1 Scope
NOTE This standard covers the materials, installation, testing, disinfection, and acceptance of exterior underground site utilities — both pressurized "wet" utilities (water service and distribution, sanitary force mains) and gravity sanitary sewer, together with the underground "dry" utility duct banks and conduits that carry electrical and telecommunications cable. (1.1)
NOTE The scope begins 5 feet outside the exterior face of the building, where the interior plumbing and electrical scopes leave off, and extends to the project-defined point of connection: the tap or meter at the public water main, the connection to the public sanitary main or on-site treatment facility, and the utility owner's pad, vault, or pole base for electric and telecom service. (1.2)
NOTE Site utilities differ from interior building systems in three ways that drive nearly every requirement of this standard. (1.3)
1.4First, they are buried — once backfilled and paved over, a defect cannot be seen and is enormously expensive to reach, so the integrity of the joint, the embedment, and the test must be established and documented before the trench is closed.
NOTE Second, the wet utilities are pressurized and life-safety critical: a leak in a domestic or fire water main does not merely waste water, it can undermine pavement, contaminate the potable supply through back-siphonage, or starve a fire main of the flow a sprinkler system depends on. (1.5)
NOTE Third, water and sewer in the same corridor present a public-health hazard if a sewer leak can reach a water main, which is why the separation requirements in this standard are mandatory and are enforced by the plumbing code and the state drinking-water regulations, not merely by good practice. (1.6)
1.7 Boundary With Adjacent Standards
1.7.1The boundary with adjacent standards is deliberate and the Contractor shall observe it.
1.7.2Site storm drainage is a separate scope governed by Storm Drainage, and this standard does not repeat storm-drainage material, structure, or testing requirements. 1.7.3Where a storm line shares a trench or crossing with a water or sanitary line, the separation and crossing rules in this standard govern that interface.
1.7.4Trench excavation, dewatering, shoring, trench-bottom stabilization, and trench backfill above the pipe zone are governed by Earthwork; this standard states only the bedding and pipe-zone embedment requirements specific to utility pipe and defers all general trenching to Earthwork. 1.7.6For the dry utilities, this standard covers the raceway pathway — the duct bank, conduit, spacers, encasement, and pull/splice structures — but not the conductors, cable, terminations, or grounding pulled through it, which are covered by the electrical standards.
NOTE The civil and electrical drawings carry essentially all design-specific information for site utilities: pipe and conduit sizes, materials, horizontal alignment, invert and top-of-duct elevations, slopes, valve and hydrant locations, duct-bank configuration, and points of connection. (1.8.1)
1.8.2The Contractor shall install the systems as designed.
1.8.3The Contractor shall report to the Engineer of Record any condition — utility conflict, inadequate cover, insufficient separation, or differing site condition — that would prevent the designed system from being constructed as drawn.
2 Referenced Standards
2.1Materials, manufacturing, installation, testing, and disinfection shall comply with the latest adopted edition of the following standards and codes.
| Standard |
Title |
| AWWA C150/A21.50 |
Thickness Design of Ductile-Iron Pipe |
| AWWA C151/A21.51 |
Ductile-Iron Pipe, Centrifugally Cast, for Water |
| AWWA C104/A21.4 |
Cement-Mortar Lining for Ductile-Iron Pipe and Fittings for Water |
| AWWA C105/A21.5 |
Polyethylene Encasement for Ductile-Iron Pipe Systems |
| AWWA C110/A21.10 |
Ductile-Iron and Gray-Iron Fittings |
| AWWA C111/A21.11 |
Rubber-Gasket Joints for Ductile-Iron Pressure Pipe and Fittings |
| AWWA C153/A21.53 |
Ductile-Iron Compact Fittings |
| AWWA C600 |
Installation of Ductile-Iron Mains and Their Appurtenances |
| AWWA C900 |
Polyvinyl Chloride (PVC) Pressure Pipe and Fabricated Fittings, 4 In. Through 60 In. |
| AWWA C605 |
Underground Installation of Polyvinyl Chloride (PVC) and Molecularly Oriented PVC (PVCO) Pressure Pipe and Fittings |
| AWWA C651 |
Disinfecting Water Mains |
| AWWA C800 |
Underground Service Line Valves and Fittings |
| AWWA C502 |
Dry-Barrel Fire Hydrants |
| AWWA C509 / C515 |
Resilient-Seated Gate Valves for Water Supply Service |
| AWWA M23 |
PVC Pipe — Design and Installation (manual of practice) |
| ASTM D2321 |
Underground Installation of Thermoplastic Pipe for Sewers and Other Gravity-Flow Applications |
| ASTM D3034 |
Type PSM Poly(Vinyl Chloride) (PVC) Sewer Pipe and Fittings (SDR 35) |
| ASTM F679 |
Poly(Vinyl Chloride) (PVC) Large-Diameter Plastic Gravity Sewer Pipe and Fittings |
| ASTM D3212 |
Joints for Drain and Sewer Plastic Pipes Using Flexible Elastomeric Seals |
| ASTM F477 |
Elastomeric Seals (Gaskets) for Joining Plastic Pipe |
| ASTM F1417 |
Installation Acceptance of Plastic Non-Pressure Sewer Lines Using Low-Pressure Air |
| ASTM C76 |
Reinforced Concrete Culvert, Storm Drain, and Sewer Pipe (where RCP sanitary is specified) |
| ASTM C443 |
Joints for Concrete Pipe and Manholes, Using Rubber Gaskets |
| ASTM C478 |
Circular Precast Reinforced Concrete Manhole Sections |
| ASTM C923 |
Resilient Connectors Between Concrete Manhole Structures, Pipes, and Laterals |
| ASTM F714 |
Polyethylene (PE) Plastic Pipe (DR-PR) Based on Outside Diameter |
| ASTM D3035 |
Polyethylene (PE) Plastic Pipe (DR-PR) Based on Controlled Outside Diameter |
| ASTM D3261 |
Butt Heat Fusion Polyethylene (PE) Plastic Fittings for PE Pipe and Tubing |
| ASTM D2657 |
Heat Fusion Joining of Polyethylene Pipe and Fittings |
| ASTM D2774 |
Underground Installation of Thermoplastic Pressure Piping |
| ASTM D1557 / D698 |
Laboratory Compaction Characteristics of Soil (Modified / Standard Effort) |
| ASTM D2487 |
Classification of Soils for Engineering Purposes (Unified Soil Classification System) |
| NEMA TC-2 |
Electrical Polyvinyl Chloride (PVC) Conduit |
| NEMA TC-6 & 8 |
PVC Plastic Utilities Duct for Underground Installation |
| UL 651 |
Schedule 40, 80, Type EB, and A Rigid PVC Conduit and Fittings |
| NFPA 70 |
National Electrical Code (NEC), Article 300.5 (cover) and Article 305 (underground) |
| Ten States Standards |
Recommended Standards for Water Works / for Wastewater Facilities (water-sewer separation) |
NOTE State drinking-water and wastewater regulations and the adopted plumbing code establish the mandatory water-sewer separation requirements; the Ten States Standards (Recommended Standards for Water Works and for Wastewater Facilities) are referenced as the widely adopted source of those values, but the governing separation distances are those of the state agency and AHJ having jurisdiction over the project. (2.2)
2.3Where contract documents, adopted codes, the utility owner's standards, or referenced standards conflict, the more stringent requirement shall govern unless the Engineer of Record directs otherwise in writing.
2.4The water or sewer utility owner's published standard specifications and details govern all work within the public right-of-way and at the point of connection, and the Contractor shall obtain and follow them.
2.5The Contractor shall confirm the governing edition of the separation requirements with the AHJ and the utility owner before work in the right-of-way begins.
3 Submittals
3.1 Action Submittals
3.1.1The Contractor shall submit the following for the Engineer of Record's review and acceptance prior to procurement, fabrication, or installation:
- Product data for all pressure pipe and fittings (ductile iron per AWWA C151 with the pressure or thickness class; PVC per AWWA C900 with the DR/pressure class; HDPE per ASTM F714/D3035 with the DR and PE material designation), indicating the manufacturer, applicable standard, joint type, lining, and gasket standard (AWWA C111 or ASTM F477)
- Product data for all gravity sanitary sewer pipe and fittings, indicating the standard (ASTM D3034 SDR 35, ASTM F679, or ASTM C76), the SDR or class, the joint type, and the gasket standard (ASTM D3212 / F477 or ASTM C443)
- Product data for valves (gate, butterfly, tapping), valve boxes, fire hydrants (AWWA C502), service saddles and corporation/curb stops (AWWA C800), air-release/vacuum valves on force mains, and restrained-joint and mechanical-joint fittings, with pressure ratings
- Product data for dry-utility conduit and duct (NEMA TC-2 PVC conduit, NEMA TC-6 & 8 PVC duct, or HDPE duct), conduit spacers, end bells, and pull/splice structures (precast handholes, manholes, and pull boxes) with load rating
- Shop drawings for sanitary manholes, drop connections, and any cast-in-place structures, including resilient pipe connectors per ASTM C923 and the manhole joint sealing method
- Shop drawings and a duct-bank section detail showing conduit count, configuration, spacer type and spacing, reinforcing (where specified), concrete encasement dimensions and cover, and minimum bend radius
- Bedding and embedment material gradations conforming to ASTM D2321 Class I or Class II, with sieve analyses for each proposed source
- Thrust-restraint design and details for the pressure systems, indicating restrained-length calculations or thrust-block sizing for each bend, tee, reducer, valve, hydrant, and dead end, with the design test pressure and the assumed soil bearing value
- Tracer wire, warning/marking tape, and conduit-marker product data, with the APWA color code for each system
- A written test plan covering hydrostatic and leakage testing of pressure pipe (per AWWA C600/C605), low-pressure air and deflection (mandrel) testing of gravity sewer (per ASTM F1417 and D2321), force-main pressure testing, and a duct-bank mandrel/proof test, including test pressures, durations, allowable leakage, and the testing agency
- A water-main disinfection plan per AWWA C651, indicating the disinfection method (continuous-feed, slug, or tablet), the chlorine concentration and contact time, the dechlorination method for the disinfection water, and the bacteriological sampling and clearance procedure
☐ Pressure pipe and fitting product data (DIP / PVC / HDPE) with class and joint
☐ Gravity sanitary sewer pipe and fitting product data with SDR/class and joint
☐ Valve, hydrant, and service fitting product data (AWWA C502, C509/C515, C800)
☐ Dry-utility conduit/duct and pull-structure product data
☐ Sanitary manhole and drop-connection shop drawings
☐ Duct-bank section detail (configuration, spacers, encasement, cover)
☐ Bedding and embedment material gradations (ASTM D2321 classification)
☐ Thrust-restraint design and details for pressure systems
☐ Tracer wire, marking tape, and conduit-marker product data
☐ Test plan (hydrostatic, leakage, air, deflection, duct mandrel)
☐ Water-main disinfection plan (AWWA C651)
3.1.2Below-grade work for which submittals are pending shall not be installed.
3.2 Closeout Submittals
3.2.1Prior to substantial completion the Contractor shall provide:
- As-built record drawings showing the installed plan and profile of all utility pipe, conduit, valves, fittings, hydrants, and structures, with station and offset to permanent reference points, finished rim and all pipe invert and top-of-duct elevations at each structure, and every material and size installed by reach
- Field test reports for all hydrostatic/leakage tests, force-main tests, low-pressure air tests, deflection (mandrel) tests, and duct-bank proof/mandrel tests, signed by the testing technician, with pass/fail determination for each reach
- Water-main disinfection records: the chlorination method and dosage, the contact time, the dechlorination record for disposal of the chlorinated water, and the laboratory bacteriological clearance results (consecutive satisfactory samples) demonstrating the main is safe for service
- Valve and hydrant location and operation records, including the number of turns to open and the direction of operation, and tie-out dimensions to valve boxes
- Tracer-wire continuity test results for each pressure and force-main reach
- Manufacturer warranties for valves, hydrants, castings, and precast structures
- AHJ and utility owner acceptance documentation for connections to public infrastructure
☐ As-built record drawings (plan and profile, with elevations and tie-outs)
☐ Field test reports (hydrostatic, leakage, force-main, air, deflection, duct mandrel)
☐ Water-main disinfection and bacteriological clearance records
☐ Valve and hydrant location and operation records
☐ Tracer-wire continuity test results
☐ Manufacturer warranties for valves, hydrants, castings, and precast structures
☐ AHJ and utility owner acceptance documentation
4 Quality Assurance
4.1 Installer Qualifications
4.1.1Site utility 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.
4.1.2Personnel making heat-fused HDPE joints shall be qualified in accordance with ASTM D2657 for the fusion procedure and equipment being used.
4.1.3Fusion-machine operators shall maintain a data-logged record of each fusion joint (heater temperature, fusion pressure, and cool time) where data-logging fusion equipment is used.
4.1.4Personnel assembling gasketed pressure and gravity joints shall be familiar with the manufacturer's joint-assembly procedure, including gasket seating, lubricant application, and home-mark verification.
4.2 Listing and Marking
4.2.1All pipe, fittings, gaskets, valves, hydrants, conduit, and precast structures shall bear the manufacturer's identification, the applicable standard designation, the pressure class or SDR (for pressure pipe) or stiffness/SDR (for gravity pipe), and a production date or batch number sufficient to trace each item to its certification.
4.2.2Products that contact potable water shall be certified to NSF/ANSI 61 for drinking-water system components.
4.2.3Unmarked pipe, fittings, or structures shall be rejected and removed from the project regardless of supplier documentation.
4.3 Pre-Installation Conference
4.3.1Prior to beginning site utility installation the Contractor shall participate in a pre-installation conference with the Contractor's site-utility superintendent, the geotechnical engineer of record, the civil engineer of record, the AHJ and utility owner inspectors (where required), and the testing agency, to review materials, joint types, separation requirements, bedding and embedment, the testing and disinfection program, and the inspection hold points.
4.4 Inspection Hold Points
4.4.1The Contractor shall provide the Engineer of Record and the AHJ/utility owner inspector with not less than 24 hours' notice before each of the following hold points:
- Trench bottom and bedding placement, before pipe or conduit installation
- Pipe alignment, slope, and joint assembly, before initial backfill
- Thrust-restraint installation (restrained joints or thrust blocks) at every fitting, before backfill
- Water-sewer separation and crossing conditions at every crossing, before backfill
- Duct-bank conduit placement and spacer/tie-down, before concrete encasement is poured
- Pressure/leakage test, low-pressure air test, and deflection (mandrel) test
- Water-main disinfection and bacteriological clearance, before the main is placed in service
- Casting/valve-box setting and grade, before final pavement placement
4.4.2No work past a hold point shall proceed until the inspection is released.
5 Environmental and Service Conditions
5.1 Frost Depth and Minimum Cover
5.1.1Minimum cover over water main and force main for frost protection shall be as scheduled below and as indicated on the drawings.
5.1.2Pressurized water service, distribution mains, and force mains shall be installed with cover not less than the local frost-penetration depth plus a margin, and not less than the cover required by the utility owner and the drawings, so that the line and any trapped water do not freeze.
5.1.3The Contractor shall confirm the governing frost depth and the minimum cover for the project locality.
5.1.4Gravity sanitary sewer cover is governed primarily by the design invert elevations and slope, not by frost, but shall still meet the structural minimum cover for the pipe material and live load.
5.2 Corrosive Soils
NOTE The standard protection for ductile iron in aggressive soil is loose polyethylene encasement installed in accordance with AWWA C105; bonded coatings and cathodic protection are used where the corrosion engineer requires them. (5.2.1)
Loose polyethylene encasement per AWWA C105 (standard for aggressive soil)
Polyethylene encasement plus cathodic protection (severe / stray current)
Bonded coating system per corrosion engineer
Not required — soil not classified aggressive
5.2.2Where the geotechnical or corrosion investigation indicates aggressive soils (low resistivity, high chloride or sulfate content, or stray-current exposure), ductile iron pipe and fittings shall be protected.
5.2.3PVC and HDPE pipe are not subject to galvanic or electrolytic corrosion and require no such protection, but their metallic appurtenances (bolts, glands, tie rods, valves) do and shall be protected.
5.2.4The Contractor shall not omit polyethylene encasement on ductile iron in soils identified as aggressive.
5.3 Groundwater and Flotation
5.3.1Where the trench extends below the groundwater table, the line shall be installed and backfilled with enough cover to resist flotation before dewatering is discontinued, in accordance with Earthwork. 5.3.2The Contractor shall not place pipe in standing water.
NOTE Empty PVC and HDPE pressure pipe and empty gravity sewer are buoyant and float out of alignment in a flooded trench, and standing water contaminates gaskets and fusion faces and washes out bedding under the pipe. (5.3.3)
6 Materials — Water Service and Distribution
6.1 Ductile Iron Pressure Pipe
Pressure Class 150
Pressure Class 200
Pressure Class 250
Pressure Class 350
Per drawings / thickness design (AWWA C150)
6.1.1Ductile iron pipe for site water service and distribution shall conform to AWWA C151/A21.51, with the pressure class or thickness class designed in accordance with AWWA C150/A21.50 for the working pressure, surge, depth of cover, trench type, and live load — as indicated on the drawings.
6.1.2Ductile iron pipe for potable service shall be cement-mortar lined in accordance with AWWA C104/A21.4 to protect the interior and preserve water quality.
6.1.3Joints for ductile iron shall be push-on or mechanical-joint rubber-gasket joints conforming to AWWA C111/A21.11, with restrained joints (boltless restrained push-on, or mechanical joint with restraint glands or tie rods) provided where thrust restraint is required.
6.1.4Fittings shall be ductile iron conforming to AWWA C110/A21.10 or compact fittings to AWWA C153/A21.53, of a pressure rating not less than the pipe.
NOTE Ductile iron is the standard choice where high strength, resistance to surge and external load, and tolerance to point loading are required — under roadways and heavy live load, at crossings, at restrained fitting assemblies, and on fire mains where the consequence of failure is high. (6.1.5)
6.2 PVC Pressure Pipe
DR 25 — Pressure Class 165 psi
DR 18 — Pressure Class 235 psi
DR 14 — Pressure Class 305 psi
Per drawings
6.2.1PVC pressure pipe for site water distribution shall conform to AWWA C900, in the dimension ratio (DR) / pressure class indicated on the drawings, with cast-iron-equivalent outside diameters so that it is compatible with ductile iron fittings, valves, and restraint hardware.
6.2.2PVC pressure pipe shall be installed per AWWA C605.
6.2.3PVC pressure pipe shall not be used where the drawings require ductile iron (typically under heavy live load, at restrained assemblies, or where the utility owner mandates DIP).
6.2.4Joints for AWWA C900 PVC shall be integral bell gasketed push-on joints with gaskets conforming to ASTM F477, assembled to the home mark; solvent-cement joints shall not be used on buried pressure mains.
6.2.5Fittings on PVC pressure pipe shall be ductile iron (AWWA C110 or C153) restrained or thrust-blocked as required.
6.2.6PVC pressure pipe shall be provided with the same thrust-restraint provisions as ductile iron at all bends, tees, reducers, valves, hydrants, and dead ends.
NOTE PVC pressure pipe is widely used for site domestic-water distribution because it is economical, corrosion-immune, and easily handled, and as a flexible pipe it depends on proper bedding and embedment for support. (6.2.7)
6.3 Valves, Hydrants, and Service Fittings
Resilient-seated gate valve, AWWA C509/C515 (standard for distribution)
Butterfly valve, AWWA C504 (larger diameters where indicated)
Tapping valve with tapping sleeve (wet tap to existing main)
Per drawings
6.3.1Distribution valves shall be resilient-seated gate valves conforming to AWWA C509 or C515 (or butterfly valves to AWWA C504 where indicated for larger sizes), each with a valve box brought to grade.
6.3.2Fire hydrants shall be dry-barrel hydrants conforming to AWWA C502, set plumb on a concrete or stone bearing pad with a drainage pocket and restrained to the main.
6.3.3Tapping the existing main shall use a tapping sleeve and tapping valve under pressure (wet tap) where the main cannot be taken out of service.
6.3.4Service-line taps, corporation stops, and curb stops shall conform to AWWA C800.
7 Materials — Sanitary Sewer
7.1 Gravity Sewer Pipe
7.1.1Gravity sanitary sewer pipe shall be as indicated on the drawings, in one of the following:
- PVC SDR 35 sewer pipe conforming to ASTM D3034 (4 in. through 15 in.), with gasketed bell-and-spigot joints per ASTM D3212 and gaskets per ASTM F477
- PVC large-diameter sewer pipe conforming to ASTM F679 (18 in. and larger), gasketed per ASTM D3212
- Reinforced concrete pipe conforming to ASTM C76 with gasketed joints per ASTM C443, where the drawings specify RCP (large diameter, heavy cover, or utility-owner requirement)
PVC SDR 35 (ASTM D3034) — 4 in. through 15 in., gasketed per ASTM D3212
PVC large-diameter (ASTM F679) — 18 in. and larger, gasketed per ASTM D3212
Reinforced concrete pipe (ASTM C76), gasketed per ASTM C443
Per drawings
7.1.2PVC SDR 35 gravity sewer shall be installed per ASTM D2321, with the deflection limit and embedment requirements stated in this standard.
7.1.3Solvent-cement joints shall not be used on buried gravity sewer; the gasketed joint accommodates the thermal and ground movement that solvent-cement joints cannot, and is the recognized standard for buried gravity sewer.
NOTE PVC SDR 35 is the predominant gravity-sewer material for commercial site work, and as a flexible pipe it depends on proper installation per ASTM D2321 for support. (7.1.4)
7.2 Sanitary Manholes
7.2.1Sanitary sewer manholes shall be circular precast reinforced concrete conforming to ASTM C478, with every pipe connection made through a resilient connector conforming to ASTM C923 (cast-in or core-drilled boot) — never a rigid mortared penetration.
7.2.2Sanitary manholes shall be made watertight against both exfiltration of sewage and infiltration of groundwater.
7.2.3Manhole section joints shall be sealed with confined O-ring gaskets (ASTM C443) or preformed butyl sealant, and the structure shall pass a vacuum or exfiltration test as required by the utility owner.
7.2.4Where an incoming sewer enters more than 24 inches above the outlet invert, a drop connection (external drop preferred for sanitary service) shall be provided so flow does not cascade onto the bench.
7.2.5The detailed manhole, casting, and structure-installation requirements parallel those in Storm Drainage and shall be applied to sanitary structures with the added watertightness and resilient-connector requirements of this section. 7.3 Force Mains and Low-Pressure Sewer
HDPE (ASTM F714/D3035, PE4710), butt-fused per ASTM D2657
PVC pressure pipe (AWWA C900), gasketed, restrained at fittings
Ductile iron (AWWA C151), lined for wastewater, restrained joints
Per drawings
7.3.1Sanitary force mains (the pressurized discharge from a lift station or grinder/pump system) shall be ductile iron (AWWA C151, lined for wastewater service), PVC pressure pipe (AWWA C900), or HDPE (ASTM F714/D3035, butt-fused), as indicated.
7.3.2A force main shall meet the pressure-pipe joint, thrust-restraint, and hydrostatic-testing requirements of this standard, not the gravity-sewer requirements.
7.3.3Force mains shall be provided with air-release/vacuum valves at high points to vent accumulated gas and prevent air-lock and surge.
NOTE HDPE is favored for force mains and low-pressure sewer because its fully fused, restrained, leak-free joint eliminates exfiltration of wastewater and infiltration, and tolerates ground movement. (7.3.4)
7.4 HDPE Pipe and Fusion
7.4.1Where HDPE is specified (force mains, low-pressure sewer, directional-drill crossings, or pressure water under special conditions), the pipe shall conform to ASTM F714 or D3035 with a minimum material designation of PE4710 and the DR indicated on the drawings.
7.4.2HDPE shall be joined by butt heat fusion conforming to ASTM D2657 using fittings conforming to ASTM D3261, producing a homogeneous, fully restrained, leak-free joint.
7.4.3Fusion shall be performed by a qualified operator following the pipe manufacturer's fusion procedure for the heater temperature, interfacial fusion pressure, and cool time.
7.4.4The external and internal fusion beads shall be uniform and continuous, and any joint with an irregular, cold, or off-center bead shall be cut out and re-fused.
7.4.5HDPE shall be installed per ASTM D2774.
8 Materials — Dry-Utility Duct Banks and Conduit
8.1 Conduit and Duct
NOTE The conduit and duct sizes, the number of ducts, and the assignment of ducts to electrical and telecom service are as indicated on the electrical drawings. (8.1.1)
PVC Schedule 40, NEMA TC-2 / UL 651 (concrete-encased duct bank)
PVC Schedule 80, NEMA TC-2 / UL 651 (direct burial / exposed-to-damage / risers)
PVC utilities duct, NEMA TC-6 & 8 (concrete-encased)
HDPE duct (directional drill / continuous-length runs)
Per electrical drawings
8.1.2Underground raceway for electrical and telecommunications cable shall be rigid PVC conduit conforming to NEMA TC-2 and UL 651 (Schedule 40 or Schedule 80 as indicated), PVC utilities duct conforming to NEMA TC-6 & 8, or HDPE duct, as indicated on the electrical drawings.
8.1.3Schedule 80 PVC, or steel conduit, shall be used at locations exposed to physical damage and at the stub-up/riser where the duct turns vertical out of the ground, as required by NFPA 70 (NEC).
8.1.4The Contractor shall provide a pull tape and shall mandrel each completed duct before turnover to demonstrate it is clear and round.
8.2 Concrete-Encased vs. Direct-Buried
NOTE The drawings establish whether each dry-utility run is concrete-encased or direct-buried. (8.2.1)
○ Concrete-encased — conduits on spacers, fully encased (primary / under roadway)
○ Direct-buried — conduits in sand/select bedding, no encasement (secondary / telecom)
○ Per electrical drawings
8.2.2The Contractor shall not substitute direct burial for a concrete-encased run shown on the drawings, because the encasement is a structural and thermal design element.
NOTE Concrete encasement is used for primary feeders, for runs under roadways and heavy live load, and wherever the design requires the duct configuration to be held rigidly to dissipate cable heat and to protect the cable from future excavation. (8.2.3)
NOTE Direct-buried conduit (individual conduits laid in the trench without encasement) is used for secondary, lighting, and telecom runs where the design does not require encasement. (8.2.4)
8.3 Tracer Wire and Marking Tape
☐ Continuous No. 12 AWG (min.) solid-copper tracer wire, brought to grade at access points
☐ Tracer-wire splices made with waterproof direct-bury connectors
☐ Tracer-wire continuity tested at final inspection
☐ Detectable warning/marking tape above pipe in APWA color code
8.3.1Every non-metallic buried utility — PVC and HDPE water, force main, and gravity sewer, and non-metallic conduit — shall be installed with a continuous insulated solid-copper tracer wire (No. 12 AWG minimum) taped to or laid alongside the pipe, brought up to grade at valve boxes, structures, and termination points so the line can be located after burial.
8.3.2Tracer-wire splices shall be made with waterproof, direct-bury connectors, and continuity shall be tested at final inspection.
8.3.3A detectable warning/marking tape shall be buried in the trench backfill above the pipe (typically 12 to 18 inches below grade) printed with the utility identification, in the APWA uniform color code: blue for potable water, green for sanitary sewer, red for electrical, and orange for communications.
9 Excavation, Bedding, and Backfill
9.1 General Trench Requirements
9.1.2In case of conflict between this standard and Earthwork on pipe and conduit bedding and embedment, the more stringent governs. 9.1.3The trench bottom shall be excavated to the pipe invert (or bottom-of-duct) grade minus the bedding thickness, on a uniform grade without dips or reverse gradient, and shall be observed and accepted by the geotechnical engineer before bedding is placed.
9.2 Bedding and Embedment
ASTM D2321 Class I — open-graded crushed stone (preferred, flexible pipe)
ASTM D2321 Class II — clean, well-graded sand or gravel
Granular bedding shaped to pipe barrel (ductile iron)
Per drawings
85100
Default: 95 percent of maximum dry density
9.2.1Bedding and pipe-zone embedment for flexible thermoplastic pipe (PVC pressure and gravity, HDPE) shall conform to ASTM D2321 Class I (open-graded crushed stone, preferred) or Class II (clean, well-graded sand or gravel), placed and worked into the haunches so the pipe is uniformly supported.
9.2.2Ductile iron pipe shall be bedded on granular material shaped to provide uniform support along the barrel, with the bell holes excavated so the pipe bears on the barrel and not on the bells.
9.2.3Class I crushed stone in the pipe zone is placed by self-consolidation and needs no mechanical compaction; Class II sand or gravel shall be compacted to the density indicated (typically 90 percent in general areas, 95 percent under pavements and structures).
9.2.4Heavy compaction equipment shall not operate directly over the pipe until at least 12 inches of cover has been placed, to avoid crushing or over-deflecting flexible pipe.
9.2.5Backfill above the pipe zone shall follow Earthwork for the applicable area, and pavement-zone backfill shall be compacted to the requirement of Aggregate Base Course and Earthwork to prevent the trench settlement that causes longitudinal pavement cracking over utility trenches. NOTE The embedment for flexible pipe is the primary structural support for the pipe and is not optional, and inadequate haunching is the most common cause of excessive deflection. (9.2.6)
10 Installation
10.1 Separation of Water and Sewer
Maintain 10 ft horizontal / 18 in vertical — no mitigation required (standard)
Water main on separate undisturbed shelf, 18 in above sewer (AHJ approved)
Sewer constructed of pressure pipe with restrained/fused joints across crossing
Sewer (or water) encased in carrier pipe 10 ft each side of crossing
10.1.1Water mains and sanitary sewers (and force mains) shall be separated to protect the potable supply from contamination, in accordance with the adopted plumbing code and the state drinking-water and wastewater regulations (the Ten States Standards values are the widely adopted reference).
10.1.2The Contractor shall maintain a minimum 10-foot horizontal separation, measured edge to edge, between any water main and any sanitary sewer or force main.
10.1.3Where 10 feet horizontal cannot be achieved, the water main shall be installed in a separate trench or on an undisturbed earth shelf, with the bottom of the water main at least 18 inches above the top of the sewer, and only with the AHJ's approval.
10.1.4At crossings, the water main shall cross with at least 18 inches of vertical clearance, preferably above the sewer, and the crossing shall be arranged so the sewer joints are as far as practicable from the water main, with a full length of sewer pipe centered on the crossing.
10.1.5Where the required separation cannot be obtained, the sewer shall be constructed of pressure-rated pipe with restrained or fully welded/fused joints, or be encased, for 10 feet on each side of the crossing.
10.2 Pipe Laying, Cover, and Alignment
18 in — direct-buried PVC conduit not under roadway
24 in — under driveways, parking, and roadways subject to vehicular traffic
Per NEC Table 300.5 for the wiring method and location
10.2.1Pressure pipe (water and force main) shall be laid to the alignment and depth indicated, with cover not less than the frost/minimum-cover requirement.
10.2.2Gravity sanitary sewer shall be laid beginning at the downstream end and progressing upstream, bells facing upstream, to the design invert and slope, verified with a pipe laser on every reach longer than 100 feet.
10.2.3The completed sewer shall have a uniform grade with no sag ("belly") that would collect solids and could not be cleaned by rodding.
10.2.4Each gasketed joint shall be assembled with the gasket correctly seated, the manufacturer's lubricant applied, and the spigot advanced to the home mark — not past it, which can roll the gasket.
10.2.5Conduit and duct shall be laid to the top-of-duct elevation and minimum bend radius indicated, with no field bend tighter than the conduit's minimum radius and with a pull tape installed.
10.3 Thrust Restraint
Restrained joints (restrained length per design pressure) — preferred
Poured concrete thrust blocks against undisturbed soil
Combination — restrained joints with thrust blocks at major fittings
Not applicable — fully fused HDPE (restraint only at terminations)
Per thrust-restraint details
10.3.1Each bend, tee, cross, reducer, valve, hydrant, and dead end in a pressure system shall be restrained so the fitting cannot pull apart or blow off the main when the line is pressurized.
10.3.2Thrust restraint shall be provided by restrained joints (restrained push-on or mechanical-joint glands and tie rods on ductile iron, and equivalent restraint on PVC and HDPE) for the restrained length calculated for the test pressure, or by poured concrete thrust blocks bearing against undisturbed trench wall sized for the thrust and the soil bearing value, as indicated on the thrust-restraint details.
10.3.3Thrust blocks shall bear against undisturbed soil, shall not encase the joint (so the joint remains accessible), and shall be allowed to cure before the line is pressure tested.
10.3.4The Contractor shall not backfill any fitting until its restraint is installed and inspected.
10.3.5HDPE, because its fused joints are fully restrained and continuous, generally requires no separate thrust restraint along its fused length, but transitions to gasketed pipe or mechanical fittings at the HDPE termination do require restraint.
NOTE Every change in direction or termination in a pressure system develops an unbalanced thrust force when the line is pressurized. (10.3.6)
10.4 Duct-Bank Assembly and Encasement
25004000
Default: 3000 psi at 28 days
10.4.1Conduits in a concrete-encased duct bank shall be assembled on interlocking spacers (base spacers and intermediate spacers) that hold the array in the configuration shown, with the spacing maintained so concrete flows fully around and between every conduit.
10.4.2The assembled duct bank shall be anchored against flotation during the concrete pour (the empty conduits are buoyant in wet concrete) by tying the array down to the trench or staking it.
10.4.3Concrete for encasement shall be as specified on the drawings (commonly 3,000 psi minimum); where the drawings call for it the concrete is dyed red for electrical identification.
10.4.4Conduit joints shall be solvent-welded watertight so concrete does not intrude into the bore, and the bell ends at structures shall use end bells to protect the cable jacket.
10.4.5After the encasement has cured, each duct shall be proved clear with a mandrel and a pull tape left in place.
11 Testing
11.1 Hydrostatic and Leakage Test — Pressure Pipe
○ Allowable leakage per AWWA C600/C605 formula (diameter, length, joints, pressure)
○ Zero measurable leakage (fused HDPE force main)
11.1.1After the pressure main (water or force main) has been backfilled with thrust restraint in place and cured, it shall be slowly filled, all air expelled through hydrants or air valves, and pressure-tested hydrostatically in accordance with AWWA C600 (ductile iron) or AWWA C605 (PVC) — or the manufacturer's procedure for HDPE.
11.1.2The test pressure shall be as indicated, commonly 1.5 times the working pressure or 150 psi minimum, held for the specified duration, and the allowable leakage during the test shall not exceed the rate computed by the applicable AWWA formula (a function of pipe diameter, length, number of joints, and test pressure).
11.1.3The Contractor shall locate and repair any leak that causes the makeup water to exceed the allowable leakage, and shall re-test.
11.1.4Pipe shall not be tested before thrust blocks have reached adequate strength.
11.2 Low-Pressure Air and Deflection Tests — Gravity Sewer
57.5
Default: 5 percent of base inside diameter
○ Not earlier than 30 days after final backfill and cover load (standard)
○ Per utility owner / drawings
11.2.1Gravity sanitary sewer shall be tested for leakage by the low-pressure air test in accordance with ASTM F1417 (or by an exfiltration/infiltration water test where the utility owner requires it): the reach between manholes is plugged, pressurized with air to the starting test pressure, allowed to stabilize, and the time for a specified pressure drop is measured against the minimum hold time for the pipe diameter and length.
11.2.2Flexible gravity pipe (PVC) shall be deflection-tested by pulling a rigid mandrel through the line not earlier than 30 days after final backfill.
11.2.3The installed deflection shall not exceed 5 percent of the pipe's base inside diameter, and any reach that will not pass the mandrel shall be uncovered, re-bedded, and re-tested.
11.3 Manhole and Duct-Bank Tests
○ Vacuum test (standard for precast manholes)
○ Exfiltration / infiltration water test
○ Per utility owner
11.3.1Sanitary manholes shall be tested for watertightness by vacuum test or by exfiltration test as required by the utility owner, before the system is placed in service.
11.3.2Each completed duct in a duct bank, whether encased or direct-buried, shall be proved with a mandrel sized for the conduit (to confirm it is clear and round) and shall be left with a pull tape; ducts that will not pass the mandrel shall be cleared or replaced before turnover.
12 Disinfection of Water Mains
Continuous-feed (chlorine fed to fill water, 25 mg/L, 24-hour contact)
Slug method (high-concentration slug moved through main)
Tablet method (where permitted by AWWA C651 for the conditions)
○ Two consecutive satisfactory (coliform-absent) sample sets, 24 hours apart (standard)
○ Per state drinking-water regulation / utility owner
○ Dechlorinate to permitted residual and dispose per discharge permit (required)
12.1New and repaired potable water mains shall be disinfected in accordance with AWWA C651 before being placed in service.
12.2After the hydrostatic test, the main shall be flushed at a velocity adequate to remove construction debris, then disinfected by one of the AWWA C651 methods — continuous-feed, slug, or tablet — to achieve the required free-chlorine residual throughout the main for the required contact time (the continuous-feed and slug methods are the standards for site distribution mains; tablet methods are limited by AWWA C651 to specific conditions).
12.3After the contact period, the heavily chlorinated water shall be dechlorinated and disposed of in accordance with AWWA C651 and the project's discharge permit — it shall not be discharged to a watercourse or storm system without neutralization.
12.4The main shall then be flushed and sampled, and shall not be placed in service until two consecutive sets of bacteriological samples taken at least 24 hours apart are satisfactory (absence of coliform).
12.5Where the first samples fail, the main shall be re-disinfected, re-flushed, and re-sampled.
13 Delivery, Storage, and Handling
☐ Pipe stored on level dunnage, supported against deformation
☐ PVC and HDPE protected from prolonged UV exposure
☐ Gaskets stored clean, cool, out of sunlight; rejected if damaged
☐ Pipe interiors capped/plugged when work stops
☐ Conduit/duct ends capped to keep bore clean
13.1Pipe, fittings, valves, hydrants, conduit, and gaskets shall be delivered, stored, and handled to prevent damage and contamination.
13.2Pipe shall be stored on level dunnage, supported to prevent bending and out-of-round deformation.
13.3PVC and HDPE pipe shall be protected from prolonged ultraviolet exposure (covered or stored out of direct sun), because UV degrades the polymer over extended exposure.
13.4Gaskets shall be stored clean, cool, and out of sunlight, and shall not be used if cut, weathered, or deformed.
13.5Pipe interiors shall be kept clean and shall be capped or plugged when work stops, to keep debris, animals, and contamination out — this is especially important for potable water main, where a contaminated interior must be disinfected again.
13.6Conduit and duct shall be stored with end caps to keep the bore clean.
13.7The Contractor shall inspect every length and fitting for damage before installation and shall reject and remove damaged material from the project.
14 Warranty
14.1The Contractor shall warrant the site utility installation against leaks, joint failures, settlement, deflection beyond the acceptance limit, and defects in materials and workmanship for a period of not less than one year from substantial completion, or for the period stated in the contract documents or required by the utility owner if longer.
14.2Any leak in a pressure main or force main, any exfiltration or infiltration in a gravity sewer or manhole, any pavement settlement attributable to inadequate trench backfill compaction over a utility trench, and any duct that becomes obstructed shall be corrected at the Contractor's expense, including pavement and surface restoration and, for potable water, re-disinfection and re-clearance.
14.3The installation shall satisfy the utility owner's acceptance and bonding requirements where the system is to be turned over to the public utility for ownership and maintenance.