base to riser, riser to riser, riser to cone, cone to top slab) shall be sealed with butyl rubber preformed flexible joint sealant conforming to ASTM C990, or with confined O-ring rubber gaskets conforming to ASTM C443 where the manhole sections are manufactured for gasketed joints. Mortar-only manhole section joints are not acceptable for new construction; the preformed sealant or gasket provides the watertightness that mortar alone cannot maintain through ground movement and freeze-thaw cycles.
−
−## Manhole Step and Ladder
−
−Manhole steps shall be plastic-coated steel reinforcing bar or copolymer polypropylene plastic conforming to ASTM C478 step requirements, embedded in the precast sections in accordance with the section drawings. Step spacing shall not exceed 16 inches vertically. Manholes deeper than 20 feet shall include a fixed steel ladder in lieu of cast-in steps where required by OSHA confined space entry provisions or local regulation; the ladder design shall be reviewed by the Engineer of Record before installation.
−
−```datasheet
−label: Manhole Step Material
−type: radio
−options:
− - "Copolymer polypropylene plastic over steel reinforcing bar (ASTM C478)"
− - "Cast-in steel reinforcing bar — coated"
− - "Fixed steel ladder (manholes 20 ft and deeper)"
− - "Per drawings"
−default: "Copolymer polypropylene plastic over steel reinforcing bar (ASTM C478)"
−```
−
−## Inlets
−
−Inlets collect surface runoff and convey it into the storm sewer. Inlet selection is established by the civil drawings based on inlet location, gutter or sheet flow conditions, and the inlet's intended hydraulic capacity. The principal inlet types used in commercial site work are:
−
−- **Curb inlet:** A vertical opening in the back of curb, with no grate in the gutter line. Curb inlets accept gutter flow through the vertical opening and are resistant to clogging by leaves and debris. They are the preferred inlet type on continuous-grade gutters where vehicular tire interaction with grates would be a concern.
−- **Grate inlet:** A horizontal opening in the gutter line covered by a cast iron or ductile iron grate. Grate inlets accept gutter flow primarily through the grate openings; they have high capacity per linear foot when the grate is clear, but capacity drops substantially when the grate becomes partially blocked by debris.
−- **Combination inlet:** A curb inlet and a grate inlet acting together at the same location, providing both the high capacity of the grate and the debris-tolerance of the curb opening. Combination inlets are appropriate at sag locations where ponding would result if the grate clogged.
−- **Area drain / yard drain:** A small precast or cast-in-place inlet with a grate, located in a paved area or landscaped low point to drain a localized area. Area drains in vehicular areas shall use the same casting load class as the surrounding pavement.
−- **Trench drain:** A linear surface drain used to collect sheet flow across a paved area, typically at vehicular entrances, loading docks, or wide pedestrian plazas. Trench drains shall be specified separately from this standard where used.
−
−```datasheet
−label: Inlet Type by Location
−type: select
−drawing_ref: true
−options:
− - "Curb inlet — continuous grade"
− - "Grate inlet — gutter line"
− - "Combination inlet — sag location"
− - "Area drain / yard drain — paved low point"
− - "Area drain / yard drain — landscaped low point"
− - "Per drawings"
−default: "Per drawings"
−```
−
−Inlet structure dimensions, throat or grate opening size, sump depth (if any), and pipe connection elevations shall be as indicated on [[drawing: the inlet schedule and inlet details]]. The civil engineer of record has computed inlet capacities based on the design gutter flow and the rating curves for the specified inlet type; the Contractor shall not substitute one inlet type for another without the Engineer's approval, because the substitution alters the hydraulic capacity assumed in the design.
−
−The Contractor shall recognize that inlet capacity calculations are typically performed using HEC-22 or equivalent methods, which assume that grates are not clogged. Field experience indicates that grates in tree-lined or leaf-heavy areas can lose 30 to 50 percent of theoretical capacity in fall and spring. The civil engineer applies a clogging factor in the design; the Contractor's responsibility is to install the specified inlet correctly and to assist the Owner with the operations and maintenance information needed to keep grates clear.
−
−## Junction Structures and Inline Cleanouts
−
−Where two or more pipes meet at angles that exceed the standard manhole bench geometry, a junction structure shall be provided as indicated. Junction structures shall be cast-in-place reinforced concrete or precast box structures sized to accommodate the converging pipe inverts with smooth, swept channels that direct flow from each incoming pipe to the outgoing pipe with minimum hydraulic loss. The interior shall be benched in mortar above the spring line of the largest pipe to provide a walkable maintenance surface.
−
−Inline cleanouts (lateral cleanouts on individual roof drain or area drain lateral connections) shall be brought to grade with a cast iron or PVC riser and a watertight access plug; cleanouts shall be installed at every change of direction greater than 45 degrees on lateral pipe runs and at every 100 feet of straight run on pipe smaller than 18 inches.
−
−## Headwalls, Flared End Sections, and Outfalls
−
−Where storm drainage discharges to an open swale, ditch, or detention/retention basin, a headwall or flared end section shall be provided at the outfall to control erosion, anchor the pipe end, and provide a clean transition between the pipe and the open channel. Headwalls shall be cast-in-place reinforced concrete or precast as indicated; flared end sections shall be precast concrete (for RCP) or metal/polymer (for HDPE and PVC) of the manufacturer's standard configuration matching the pipe.
−
−```datasheet
−label: Outfall Termination
−type: select
−drawing_ref: true
−options:
− - "Cast-in-place concrete headwall with wingwalls"
− - "Precast concrete headwall"
− - "Precast concrete flared end section (RCP)"
− - "HDPE / PVC flared end section (manufacturer's standard)"
− - "Riprap apron downstream of pipe end — no headwall"
− - "Per drawings"
−default: "Per drawings"
−```
−
−A riprap apron, an energy dissipator (e.g., a stilling basin or a baffled outlet), or a combination thereof shall be provided downstream of any outfall where the outlet velocity at the design flow exceeds the permissible velocity of the receiving channel. Riprap gradation and apron dimensions shall be as indicated on the drawings; under-sizing the riprap apron causes scour at the pipe outlet that progressively undermines the headwall and the last pipe joint.
−
−# Castings
−
−## General
−
−All inlet frames, manhole frames, manhole covers, inlet grates, and area drain grates ("castings") shall be gray iron conforming to ASTM A48 or ductile iron conforming to ASTM A536, listed in accordance with AASHTO M306. Castings shall be free of visible defects (cracks, cold shuts, blowholes, inclusions), shall be machined at mating surfaces where required to seat the cover or grate flat in the frame without rocking, and shall bear the foundry identification and the AASHTO M306 mark.
−
−## Casting Material
−
−```datasheet
−label: Casting Material
−type: radio
−options:
− - "Gray iron per ASTM A48 (Class 35B typical for street castings)"
− - "Ductile iron per ASTM A536 (Grade 70-50-05 typical for heavy-load castings)"
− - "Mix — ductile iron lid or grate with gray iron frame (cost-effective for H-25 loading)"
− - "Per drawings"
−default: "Gray iron per ASTM A48 (Class 35B typical for street castings)"
−```
−
−Gray iron conforming to ASTM A48 Class 35B is the standard material for the majority of street and parking lot castings; it provides good compressive strength and excellent wear and corrosion resistance for the load class typical of HS-20 vehicular loading. Ductile iron conforming to ASTM A536 (commonly Grade 65-45-12 or 70-50-05) is used where loads exceed HS-20, where impact loading is anticipated (e.g., at airport service roads, intermodal facilities, or heavy industrial yards), or where the engineer specifies the higher tensile and yield strength of ductile iron. A common cost-effective configuration is a gray iron frame with a ductile iron lid or grate; the heavier-loaded element (the lid that takes the wheel load) gets the more expensive material.
−
−## Casting Load Class
−
−```datasheet
−label: Casting Load Rating
−type: select
−drawing_ref: true
−options:
− - "Light duty — pedestrian / non-traffic only"
− - "Medium duty — light vehicular (parking lot, driveway)"
− - "H-20 / HS-20 — standard highway loading"
− - "H-25 / HS-25 — heavy highway loading"
− - "Heavy industrial — airport, intermodal, container yard"
− - "Per drawings"
−default: "H-20 / HS-20 — standard highway loading"
−```
−
−The casting load class shall match the live load applicable to the location: HS-20 is the standard for typical commercial parking and drives; HS-25 is used for state DOT roadways and for routes carrying heavy truck traffic. Pedestrian-only castings (e.g., in non-traffic plazas) may use lighter-class castings, but the Contractor shall confirm that the castings are not located on a fire-lane or service-vehicle route where vehicular load is intermittent but real. Under-rated castings in vehicular areas can crack under repeated heavy axle loads and become safety hazards.
−
−## Self-Sealing Covers and Bolted Lids
−
−Where castings are subject to occasional surcharge — at sag inlets in low-lying areas, at structures within a flood plain, or where the storm system is designed to surcharge to grade during the extreme event — covers shall be self-sealing (gasketed seat) or bolted in place to prevent the cover from being displaced by surcharge pressure. Bolted lids shall use stainless steel or hot-dip galvanized fasteners; carbon steel fasteners corrode within the manhole environment and become unusable within a few years.
−
−```datasheet
−label: Bolted or Gasketed Manhole Cover
−type: radio
−options:
− - "Not required — non-flood-prone location"
− - "Gasketed self-seating cover (storm surcharge possible)"
− - "Bolted lid with stainless steel fasteners (flood plain or flood-prone)"
− - "Per drawings"
−default: "Not required — non-flood-prone location"
−```
−
−## Adjustment Rings
−
−Adjustment between the top of the precast structure cone or top slab and the bottom of the cast iron frame shall be made with precast concrete adjustment rings, precast HDPE or recycled rubber adjustment rings, or with mortared brick — as permitted by the local utility owner. The total height of adjustment shall not exceed 12 inches without the Engineer's approval; tall stacks of adjustment rings are inherently unstable under traffic loading and tend to settle, dislocate, and leak. Where more than 12 inches of adjustment is needed, a custom riser section shall be specified.
−
−```datasheet
−label: Casting-to-Structure Adjustment Method
−type: radio
−options:
− - "Precast concrete adjustment rings — mortared between rings and to frame"
− - "Precast HDPE / recycled rubber adjustment rings"
− - "Mortared brick (where permitted by utility owner)"
− - "Custom precast riser (where adjustment exceeds 12 in.)"
−default: "Precast concrete adjustment rings — mortared between rings and to frame"
−```
−
−The Contractor shall set the cast iron frame on a continuous mortar bed at the top adjustment ring, with the inside face of the frame flush with the inside face of the structure, and with the top of the frame matched to the finished pavement or grade. Castings set proud of pavement create plowing and pedestrian-trip hazards; castings set low cause water to pond around the rim and accelerate pavement deterioration.
−
−# Excavation and Trench Preparation
−
−## General Trench Requirements
−
−Trench excavation for storm drainage piping shall conform to the requirements of [[sync/earthwork]] for trench excavation, dewatering, slope stability, and shoring or trench protection. The requirements specific to storm drainage trenching are stated below; in case of conflict between this standard and [[sync/earthwork]], the more stringent requirement governs.
−
−Trench width at the springline of the pipe shall be the minimum needed for safe worker access, pipe installation, and joint assembly, plus the haunching room required by the pipe manufacturer and ASTM D2321 for flexible pipe. Minimum trench width at the springline shall be the pipe outside diameter plus 16 inches (8 inches on each side) for pipes up to 24 inches in diameter, and shall be confirmed against the manufacturer's installation manual for larger sizes. Excessive trench width increases bedding and backfill quantities and, for rigid pipe, increases the bedding factor required to carry the live load.
−
−The trench bottom shall be excavated to the pipe invert grade minus the bedding thickness, on a uniform longitudinal slope matching the design pipe slope without dips, sags, or reverse gradient. Where the trench bottom is over-excavated below design grade — whether by accident or to remove an unsuitable zone — the over-excavation shall be backfilled with compacted granular bedding material to the design bedding bottom elevation, with the geotechnical engineer's concurrence on the lift thickness and compaction requirement.
−
−## Trench Bottom Stability
−
−The bottom of every storm drainage trench shall be observed by the geotechnical engineer of record (or the Owner's designated inspector) before bedding is placed, to confirm that the trench bottom is competent and uniform. Soft, wet, or pumping trench bottom conditions shall be remediated before bedding is placed. Remediation options include over-excavation and replacement with crushed stone, geotextile separation with granular fill, or — where conditions warrant — a flowable fill foundation course as directed by the geotechnical engineer.
−
−```datasheet
−label: Trench Bottom Stabilization (where soft)
−type: select
−options:
− - "Over-excavate and replace with compacted crushed stone working layer — 12 in. minimum"
− - "Over-excavate, place geotextile, then crushed stone — soft cohesive subgrade"
− - "Controlled low-strength material (CLSM) foundation course"
− - "Not required — competent native bearing"
−default: "Not required — competent native bearing"
−```
−
−The Contractor shall not place pipe directly on bedded mud, on standing water, or on disturbed loose material. The bedding-to-pipe load transfer assumed in the pipe design is destroyed if the bedding is bedded on unstable material; the result is differential settlement that breaks joints and creates sags in the completed pipe. The geotechnical engineer's documentation of trench bottom acceptance for each reach shall be retained in the project record.
−
−## Dewatering
−
−Trenches that extend below the groundwater table shall be dewatered continuously throughout pipe installation, bedding and pipe-zone backfill placement, and until enough cover has been placed to resist pipe flotation. Dewatering shall conform to the requirements of [[sync/earthwork]]. The Contractor shall not place pipe in standing water; doing so causes bedding washout under the pipe, gasket contamination at the joints, and uncontrolled buoyancy that displaces pipe alignment.
−
−Dewatering discharge shall be conducted through sediment-control measures (sediment bag, settling basin, or other approved BMP) and shall comply with the project NPDES permit and any local stormwater discharge requirements. Discharge of dewatering flow directly to the newly-installed storm system shall be avoided where practical, and shall be filtered if necessary.
−
−# Bedding and Pipe Zone Backfill
−
−## Bedding Class
−
−Pipe bedding shall be classified in accordance with ASTM D2321 for flexible pipe (HDPE, PVC) and in accordance with the bedding factor convention of the rigid pipe industry for RCP. The bedding class for each reach shall be as indicated on the trench detail or the pipe schedule.
−
−```datasheet
−label: Bedding Class
−type: select
−drawing_ref: true
−options:
− - "ASTM D2321 Class I — open-graded crushed stone (preferred for flexible pipe)"
− - "ASTM D2321 Class II — clean coarse-grained, well-graded sand or gravel"
− - "ASTM D2321 Class III — coarse-grained with fines"
− - "Class B bedding (rigid pipe — granular shaped to pipe bottom)"
− - "Class A bedding (rigid pipe — concrete cradle, special applications)"
− - "Per drawings"
−default: "ASTM D2321 Class I — open-graded crushed stone (preferred for flexible pipe)"
−```
−
−Class I (open-graded crushed stone, typically 3/4 in. or 1/2 in. clean) is the preferred bedding for flexible pipe because it does not require compaction beyond placement and self-consolidation, achieves predictable shape stability in the haunch zone, and provides drainage that prevents migration of fines from the surrounding soil. Class II (clean, well-graded sand or gravel) is acceptable where Class I material is not available locally; Class II requires careful placement and compaction to achieve the required density in the haunches.
−
−## Bedding Thickness
−
−The granular bedding course shall extend from the trench bottom to the underside of the pipe at the full design pipe slope, with a thickness as indicated below and as shown on the trench detail.
−
−```datasheet
−label: Bedding Course Thickness (Below Pipe)
−type: range
−unit: in
−drawing_ref: true
−options:
− min: 4
− max: 12
− setpoints: [4, 6, 9, 12]
−default: 6
−```
−
−A 4-inch minimum bedding course is the typical default for pipes up to 24 inches in diameter on competent native subgrade. Larger pipes and pipes installed in soft subgrade conditions require thicker bedding (6 inches to 12 inches) to distribute the pipe load and to prevent point bearing on residual rock or hard spots in the trench bottom. The bedding course shall be shaped to match the bottom of the pipe at the spring line for rigid pipe (so that the pipe bears uniformly along its full length), and shall be left level for flexible pipe (which is supported in the haunch by Class I or Class II material worked in after pipe placement).
−
−## Pipe Zone (Haunching) Backfill
−
−The pipe zone is the region of the trench from the top of the bedding to a point 6 to 12 inches above the top of the pipe. This zone provides the primary structural support for flexible pipe and shall be filled with the same Class I or Class II material as the bedding, placed in lifts and worked into the haunches with shovel slicing or rod tamping for the lower haunches, and compacted in subsequent lifts up to the top of the pipe zone.
−
−```datasheet
−label: Pipe Zone Backfill Material
−type: radio
−options:
− - "Same as bedding — Class I (3/4-in. or 1/2-in. clean crushed stone)"
− - "Same as bedding — Class II (clean sand or gravel)"
− - "Native suitable material — for rigid pipe only, with Engineer approval"
− - "Per drawings"
−default: "Same as bedding — Class I (3/4-in. or 1/2-in. clean crushed stone)"
−```
−
−```datasheet
−label: Pipe Zone Backfill Compaction
−type: select
−unit: percent of Standard Proctor maximum dry density
−options:
− - "Class I crushed stone — placed by self-consolidation, no compaction required"
− - "Class II sand or gravel — 90 percent (general)"
− - "Class II sand or gravel — 95 percent (under structures or pavements)"
− - "Per geotechnical engineer"
−default: "Class I crushed stone — placed by self-consolidation, no compaction required"
−```
−
−Heavy compaction equipment shall not operate directly over the pipe until at least 12 inches of cover has been placed and compacted in lifts. Vibratory compaction over flexible pipe with insufficient cover produces large dynamic loads on the pipe and can crush or deflect the pipe beyond the acceptable 5 percent limit. The Contractor shall use hand-operated plate compactors or jumping jack tampers within the pipe zone, transitioning to heavier equipment only after enough cover has been placed to protect the pipe.
−
−## Minimum and Maximum Cover
−
−Minimum cover from the top of the pipe to the finished surface shall be as indicated on the drawings and shall not be less than the manufacturer's published minimum for the pipe material, pipe class or stiffness, and applicable live load. Typical minimum cover values are:
−
−- Reinforced concrete pipe: 12 inches under HS-20 loading for Class III and higher classes
−- HDPE dual-wall pipe: 12 inches in unpaved areas, 18 inches under HS-20 pavement, for PS 46 Type S pipe
−- PVC sewer pipe (SDR 35, F949, F679): 12 inches in unpaved areas, 18 inches under HS-20 pavement
−
−```datasheet
−label: Minimum Cover Over Top of Pipe (HS-20 Pavement)
−type: select
−unit: in
−drawing_ref: true
−options:
− - "12 in. (RCP Class III or higher)"
− - "18 in. (HDPE / PVC under pavement)"
− - "24 in. (heavy duty / HS-25)"
− - "Per pipe manufacturer for selected pipe class"
−default: "Per pipe manufacturer for selected pipe class"
−```
−
−Maximum cover shall not exceed the pipe manufacturer's published maximum for the pipe class and trench configuration. Deep cover applications (typically deeper than 16 to 20 feet, depending on pipe size and class) require structural review by the civil engineer of record and may require a higher pipe class or a different pipe material. The Contractor shall not exceed the maximum cover shown on the drawings without the Engineer's review.
−
−## Trench Backfill Above the Pipe Zone
−
−Trench backfill from the top of the pipe zone to the underside of pavement or finished grade shall conform to the trench backfill requirements of [[sync/earthwork]] for the applicable area: structural fill compacted to 95 percent of Modified Proctor under pavements and within 5 feet of structures, and general site fill compacted to 90 percent of Standard Proctor in unpaved areas remote from structures.
−
−Backfill in the pavement zone (typically the upper 18 to 36 inches below pavement subgrade) is the source of most pavement settlement and longitudinal cracking observed over utility trenches. Inadequate compaction in the upper trench backfill is the single most common storm drainage installation deficiency that affects the rest of the project. The geotechnical engineer's testing of trench backfill compaction is not optional; tests shall be performed at the frequencies specified in [[sync/earthwork]] and any failing test shall result in scarification and re-compaction.
−
−# Pipe Installation
−
−## Pipe Laying and Alignment
−
−Pipe shall be laid in the trench beginning at the downstream end and progressing upstream, with bells (or hub ends, depending on pipe type) facing upstream. This orientation places the spigot into the bell with the flow direction, so that any minor joint imperfection does not collect debris and so that joint home depth marks are visible from the upstream end. Each pipe section shall be aligned to the design center line and grade before the joint is made; once the joint is home, alignment adjustment requires re-jointing.
−
−Pipe alignment shall be checked with a laser, transit, or string line set to the design center line. Pipe grade shall be verified by transferring grades from offset stakes or from a laser receiver mounted in the pipe. Pipe-to-pipe alignment shall be such that no joint is deflected beyond the manufacturer's permissible deflection limit; permissible deflection at gasketed joints typically ranges from 1.5 to 5 degrees depending on pipe size and joint type. Where the design alignment requires a deflection exceeding the joint's permissible limit, a fitting shall be used in place of a deflected joint, or the alignment shall be reviewed by the Engineer.
−
−```datasheet
−label: Pipe Alignment Verification Method
−type: select
−options:
− - "Pipe laser — required for grade verification on continuous reaches"
− - "Transit and offset stakes"
− - "String line and grade boards"
− - "Per drawings / engineer's recommendation"
−default: "Pipe laser — required for grade verification on continuous reaches"
−```
−
−A pipe laser is the standard method for verifying both alignment and grade on storm sewer reaches and is required for any reach longer than 100 feet. Hand-leveling and string-line methods are acceptable only for short reaches between structures and shall be checked against the design invert at each structure before joints are made.
−
−## Joint Assembly — Gasketed Pipe (RCP, HDPE, PVC)
−
−The bell or hub of each pipe shall be inspected before the spigot is inserted: the bell shall be clean of debris, the gasket groove shall be inspected to confirm the gasket is correctly seated all the way around the circumference, and any contamination on the gasket shall be removed. Lubricant approved by the pipe manufacturer shall be applied to the gasket and to the spigot in accordance with the manufacturer's installation instructions; the use of incompatible lubricants (e.g., petroleum-based products on EPDM gaskets) is not acceptable and will degrade the gasket.
−
−The spigot shall be inserted into the bell using equipment appropriate for the pipe size and weight: a come-along or chain hoist with a softener strap for small pipe, a hydraulic puller for large RCP, or a slip-fit assembly for HDPE and PVC where the pipe is light enough to be pushed home by hand or with light mechanical assistance. The spigot shall be advanced until the home-mark on the spigot is at the bell face or until the spigot shoulder contacts the bell, whichever applies to the joint design. The joint shall not be over-inserted past the home mark; over-insertion can roll or pinch the gasket and create a leak path.
−
−After each joint is assembled, the Contractor shall check the joint home depth around the full circumference using a feeler gauge or by reaching into the bell where access permits. Any joint that does not seat fully shall be disassembled, the gasket inspected and re-seated (or replaced if damaged), and the joint re-made before backfill proceeds.
−
−## Joint Assembly — Mechanical Couplings
−
−Where mechanical couplings are used at transitions (between dissimilar pipe materials, at field cut-ins, or at connections to existing piping), the coupling shall be of a type listed for the materials being joined, with the gasket sized for the actual outside diameters of the pipes — not for the nominal diameters. Concrete pipe outside diameters, HDPE outside diameters, and PVC outside diameters differ for the same nominal size; using a coupling sized for one material on another will result in over-compressed or under-compressed gaskets and joint failure.
−
−```datasheet
−label: Pipe Joining at Material Transitions
−type: select
−options:
− - "Manufacturer's listed transition coupling for the specific OD pair"
− - "Compression repair coupling with stainless steel band (small repair only)"
− - "Cast-in-place concrete collar (RCP transitions only)"
− - "Per drawings"
−default: "Manufacturer's listed transition coupling for the specific OD pair"
−```
−
−## Cutting Pipe to Length
−
−Pipe may be cut to length to meet structures or to make field adjustments. Cuts shall be square (perpendicular to the pipe axis), shall be deburred and chamfered on the spigot end to allow gasket entry without rolling the gasket, and shall not damage the bell of the upstream pipe. For RCP, cutting shall be performed with a diamond saw; flame-cutting and impact methods that crack the concrete are not acceptable. For HDPE and PVC, cuts shall be made with a saw or pipe cutter producing a clean perpendicular face.
−
−## Sag and Belly Avoidance
−
−The completed pipe shall have a uniform grade matching the design invert elevations at each structure. Sags ("bellies") in the pipe between structures collect sediment, reduce capacity, and cannot be cleaned with conventional rodding equipment. The Contractor shall verify the as-laid invert at each joint and shall report any deviation from grade exceeding the manufacturer's installation tolerance to the Engineer. Sags discovered after backfill placement are difficult and expensive to correct; the time to catch them is during pipe laying, before backfill.
−
−## Connection to Existing Storm Systems
−
−Where the work connects to an existing manhole, inlet, or pipe, the Contractor shall coordinate with the utility owner and the Engineer in advance to confirm the connection method, the AHJ requirements, any flow-bypass needs during the cut-in, and the inspection hold points. Core-drilling into existing precast structures is the preferred method for new pipe connections; the core shall be drilled with a diamond core barrel sized for the new pipe with appropriate annular clearance for a resilient connector boot.
−
−Cut-ins on existing in-service pipe shall be performed only with the utility owner's approval and only after the Contractor has plan for managing flows during the work — including bypass pumping if required. The Contractor shall protect downstream systems from sediment and construction debris introduced during the cut-in by installing temporary inlet protection or a downstream sediment trap before the cut-in begins.
−
−```datasheet
−label: Connection to Existing System — Coordination
−type: checkbox
−options:
− - "Utility owner pre-construction coordination meeting completed"
− - "Bypass pumping plan (where required for in-service systems)"
− - "Downstream sediment protection installed before cut-in"
− - "AHJ inspection scheduled for connection witnessing"
− - "As-built record updated with connection station and invert"
−default: "AHJ inspection scheduled for connection witnessing"
−```
−
−# Structure Installation
−
−## Base Placement
−
−Precast manhole bases shall be set on a compacted granular bedding course (typically 6 to 12 inches of Class I or Class II material) shaped to provide a level, uniform bearing surface at the design invert elevation of the lowest pipe. Cast-in-place bases shall be placed on a bedding course, with reinforcement and pipe penetration formwork installed before concrete placement.
−
−The base shall be set level and at the elevation that places the lowest pipe invert at the design value. The base elevation shall be verified before pipe is connected to the structure; small adjustments in base elevation propagate into structure barrel height and frame elevation and are very expensive to correct once riser sections are stacked.
−
−## Riser, Cone, and Top Slab Installation
−
−Precast riser sections shall be lifted and set with the lifting hardware specified by the manufacturer (typically lift inserts cast into the riser). The joint between sections shall be cleaned, the preformed butyl sealant (ASTM C990) or the O-ring gasket (ASTM C443) placed in the joint, and the upper section lowered onto the lower section so that the sealant or gasket is uniformly compressed around the full circumference. The Contractor shall verify that the upper section seats fully before releasing the load on the crane.
−
−Eccentric cones shall be oriented with the offset on the side opposite the inflow pipe where possible, so that the manhole ladder or step alignment is over solid bench. The cone-to-top-slab joint and the cone-to-frame interface shall be sealed in the same manner as the section-to-section joints.
−
−## Bench and Channel Construction
−
−The bench inside the manhole shall be shaped to direct flow smoothly from each inlet pipe to the outlet pipe with minimum hydraulic loss. The channel through the bench shall be the full inside diameter of the largest pipe (or the outlet pipe) at the springline elevation, with the bench sloped at 1 inch per foot from the channel edge toward the outside wall to drain. Bench material shall be cement mortar, cast-in-place concrete, or factory-formed channel inserts; smooth, hard-troweled mortar resists abrasion and is easier to maintain than rough, hand-floated material.
−
−```datasheet
−label: Manhole Bench / Channel Construction
−type: select
−options:
− - "Cast-in-place concrete bench, hand-formed channel"
− - "Cement mortar bench, hand-troweled smooth"
− - "Factory-formed channel insert (where available for the pipe pattern)"
− - "Per drawings"
−default: "Cement mortar bench, hand-troweled smooth"
−```
−
−The channel through the manhole shall be at full pipe diameter at the inverts and shall not present a step, lip, or change of section that would catch debris. Manhole inverts shall match the pipe invert elevations exactly; a manhole channel that sits below the pipe invert creates a sump that collects sediment, and a channel that sits above the pipe invert restricts flow.
−
−## Drop Connections
−
−Where an incoming pipe enters the manhole at an elevation more than 24 inches above the outlet invert, an external or internal drop connection shall be provided as indicated on the drawings, so that flow is conveyed from the high inlet to the outlet without spilling onto the manhole bench. External drops (a vertical pipe outside the manhole barrel connecting the inlet pipe to a low connection into the manhole) are preferred for sanitary applications; in storm applications, internal drops (a vertical pipe inside the manhole) are acceptable and are commonly used.
−
−## Setting Frames and Castings
−
−After backfill around the structure has been compacted to grade, the frame shall be set on the structure with adjustment rings as described in the Castings section above. The frame shall be set level, square, and at the elevation that places the top of the casting at finished pavement or grade. Mortar joints between the structure top, the adjustment rings, and the frame shall be smooth on the inside of the structure (so as not to interfere with future re-grading or replacement of the frame), and shall be installed without voids that would allow infiltration.
−
−Where the frame is set in advance of final pavement placement, the Contractor shall protect the frame and the structure rim during paving operations. Pavers driving over an unsupported frame can rock the frame loose; the Contractor shall coordinate frame setting with pavement placement so that the frame is set to final grade as the pavement is placed around it, or so that the frame is temporarily protected by a steel plate and re-set to final grade after paving.
−
−# Testing
−
−## Pipe Leakage and Joint Testing
−
−All storm drainage pipe shall be tested for leakage after pipe-zone backfill is complete and before final trench backfill is closed above the pipe zone. The test method shall be one of the following, as indicated on the drawings or directed by the Engineer.
−
−```datasheet
−label: Pipe Leakage Test Method
−type: select
−options:
− - "Low-pressure air test per ASTM F1417 (PVC and HDPE)"
− - "Hydrostatic test (head pressure)"
− - "Joint-by-joint pressure test (large-diameter RCP only)"
− - "Vacuum test (manholes and select structures)"
− - "Not required — confirm AHJ acceptance criteria"
−default: "Low-pressure air test per ASTM F1417 (PVC and HDPE)"
−```
−
−The low-pressure air test per ASTM F1417 is the standard production test for PVC and HDPE storm sewer reaches between structures. The reach shall be plugged at both manholes with test plugs rated for the test pressure and physically restrained against blow-out. Air shall be introduced gradually to the test pressure (typically 3.5 psi above any backpressure from groundwater), and the pressure drop shall be measured over the test hold period specified in ASTM F1417 for the pipe size and length. Test plugs and end caps shall be confirmed rated for the test pressure before pressurizing; restraining a plug improperly is a major safety hazard.
−
−The hydrostatic test (water column or head test) is acceptable for any pipe material and is the reference method for pipe and joint leakage. The reach shall be plugged at the downstream end, filled with water from the upstream manhole to a head of 2 to 5 feet above the upstream pipe crown, and held without makeup water for not less than 1 hour. Any drop in water level indicates leakage and shall be investigated. The hydrostatic test is impractical where the upstream invert is below grade with no manhole available as the water column, and where freezing weather precludes water testing.
−
−Joint-by-joint pressure testing — pressurizing only the individual joint annulus with a packer testing device — is used on large-diameter RCP (typically 48 inches and larger) where reach-length water testing is impractical. The test is performed with specialized equipment per the device manufacturer's procedure and is observed by the Engineer or AHJ inspector.
−
−## Manhole Vacuum Testing
−
−Precast manholes shall be vacuum tested to confirm watertight construction of the structure joints, the pipe-to-structure connections, and the cone and top slab seals. The vacuum test shall be performed after the structure is complete and before exterior backfill is placed (where possible) or, where backfill must be placed before the casting is set, after the casting is set but before final paving over the structure.
−
−```datasheet
−label: Manhole Vacuum Test
−type: radio
−options:
− - "Required — all storm drainage manholes per ASTM C1244 procedure"
− - "Required — manholes with cast-in resilient connectors per ASTM C923"
− - "Not required — confirm AHJ acceptance criteria"
−default: "Required — all storm drainage manholes per ASTM C1244 procedure"
−```
−
−The vacuum test plug shall be sealed at the top of the cone, the manhole evacuated to 10 inches of mercury (approximately 5 psi), and the pump valved off. The vacuum shall hold for the duration specified in the procedure (typically 1 minute for manholes up to 12 feet deep, longer for deeper structures) with a maximum allowable pressure rise of 1 inch of mercury. A manhole that fails the vacuum test shall be inspected for the leak path — typically at a section joint, a pipe connector, or the cone seal — and the leak shall be sealed by re-tightening the joint, regrouting, or applying an approved external sealant; the structure shall be re-tested until it passes.
−
−## Deflection Testing of Flexible Pipe
−
−All HDPE and PVC pipe shall be deflection-tested by mandrel pull-through after final backfill has been placed and the trench has been left undisturbed for at least 30 days, or after the final cover load (including pavement) has been placed, whichever is later. The 30-day wait permits the soil envelope around the pipe to equilibrate to its post-construction shape; testing too soon after backfill can produce passing results that fail later.
−
−```datasheet
−label: Deflection Test — Mandrel Limit
−type: radio
−options:
− - "5 percent maximum deflection (standard for storm sewer flexible pipe)"
− - "7.5 percent maximum deflection (where permitted by AHJ for storm-only)"
− - "Per pipe manufacturer's installation manual"
−default: "5 percent maximum deflection (standard for storm sewer flexible pipe)"
−```
−
−The mandrel shall be a go/no-go device sized to the minimum allowable inside diameter at the specified deflection limit (5 percent or 7.5 percent of the nominal inside diameter). The mandrel shall be pulled through the reach by hand or with light mechanical aid, without using a winch or other force that could damage the pipe; if the mandrel cannot be pulled through with reasonable manual force, the pipe has failed the deflection limit and the cause shall be investigated. Common causes of excessive deflection are inadequate haunch compaction, premature loading by heavy equipment, or use of unsuitable bedding material.
−
−Pipe failing the deflection test shall be repaired by removing and re-bedding the affected reach, by installing a structural liner approved by the Engineer, or by replacement of the affected reach. The Contractor shall not abandon a failed deflection result by "rounding up" the mandrel or by using a smaller mandrel than required by the specification.
−
−## Test Reporting
−
−Test results — pass and fail — shall be documented on testing forms that include the reach identification (upstream and downstream structure numbers), pipe material and size, test method, test pressure or head, hold time, start and end pressure or water level readings, and the names of the Contractor's test foreman and the witnessing inspector. Failed tests shall not be re-tested without first identifying and correcting the cause of failure; both the failure and the successful retest shall be recorded.
−
−# Cleaning
−
−After all testing is complete and before the system is turned over to the Owner or the AHJ, the entire storm drainage system shall be cleaned of debris, sediment, mortar droppings, and any construction materials. Cleaning shall be performed by jet-flushing, by mechanical bucketing, or by other methods suited to the pipe size and configuration. Sediment removed during cleaning shall be disposed of off-site or, where the project has an on-site stormwater facility, at an Owner-approved location.
−
−```datasheet
−label: Final System Cleaning Method
−type: select
−options:
− - "Jet flushing with water — vacuum recovery of debris"
− - "Mechanical bucket cleaning (large-diameter pipe)"
− - "Manual cleanout (small structures and areas)"
− - "Per AHJ acceptance requirement"
−default: "Jet flushing with water — vacuum recovery of debris"
−```
−
−Inlet sumps, manhole benches, and the inverts of all structures shall be flushed and inspected to confirm clean condition. Inlet grates and frames shall be cleaned of construction debris and tested for free seating in the frame. The Contractor shall not turn the system over with inlet protection bags or temporary sediment controls still in place; those devices were appropriate during construction but reduce hydraulic capacity below design value and shall be removed at closeout.
−
−After cleaning, the Contractor shall conduct a final walk-through inspection with the Engineer and the AHJ inspector (where required), opening each structure to verify clean condition. Any sediment, debris, or visible damage discovered shall be addressed before final acceptance.
−
−# Pre-Treatment and Water Quality Structures
−
−Where the project includes pre-treatment or water quality structures within the storm drainage system — including oil-water separators, hydrodynamic separators, gross particle separators, sand filters, or bioretention discharge structures — those structures are typically proprietary devices governed by the manufacturer's installation instructions and the civil drawings. The pipe and structure installation provisions of this standard apply to the pipe connections into and out of the device; the device itself shall be installed per the manufacturer's instructions and the civil details.
−
−```datasheet
−label: Pre-Treatment / Water Quality Structures Included
−type: checkbox
−options:
− - "Oil-water separator (typically required at fueling, vehicle service, or industrial yard areas)"
− - "Hydrodynamic separator (gross debris removal upstream of detention)"
− - "Gross particle / debris separator"
− - "Sediment forebay (within or upstream of detention basin)"
− - "Bioretention discharge structure"
− - "Not included — confirm SWPPP / MS4 program requirements"
−default: "Not included — confirm SWPPP / MS4 program requirements"
−```
−
−Oil-water separators are required by local stormwater regulations or by the NPDES MS4 program for runoff originating in vehicular fueling, vehicle service, or industrial yard areas. Where required, the separator shall be located upstream of the storm system connection to the public infrastructure and shall be sized per the manufacturer's procedure for the contributing drainage area and the design storm. The Contractor shall not omit a specified water-quality structure; doing so creates a downstream permit violation and an Owner liability that survives the warranty period.
−
−# Acceptance
−
−Final acceptance of the storm drainage system shall require:
−
−- Completion of all testing (pipe leakage, deflection, manhole vacuum) with passing results on every reach and every structure
−- AHJ inspection and release of any portion of the system connected to public infrastructure
−- Submission of complete as-built drawings showing installed pipe alignments, structure rim and invert elevations, casting types, and any deviations from design
−- Final cleaning of pipe and structures with confirmation by walk-through inspection
−- Removal of all temporary construction stormwater controls within the storm system (inlet protection, sediment traps, bypass pumping equipment)
−- Submission of all closeout documentation listed in the Submittals section
−
−```datasheet
−label: Acceptance Documentation Required
−type: checkbox
−options:
− - "Pipe leakage test reports — all reaches"
− - "Deflection test reports — all flexible pipe reaches"
− - "Manhole vacuum test reports — all structures"
− - "As-built record drawings with rim and invert schedule"
− - "AHJ acceptance documentation"
− - "Final cleaning certification"
− - "Casting and structure warranty documentation"
−default: "Pipe leakage test reports — all reaches"
−```
−
−The Owner's acceptance of the storm drainage system at substantial completion does not waive the Contractor's warranty obligations or the Contractor's liability for latent defects discovered after acceptance. Storm drainage defects that affect site hydraulics may not become apparent until the first significant rainfall event after acceptance; the Contractor shall remain responsive to defect reports throughout the warranty period.
−
−# Warranty
−
−The Contractor shall warrant the storm drainage system, including all pipe, joints, structures, castings, bedding and backfill, and connections, against defects in materials and workmanship for the project warranty period beginning at substantial completion. Warranty obligations include correction of leaks, settlement at pavement repairs over trenches, excessive pipe deflection developing after acceptance, casting movement or rocking, and structure rim settlement.
−
−```datasheet
−label: Storm Drainage Warranty Period
−type: select
−options:
− - "1 year from substantial completion"
− - "2 years from substantial completion"
− - "Per AHJ or utility owner requirement (typically 1 to 2 years)"
−default: "1 year from substantial completion"
−```
−
−Settlement at pavement repairs over storm trenches is a particularly common warranty item; even properly installed trench backfill consolidates slightly over the first one or two seasonal cycles, and pavement that was at grade at the time of paving may sag visibly at a year or two after completion. The Contractor's warranty shall cover such settlement when it can be attributed to trench backfill consolidation and not to subgrade conditions outside the trench. Manufacturer warranties for castings, precast structures, and proprietary water-quality devices shall be passed through to the Owner as part of the closeout documentation; where a manufacturer warranty extends beyond the Contractor's installation warranty, the Contractor shall assign the manufacturer warranty to the Owner at closeout.
−
−The warranty does not relieve the Contractor of liability for non-conforming installation discovered after the warranty period. Pipe installed at incorrect slope, structures with leaking joints concealed by exterior backfill, castings under-rated for the load class of the location, or pipe materials substituted from the specified standard remain the Contractor's responsibility as latent defects whenever discovered.
+---
+title: Storm Drainage
+category: Sitework
+toc_depth: 3
+description: >
+ When to use: Site storm water collection and conveyance for commercial, institutional, and industrial building projects, including curb inlets, grate inlets, combination inlets, area drains, yard drains, storm sewer mains and laterals, manholes, junction structures, headwalls, flared end sections, outfalls, and connections to municipal storm systems or on-site detention and retention facilities. Covers gravity storm drainage piping on the site side of the building from the first structure downstream of any building roof drain leader connection out to the public right-of-way, including pipe materials (reinforced concrete, HDPE corrugated, PVC profile-wall, PVC SDR sewer, ductile iron), structures, castings, excavation and bedding, installation, connection to existing systems, testing, and acceptance.
+ Not intended for: Roof drainage piping that runs vertically through the building (governed by the adopted plumbing code and outside the site utility scope); sanitary drain, waste, and vent piping inside the building or building sewer (see [[sync/sanitary-waste-and-vent-piping]]); building-perimeter foundation drainage and footing drains (see [[sync/foundation-drainage]]); subsurface agricultural drainage; storm water quality treatment devices and detention/retention basin earthwork and structural design (those are designed by the civil engineer of record and may reference this standard for the piping that connects to them); roadway pavement and aggregate base course (see [[sync/aggregate-base-course]]); culverts under state DOT roadways (governed by the state DOT standard specifications); and dewatering or temporary construction stormwater controls (see [[sync/earthwork]] and the project SWPPP).
+---
+
+# Scope {toc}
+
+## This standard covers the materials, fabrication, installation, testing, and acceptance of site storm drainage systems that collect surface runoff from paved and unpaved site areas, convey it through gravity piping and structures, and discharge it either to a municipal storm sewer, to an on-site stormwater management facility, or to a permitted outfall. {note}
+## The scope begins at the throat of each curb inlet, the rim of each grate or area drain, and the first downstream structure or fitting receiving a roof drain leader from the building, and ends at the project-defined point of connection to the public storm system or to the inlet structure of the on-site stormwater facility. {note}
+
+## Storm drainage is the scope most directly responsible for the long-term flood performance of the site; under-sized or poorly graded storm systems fail by overtopping, ponding, surcharging back into adjacent properties, and gradually filling with sediment until what was designed as a 10-year system performs at the 2-year level, and errors in alignment, invert elevations, bedding, and joint integrity propagate forward as settlement at pavement repairs, exfiltration into adjacent utility trenches, and infiltration of groundwater that consumes the design capacity. {note}
+
+## The civil drawings carry essentially all of the design-specific information for storm drainage — pipe sizes, slopes, invert elevations, structure rim and invert schedules, manhole types, and inlet types are drawing-driven for nearly every project — and this standard governs the means and methods, the material requirements, and the installation and testing protocols within which the drawings operate. {note}
+
+## Design Responsibility {toc}
+### This standard does not include the hydrologic or hydraulic design of the storm drainage system. {note}
+### The civil engineer of record establishes the design storm, runoff calculation method (rational method, NRCS curve number method, or hydrograph-based methods such as HydroCAD or SWMM), pipe sizing, inlet capacities, and structure schedules. {note}
+
+### The Contractor shall install the system as designed.
+
+### The Contractor shall report to the Engineer of Record any condition that would prevent the designed system from being constructed as drawn — including conflicts with other utilities, inadequate cover, insufficient slope, or differing site conditions at the trench bottom.
+
+### Work under this standard shall be coordinated with [[sync/earthwork]] for trench excavation, dewatering, and backfill, with [[sync/foundation-drainage]] for the building-perimeter system that may discharge to storm structures, and with [[sync/aggregate-base-course]] for pavement structure that drains into curb inlets and area drains and that bears on completed storm trench backfill.
+
+# Referenced Standards {toc}
+
+## Materials, manufacturing, installation, and testing shall comply with the latest adopted edition of the following standards.
+
+## Where contract documents, adopted codes, or referenced standards conflict, the more stringent requirement shall govern unless the Engineer of Record directs otherwise in writing.
+
+## Standards Table {toc}
+
+| Standard | Title |
+|----------|-------|
+| ASTM C76 | Standard Specification for Reinforced Concrete Culvert, Storm Drain, and Sewer Pipe |
+| ASTM C361 | Standard Specification for Reinforced Concrete Low-Head Pressure Pipe |
+| ASTM C443 | Standard Specification for Joints for Concrete Pipe and Manholes, Using Rubber Gaskets |
+| ASTM C478 | Standard Specification for Circular Precast Reinforced Concrete Manhole Sections |
+| ASTM C923 | Standard Specification for Resilient Connectors Between Reinforced Concrete Manhole Structures, Pipes, and Laterals |
+| ASTM C990 | Standard Specification for Joints for Concrete Pipe, Manholes, and Precast Box Sections Using Preformed Flexible Joint Sealants |
+| ASTM D2321 | Standard Practice for Underground Installation of Thermoplastic Pipe for Sewers and Other Gravity-Flow Applications |
+| ASTM D3034 | Standard Specification for Type PSM Poly(Vinyl Chloride) (PVC) Sewer Pipe and Fittings |
+| ASTM D3212 | Standard Specification for Joints for Drain and Sewer Plastic Pipes Using Flexible Elastomeric Seals |
+| ASTM F477 | Standard Specification for Elastomeric Seals (Gaskets) for Joining Plastic Pipe |
+| ASTM F679 | Standard Specification for Poly(Vinyl Chloride) (PVC) Large-Diameter Plastic Gravity Sewer Pipe and Fittings |
+| ASTM F949 | Standard Specification for Poly(Vinyl Chloride) (PVC) Corrugated Sewer Pipe With a Smooth Interior and Fittings |
+| ASTM F1417 | Standard Practice for Installation Acceptance of Plastic Non-Pressure Sewer Lines Using Low-Pressure Air |
+| ASTM F2306 | Standard Specification for 12 in. to 60 in. Annular Corrugated Profile-Wall Polyethylene (PE) Pipe and Fittings for Gravity-Flow Storm Sewer and Subsurface Drainage Applications |
+| AASHTO M294 | Standard Specification for Corrugated Polyethylene Pipe, 300- to 1500-mm (12- to 60-in.) Diameter |
+| AASHTO M252 | Standard Specification for Corrugated Polyethylene Drainage Pipe (3 in. to 10 in.) |
+| AASHTO M306 | Standard Specification for Drainage, Sewer, Utility, and Related Castings |
+| ASTM A48/A48M | Standard Specification for Gray Iron Castings |
+| ASTM A536 | Standard Specification for Ductile Iron Castings |
+| AASHTO HS-20 / HS-25 | Standard Highway Loadings for Bridge and Culvert Design (referenced for casting and structure live load) |
+| ASTM C150 | Standard Specification for Portland Cement |
+| ASTM C913 | Standard Specification for Precast Concrete Water and Wastewater Structures |
+| EPA NPDES CGP | Construction General Permit (National Pollutant Discharge Elimination System) |
+
+### State DOT standard specifications (e.g., FDOT, Caltrans, TxDOT, NJDOT) and local public works manuals are referenced as concept where work connects to public infrastructure. {note}
+
+### The specific governing edition shall be confirmed with the Authority Having Jurisdiction (AHJ) and the public works department or utility owner before work in the right-of-way begins.
+
+### Local stormwater management permitting requirements — including any municipal separate storm sewer system (MS4) program requirements — shall be identified by the Contractor as part of pre-construction planning.
+
+### The SWPPP shall comply with the project's coverage under the EPA Construction General Permit or the state-equivalent NPDES permit.
+
+# Submittals {toc}
+
+## Action Submittals {toc}
+
+### The Contractor shall submit the following for the Engineer of Record's review and acceptance prior to procurement, fabrication, or installation of any portion of the storm drainage system:
+
+- Product data for all pipe and fitting materials, indicating the manufacturer, the applicable ASTM or AASHTO standard, the class or pipe stiffness (PS) where applicable, the wall thickness or SDR, the joint type, the gasket material and the applicable joint standard (ASTM C443, C990, D3212, or F477)
+- Product data and shop drawings for precast manholes, junction structures, inlets, and headwalls, including the manufacturer's standard sections and adjustments, eccentric/concentric cone configurations, base type (monolithic or separate), pipe connection details (cast-in resilient connectors per ASTM C923 or core-drilled with boot), reinforcement schedules, lift-and-set hardware, and AASHTO HS-20 or HS-25 load rating
+- Casting product data for all frames, grates, covers, and lids, indicating the casting standard (ASTM A48 for gray iron or ASTM A536 for ductile iron), the AASHTO M306 listing, the load rating, the clear opening dimensions, and any local public works pattern conformance where the casting is at or within the public right-of-way
+- Bedding and backfill material gradations conforming to ASTM D2321 Class I or Class II as specified, including sieve analyses for each source proposed
+- Trench excavation and dewatering plan where storm drainage trenches will exceed 5 feet in depth or where groundwater is anticipated; this submittal may reference and incorporate the project earthwork submittal under [[sync/earthwork]] for the same trench work
+- Pipe joint testing plan, including the proposed method (low-pressure air per ASTM F1417, hydrostatic, or joint-by-joint pressure test for large-diameter pipe), the test pressures and durations, the testing agency and equipment, and the sections to be tested
+- Deflection testing plan for all flexible pipe (HDPE and PVC), including the timing relative to backfill placement and the mandrel sizes for each pipe diameter being installed
+- Connection details and any required permits or utility owner approvals for connection to existing storm systems or to municipal infrastructure
+- Working storm drainage plan (record-set markup) that the Contractor maintains and updates daily, showing actual horizontal and vertical alignments of pipe and structures as installed
+
+```datasheet
+label: Action Submittals Required
+type: checkbox
+options:
+ - "Pipe and fitting product data with applicable standard, class, and joint type"
+ - "Precast manhole and structure shop drawings with load rating"
+ - "Frame, grate, and cover casting product data with AASHTO M306 listing"
+ - "Bedding and backfill material gradations (ASTM D2321 classification)"
+ - "Trench excavation and dewatering plan"
+ - "Pipe joint testing plan"
+ - "Deflection testing plan (flexible pipe)"
+ - "Existing-system connection details and utility owner approvals"
+ - "Working record-set markup procedure"
+default: "Pipe and fitting product data with applicable standard, class, and joint type"
+```
+
+### Below-grade work for which submittals are pending shall not be installed.
+
+## Closeout Submittals {toc}
+
+### Prior to substantial completion the Contractor shall provide:
+
+- As-built storm drainage record drawings showing the installed plan and profile of all pipe, including station and offset to permanent reference points, finished rim elevation and all pipe invert elevations at every structure, every casting model number installed, every pipe size and material installed by reach, and any deviations from the contract documents
+- Field test reports for all pressure or air tests, leakage tests, deflection tests, and structure vacuum tests, signed by the testing technician, with pass/fail determination for each pipe reach and structure
+- Manufacturer warranties for castings, precast structures, and any specialty products
+- Final cleanout / flushing certification confirming that pipe and structures have been cleared of debris, sediment, and construction materials before turnover to the Owner or to the AHJ
+- AHJ acceptance documentation where the system connects to public storm infrastructure or where the local jurisdiction issues a separate acceptance for the on-site storm system
+
+```datasheet
+label: Closeout Submittals Required
+type: checkbox
+options:
+ - "As-built storm drainage record drawings with rim and invert elevations"
+ - "Field test reports (pressure/air, leakage, deflection, vacuum)"
+ - "Manufacturer warranties for castings, structures, and specialty products"
+ - "Final cleanout / flushing certification"
+ - "AHJ acceptance documentation"
+default: "As-built storm drainage record drawings with rim and invert elevations"
+```
+
+# Quality Assurance {toc}
+
+## Installer Qualifications {toc}
+
+### Storm drainage piping and structures shall be installed by a contractor with verifiable experience on at least three projects of comparable size and complexity within the preceding five years.
+
+### Personnel installing gasketed joints (concrete, HDPE, or PVC) shall be familiar with the manufacturer's recommended joint assembly procedure, including gasket installation, lubricant application, and home-mark verification.
+
+### Installation of large-diameter reinforced concrete pipe — 36 inches and larger — shall be performed by personnel experienced with the rigging, jointing, and bell-and-spigot home requirements of that pipe size.
+
+### Pipe installation crews working on RCP for the first time on a project shall demonstrate joint assembly on the first three sections in the presence of the Engineer's inspector before proceeding with production work.
+
+## Listing and Marking {toc}
+
+### All pipe, fittings, gaskets, castings, and precast structures shall bear the manufacturer's identification, the applicable standard designation, and the production date or batch number sufficient to trace each item to its certification documents.
+
+### Unmarked pipe or structures shall be rejected and removed from the project regardless of supplier documentation.
+
+### Castings used at or within the public right-of-way shall bear the AASHTO M306 mark, the foundry identification, and any local public works pattern number required by the utility owner.
+
+### Castings without the M306 mark shall not be installed in vehicular areas.
+
+## Pre-Installation Conference {toc}
+
+### Prior to beginning storm drainage installation the Contractor shall participate in a pre-installation conference attended by the Contractor's superintendent for site utilities, the Owner's geotechnical engineer of record, the civil engineer of record, the AHJ inspector (where required), and the testing agency.
+
+### The conference shall review the pipe materials and joint types, the bedding and backfill requirements, the testing program, the inspection hold points, the procedures for connection to existing systems, and the protocols for dealing with differing site conditions.
+
+## Inspection Hold Points {toc}
+
+### The Contractor shall provide the Engineer of Record and the AHJ inspector with not less than 24 hours' notice before each of the following inspection hold points, and no work past a hold point shall proceed until the inspection is completed and released:
+
+- Trench bottom and bedding placement, before pipe installation
+- Pipe alignment, slope, and joint assembly, before initial backfill
+- Structure base placement, before structure sections are stacked
+- Structure pipe penetrations and resilient connector seating, before grouting or sealing
+- Backfill compaction in the pipe zone, before pavement subgrade preparation
+- Final pipe testing (air, hydrostatic, or joint test) and deflection testing for flexible pipe
+- Casting setting and grade, before final pavement placement
+
+# Pipe Materials {toc}
+
+## Primary Material Selection {toc}
+
+### The pipe material for each reach shall be as indicated on the storm drainage plan, profile, and pipe schedule.
+
+### Where the drawings permit more than one material for a given reach, the Contractor shall submit the proposed material for that reach for the Engineer's acceptance.
+
+### The Contractor shall not mix materials within a continuous reach between structures without an approved transition fitting.
+
+### Different materials may be used in different reaches of the same system where the drawings so indicate.
+
+## Primary Material Datasheet {toc}
+
+```datasheet
+label: Primary Storm Sewer Pipe Material
+type: select
+drawing_ref: true
+options:
+ - "Reinforced concrete pipe (RCP) per ASTM C76, gasketed bell-and-spigot joints per ASTM C443"
+ - "HDPE dual-wall corrugated pipe per AASHTO M294 Type S / ASTM F2306, gasketed joints per ASTM D3212"
+ - "PVC profile-wall pipe per ASTM F949, gasketed joints per ASTM D3212"
+ - "PVC SDR 35 sewer pipe per ASTM D3034, gasketed joints per ASTM D3212"
+ - "PVC large-diameter sewer pipe per ASTM F679, gasketed joints per ASTM D3212"
+ - "Ductile iron pipe (specialty applications, see drawings)"
+ - "Per drawings"
+default: "Per drawings"
+```
+
+### Material selection is a civil engineering decision, not a means-and-methods decision, and is established by the civil drawings; the narrative that follows describes the conditions under which each material is appropriate so that the Contractor can recognize and report mismatches between drawn material and field condition. {note}
+
+## Reinforced Concrete Pipe (RCP) {toc}
+
+### Reinforced concrete pipe conforming to ASTM C76 is the long-standing standard for large-diameter storm sewers, public storm mains, and any reach where high structural strength, long service life, and tolerance to heavy live loads with shallow cover are required. {note}
+### RCP is available in five classes (Class I through Class V) reflecting increasing strength designations under the three-edge bearing test. {note}
+
+```datasheet
+label: RCP Strength Class
+type: select
+drawing_ref: true
+options:
+ - "Class II (0.01-in. crack 1000-D, ultimate 1500-D)"
+ - "Class III (0.01-in. crack 1350-D, ultimate 2000-D)"
+ - "Class IV (0.01-in. crack 2000-D, ultimate 3000-D)"
+ - "Class V (0.01-in. crack 3000-D, ultimate 3750-D)"
+ - "Per pipe schedule"
+default: "Class III (0.01-in. crack 1350-D, ultimate 2000-D)"
+```
+
+### The class for each reach shall be as indicated on the pipe schedule and shall be chosen by the civil engineer based on cover depth, live load, trench width, and bedding class.
+
+### Class III RCP is the most commonly specified class for typical commercial site storm drainage with cover depths of approximately 3 to 12 feet and HS-20 live loading, while Class IV and Class V are used where cover is shallow, where trench widths exceed the standard installation envelope, or where unusually heavy live loading is anticipated; the class designation reflects the structural design assumption of the civil engineer. {note}
+
+### The Contractor shall not substitute a lower class than indicated under any circumstances.
+
+### RCP joints shall be gasketed bell-and-spigot or single-offset joints with confined O-ring or profile gaskets conforming to ASTM C443.
+
+### Mortar-only joints, mastic-only joints, and "tongue and groove" joints without a gasket are not acceptable for new storm drainage construction.
+
+### The gasket creates the watertight seal; any mortar or external sealant is supplemental and does not substitute for the gasket. {note}
+
+### The Contractor shall verify that the gasket has been seated correctly in its groove before stabbing the joint, shall apply lubricant per the manufacturer's instructions, and shall confirm that the joint is fully home — typically verified by a paint mark or stencil on the spigot indicating the design home depth.
+
+## HDPE Corrugated Dual-Wall Pipe {toc}
+
+### High-density polyethylene corrugated dual-wall pipe conforming to AASHTO M294 Type S (12 in. and larger) or AASHTO M252 (3 in. through 10 in.), and to ASTM F2306 for the 12-in. through 60-in. size range, is widely used for site storm drainage in private development where cover depth, live load, and pipe size are within the range supported by the AASHTO design specifications. {note}
+
+```datasheet
+label: HDPE Pipe Stiffness (PS) Minimum
+type: radio
+unit: psi at 5 percent deflection
+options:
+ - "46 psi (AASHTO M294 / ASTM F2306 minimum, Type S)"
+ - "Higher PS as specified by civil engineer for deep cover or surcharge"
+default: "46 psi (AASHTO M294 / ASTM F2306 minimum, Type S)"
+```
+
+### HDPE is a flexible pipe — its performance depends on the soil envelope around it, and proper bedding and haunching are critical to long-term shape stability. {note}
+
+### HDPE joints shall be bell-and-spigot joints with elastomeric gaskets conforming to ASTM F477 and meeting the watertight performance requirements of ASTM D3212.
+
+### The HDPE gasket shall be factory-installed in the bell.
+
+### Joints relying solely on a slip-fit or on a snap-ring without a continuous gasket are not acceptable for storm drainage applications connected to permanent infrastructure.
+
+### The Contractor shall confirm the HDPE joint type and gasket configuration against the product submittal and shall use only the manufacturer's recommended lubricant.
+
+### HDPE pipe shall be installed in accordance with ASTM D2321 with embedment material conforming to ASTM D2321 Class I or Class II crushed stone or gravel placed to the depths specified in the Bedding and Pipe Zone Backfill section of this standard.
+
+### The maximum allowable installed deflection of HDPE pipe shall be 5 percent of the nominal inside diameter, measured by mandrel pull-through not earlier than 30 days after final backfill and final cover load have been placed.
+
+## PVC Sewer and Profile-Wall Pipe {toc}
+
+### Polyvinyl chloride pipe is acceptable for storm drainage in the configurations indicated on the drawings, in any of the following standards: {note}
+
+- ASTM D3034 SDR 35 (4-in. through 15-in. nominal), solid-wall gasketed sewer pipe
+- ASTM F679 (18-in. and larger), solid-wall gasketed large-diameter sewer pipe
+- ASTM F949 (4-in. through 36-in.), corrugated/profile-wall PVC pipe with smooth interior
+
+```datasheet
+label: PVC Pipe Type for Storm Drainage
+type: select
+drawing_ref: true
+options:
+ - "SDR 35 solid wall (ASTM D3034) — 4 in. through 15 in."
+ - "Large-diameter solid wall (ASTM F679) — 18 in. and larger"
+ - "Profile-wall (ASTM F949) — 4 in. through 36 in."
+ - "Per drawings"
+default: "Per drawings"
+```
+
+### PVC pipe joints shall be bell-and-spigot integral gasketed joints conforming to ASTM D3212, with gaskets conforming to ASTM F477.
+
+### Solvent cement joints are not permitted for buried storm sewer service.
+
+### The storm system is subject to differential thermal and ground movement that solvent-cement joints do not accommodate, and the gasketed joint is the recognized standard for buried gravity sewer. {note}
+
+### The Contractor shall verify that all PVC pipe delivered to the site is rated for the storm sewer service — the pipe shall be marked with the applicable ASTM standard and shall not be DWV or Schedule 40 pressure pipe re-purposed as a sewer material.
+
+### PVC pipe is, like HDPE, a flexible pipe and is subject to the same maximum installed deflection limit of 5 percent.
+
+### PVC pipe shall be installed in accordance with ASTM D2321 with the same bedding and pipe-zone embedment requirements as HDPE.
+
+## Ductile Iron Pipe — Specialty Applications {toc}
+
+### Ductile iron pipe is occasionally used for storm drainage in specialty locations: under heavy equipment foundations, under building footings where structural drawings require it, in seismic regions where high joint deflection tolerance is needed, or where the storm system crosses sanitary or pressure utilities at constrained vertical separation. {note}
+
+### Where ductile iron is specified, the pipe material, joint type, lining, and class shall be as indicated on the drawings.
+
+### The requirements of this standard for bedding, jointing, testing, and structure connection apply to ductile iron pipe.
+
+# Structures {toc}
+
+## Manholes and Junction Structures {toc}
+
+### Storm drainage manholes and junction structures shall be furnished by the type and size indicated on the structure schedule and detailed below.
+
+```datasheet
+label: Manhole Type
+type: select
+drawing_ref: true
+options:
+ - "Precast circular concrete (ASTM C478), monolithic base"
+ - "Precast circular concrete (ASTM C478), separate precast base"
+ - "Cast-in-place concrete structure per drawings"
+ - "Per structure schedule"
+default: "Precast circular concrete (ASTM C478), monolithic base"
+```
+
+```datasheet
+label: Minimum Manhole Inside Diameter — by Largest Pipe Connection
+type: select
+drawing_ref: true
+options:
+ - "48-in. manhole — pipes up to 24 in."
+ - "60-in. manhole — pipes 27 in. through 36 in."
+ - "72-in. manhole — pipes 42 in. through 48 in."
+ - "84-in. manhole or larger — pipes 54 in. and larger"
+ - "Per structure schedule"
+default: "Per structure schedule"
+```
+
+### Storm drainage manholes shall be circular precast reinforced concrete structures conforming to ASTM C478.
+
+### Cast-in-place concrete structures may be used where indicated on the drawings, typically for unusual geometries (junction structures with multiple inlet pipes at varying elevations, energy dissipation structures, or weir structures within the storm system).
+
+### Brick or masonry block manholes shall not be used for new storm drainage construction unless specifically required to match existing infrastructure under a renovation scope.
+
+### Manhole barrel diameter, riser sections, eccentric or concentric cone, top slab type, and adjustment ring stack shall be as indicated on [[drawing: the structure schedule and manhole details]].
+
+### Standard interior barrel diameters for storm drainage manholes are 48 inches and 60 inches, while larger diameters (72-inch, 84-inch, 96-inch) are used at junction structures, at structures with large incoming pipes, or where personnel access for cleaning and inspection requires it. {note}
+
+### Manhole sizing is a function of the largest pipe entering or leaving the structure, the angle between pipes at the junction, and the maintenance access required; under-sized manholes cannot accommodate the bench shaping required to direct flow smoothly between inlet and outlet pipes, with the result being hydraulic loss at the structure and accelerated sediment deposition. {note}
+
+### The Contractor shall verify the structure size on the schedule against the pipe sizes converging at that structure before fabricating or ordering precast components.
+
+## Pipe Connections to Structures {toc}
+
+### The connection method for every pipe entering or leaving a structure shall be as detailed below.
+
+```datasheet
+label: Pipe-to-Structure Connection
+type: radio
+options:
+ - "Cast-in resilient connector (ASTM C923) at precast fabrication"
+ - "Field-cored opening with boot-type resilient connector (ASTM C923)"
+ - "Cast-in-place structure with rigid penetration and flexible gasket sleeve"
+ - "Per drawings"
+default: "Cast-in resilient connector (ASTM C923) at precast fabrication"
+```
+
+### Every pipe entering or leaving a precast manhole or junction structure shall be connected by either a cast-in-place resilient connector conforming to ASTM C923, or by a core-drilled opening fitted with a boot-type resilient connector also conforming to ASTM C923.
+
+### Direct mortared pipe penetrations through a precast structure wall without a resilient connector are not acceptable.
+
+### The dissimilar thermal and mechanical movement of pipe and structure cracks rigid mortar seals and causes both exfiltration of storm flow and infiltration of groundwater. {note}
+
+### The cast-in resilient connector is the preferred method because it provides factory quality control on the seal-to-structure interface, while the core-drilled-and-boot method is acceptable for field connections that were not anticipated at precast fabrication, provided the core hole is drilled cleanly with a diamond core barrel and the boot is sized correctly for the pipe outside diameter. {note}
+
+## Manhole Joints {toc}
+
+### Joints between precast manhole sections (base to riser, riser to riser, riser to cone, cone to top slab) shall be sealed with butyl rubber preformed flexible joint sealant conforming to ASTM C990, or with confined O-ring rubber gaskets conforming to ASTM C443 where the manhole sections are manufactured for gasketed joints.
+
+### Mortar-only manhole section joints are not acceptable for new construction.
+
+### The preformed sealant or gasket provides the watertightness that mortar alone cannot maintain through ground movement and freeze-thaw cycles. {note}
+
+## Manhole Step and Ladder {toc}
+
+### The manhole step or ladder system shall be as detailed below.
+
+```datasheet
+label: Manhole Step Material
+type: radio
+options:
+ - "Copolymer polypropylene plastic over steel reinforcing bar (ASTM C478)"
+ - "Cast-in steel reinforcing bar — coated"
+ - "Fixed steel ladder (manholes 20 ft and deeper)"
+ - "Per drawings"
+default: "Copolymer polypropylene plastic over steel reinforcing bar (ASTM C478)"
+```
+
+### Manhole steps shall be plastic-coated steel reinforcing bar or copolymer polypropylene plastic conforming to ASTM C478 step requirements, embedded in the precast sections in accordance with the section drawings.
+
+### Step spacing shall not exceed 16 inches vertically.
+
+### Manholes deeper than 20 feet shall include a fixed steel ladder in lieu of cast-in steps where required by OSHA confined space entry provisions or local regulation.
+
+### The ladder design shall be reviewed by the Engineer of Record before installation.
+
+## Inlets {toc}
+
+### Inlet selection is established by the civil drawings based on inlet location, gutter or sheet flow conditions, and the inlet's intended hydraulic capacity. {note}
+### The principal inlet types used in commercial site work are: {note}
+
+- **Curb inlet:** A vertical opening in the back of curb, with no grate in the gutter line. Curb inlets accept gutter flow through the vertical opening and are resistant to clogging by leaves and debris. They are the preferred inlet type on continuous-grade gutters where vehicular tire interaction with grates would be a concern.
+- **Grate inlet:** A horizontal opening in the gutter line covered by a cast iron or ductile iron grate. Grate inlets accept gutter flow primarily through the grate openings; they have high capacity per linear foot when the grate is clear, but capacity drops substantially when the grate becomes partially blocked by debris.
+- **Combination inlet:** A curb inlet and a grate inlet acting together at the same location, providing both the high capacity of the grate and the debris-tolerance of the curb opening. Combination inlets are appropriate at sag locations where ponding would result if the grate clogged.
+- **Area drain / yard drain:** A small precast or cast-in-place inlet with a grate, located in a paved area or landscaped low point to drain a localized area.
+- **Trench drain:** A linear surface drain used to collect sheet flow across a paved area, typically at vehicular entrances, loading docks, or wide pedestrian plazas.
+
+```datasheet
+label: Inlet Type by Location
+type: select
+drawing_ref: true
+options:
+ - "Curb inlet — continuous grade"
+ - "Grate inlet — gutter line"
+ - "Combination inlet — sag location"
+ - "Area drain / yard drain — paved low point"
+ - "Area drain / yard drain — landscaped low point"
+ - "Per drawings"
+default: "Per drawings"
+```
+
+### Area drains in vehicular areas shall use the same casting load class as the surrounding pavement.
+
+### Trench drains shall be specified separately from this standard where used.
+
+### Inlet structure dimensions, throat or grate opening size, sump depth (if any), and pipe connection elevations shall be as indicated on [[drawing: the inlet schedule and inlet details]].
+
+### The Contractor shall not substitute one inlet type for another without the Engineer's approval.
+
+### The civil engineer of record has computed inlet capacities based on the design gutter flow and the rating curves for the specified inlet type, and substitution alters the hydraulic capacity assumed in the design. {note}
+
+### Inlet capacity calculations are typically performed using HEC-22 or equivalent methods, which assume that grates are not clogged, but field experience indicates that grates in tree-lined or leaf-heavy areas can lose 30 to 50 percent of theoretical capacity in fall and spring; the civil engineer applies a clogging factor in the design, and the Contractor's responsibility is to install the specified inlet correctly and to assist the Owner with the operations and maintenance information needed to keep grates clear. {note}
+
+## Junction Structures and Inline Cleanouts {toc}
+
+### Where two or more pipes meet at angles that exceed the standard manhole bench geometry, a junction structure shall be provided as indicated.
+
+### Junction structures shall be cast-in-place reinforced concrete or precast box structures sized to accommodate the converging pipe inverts with smooth, swept channels that direct flow from each incoming pipe to the outgoing pipe with minimum hydraulic loss.
+
+### The junction structure interior shall be benched in mortar above the spring line of the largest pipe to provide a walkable maintenance surface.
+
+### Inline cleanouts (lateral cleanouts on individual roof drain or area drain lateral connections) shall be brought to grade with a cast iron or PVC riser and a watertight access plug.
+
+### Cleanouts shall be installed at every change of direction greater than 45 degrees on lateral pipe runs and at every 100 feet of straight run on pipe smaller than 18 inches.
+
+## Headwalls, Flared End Sections, and Outfalls {toc}
+
+### The outfall termination type shall be as detailed below.
+
+```datasheet
+label: Outfall Termination
+type: select
+drawing_ref: true
+options:
+ - "Cast-in-place concrete headwall with wingwalls"
+ - "Precast concrete headwall"
+ - "Precast concrete flared end section (RCP)"
+ - "HDPE / PVC flared end section (manufacturer's standard)"
+ - "Riprap apron downstream of pipe end — no headwall"
+ - "Per drawings"
+default: "Per drawings"
+```
+
+### Where storm drainage discharges to an open swale, ditch, or detention/retention basin, a headwall or flared end section shall be provided at the outfall to control erosion, anchor the pipe end, and provide a clean transition between the pipe and the open channel.
+
+### Headwalls shall be cast-in-place reinforced concrete or precast as indicated.
+
+### Flared end sections shall be precast concrete (for RCP) or metal/polymer (for HDPE and PVC) of the manufacturer's standard configuration matching the pipe.
+
+### A riprap apron, an energy dissipator (e.g., a stilling basin or a baffled outlet), or a combination thereof shall be provided downstream of any outfall where the outlet velocity at the design flow exceeds the permissible velocity of the receiving channel.
+
+### Riprap gradation and apron dimensions shall be as indicated on the drawings.
+
+### Under-sizing the riprap apron causes scour at the pipe outlet that progressively undermines the headwall and the last pipe joint. {note}
+
+# Castings {toc}
+
+## General {toc}
+
+### All inlet frames, manhole frames, manhole covers, inlet grates, and area drain grates ("castings") shall be gray iron conforming to ASTM A48 or ductile iron conforming to ASTM A536, listed in accordance with AASHTO M306.
+
+### Castings shall be free of visible defects (cracks, cold shuts, blowholes, inclusions), shall be machined at mating surfaces where required to seat the cover or grate flat in the frame without rocking, and shall bear the foundry identification and the AASHTO M306 mark.
+
+## Casting Material {toc}
+
+```datasheet
+label: Casting Material
+type: radio
+options:
+ - "Gray iron per ASTM A48 (Class 35B typical for street castings)"
+ - "Ductile iron per ASTM A536 (Grade 70-50-05 typical for heavy-load castings)"
+ - "Mix — ductile iron lid or grate with gray iron frame (cost-effective for H-25 loading)"
+ - "Per drawings"
+default: "Gray iron per ASTM A48 (Class 35B typical for street castings)"
+```
+
+### Gray iron conforming to ASTM A48 Class 35B is the standard material for the majority of street and parking lot castings, providing good compressive strength and excellent wear and corrosion resistance for the load class typical of HS-20 vehicular loading, while ductile iron conforming to ASTM A536 (commonly Grade 65-45-12 or 70-50-05) is used where loads exceed HS-20, where impact loading is anticipated (e.g., at airport service roads, intermodal facilities, or heavy industrial yards), or where the engineer specifies the higher tensile and yield strength of ductile iron; a common cost-effective configuration is a gray iron frame with a ductile iron lid or grate, where the heavier-loaded element that takes the wheel load gets the more expensive material. {note}
+
+## Casting Load Class {toc}
+
+```datasheet
+label: Casting Load Rating
+type: select
+drawing_ref: true
+options:
+ - "Light duty — pedestrian / non-traffic only"
+ - "Medium duty — light vehicular (parking lot, driveway)"
+ - "H-20 / HS-20 — standard highway loading"
+ - "H-25 / HS-25 — heavy highway loading"
+ - "Heavy industrial — airport, intermodal, container yard"
+ - "Per drawings"
+default: "H-20 / HS-20 — standard highway loading"
+```
+
+### The casting load class shall match the live load applicable to the location.
+
+### HS-20 is the standard for typical commercial parking and drives, HS-25 is used for state DOT roadways and routes carrying heavy truck traffic, and pedestrian-only castings (e.g., in non-traffic plazas) use lighter-class castings; under-rated castings in vehicular areas can crack under repeated heavy axle loads and become safety hazards. {note}
+
+### The Contractor shall confirm that pedestrian-class castings are not located on a fire-lane or service-vehicle route where vehicular load is intermittent but real.
+
+## Self-Sealing Covers and Bolted Lids {toc}
+
+### The cover restraint type shall be as detailed below.
+
+```datasheet
+label: Bolted or Gasketed Manhole Cover
+type: radio
+options:
+ - "Not required — non-flood-prone location"
+ - "Gasketed self-seating cover (storm surcharge possible)"
+ - "Bolted lid with stainless steel fasteners (flood plain or flood-prone)"
+ - "Per drawings"
+default: "Not required — non-flood-prone location"
+```
+
+### Where castings are subject to occasional surcharge — at sag inlets in low-lying areas, at structures within a flood plain, or where the storm system is designed to surcharge to grade during the extreme event — covers shall be self-sealing (gasketed seat) or bolted in place to prevent the cover from being displaced by surcharge pressure.
+
+### Bolted lids shall use stainless steel or hot-dip galvanized fasteners.
+
+### Carbon steel fasteners corrode within the manhole environment and become unusable within a few years. {note}
+
+## Adjustment Rings {toc}
+
+### The casting-to-structure adjustment method shall be as detailed below.
+
+```datasheet
+label: Casting-to-Structure Adjustment Method
+type: radio
+options:
+ - "Precast concrete adjustment rings — mortared between rings and to frame"
+ - "Precast HDPE / recycled rubber adjustment rings"
+ - "Mortared brick (where permitted by utility owner)"
+ - "Custom precast riser (where adjustment exceeds 12 in.)"
+default: "Precast concrete adjustment rings — mortared between rings and to frame"
+```
+
+### Adjustment between the top of the precast structure cone or top slab and the bottom of the cast iron frame shall be made with precast concrete adjustment rings, precast HDPE or recycled rubber adjustment rings, or with mortared brick — as permitted by the local utility owner.
+
+### The total height of adjustment shall not exceed 12 inches without the Engineer's approval.
+
+### Where more than 12 inches of adjustment is needed, a custom riser section shall be specified.
+
+### Tall stacks of adjustment rings are inherently unstable under traffic loading and tend to settle, dislocate, and leak. {note}
+
+### The Contractor shall set the cast iron frame on a continuous mortar bed at the top adjustment ring, with the inside face of the frame flush with the inside face of the structure, and with the top of the frame matched to the finished pavement or grade.
+
+### Castings set proud of pavement create plowing and pedestrian-trip hazards, and castings set low cause water to pond around the rim and accelerate pavement deterioration. {note}
+
+# Excavation and Trench Preparation {toc}
+
+## General Trench Requirements {toc}
+
+### Trench excavation for storm drainage piping shall conform to the requirements of [[sync/earthwork]] for trench excavation, dewatering, slope stability, and shoring or trench protection.
+
+### In case of conflict between this standard and [[sync/earthwork]], the more stringent requirement governs.
+
+### Trench width at the springline of the pipe shall be the minimum needed for safe worker access, pipe installation, and joint assembly, plus the haunching room required by the pipe manufacturer and ASTM D2321 for flexible pipe.
+
+### Minimum trench width at the springline shall be the pipe outside diameter plus 16 inches (8 inches on each side) for pipes up to 24 inches in diameter, and shall be confirmed against the manufacturer's installation manual for larger sizes.
+
+### Excessive trench width increases bedding and backfill quantities and, for rigid pipe, increases the bedding factor required to carry the live load. {note}
+
+### The trench bottom shall be excavated to the pipe invert grade minus the bedding thickness, on a uniform longitudinal slope matching the design pipe slope without dips, sags, or reverse gradient.
+
+### Where the trench bottom is over-excavated below design grade — whether by accident or to remove an unsuitable zone — the over-excavation shall be backfilled with compacted granular bedding material to the design bedding bottom elevation, with the geotechnical engineer's concurrence on the lift thickness and compaction requirement.
+
+## Trench Bottom Stability {toc}
+
+### Where the trench bottom is soft, the stabilization method shall be as detailed below.
+
+```datasheet
+label: Trench Bottom Stabilization (where soft)
+type: select
+options:
+ - "Over-excavate and replace with compacted crushed stone working layer — 12 in. minimum"
+ - "Over-excavate, place geotextile, then crushed stone — soft cohesive subgrade"
+ - "Controlled low-strength material (CLSM) foundation course"
+ - "Not required — competent native bearing"
+default: "Not required — competent native bearing"
+```
+
+### The bottom of every storm drainage trench shall be observed by the geotechnical engineer of record (or the Owner's designated inspector) before bedding is placed, to confirm that the trench bottom is competent and uniform.
+
+### Soft, wet, or pumping trench bottom conditions shall be remediated before bedding is placed.
+
+### Remediation options include over-excavation and replacement with crushed stone, geotextile separation with granular fill, or — where conditions warrant — a flowable fill foundation course as directed by the geotechnical engineer. {note}
+
+### The Contractor shall not place pipe directly on bedded mud, on standing water, or on disturbed loose material.
+
+### The bedding-to-pipe load transfer assumed in the pipe design is destroyed if the bedding is bedded on unstable material, with the result being differential settlement that breaks joints and creates sags in the completed pipe. {note}
+
+### The geotechnical engineer's documentation of trench bottom acceptance for each reach shall be retained in the project record.
+
+## Dewatering {toc}
+
+### Trenches that extend below the groundwater table shall be dewatered continuously throughout pipe installation, bedding and pipe-zone backfill placement, and until enough cover has been placed to resist pipe flotation.
+
+### Dewatering shall conform to the requirements of [[sync/earthwork]].
+
+### The Contractor shall not place pipe in standing water.
+
+### Placing pipe in standing water causes bedding washout under the pipe, gasket contamination at the joints, and uncontrolled buoyancy that displaces pipe alignment. {note}
+
+### Dewatering discharge shall be conducted through sediment-control measures (sediment bag, settling basin, or other approved BMP) and shall comply with the project NPDES permit and any local stormwater discharge requirements.
+
+### Discharge of dewatering flow directly to the newly-installed storm system shall be avoided where practical, and shall be filtered if necessary.
+
+# Bedding and Pipe Zone Backfill {toc}
+
+## Bedding Class {toc}
+
+### The bedding class for each reach shall be as detailed below.
+
+```datasheet
+label: Bedding Class
+type: select
+drawing_ref: true
+options:
+ - "ASTM D2321 Class I — open-graded crushed stone (preferred for flexible pipe)"
+ - "ASTM D2321 Class II — clean coarse-grained, well-graded sand or gravel"
+ - "ASTM D2321 Class III — coarse-grained with fines"
+ - "Class B bedding (rigid pipe — granular shaped to pipe bottom)"
+ - "Class A bedding (rigid pipe — concrete cradle, special applications)"
+ - "Per drawings"
+default: "ASTM D2321 Class I — open-graded crushed stone (preferred for flexible pipe)"
+```
+
+### Pipe bedding shall be classified in accordance with ASTM D2321 for flexible pipe (HDPE, PVC) and in accordance with the bedding factor convention of the rigid pipe industry for RCP.
+
+### The bedding class for each reach shall be as indicated on the trench detail or the pipe schedule.
+
+### Class I (open-graded crushed stone, typically 3/4 in. or 1/2 in. clean) is the preferred bedding for flexible pipe because it does not require compaction beyond placement and self-consolidation, achieves predictable shape stability in the haunch zone, and provides drainage that prevents migration of fines from the surrounding soil, while Class II (clean, well-graded sand or gravel) is acceptable where Class I material is not available locally but requires careful placement and compaction to achieve the required density in the haunches. {note}
+
+## Bedding Thickness {toc}
+
+### The granular bedding course shall extend from the trench bottom to the underside of the pipe at the full design pipe slope, with a thickness as indicated below and as shown on the trench detail.
+
+```datasheet
+label: Bedding Course Thickness (Below Pipe)
+type: range
+unit: in
+drawing_ref: true
+options:
+ min: 4
+ max: 12
+ setpoints: [4, 6, 9, 12]
+default: 6
+```
+
+### A 4-inch minimum bedding course is the typical default for pipes up to 24 inches in diameter on competent native subgrade, while larger pipes and pipes installed in soft subgrade conditions require thicker bedding (6 inches to 12 inches) to distribute the pipe load and to prevent point bearing on residual rock or hard spots in the trench bottom. {note}
+
+### The bedding course shall be shaped to match the bottom of the pipe at the spring line for rigid pipe so that the pipe bears uniformly along its full length, and shall be left level for flexible pipe (which is supported in the haunch by Class I or Class II material worked in after pipe placement).
+
+## Pipe Zone (Haunching) Backfill {toc}
+
+### The pipe zone is the region of the trench from the top of the bedding to a point 6 to 12 inches above the top of the pipe. {note}
+### This zone provides the primary structural support for flexible pipe. {note}
+
+```datasheet
+label: Pipe Zone Backfill Material
+type: radio
+options:
+ - "Same as bedding — Class I (3/4-in. or 1/2-in. clean crushed stone)"
+ - "Same as bedding — Class II (clean sand or gravel)"
+ - "Native suitable material — for rigid pipe only, with Engineer approval"
+ - "Per drawings"
+default: "Same as bedding — Class I (3/4-in. or 1/2-in. clean crushed stone)"
+```
+
+```datasheet
+label: Pipe Zone Backfill Compaction
+type: select
+unit: percent of Standard Proctor maximum dry density
+options:
+ - "Class I crushed stone — placed by self-consolidation, no compaction required"
+ - "Class II sand or gravel — 90 percent (general)"
+ - "Class II sand or gravel — 95 percent (under structures or pavements)"
+ - "Per geotechnical engineer"
+default: "Class I crushed stone — placed by self-consolidation, no compaction required"
+```
+
+### The pipe zone shall be filled with the same Class I or Class II material as the bedding, placed in lifts and worked into the haunches with shovel slicing or rod tamping for the lower haunches, and compacted in subsequent lifts up to the top of the pipe zone.
+
+### Heavy compaction equipment shall not operate directly over the pipe until at least 12 inches of cover has been placed and compacted in lifts.
+
+### Vibratory compaction over flexible pipe with insufficient cover produces large dynamic loads on the pipe and can crush or deflect the pipe beyond the acceptable 5 percent limit. {note}
+
+### The Contractor shall use hand-operated plate compactors or jumping jack tampers within the pipe zone, transitioning to heavier equipment only after enough cover has been placed to protect the pipe.
+
+## Minimum and Maximum Cover {toc}
+
+### The minimum cover over the top of the pipe shall be as detailed below.
+
+```datasheet
+label: Minimum Cover Over Top of Pipe (HS-20 Pavement)
+type: select
+unit: in
+drawing_ref: true
+options:
+ - "12 in. (RCP Class III or higher)"
+ - "18 in. (HDPE / PVC under pavement)"
+ - "24 in. (heavy duty / HS-25)"
+ - "Per pipe manufacturer for selected pipe class"
+default: "Per pipe manufacturer for selected pipe class"
+```
+
+### Minimum cover from the top of the pipe to the finished surface shall be as indicated on the drawings and shall not be less than the manufacturer's published minimum for the pipe material, pipe class or stiffness, and applicable live load.
+
+### Typical minimum cover values are: reinforced concrete pipe, 12 inches under HS-20 loading for Class III and higher classes; HDPE dual-wall pipe, 12 inches in unpaved areas and 18 inches under HS-20 pavement for PS 46 Type S pipe; and PVC sewer pipe (SDR 35, F949, F679), 12 inches in unpaved areas and 18 inches under HS-20 pavement. {note}
+
+### Maximum cover shall not exceed the pipe manufacturer's published maximum for the pipe class and trench configuration.
+
+### Deep cover applications (typically deeper than 16 to 20 feet, depending on pipe size and class) require structural review by the civil engineer of record and may require a higher pipe class or a different pipe material.
+
+### The Contractor shall not exceed the maximum cover shown on the drawings without the Engineer's review.
+
+## Trench Backfill Above the Pipe Zone {toc}
+
+### Trench backfill from the top of the pipe zone to the underside of pavement or finished grade shall conform to the trench backfill requirements of [[sync/earthwork]] for the applicable area: structural fill compacted to 95 percent of Modified Proctor under pavements and within 5 feet of structures, and general site fill compacted to 90 percent of Standard Proctor in unpaved areas remote from structures.
+
+### Backfill in the pavement zone (typically the upper 18 to 36 inches below pavement subgrade) is the source of most pavement settlement and longitudinal cracking observed over utility trenches, and inadequate compaction in the upper trench backfill is the single most common storm drainage installation deficiency that affects the rest of the project. {note}
+
+### Trench backfill compaction shall be tested by the geotechnical engineer at the frequencies specified in [[sync/earthwork]], and any failing test shall result in scarification and re-compaction.
+
+# Pipe Installation {toc}
+
+## Pipe Laying and Alignment {toc}
+
+### The alignment verification method shall be as detailed below.
+
+```datasheet
+label: Pipe Alignment Verification Method
+type: select
+options:
+ - "Pipe laser — required for grade verification on continuous reaches"
+ - "Transit and offset stakes"
+ - "String line and grade boards"
+ - "Per drawings / engineer's recommendation"
+default: "Pipe laser — required for grade verification on continuous reaches"
+```
+
+### Pipe shall be laid in the trench beginning at the downstream end and progressing upstream, with bells (or hub ends, depending on pipe type) facing upstream.
+
+### This orientation places the spigot into the bell with the flow direction, so that any minor joint imperfection does not collect debris and so that joint home depth marks are visible from the upstream end. {note}
+
+### Each pipe section shall be aligned to the design center line and grade before the joint is made.
+
+### Once the joint is home, alignment adjustment requires re-jointing.
+
+### Pipe alignment shall be checked with a laser, transit, or string line set to the design center line.
+
+### Pipe grade shall be verified by transferring grades from offset stakes or from a laser receiver mounted in the pipe.
+
+### Pipe-to-pipe alignment shall be such that no joint is deflected beyond the manufacturer's permissible deflection limit; permissible deflection at gasketed joints typically ranges from 1.5 to 5 degrees depending on pipe size and joint type.
+
+### Where the design alignment requires a deflection exceeding the joint's permissible limit, a fitting shall be used in place of a deflected joint, or the alignment shall be reviewed by the Engineer.
+
+### A pipe laser is the standard method for verifying both alignment and grade on storm sewer reaches and is required for any reach longer than 100 feet.
+
+### Hand-leveling and string-line methods are acceptable only for short reaches between structures and shall be checked against the design invert at each structure before joints are made.
+
+## Joint Assembly — Gasketed Pipe (RCP, HDPE, PVC) {toc}
+
+### Before the spigot is inserted, the bell or hub of each pipe shall be inspected so that the bell is clean of debris, the gasket groove is confirmed to have the gasket correctly seated all the way around the circumference, and any contamination on the gasket is removed.
+
+### Lubricant approved by the pipe manufacturer shall be applied to the gasket and to the spigot in accordance with the manufacturer's installation instructions.
+
+### The use of incompatible lubricants (e.g., petroleum-based products on EPDM gaskets) is not acceptable and will degrade the gasket.
+
+### The spigot shall be inserted into the bell using equipment appropriate for the pipe size and weight: a come-along or chain hoist with a softener strap for small pipe, a hydraulic puller for large RCP, or a slip-fit assembly for HDPE and PVC where the pipe is light enough to be pushed home by hand or with light mechanical assistance.
+
+### The spigot shall be advanced until the home-mark on the spigot is at the bell face or until the spigot shoulder contacts the bell, whichever applies to the joint design.
+
+### The joint shall not be over-inserted past the home mark.
+
+### Over-insertion can roll or pinch the gasket and create a leak path. {note}
+
+### After each joint is assembled, the Contractor shall check the joint home depth around the full circumference using a feeler gauge or by reaching into the bell where access permits.
+
+### Any joint that does not seat fully shall be disassembled, the gasket inspected and re-seated (or replaced if damaged), and the joint re-made before backfill proceeds.
+
+## Joint Assembly — Mechanical Couplings {toc}
+
+### The joining method at material transitions shall be as detailed below.
+
+```datasheet
+label: Pipe Joining at Material Transitions
+type: select
+options:
+ - "Manufacturer's listed transition coupling for the specific OD pair"
+ - "Compression repair coupling with stainless steel band (small repair only)"
+ - "Cast-in-place concrete collar (RCP transitions only)"
+ - "Per drawings"
+default: "Manufacturer's listed transition coupling for the specific OD pair"
+```
+
+### Where mechanical couplings are used at transitions (between dissimilar pipe materials, at field cut-ins, or at connections to existing piping), the coupling shall be of a type listed for the materials being joined, with the gasket sized for the actual outside diameters of the pipes — not for the nominal diameters.
+
+### Concrete pipe outside diameters, HDPE outside diameters, and PVC outside diameters differ for the same nominal size, so using a coupling sized for one material on another will result in over-compressed or under-compressed gaskets and joint failure. {note}
+
+## Cutting Pipe to Length {toc}
+
+### Pipe may be cut to length to meet structures or to make field adjustments.
+
+### Cuts shall be square (perpendicular to the pipe axis), shall be deburred and chamfered on the spigot end to allow gasket entry without rolling the gasket, and shall not damage the bell of the upstream pipe.
+
+### For RCP, cutting shall be performed with a diamond saw; flame-cutting and impact methods that crack the concrete are not acceptable.
+
+### For HDPE and PVC, cuts shall be made with a saw or pipe cutter producing a clean perpendicular face.
+
+## Sag and Belly Avoidance {toc}
+
+### The completed pipe shall have a uniform grade matching the design invert elevations at each structure.
+
+### Sags ("bellies") in the pipe between structures collect sediment, reduce capacity, and cannot be cleaned with conventional rodding equipment, and sags discovered after backfill placement are difficult and expensive to correct, so the time to catch them is during pipe laying, before backfill. {note}
+
+### The Contractor shall verify the as-laid invert at each joint and shall report any deviation from grade exceeding the manufacturer's installation tolerance to the Engineer.
+
+## Connection to Existing Storm Systems {toc}
+
+### Coordination for connection to an existing system shall address the items listed below.
+
+```datasheet
+label: Connection to Existing System — Coordination
+type: checkbox
+options:
+ - "Utility owner pre-construction coordination meeting completed"
+ - "Bypass pumping plan (where required for in-service systems)"
+ - "Downstream sediment protection installed before cut-in"
+ - "AHJ inspection scheduled for connection witnessing"
+ - "As-built record updated with connection station and invert"
+default: "AHJ inspection scheduled for connection witnessing"
+```
+
+### Where the work connects to an existing manhole, inlet, or pipe, the Contractor shall coordinate with the utility owner and the Engineer in advance to confirm the connection method, the AHJ requirements, any flow-bypass needs during the cut-in, and the inspection hold points.
+
+### Core-drilling into existing precast structures is the preferred method for new pipe connections; the core shall be drilled with a diamond core barrel sized for the new pipe with appropriate annular clearance for a resilient connector boot.
+
+### Cut-ins on existing in-service pipe shall be performed only with the utility owner's approval and only after the Contractor has a plan for managing flows during the work — including bypass pumping if required.
+
+### The Contractor shall protect downstream systems from sediment and construction debris introduced during the cut-in by installing temporary inlet protection or a downstream sediment trap before the cut-in begins.
+
+# Structure Installation {toc}
+
+## Base Placement {toc}
+
+### Precast manhole bases shall be set on a compacted granular bedding course (typically 6 to 12 inches of Class I or Class II material) shaped to provide a level, uniform bearing surface at the design invert elevation of the lowest pipe.
+
+### Cast-in-place bases shall be placed on a bedding course, with reinforcement and pipe penetration formwork installed before concrete placement.
+
+### The base shall be set level and at the elevation that places the lowest pipe invert at the design value.
+
+### The base elevation shall be verified before pipe is connected to the structure.
+
+### Small adjustments in base elevation propagate into structure barrel height and frame elevation and are very expensive to correct once riser sections are stacked. {note}
+
+## Riser, Cone, and Top Slab Installation {toc}
+
+### Precast riser sections shall be lifted and set with the lifting hardware specified by the manufacturer (typically lift inserts cast into the riser).
+
+### The joint between sections shall be cleaned, the preformed butyl sealant (ASTM C990) or the O-ring gasket (ASTM C443) placed in the joint, and the upper section lowered onto the lower section so that the sealant or gasket is uniformly compressed around the full circumference.
+
+### The Contractor shall verify that the upper section seats fully before releasing the load on the crane.
+
+### Eccentric cones shall be oriented with the offset on the side opposite the inflow pipe where possible, so that the manhole ladder or step alignment is over solid bench.
+
+### The cone-to-top-slab joint and the cone-to-frame interface shall be sealed in the same manner as the section-to-section joints.
+
+## Bench and Channel Construction {toc}
+
+### The manhole bench and channel construction shall be as detailed below.
+
+```datasheet
+label: Manhole Bench / Channel Construction
+type: select
+options:
+ - "Cast-in-place concrete bench, hand-formed channel"
+ - "Cement mortar bench, hand-troweled smooth"
+ - "Factory-formed channel insert (where available for the pipe pattern)"
+ - "Per drawings"
+default: "Cement mortar bench, hand-troweled smooth"
+```
+
+### The bench inside the manhole shall be shaped to direct flow smoothly from each inlet pipe to the outlet pipe with minimum hydraulic loss.
+
+### The channel through the bench shall be the full inside diameter of the largest pipe (or the outlet pipe) at the springline elevation, with the bench sloped at 1 inch per foot from the channel edge toward the outside wall to drain.
+
+### Bench material shall be cement mortar, cast-in-place concrete, or factory-formed channel inserts.
+
+### Smooth, hard-troweled mortar resists abrasion and is easier to maintain than rough, hand-floated material. {note}
+
+### The channel through the manhole shall be at full pipe diameter at the inverts and shall not present a step, lip, or change of section that would catch debris.
+
+### Manhole inverts shall match the pipe invert elevations exactly.
+
+### A manhole channel that sits below the pipe invert creates a sump that collects sediment, and a channel that sits above the pipe invert restricts flow. {note}
+
+## Drop Connections {toc}
+
+### Where an incoming pipe enters the manhole at an elevation more than 24 inches above the outlet invert, an external or internal drop connection shall be provided as indicated on the drawings, so that flow is conveyed from the high inlet to the outlet without spilling onto the manhole bench.
+
+### External drops (a vertical pipe outside the manhole barrel connecting the inlet pipe to a low connection into the manhole) are preferred for sanitary applications, while in storm applications internal drops (a vertical pipe inside the manhole) are acceptable and are commonly used. {note}
+
+## Setting Frames and Castings {toc}
+
+### After backfill around the structure has been compacted to grade, the frame shall be set on the structure with adjustment rings as described in the Castings section above.
+
+### The frame shall be set level, square, and at the elevation that places the top of the casting at finished pavement or grade.
+
+### Mortar joints between the structure top, the adjustment rings, and the frame shall be smooth on the inside of the structure (so as not to interfere with future re-grading or replacement of the frame), and shall be installed without voids that would allow infiltration.
+
+### Where the frame is set in advance of final pavement placement, the Contractor shall protect the frame and the structure rim during paving operations.
+
+### Where the frame is set in advance of final pavement placement, the Contractor shall coordinate frame setting with pavement placement so that the frame is set to final grade as the pavement is placed around it, or so that the frame is temporarily protected by a steel plate and re-set to final grade after paving, because pavers driving over an unsupported frame can rock the frame loose.
+
+# Testing {toc}
+
+## Pipe Leakage and Joint Testing {toc}
+
+### The pipe leakage test method shall be as detailed below.
+
+```datasheet
+label: Pipe Leakage Test Method
+type: select
+options:
+ - "Low-pressure air test per ASTM F1417 (PVC and HDPE)"
+ - "Hydrostatic test (head pressure)"
+ - "Joint-by-joint pressure test (large-diameter RCP only)"
+ - "Vacuum test (manholes and select structures)"
+ - "Not required — confirm AHJ acceptance criteria"
+default: "Low-pressure air test per ASTM F1417 (PVC and HDPE)"
+```
+
+### All storm drainage pipe shall be tested for leakage after pipe-zone backfill is complete and before final trench backfill is closed above the pipe zone.
+
+### The test method shall be one of the following, as indicated on the drawings or directed by the Engineer.
+
+### The low-pressure air test per ASTM F1417 is the standard production test for PVC and HDPE storm sewer reaches between structures, with the reach plugged at both manholes using test plugs rated for the test pressure and physically restrained against blow-out, air introduced gradually to the test pressure (typically 3.5 psi above any backpressure from groundwater), and the pressure drop measured over the test hold period specified in ASTM F1417 for the pipe size and length. {note}
+
+### Test plugs and end caps shall be confirmed rated for the test pressure before pressurizing.
+
+### The hydrostatic test (water column or head test) is acceptable for any pipe material and is the reference method for pipe and joint leakage, with the reach plugged at the downstream end, filled with water from the upstream manhole to a head of 2 to 5 feet above the upstream pipe crown, and held without makeup water for not less than 1 hour so that any drop in water level indicates leakage; the hydrostatic test is impractical where the upstream invert is below grade with no manhole available as the water column, and where freezing weather precludes water testing. {note}
+
+### Joint-by-joint pressure testing — pressurizing only the individual joint annulus with a packer testing device — is used on large-diameter RCP (typically 48 inches and larger) where reach-length water testing is impractical, and the test is performed with specialized equipment per the device manufacturer's procedure and is observed by the Engineer or AHJ inspector. {note}
+
+## Manhole Vacuum Testing {toc}
+
+### The manhole vacuum test requirement shall be as detailed below.
+
+```datasheet
+label: Manhole Vacuum Test
+type: radio
+options:
+ - "Required — all storm drainage manholes per ASTM C1244 procedure"
+ - "Required — manholes with cast-in resilient connectors per ASTM C923"
+ - "Not required — confirm AHJ acceptance criteria"
+default: "Required — all storm drainage manholes per ASTM C1244 procedure"
+```
+
+### Precast manholes shall be vacuum tested to confirm watertight construction of the structure joints, the pipe-to-structure connections, and the cone and top slab seals.
+
+### The vacuum test shall be performed after the structure is complete and before exterior backfill is placed (where possible) or, where backfill must be placed before the casting is set, after the casting is set but before final paving over the structure.
+
+### The vacuum test plug is sealed at the top of the cone, the manhole evacuated to 10 inches of mercury (approximately 5 psi), and the pump valved off, with the vacuum held for the duration specified in the procedure (typically 1 minute for manholes up to 12 feet deep, longer for deeper structures) and a maximum allowable pressure rise of 1 inch of mercury. {note}
+
+### A manhole that fails the vacuum test shall be inspected for the leak path — typically at a section joint, a pipe connector, or the cone seal — and the leak shall be sealed by re-tightening the joint, regrouting, or applying an approved external sealant.
+
+### A manhole that fails the vacuum test shall be re-tested until it passes.
+
+## Deflection Testing of Flexible Pipe {toc}
+
+### The maximum deflection limit for flexible pipe shall be as detailed below.
+
+```datasheet
+label: Deflection Test — Mandrel Limit
+type: radio
+options:
+ - "5 percent maximum deflection (standard for storm sewer flexible pipe)"
+ - "7.5 percent maximum deflection (where permitted by AHJ for storm-only)"
+ - "Per pipe manufacturer's installation manual"
+default: "5 percent maximum deflection (standard for storm sewer flexible pipe)"
+```
+
+### All HDPE and PVC pipe shall be deflection-tested by mandrel pull-through after final backfill has been placed and the trench has been left undisturbed for at least 30 days, or after the final cover load (including pavement) has been placed, whichever is later.
+
+### The 30-day wait permits the soil envelope around the pipe to equilibrate to its post-construction shape, and testing too soon after backfill can produce passing results that fail later. {note}
+
+### The mandrel shall be a go/no-go device sized to the minimum allowable inside diameter at the specified deflection limit (5 percent or 7.5 percent of the nominal inside diameter).
+
+### The mandrel shall be pulled through the reach by hand or with light mechanical aid, without using a winch or other force that could damage the pipe.
+
+### If the mandrel cannot be pulled through with reasonable manual force, the pipe has failed the deflection limit and the cause shall be investigated.
+
+### Common causes of excessive deflection are inadequate haunch compaction, premature loading by heavy equipment, or use of unsuitable bedding material. {note}
+
+### Pipe failing the deflection test shall be repaired by removing and re-bedding the affected reach, by installing a structural liner approved by the Engineer, or by replacement of the affected reach.
+
+### The Contractor shall not abandon a failed deflection result by "rounding up" the mandrel or by using a smaller mandrel than required by the specification.
+
+## Test Reporting {toc}
+
+### Test results — pass and fail — shall be documented on testing forms that include the reach identification (upstream and downstream structure numbers), pipe material and size, test method, test pressure or head, hold time, start and end pressure or water level readings, and the names of the Contractor's test foreman and the witnessing inspector.
+
+### Failed tests shall not be re-tested without first identifying and correcting the cause of failure.
+
+### Both the failure and the successful retest shall be recorded.
+
+# Cleaning {toc}
+
+## After all testing is complete and before the system is turned over to the Owner or the AHJ, the entire storm drainage system is cleaned of debris, sediment, mortar droppings, and any construction materials. {note}
+
+```datasheet
+label: Final System Cleaning Method
+type: select
+options:
+ - "Jet flushing with water — vacuum recovery of debris"
+ - "Mechanical bucket cleaning (large-diameter pipe)"
+ - "Manual cleanout (small structures and areas)"
+ - "Per AHJ acceptance requirement"
+default: "Jet flushing with water — vacuum recovery of debris"
+```
+
+## Cleaning shall be performed by jet-flushing, by mechanical bucketing, or by other methods suited to the pipe size and configuration.
+
+## Sediment removed during cleaning shall be disposed of off-site or, where the project has an on-site stormwater facility, at an Owner-approved location.
+
+## Inlet sumps, manhole benches, and the inverts of all structures shall be flushed and inspected to confirm clean condition.
+
+## Inlet grates and frames shall be cleaned of construction debris and tested for free seating in the frame.
+
+## The Contractor shall not turn the system over with inlet protection bags or temporary sediment controls still in place.
+
+## Inlet protection bags and temporary sediment controls shall be removed at closeout.
+
+## Inlet protection bags and temporary sediment controls were appropriate during construction but reduce hydraulic capacity below design value. {note}
+
+## After cleaning, the Contractor shall conduct a final walk-through inspection with the Engineer and the AHJ inspector (where required), opening each structure to verify clean condition.
+
+## Any sediment, debris, or visible damage discovered shall be addressed before final acceptance.
+
+# Pre-Treatment and Water Quality Structures {toc}
+
+## Where the project includes pre-treatment or water quality structures within the storm drainage system — including oil-water separators, hydrodynamic separators, gross particle separators, sand filters, or bioretention discharge structures — those structures are typically proprietary devices governed by the manufacturer's installation instructions and the civil drawings. {note}
+
+```datasheet
+label: Pre-Treatment / Water Quality Structures Included
+type: checkbox
+options:
+ - "Oil-water separator (typically required at fueling, vehicle service, or industrial yard areas)"
+ - "Hydrodynamic separator (gross debris removal upstream of detention)"
+ - "Gross particle / debris separator"
+ - "Sediment forebay (within or upstream of detention basin)"
+ - "Bioretention discharge structure"
+ - "Not included — confirm SWPPP / MS4 program requirements"
+default: "Not included — confirm SWPPP / MS4 program requirements"
+```
+
+## The pipe and structure installation provisions of this standard apply to the pipe connections into and out of the device.
+
+## The device itself shall be installed per the manufacturer's instructions and the civil details.
+
+## Oil-water separators are required by local stormwater regulations or by the NPDES MS4 program for runoff originating in vehicular fueling, vehicle service, or industrial yard areas. {note}
+
+## Where required, the separator shall be located upstream of the storm system connection to the public infrastructure and shall be sized per the manufacturer's procedure for the contributing drainage area and the design storm.
+
+## The Contractor shall not omit a specified water-quality structure.
+
+## Omitting a specified water-quality structure creates a downstream permit violation and an Owner liability that survives the warranty period. {note}
+
+# Acceptance {toc}
+
+## Final acceptance of the storm drainage system shall require:
+
+- Completion of all testing (pipe leakage, deflection, manhole vacuum) with passing results on every reach and every structure
+- AHJ inspection and release of any portion of the system connected to public infrastructure
+- Submission of complete as-built drawings showing installed pipe alignments, structure rim and invert elevations, casting types, and any deviations from design
+- Final cleaning of pipe and structures with confirmation by walk-through inspection
+- Removal of all temporary construction stormwater controls within the storm system (inlet protection, sediment traps, bypass pumping equipment)
+- Submission of all closeout documentation listed in the Submittals section
+
+```datasheet
+label: Acceptance Documentation Required
+type: checkbox
+options:
+ - "Pipe leakage test reports — all reaches"
+ - "Deflection test reports — all flexible pipe reaches"
+ - "Manhole vacuum test reports — all structures"
+ - "As-built record drawings with rim and invert schedule"
+ - "AHJ acceptance documentation"
+ - "Final cleaning certification"
+ - "Casting and structure warranty documentation"
+default: "Pipe leakage test reports — all reaches"
+```
+
+## The Contractor shall remain responsive to defect reports throughout the warranty period.
+
+## The Owner's acceptance of the storm drainage system at substantial completion does not waive the Contractor's warranty obligations or the Contractor's liability for latent defects discovered after acceptance, and storm drainage defects that affect site hydraulics often do not become apparent until the first significant rainfall event after acceptance. {note}
+
+# Warranty {toc}
+
+## The warranty period for the storm drainage system shall be as selected below.
+
+```datasheet
+label: Storm Drainage Warranty Period
+type: select
+options:
+ - "1 year from substantial completion"
+ - "2 years from substantial completion"
+ - "Per AHJ or utility owner requirement (typically 1 to 2 years)"
+default: "1 year from substantial completion"
+```
+
+## The Contractor shall warrant the storm drainage system, including all pipe, joints, structures, castings, bedding and backfill, and connections, against defects in materials and workmanship for the project warranty period beginning at substantial completion.
+
+## Warranty obligations include correction of leaks, settlement at pavement repairs over trenches, excessive pipe deflection developing after acceptance, casting movement or rocking, and structure rim settlement.
+
+## Settlement at pavement repairs over storm trenches is a particularly common warranty item, because even properly installed trench backfill consolidates slightly over the first one or two seasonal cycles, and pavement that was at grade at the time of paving often sags visibly at a year or two after completion. {note}
+
+## The Contractor's warranty shall cover settlement when it can be attributed to trench backfill consolidation and not to subgrade conditions outside the trench.
+
+## Manufacturer warranties for castings, precast structures, and proprietary water-quality devices shall be passed through to the Owner as part of the closeout documentation.
+
+## Where a manufacturer warranty extends beyond the Contractor's installation warranty, the Contractor shall assign the manufacturer warranty to the Owner at closeout.
+
+## The warranty does not relieve the Contractor of liability for non-conforming installation discovered after the warranty period.
+
+## Pipe installed at incorrect slope, structures with leaking joints concealed by exterior backfill, castings under-rated for the load class of the location, or pipe materials substituted from the specified standard remain the Contractor's responsibility as latent defects whenever discovered. {note}