SYNC™

SynC · Editorial revision

Cast-in-Place Site Concrete Structures

Revision3
EditedOct 12, 2026
StatusCurrent
Contents

View changes in this revision   Revision history

Current revision. This is editorial revision 3, the current text of this standard. Read it on the standard's page.

SynC Standards Team — Specifier (Platform Standards) ✓ OfficialDiscloses employment SynC (SynC Platform Team)
Remake batch 22: rewritten from scratch under the authoring cheatsheet with datasheet constraints; scope boundaries restated against the remade neighbors

1 Scope

NOTE This standard governs what a cast-in-place site structure adds to the concrete standards it is built under: the exposure a structure meets in soil and runoff, the strength of its concrete, casting against earth, the ties and waterstops in walls below groundwater, the openings and penetrations through its walls, the frames, steps, and hardware built into it, the geometry particular to a headwall or a chamber, the items cast into a utility vault, the joints in its aprons and slabs, its surface protection, the dewatering and flotation of its excavation, the strength it needs before it is backfilled, and its warranty. (1.1)
NOTE The structures in scope are the concrete of the site that is formed and placed where it stands and that is not designed to hold water: (1.2)
  • drainage headwalls, endwalls, and wingwalls at culvert and storm outfalls, with their aprons and cutoff walls
  • inlets, catch basins, junction chambers, diversion structures, and outlet control structures constructed cast in place rather than precast
  • stormwater detention vaults designed under ACI 318, whose function tolerates seepage
  • electrical and communications utility vaults constructed cast in place where a precast unit does not fit the configuration or the site
  • collars, adjustment rings, and base slabs cast in place on precast units
  • trench walls, channel linings, ditch checks, and energy dissipators
  • the bases of poles, posts, and signs where the standard that furnishes the pole, post, or sign does not govern its base
NOTE Whether a storm drainage structure is precast or formed on site is selected under Storm DrainageStorm DrainageResolves to the current adopted revision.sync/storm-drainage, and whether a detention facility's underground storage is designed under ACI 350 or ACI 318 is selected under Stormwater Management SystemsStormwater Management and Detention SystemsResolves to the current adopted revision.sync/stormwater-management-systems; this standard governs the structure once those selections have made it a formed-in-place structure that is not water-retaining. A structure designed under ACI 350 to contain water, or to remain dry below groundwater by its concrete alone, is governed by Water Retaining Concrete StructuresWater-Retaining Concrete StructuresResolves to the current adopted revision.sync/water-retaining-concrete-structures whatever its function, because the concrete is then the barrier and the tightness test is the proof. (1.3)
NOTE The concrete standards on this platform are layered, and this standard sits above the material layer. The constituent materials, mixture qualification, production, delivery, placement, consolidation, weather protection, field testing, and strength acceptance of all concrete are governed by Cast In Place ConcreteCast-in-Place ConcreteResolves to the current adopted revision.sync/cast-in-place-concrete; the bars, their placement and splices, and the ACI 318 cover minimums by Concrete ReinforcementConcrete ReinforcementResolves to the current adopted revision.sync/concrete-reinforcement; the forms, ties as hardware, chamfer strips, release agents, and stripping by Concrete FormworkConcrete Formwork and AccessoriesResolves to the current adopted revision.sync/concrete-formwork; curing and finishes by Concrete Curing And FinishingConcrete Curing and FinishingResolves to the current adopted revision.sync/concrete-curing-and-finishing; joint types, layout in walls, waterstop materials and profiles, fillers, and sealants by Concrete Joints And WaterstopsConcrete Construction Joints and WaterstopsResolves to the current adopted revision.sync/concrete-joints-and-waterstops, with the waterstop products under Concrete AccessoriesConcrete Accessories and EmbedsResolves to the current adopted revision.sync/concrete-accessories. This standard restates none of that. (1.4)
NOTE The following are governed elsewhere and are outside this standard: (1.5)
  • the storm sewer behind a headwall, the outfall end treatment and scour protection, the castings at an access opening, the pipe-to-structure connector, and the bench and channel of a storm structure, under Storm DrainageStorm DrainageResolves to the current adopted revision.sync/storm-drainage
  • the detention facility, the hydraulics of its outlet control, and the measurement of its orifices and weirs at acceptance, under Stormwater Management SystemsStormwater Management and Detention SystemsResolves to the current adopted revision.sync/stormwater-management-systems
  • the gates and trash racks mounted on the structures of this standard, with the template and the opening dimension their manufacturer furnishes, under Slide Gates And Stop LogsSlide Gates and Stop LogsResolves to the current adopted revision.sync/slide-gates-and-stop-logs
  • thrust blocks and anchor blocks, under the standard whose pipe they restrain, Water Distribution PipingSite Water Distribution PipingResolves to the current adopted revision.sync/water-distribution-piping, Ductile Iron Process PipingDuctile Iron Process PipingResolves to the current adopted revision.sync/ductile-iron-process-piping, and Site UtilitiesSite UtilitiesResolves to the current adopted revision.sync/site-utilities
  • precast manholes, handholes, and vaults, under Utility Manholes And HandholesUtility Manholes and HandholesResolves to the current adopted revision.sync/utility-manholes-and-handholes, Storm DrainageStorm DrainageResolves to the current adopted revision.sync/storm-drainage, and Sanitary Sewer SystemsSanitary Sewer Systems (Site)Resolves to the current adopted revision.sync/sanitary-sewer-systems
  • paving, curbs, gutters, sidewalks, and the joints in them, under Concrete PavingConcrete Paving, Curbs, and SidewalksResolves to the current adopted revision.sync/concrete-paving; equipment pads under Concrete PadsConcrete Equipment PadsResolves to the current adopted revision.sync/concrete-pads; site retaining walls under Retaining WallsSite Retaining WallsResolves to the current adopted revision.sync/retaining-walls; building footings and foundation walls under Shallow FoundationsShallow Foundations (Spread and Strip Footings)Resolves to the current adopted revision.sync/shallow-foundations and Deep FoundationsDeep Foundations (Piles and Drilled Piers)Resolves to the current adopted revision.sync/deep-foundations
  • light pole foundations under Exterior LightingExterior and Site LightingResolves to the current adopted revision.sync/exterior-lighting, flagpole foundations under FlagpolesFlagpolesResolves to the current adopted revision.sync/flagpoles, fence post footings under Fencing And GatesFencing and GatesResolves to the current adopted revision.sync/fencing-and-gates, and bollard footings under Site Furnishings And BollardsSite Furnishings and BollardsResolves to the current adopted revision.sync/site-furnishings-and-bollards
  • excavation, sump pumping, fill, and the placement and compaction of backfill, under EarthworkEarthworkResolves to the current adopted revision.sync/earthwork; engineered dewatering and excavation support under Excavation Support And DewateringExcavation Support and DewateringResolves to the current adopted revision.sync/excavation-support-and-dewatering; the subgrade the structure bears on under Site Rough GradingSite Grading and Subgrade PreparationResolves to the current adopted revision.sync/site-rough-grading
  • post-installed anchors under Post Installed AnchorsPost-Installed Concrete and Masonry AnchorsResolves to the current adopted revision.sync/post-installed-anchors, non-shrink grout as a material under Non Shrink GroutNon-Shrink GroutResolves to the current adopted revision.sync/non-shrink-grout, and the duct bank that enters a utility vault under Underground DuctbankUnderground Electrical Duct BanksResolves to the current adopted revision.sync/underground-ductbank
  • the special inspection agency and the statement of special inspections, under Special Inspections And TestingSpecial Inspections and Structural TestingResolves to the current adopted revision.sync/special-inspections-and-testing
  • the structural design of every structure, which the Engineer of Record performs and records on the contract documents
NOTE A site structure is a small volume of concrete that is almost never looked at again. It is backfilled within days of stripping, it sits in soil that may be sulfate-bearing and water that may be salt-laden, it freezes wet every winter, and the pipe through its wall is the one path water will find. The requirements that follow are ordered around the two things that cannot be corrected after the pour: what is built into the wall, and what the wall is made of. (1.6)
1.7 Site structures shall comply with Cast In Place ConcreteCast-in-Place ConcreteResolves to the current adopted revision.sync/cast-in-place-concrete, Concrete ReinforcementConcrete ReinforcementResolves to the current adopted revision.sync/concrete-reinforcement, Concrete FormworkConcrete Formwork and AccessoriesResolves to the current adopted revision.sync/concrete-formwork, Concrete Curing And FinishingConcrete Curing and FinishingResolves to the current adopted revision.sync/concrete-curing-and-finishing, and Concrete Joints And WaterstopsConcrete Construction Joints and WaterstopsResolves to the current adopted revision.sync/concrete-joints-and-waterstops except as modified by this standard.
1.8 The locations, dimensions, elevations, reinforcement, and design loads of each structure shall be as indicated on the civil structure details and the structural general notes.
1.9 Where the contract documents, the adopted code, and a referenced standard impose conflicting requirements on the same subject, the more stringent requirement shall govern unless the Engineer of Record directs otherwise in writing.
1.10 The Contractor shall not reduce a wall thickness, a slab thickness, a footing dimension, a reinforcing bar size or spacing, or a cover from the values shown on the contract documents without the written approval of the Engineer of Record.

2 Referenced Standards

2.1 Materials, construction, and testing shall comply with the latest adopted edition of each of the following unless a specific edition is cited.
2.2 Where referenced standards conflict, the more stringent requirement shall govern unless the Engineer of Record directs otherwise in writing.
Standard Title
ACI 117 Specification for Tolerances for Concrete Construction and Materials
ACI 301 Specifications for Concrete Construction
ACI 318 Building Code Requirements for Structural Concrete and Commentary
ACI 350 Code Requirements for Environmental Engineering Concrete Structures and Commentary
ASTM C478 Circular Precast Reinforced Concrete Manhole Sections
ASTM C923 Resilient Connectors Between Reinforced Concrete Manhole Structures, Pipes, and Laterals
ASTM C1107/C1107M Packaged Dry, Hydraulic-Cement Grout (Nonshrink)
ASTM C1244 Concrete Sewer Manholes by the Negative Air Pressure (Vacuum) Test Prior to Backfill
ASTM D1056 Flexible Cellular Materials, Sponge or Expanded Rubber
ASTM F1554 Anchor Bolts, Steel, 36, 55, and 105-ksi Yield Strength
AASHTO LRFD AASHTO LRFD Bridge Design Specifications
ICC IBC International Building Code
NFPA 70 National Electrical Code

3 Submittals

3.1 Action Submittals

3.1.1 The Contractor shall submit the following for review and acceptance before reinforcement is fabricated for the structure and before concrete is placed in it:
  • The mixture class designation and the exposure classes for the concrete of each structure type, with the mixture design itself submitted under Cast In Place ConcreteCast-in-Place ConcreteResolves to the current adopted revision.sync/cast-in-place-concrete
  • Reinforcement placing drawings for each structure, showing the bars around every opening and the cover to each surface, submitted under Concrete ReinforcementConcrete ReinforcementResolves to the current adopted revision.sync/concrete-reinforcement and identified by structure
  • A penetration and embedment layout for each structure, showing every pipe opening with its invert, every conduit entry, every sleeve, the frame seat, the steps or ladder, the anchor bolts for gates and hardware, and the items cast into a vault, reconciled against the civil, electrical, and process drawings
  • The waterstop layout for each structure with construction joints below groundwater or below the design water surface, submitted under Concrete Joints And WaterstopsConcrete Construction Joints and WaterstopsResolves to the current adopted revision.sync/concrete-joints-and-waterstops
  • The anchor bolt template and the opening dimension furnished by the gate manufacturer under Slide Gates And Stop LogsSlide Gates and Stop LogsResolves to the current adopted revision.sync/slide-gates-and-stop-logs for each headwall that receives a gate
  • The form tie type and water seal proposed for walls below the seasonal high groundwater elevation
  • Product data for the annular seal, the frame seat mortar or grout, the steps or ladder, the weep hole filter, and the surface treatment
Action Submittals Requiredcheckbox
☑ Mixture class and exposure classes for each structure type
☑ Reinforcement placing drawings identified by structure
☑ Penetration and embedment layout for each structure
☐ Waterstop layout for structures with joints below groundwater or below the design water surface
☐ Gate manufacturer's anchor bolt template and opening dimension
☐ Form tie type and water seal below groundwater
☑ Product data for seals, grout, steps, filters, and surface treatment
3.1.2 Concrete shall not be placed in a structure until the submittals covering that structure have been reviewed and returned.
NOTE The penetration and embedment layout is the submittal that prevents the expensive failures. A pipe opening an inch off its invert, a conduit entry on the wrong wall, and a frame seat formed to the wrong casting are each discovered after stripping, and each is corrected by coring a reinforced wall or demolishing a top slab. The layout is reconciled against every drawing that puts something through the wall, not against the civil drawings alone. (3.1.3)

3.2 Informational Submittals

3.2.1 The Contractor shall submit the following before the first structure is formed:
  • The geotechnical report pages that state the water-soluble sulfate content of the soil and groundwater and the seasonal high groundwater elevation at the structure locations
  • The dewatering method proposed for each excavation that will be below groundwater when concrete is placed, where the method is sump pumping under EarthworkEarthworkResolves to the current adopted revision.sync/earthwork
  • The qualifications of the party that will perform the verification before concrete is placed
Informational Submittals Requiredcheckbox
☑ Geotechnical report pages for sulfate content and groundwater elevation
☐ Dewatering method for excavations below groundwater
☑ Qualifications of the party performing the pre-placement verification

3.3 Closeout Submittals

3.3.1 The Contractor shall submit the following before the structures are accepted:
  • Record drawings for each structure giving the as-built location, the top elevation, every pipe and conduit invert, every weir crest and orifice elevation, and the as-set position of every frame, gate anchor group, and cast-in item
  • The verification record made before concrete was placed in each structure
  • Strength test reports for the concrete, indexed to the structures each placement served, as required by this standard for the vaults deferred here under Stormwater Management SystemsStormwater Management and Detention SystemsResolves to the current adopted revision.sync/stormwater-management-systems
  • The backfill release record for each structure, giving the basis on which backfill against its walls was released and the date
  • The record of every opening cored after placement, with the Engineer of Record's written direction for it
  • Manufacturer warranties for steps, ladders, seals, and surface treatments, assigned to the Owner
Closeout Submittals Requiredcheckbox
☑ Record drawings with as-built inverts, elevations, and cast-in item positions
☑ Pre-placement verification record for each structure
☑ Strength test reports indexed to each structure
☑ Backfill release record for each structure
☐ Record of openings cored after placement
☐ Assigned manufacturer warranties

4 Quality Assurance

4.1 Inspection Program for Site Structures

NOTE A site structure outside the building footprint may or may not fall within the building permit, and the inspection program follows the permit. A structure within the permit is inspected under the Statement of Special Inspections that Adopted Building CodeAdopted Building CodeParameterEach project supplies its own value.adopted-building-code requires; a structure outside it is inspected under whatever program the contract documents set up, which on many sites is the Owner's testing agency at the concrete hold points and nothing more. The decision matters because the ACI 318 exemptions for isolated footings and nonstructural slabs do not describe a headwall or a vault wall, and a structure that was never inspected by anyone is the one whose reinforcement was never seen. (4.1.1)
4.1.2 The inspection program for the structures of this standard shall be as indicated in the datasheet.
Inspection Program for Site Structuresradio
○ Special inspection under the project Statement of Special Inspections
○ Inspection by the Owner's testing agency at the hold points of this standard without a Statement of Special Inspections
○ Contractor quality control with observation by the Engineer of Record at the hold points of this standard
NOTE Special inspection, where it applies, is a program under ICC IBC Chapter 17 with an approved agency, a statement, and a final report, and it is what a permitted structure requires; the Owner's testing agency at the hold points gives independent eyes on the reinforcement and the embedments without the permit apparatus, which is the program of most site work outside the building; Contractor quality control with the Engineer of Record observing is the lightest program, and it depends on the Engineer of Record actually attending the hold point rather than waiving it from the office. (4.1.3)
4.1.4 Where special inspection applies, it shall be performed as set out in the project Statement of Special Inspections and administered under Special Inspections And TestingSpecial Inspections and Structural TestingResolves to the current adopted revision.sync/special-inspections-and-testing.
4.1.5 Field sampling and testing of the concrete shall be performed by the testing agency and the technicians qualified under Cast In Place ConcreteCast-in-Place ConcreteResolves to the current adopted revision.sync/cast-in-place-concrete.

4.2 Verification Before Concrete Is Placed

4.2.1 Immediately before concrete is placed in any wall, slab, or footing of a structure, the Contractor shall verify and record the items indicated in the datasheet for that placement.
Verification Required Before Concrete Is Placedcheckbox
☑ Bearing surface is accepted, free of water, ice, loose material, and disturbed soil, and at the elevation shown
☑ Reinforcement is placed, supported, tied, and at the required cover, with the bars around every opening in place
☑ Every pipe opening, sleeve, connector, and conduit entry is at the location and invert on the reconciled layout
☑ Waterstops are continuous, spliced, and secured at every joint that requires one
☐ Form ties below groundwater carry the required water seal
☑ Frame seat, steps or ladder inserts, gate anchor bolts, and cast-in items are positioned and secured
☐ Weir and orifice forms are at the elevations shown
☑ Forms are dimensionally correct, tight, braced, chamfered where required, and treated with release agent
☐ Dewatering is maintaining the excavation free of standing water
4.2.2 Concrete shall not be placed until every deficiency found in the verification has been corrected.
4.2.3 The verification record shall identify the structure, the placement, the date, and the person who performed it.
4.2.4 Where the inspection program includes an inspector or the Engineer of Record at the placement, the Contractor shall give not less than one working day's notice of each placement and shall not place concrete until the inspector or the Engineer of Record has released it or has waived attendance in writing.
NOTE Everything on the verification list is buried by the pour. A pipe opening at the wrong invert is found when the pipe is laid to it, a missing waterstop is found by the water, and a frame seat formed to the wrong ring is found when the casting does not fit, and each of those is found after the structure is backfilled. (4.2.5)

5 Structures Covered and Their Design Basis

5.1 The cast-in-place site structures in the work shall be as indicated in the datasheet.
Cast-in-Place Site Structures in the Workcheckbox
☐ Headwalls, endwalls, and wingwalls with aprons and cutoff walls
☐ Inlets and catch basins
☐ Junction chambers, diversion structures, and outlet control structures
☐ Stormwater detention vaults designed under ACI 318
☐ Electrical and communications utility vaults
☐ Collars, adjustment rings, and base slabs on precast units
☐ Trench walls, channel linings, ditch checks, and energy dissipators
☐ Pole, post, and sign bases not governed by the furnishing standard
5.2 Each structure shall be designed by the Engineer of Record under ACI 318 for the soil, groundwater, surcharge, and vehicle loads shown on the contract documents, and the design shall be recorded on those documents.
5.3 Where a structure lies within a vehicular area, it shall be designed for the vehicle load the contract documents state, and where they state none, for the AASHTO LRFD design truck.
5.4 Footings and base slabs shall bear below Frost DepthFrost DepthParameterEach project supplies its own value.frost-depth, on a bearing surface prepared and accepted under EarthworkEarthworkResolves to the current adopted revision.sync/earthwork, unless the structure details show a design that does not depend on bearing below frost.
NOTE A headwall that heaves lifts the pipe end with it and opens the last joint, and a vault that heaves tilts its frame out of the pavement; the bearing elevation is the one dimension of a site structure that the climate sets rather than the hydraulics. (5.5)
5.6 Where a single structure is part cast in place and part precast, the contract documents shall identify which portions are governed by this standard and which by Utility Manholes And HandholesUtility Manholes and HandholesResolves to the current adopted revision.sync/utility-manholes-and-handholes, Storm DrainageStorm DrainageResolves to the current adopted revision.sync/storm-drainage, or Sanitary Sewer SystemsSanitary Sewer Systems (Site)Resolves to the current adopted revision.sync/sanitary-sewer-systems.

6 Exposure of Site Structures

NOTE A site structure is exposed to its own environment and not to the environment of the building it is priced with. An interior building mixture assigned by habit to a headwall meets freezing, thawing, deicing salt in the runoff, and sulfate in the soil that no member of the building sees, and it scales at the waterline within a few winters. The exposure classes of Cast In Place ConcreteCast-in-Place ConcreteResolves to the current adopted revision.sync/cast-in-place-concrete are assigned here for the site structures as structures of their own. (6.1)
6.2 The freeze-thaw exposure class for the concrete of site structures shall be as indicated in the datasheet.
Freeze-Thaw Exposure Class of Site Structuresselect
F0
F1
F2
F3
Derived — Climate ZoneClimate ZoneParameterEach project supplies its own value.climate-zone and whether the structure is in contact with runoff, groundwater, or deicing chemicals in service (by default)
NOTE A structure in a climate where the concrete does not freeze while wet is class F0 whatever it holds; a structure that freezes and is wetted only by rain is F1; a headwall, an apron, a channel lining, and any structure that conveys or stands in water through the freezing season is F2, because the concrete is saturated when it freezes; and a structure that receives runoff from a paved surface treated with deicing chemicals, which is every inlet, outlet, and vault beneath a parking lot or a drive in a freezing climate, is F3. The class follows those conditions and not a preference, which is why it is derived rather than chosen. (6.3)
6.4 The sulfate exposure class of each structure shall be assigned under Cast In Place ConcreteCast-in-Place ConcreteResolves to the current adopted revision.sync/cast-in-place-concrete from the water-soluble sulfate content of the soil and groundwater at the structure, as reported in the geotechnical report.
6.5 A structure that conveys or stands in water in service shall be assigned contact-with-water exposure class W1 or higher, and a structure designed to remain dry under groundwater without a membrane shall be assigned class W2.
6.6 A structure that receives runoff from a surface treated with deicing chemicals, or that is in contact with brackish water or seawater, shall be assigned corrosion-protection exposure class C2.
6.7 The maximum water-cementitious materials ratio, the air content, the cementitious materials, and the chloride limit of each mixture shall follow from the assigned exposure classes under Cast In Place ConcreteCast-in-Place ConcreteResolves to the current adopted revision.sync/cast-in-place-concrete, and this standard does not restate them.

7 Site Structure Concrete

7.1 Site structure concrete shall be furnished, delivered, placed, consolidated, tested, and accepted in accordance with Cast In Place ConcreteCast-in-Place ConcreteResolves to the current adopted revision.sync/cast-in-place-concrete.
7.2 The specified compressive strength of site structure concrete shall be as indicated in the datasheet, and not less than the minimum the assigned exposure classes require under ACI 318.
Specified Compressive Strength of Site Structure Concreterange
Not less than
psi
2500300035004000450050006000
Per drawings — the structural general notes or the civil structure details (deferred by default)
NOTE The strength of a site structure is set twice, by the structural design and by the exposure classes, and the higher governs. An F3 assignment carries a 5000 psi minimum under ACI 318 regardless of what the wall needs structurally, which is why a lightly loaded headwall in a deicing climate is specified at a strength its loads would never justify, and why the same headwall in a frost-free climate is not. (7.3)
7.4 The nominal maximum coarse aggregate size shall satisfy the section and bar-spacing limits of Cast In Place ConcreteCast-in-Place ConcreteResolves to the current adopted revision.sync/cast-in-place-concrete evaluated at the most congested location in the structure, which is the wall at a pipe opening.
7.5 The walls and base slab of a chamber or vault shall be placed in the sequence shown on the structure details, with a construction joint at the base of the walls prepared as Concrete Joints And WaterstopsConcrete Construction Joints and WaterstopsResolves to the current adopted revision.sync/concrete-joints-and-waterstops requires, unless the structure is placed monolithically.
7.6 Concrete shall not be placed in water, on a frozen or saturated bearing surface, or on a bearing surface that has been disturbed since it was accepted.

8 Reinforcement in Site Structures

8.1 Reinforcement shall be furnished, fabricated, supported, spliced, and placed in accordance with Concrete ReinforcementConcrete ReinforcementResolves to the current adopted revision.sync/concrete-reinforcement.
8.2 Concrete cover to reinforcement shall be the cover Concrete ReinforcementConcrete ReinforcementResolves to the current adopted revision.sync/concrete-reinforcement requires for the casting condition and the exposure of each surface, measured for a surface cast against earth from the earth face as it was excavated and not from the neat line.
NOTE Cover is the dimension a site structure loses most often, because its footings and base slabs are cast against the ground and the ground is not where the drawing shows it. ACI 318 asks three inches at a surface cast against and permanently exposed to earth, and a mat set on chairs at the neat-line depth over an over-excavated bottom has that cover only on paper. (8.3)
8.4 Bar supports bearing on earth shall be precast concrete blocks or supports with a bearing plate, and shall not be bricks, stones, or wood.
8.5 The bars shown on the structure details around each pipe opening, conduit entry, frame opening, and blockout shall be placed before the opening is formed, and no bar shall be cut or bent in the field to clear an opening without the Engineer of Record's written direction.
8.6 Where the exposure class of a structure is C2, the reinforcement shall be corrosion-protected where Concrete ReinforcementConcrete ReinforcementResolves to the current adopted revision.sync/concrete-reinforcement or the structure details require it, and bar supports shall not present bare steel at a surface exposed to runoff.

9 Formwork for Site Structures

9.1 Formwork shall be designed, furnished, erected, and removed in accordance with Concrete FormworkConcrete Formwork and AccessoriesResolves to the current adopted revision.sync/concrete-formwork.

9.2 Casting Against Earth

9.2.1 Footings and base slab edges shall be cast as indicated in the datasheet.
Casting of Footings and Base Slab Edgesradio
○ Formed on every face
○ Cast against neat-cut excavation faces where the soil stands vertically
NOTE Casting against the excavation saves the forms and the working room on a footing nobody will see, and it is how most headwall footings and many base slabs are placed; it costs the three inches of cover ACI 318 asks at an earth face, a width that grows with every slough of the bank, and a surface that cannot be inspected. Forming every face costs the forms and an excavation wide enough to strip them, and it gives a footing of the dimensions on the drawing. The choice follows the soil: a sand that will not stand is formed whatever the datasheet says. (9.2.2)
9.2.3 Where a footing or slab is cast against earth, the excavation faces shall be trimmed to the lines shown, loose material shall be removed before placement, and the additional width the concrete takes shall be at the Contractor's expense.
9.2.4 Walls shall be formed on both faces.

9.3 Form Ties in Walls Below Groundwater

NOTE A form tie passes through the wall at every point it holds, and in a wall that stands in groundwater each tie is a path through it. A vault that is not designed to be water-retaining still needs its ties sealed, because the alternative is a vault with a weep at every tie hole. The hardware, the working load, the break-back, and the patching are specified under Concrete FormworkConcrete Formwork and AccessoriesResolves to the current adopted revision.sync/concrete-formwork; this article adds the water seal. (9.3.1)
9.3.2 Form ties in walls that extend below Seasonal High Groundwater ElevationSeasonal High Groundwater ElevationParameterEach project supplies its own value.seasonal-high-groundwater-elevation, and in walls that stand in water in service, shall carry the water seal indicated in the datasheet.
Form Tie Water Seal in Walls Below Groundwaterradio
○ Integral waterstop washer or plate on the tie at mid-wall
○ Removable rod in a sleeve, with the sleeve removed and the hole sealed full depth
○ Taper tie with a cone at each face, the cone recess plugged and sealed
NOTE A waterstop washer welded to the tie at mid-wall lengthens the path water must travel along the tie and is what most snap ties and coil ties in a below-grade wall carry; a removable rod leaves a clean hole sealed through the full thickness, which is the tightest result and the most labor; a taper tie leaves a cone recess at each face and the tie body in the wall, and depends on each recess being sealed rather than merely patched. (9.3.3)
9.3.4 Tie holes on the face that will be against the water shall be filled before tie holes on the opposite face, with the material and method of Concrete FormworkConcrete Formwork and AccessoriesResolves to the current adopted revision.sync/concrete-formwork.

9.4 Chamfers and Formed Finish

9.4.1 Exposed external corners of walls, headwalls, wingwalls, and tops shall be chamfered with the strips furnished under Concrete FormworkConcrete Formwork and AccessoriesResolves to the current adopted revision.sync/concrete-formwork, to a leg of not less than 3/4 in. unless the structure details show a different edge.
9.4.2 The finish on exposed formed faces of site structures shall be as indicated in the datasheet, executed as Concrete Curing And FinishingConcrete Curing and FinishingResolves to the current adopted revision.sync/concrete-curing-and-finishing specifies for that finish.
Finish on Exposed Formed Facesselect
Smooth form finish with fins removed and tie holes filled
Rubbed finish
Rough form finish as cast
Form liner texture
NOTE A smooth form finish with the fins removed and the tie holes filled is what nearly every headwall and vault receives, and it is what a plywood or steel form leaves when it is set tight; a rubbed finish adds a grout rub that closes the surface voids and evens the color on a structure in public view, at the cost of a second operation on every face; a rough form finish as cast is the finish of a structure that will be buried on every face; a form liner texture is an architectural decision for a headwall or wall that faces a street or a trail. (9.4.3)
9.4.4 Faces that will be buried, and the interior faces of vaults and chambers, shall receive a rough form finish as cast with fins removed and tie holes filled, whatever finish is indicated for the exposed faces.

10 Joints and Waterstops in Site Structures

10.1 Joint types, joint layout in walls and slabs, waterstop materials and profiles, splices, joint fillers, and joint sealants shall be as specified under Concrete Joints And WaterstopsConcrete Construction Joints and WaterstopsResolves to the current adopted revision.sync/concrete-joints-and-waterstops, with the waterstop products furnished under Concrete AccessoriesConcrete Accessories and EmbedsResolves to the current adopted revision.sync/concrete-accessories.

10.2 Construction Joints Receiving a Waterstop

NOTE A site structure is not designed to hold water, and most of its construction joints never see a head of water. The ones that do are the joints below the groundwater table in a vault wall and the joints below the water surface in a structure that conveys flow, and an unstopped joint in either is the leak that lets groundwater and the soil it carries into the structure, or lets the flow out into the embankment. Which joints are stopped is the decision this article settles; what the waterstop is made of is settled under Concrete Joints And WaterstopsConcrete Construction Joints and WaterstopsResolves to the current adopted revision.sync/concrete-joints-and-waterstops. (10.2.1)
10.2.2 The construction joints in site structures that receive a waterstop shall be as indicated in the datasheet.
Construction Joints Receiving a Waterstopradio
○ Every construction joint in walls and base slabs
○ Construction joints below the seasonal high groundwater elevation and below the design water surface
○ No waterstops in the structures of this standard
NOTE Stopping every joint costs a waterstop in joints that will never see water and buys a vault that does not have to be reasoned about joint by joint; stopping only the joints below Seasonal High Groundwater ElevationSeasonal High Groundwater ElevationParameterEach project supplies its own value.seasonal-high-groundwater-elevation and below the design water surface is the usual position on a chamber or vault, and it depends on the groundwater elevation in the geotechnical report being right; no waterstops is the position of a headwall, a channel lining, and an inlet that is above groundwater and is free to drain, where a leak at a joint has nowhere to go and nothing to harm. (10.2.3)
10.2.4 Where waterstops are selected, the waterstop at the base-of-wall construction joint shall be continuous around the structure, and the splices and corners shall be made as Concrete Joints And WaterstopsConcrete Construction Joints and WaterstopsResolves to the current adopted revision.sync/concrete-joints-and-waterstops requires.
10.2.5 Construction joint surfaces shall be prepared before the adjoining placement as Concrete Joints And WaterstopsConcrete Construction Joints and WaterstopsResolves to the current adopted revision.sync/concrete-joints-and-waterstops requires, whether or not the joint receives a waterstop.

10.3 Joints in Aprons, Slabs, and Channel Linings

NOTE The joints in the aprons, channel linings, and slabs of this standard that are not under hydrostatic pressure are governed by this article, which Concrete Joints And WaterstopsConcrete Construction Joints and WaterstopsResolves to the current adopted revision.sync/concrete-joints-and-waterstops sends here; the joints in paving, curbs, gutters, and sidewalks are governed by Concrete PavingConcrete Paving, Curbs, and SidewalksResolves to the current adopted revision.sync/concrete-paving. (10.3.1)
10.3.2 Contraction joints in aprons, channel linings, and slabs not under hydrostatic pressure shall be formed, tooled, or sawed at a spacing in each direction not exceeding the value indicated in the datasheet.
Contraction Joint Spacing in Aprons and Channel Liningsrange
Not more than
ft
8101215202530
NOTE A slab cracks at a spacing set by its thickness and its restraint, and a joint spacing of two to three times the thickness in feet, which is 12 to 18 ft for a 6 in. apron, puts the joint where the crack would have been; a wider spacing is held by reinforcement that carries the crack as a tight, distributed one rather than preventing it, and a reinforced channel lining is jointed at the wider end of the range for that reason, while an unreinforced apron is jointed at the narrow end. (10.3.3)
10.3.4 Contraction joints shall be cut or formed to a depth of not less than one quarter of the slab thickness.
10.3.5 An isolation joint with a preformed filler under Concrete Joints And WaterstopsConcrete Construction Joints and WaterstopsResolves to the current adopted revision.sync/concrete-joints-and-waterstops shall be provided where an apron, lining, or slab abuts a headwall, a wall, a pipe, or a structure that will not move with it, unless the structure details show the apron tied to the wall.
10.3.6 Where a slab or apron of this standard abuts paving or a sidewalk, the joint between them shall be the isolation joint Concrete PavingConcrete Paving, Curbs, and SidewalksResolves to the current adopted revision.sync/concrete-paving requires at a fixed object.

11 Pipe Penetrations and Connections

NOTE The opening through a wall is the part of a site structure that fails. Cast correctly, it is a formed hole of the right size at the right invert with a seal around the pipe; cast wrong, it is a cored hole through reinforcement, and left unsealed it is the path by which a vault fills with groundwater and silt or a headwall washes out its embankment. The method of forming the opening and the seal in the annulus are decided separately because they are chosen for different reasons. (11.1)

11.2 Forming the Opening

11.2.1 Pipe openings through the walls of cast-in-place structures shall be formed by the method indicated in the datasheet.
Pipe Opening Method in Cast-in-Place Wallsselect
Pipe set in the forms and cast into the wall
Formed blockout, with the pipe set and the annulus sealed after the wall is placed
Cast-in sleeve or resilient connector, with the pipe inserted after the wall is placed
Opening cored after the wall is placed
NOTE Casting the pipe into the wall is a single interface and the usual method at a headwall, where the culvert end is set first and the wall is poured around it; its price is that the pipe elevation and alignment are fixed by the pipe laying and the wall has to come to them. A formed blockout lets the pipe be laid after the wall exists and sealed with grout, which suits a chamber whose pipes arrive from several directions on different days. A cast-in sleeve or connector gives the pipe a flexible, gasketed entry that moves with the pipe, which is what Storm DrainageStorm DrainageResolves to the current adopted revision.sync/storm-drainage requires where the joint performance is watertight. Coring after placement locates the opening against the laid pipe exactly, and it cuts whatever reinforcement is in its path, which is why it is the method of the opening that was missed. (11.2.2)
11.2.3 The connector or seal at the pipe-to-structure connection of a storm drainage structure shall be the one selected under Storm DrainageStorm DrainageResolves to the current adopted revision.sync/storm-drainage, and the opening shall be formed to suit it.
11.2.4 Pipe openings and their inverts shall be as indicated on the civil structure details and the pipe invert schedule.
11.2.5 Where an opening is cored after the wall is placed, other than where coring is the method indicated in the datasheet, the Contractor shall obtain the Engineer of Record's written direction before coring, and shall not sever reinforcement beyond what that direction permits.
11.2.6 An opening cored after placement shall be cut with a diamond core barrel, shall not be located within 12 in. of a construction joint or another opening without the Engineer of Record's written acceptance, and shall be recorded in the closeout submittals.
11.2.7 Pipes cast into a wall shall be set to line and grade, supported independently of the reinforcement, and protected from displacement during placement and consolidation.

11.3 Sealing the Annulus

11.3.1 The annular space between each pipe and the opening, sleeve, or blockout it passes through shall be sealed on both faces of the wall by the method indicated in the datasheet.
Seal of the Annular Space at Pipe Penetrationsselect
Non-shrink cementitious grout under ASTM C1107/C1107M
Resilient connector under ASTM C923
Modular mechanical seal with interlocking elastomer links
Hydrophilic waterstop strip with non-shrink grout
NOTE A grouted annulus is rigid, inexpensive, and what most blockouts at a headwall and most conduit entries receive; it cracks where the pipe and the wall move differently, which is why Storm DrainageStorm DrainageResolves to the current adopted revision.sync/storm-drainage does not allow it where the connection must be watertight. A resilient connector is the gasketed boot of a storm or sanitary structure and moves with the pipe. A modular mechanical seal bolts up a positive seal in a round sleeve and is the seal of a pressure pipe or a conduit through a vault wall below groundwater, at a price per penetration that a headwall does not justify. A hydrophilic strip wrapped on the pipe inside a grouted blockout swells against water and is the belt with the braces where a grouted blockout is below groundwater. (11.3.2)
11.3.3 Where the annulus is grouted, the blockout surfaces shall be roughened, cleaned, and brought to a saturated surface-dry condition, and the grout shall be placed from one side so that air is displaced ahead of it and shall completely fill the annulus.
11.3.4 Where a pipe penetrates a wall below Seasonal High Groundwater ElevationSeasonal High Groundwater ElevationParameterEach project supplies its own value.seasonal-high-groundwater-elevation, the seal shall be one that remains effective under the head of groundwater at the penetration.

11.4 Conduit Entries to Vaults

11.4.1 Conduits and duct banks entering a cast-in-place utility vault shall be cast into the wall with the end bells or terminators that Underground DuctbankUnderground Electrical Duct BanksResolves to the current adopted revision.sync/underground-ductbank requires, at the locations and elevations on the electrical vault details and the duct bank profile.
11.4.2 Conduit entries shall be plugged before concrete is placed and shall remain closed until the conductors are pulled.
11.4.3 A duct bank that enters a vault in a trench backfilled against the vault wall shall be supported so that settlement of the trench does not shear the conduits at the wall face.

12 Frames, Steps, and Hardware

12.1 Frame Seat at the Access Opening

NOTE The casting at an access opening is furnished under Storm DrainageStorm DrainageResolves to the current adopted revision.sync/storm-drainage for a storm structure and under the standard governing the system a vault serves otherwise; what the concrete trade owns is the seat it sits on and how it is held to the structure. (12.1.1)
12.1.2 The frame at each access opening shall be seated as indicated in the datasheet.
Frame Seat at the Access Openingradio
○ Frame cast into the top slab with the slab placement
○ Frame set on a mortar bed on a formed seat
○ Frame set on precast adjustment rings on a formed seat
○ Frame bolted to cast-in anchors on a formed seat
NOTE A frame cast with the top slab cannot move and cannot be adjusted, which suits a structure whose rim elevation is known before the slab is placed and will not change; a frame set on a mortar bed on a formed seat is adjusted to the final rim when it is set and is the method of most cast-in-place inlets; precast rings on the seat give the adjustment range that a structure beneath a pavement that will be overlaid needs, at the cost of mortar joints that work loose under traffic; a bolted frame is the method where the frame carries a bolted or locking cover and the anchors have to resist its prying. (12.1.3)
12.1.4 The seat shall be formed to the outside dimension of the frame furnished, level, and at the elevation that puts the finished rim at the elevation on the structure schedule with the adjustment the seating method allows.
12.1.5 Where adjustment rings are used, the ring stack shall not exceed the height Storm DrainageStorm DrainageResolves to the current adopted revision.sync/storm-drainage allows at a storm structure, and each ring shall be set on a full mortar bed.

12.2 Steps and Ladders in Cast-in-Place Structures

12.2.1 The access provision in each cast-in-place vault or chamber that a person enters shall be as indicated in the datasheet; the access provision in a precast structure is selected under the standard that furnishes it.
Access Provision in Cast-in-Place Vaults and Chambersselect
Copolymer polypropylene encased steel steps cast into the wall
Steel steps with a protective coating cast into the wall
Fiberglass-reinforced polymer steps cast into the wall
Fixed ladder anchored to the wall after stripping
No steps or ladder
NOTE Cast-in steps make routine entry a one-person task and are what most owners of storm and utility structures expect; the polypropylene-encased step is the one ASTM C478 describes and does not corrode, the coated steel step corrodes at any break in the coating, and the fiberglass step neither corrodes nor conducts, which matters in an electrical vault. A fixed ladder is set to the finished wall and can be replaced, and it is the provision of a structure deeper than a step column serves comfortably. No steps is the position of an owner who has had a corroded step fail under a worker and now enters every structure on portable equipment, and of any structure a person will never enter. (12.2.2)
12.2.3 Cast-in steps shall be set in the forms before placement, aligned in a single vertical column beneath the access opening, at a vertical spacing not exceeding 16 in., with the lowest step not more than 24 in. above the floor or bench, and each step shall withstand the pull-out and vertical loads ASTM C478 requires.
12.2.4 A fixed ladder shall be anchored with the anchors selected under this standard for hardware, and shall be furnished under Miscellaneous MetalsMiscellaneous MetalsResolves to the current adopted revision.sync/miscellaneous-metals.
12.2.5 Where the structure is deeper than 20 ft, a fixed ladder or an intermediate landing shall be provided where the Owner's confined-space entry program or the Authority Having Jurisdiction requires one.

12.3 Anchorage of Gates, Grates, and Hardware

12.3.1 Gates, trash racks, safety grates, ladders, and other hardware mounted on the faces of site structures shall be anchored by the method indicated in the datasheet.
Anchorage of Gates, Grates, and Hardware to the Structureradio
○ Cast-in anchor bolts set to the manufacturer's template
○ Post-installed adhesive anchors
○ Post-installed mechanical anchors
NOTE Cast-in anchor bolts develop their capacity in the concrete that closes around them and cannot be moved once it has, so they depend on the template arriving before the pour and on the hardware matching it when it arrives; adhesive anchors are set to the delivered hardware after stripping and develop their capacity in a cleaned hole under an installer the evaluation report qualifies, and they are the anchorage of a flap gate added to a headwall and of nearly every trash rack; mechanical anchors set faster than adhesive and need no cure, and they are selected where the concrete is thick enough for their expansion and the loads are small. (12.3.2)
12.3.3 Cast-in anchor bolts shall conform to ASTM F1554 and shall be furnished and set in accordance with Concrete AccessoriesConcrete Accessories and EmbedsResolves to the current adopted revision.sync/concrete-accessories, and post-installed anchors shall be furnished and installed in accordance with Post Installed AnchorsPost-Installed Concrete and Masonry AnchorsResolves to the current adopted revision.sync/post-installed-anchors.
12.3.4 Anchor bolts, inserts, and hardware exposed to runoff or groundwater shall be hot-dip galvanized or stainless steel.
12.3.5 Where a gate or a trash rack is mounted on a wall of a structure of this standard, the opening through the wall shall be formed to the dimension and the anchor bolts set to the template furnished by the gate manufacturer under Slide Gates And Stop LogsSlide Gates and Stop LogsResolves to the current adopted revision.sync/slide-gates-and-stop-logs, and the mounting face shall be formed flat and plumb within the tolerance that manufacturer publishes.
NOTE The gate is furnished to the opening and not the other way round. A headwall formed before the gate manufacturer's template is in hand receives a gate that is drilled and shimmed to fit, and a gate that is shimmed does not seat. (12.3.6)

13 Headwalls, Endwalls, and Wingwalls

NOTE A headwall anchors the last pipe joint against the drag and uplift of the discharge, retains the embankment at the pipe opening, and presents a defined edge to the channel; its wingwalls flare from it to hold the fill and turn the flow. The end treatment at an outfall is selected under Storm DrainageStorm DrainageResolves to the current adopted revision.sync/storm-drainage; this article governs the headwall once that selection has made it cast in place. (13.1)
13.2 The plan geometry, wall heights, footing dimensions, and reinforcement of each headwall shall be as indicated on the outfall and headwall details.
13.3 The flare angle of the wingwalls, measured from the pipe axis, shall be as indicated in the datasheet.
Wingwall Flare Angle From the Pipe Axisrange
degrees
090
Per drawings — the outfall and headwall details (deferred by default)
NOTE A flare of zero puts the wingwalls parallel to the pipe and is a U-wall that suits a steep bank; 30 to 45 degrees is the flare of most outfalls, turning the flow into the channel while holding the embankment; 90 degrees is a straight endwall with no flare, which suits a pipe that discharges square into a wide channel. The angle is a hydraulic and grading decision of the civil engineer, and the datasheet carries it only so the forms are built to the right angle. (13.4)
13.5 The apron and cutoff wall at the toe of the headwall shall be as indicated in the datasheet.
Apron and Cutoff Wall at the Headwallradio
○ Integral concrete apron with a downstream cutoff wall
○ Integral concrete apron without a cutoff wall
○ No concrete apron, with scour protection under the storm drainage standard
NOTE A concrete apron with a cutoff wall at its downstream edge carries the discharge onto a surface that cannot scour and keeps the channel from undermining the apron edge, and it is the apron of an outfall whose velocity exceeds what riprap will hold; an apron without a cutoff is the lesser structure where the channel downstream is lined or the velocity is low; no concrete apron puts the energy dissipation entirely in the riprap or the dissipator that Storm DrainageStorm DrainageResolves to the current adopted revision.sync/storm-drainage specifies, which is the position of most small outfalls. (13.6)
13.7 Where an apron is provided, it shall be cast integrally with the headwall footing or tied to it with the dowels shown on the headwall details, and its downstream cutoff wall, where provided, shall extend below the apron to the depth shown.
13.8 Weep holes through wingwalls and headwalls that retain fill shall be as indicated in the datasheet.
Weep Holes Through Walls That Retain Fillradio
○ Provided with a filter at each weep
○ Not provided
13.9 Where weep holes are provided, their spacing along the wall shall not exceed the value indicated in the datasheet.
Weep Hole Spacing Along the Wallrange
Not more than
ft
4681012
NOTE A weep relieves the water that collects behind a wall that retains fill, and a wingwall with no weep and no drain behind it carries a hydrostatic load its design may not include; a weep also admits the fines of the backfill unless it is filtered, which is why each weep carries a geotextile wrap or a gravel pocket behind it. Walls that retain less than 2 ft of fill and walls with a drainage system under Foundation DrainageFoundation DrainageResolves to the current adopted revision.sync/foundation-drainage or SubdrainageSubdrainageResolves to the current adopted revision.sync/subdrainage behind them are the ones built without weeps. (13.10)
13.11 Weep holes shall be not less than 3 in. in diameter, shall be set with their inverts not more than 6 in. above the finished grade or apron at the exposed face, and shall be backed by a gravel pocket wrapped in a geotextile or by a prefabricated weep filter.
13.12 The headwall shall be constructed before the receiving channel is put into service, and the pipe outlet shall be protected from erosion until the headwall, the apron, and the scour protection under Storm DrainageStorm DrainageResolves to the current adopted revision.sync/storm-drainage are complete.

14 Inlets, Junction Chambers, and Outlet Control Structures

NOTE A cast-in-place inlet or chamber is built where a precast unit does not fit: at a junction with too many pipes, at a diversion whose walls are at odd angles, at an outlet control structure whose weir and orifice plate geometry is custom. What it adds to a vault is a hydraulic function, and the elevations that function depends on are formed into it. (14.1)
14.2 The bench and channel of a storm drainage junction structure shall be as selected under Storm DrainageStorm DrainageResolves to the current adopted revision.sync/storm-drainage, and the flow channel shall be formed or placed to the inverts on the structure schedule.
14.3 The weir crests, orifice inverts, and overflow elevations of an outlet control structure shall be formed to the elevations on the outlet control structure detail, and the forms shall be checked against those elevations before concrete is placed.
14.4 The elevations of weir crests, orifice inverts, pipe inverts, and channel inverts in the completed structure shall be within the tolerance indicated in the datasheet of the elevations shown.
Elevation Tolerance of Weirs, Orifices, and Invertsrange
Not more than
in
0.1250.250.50.751
NOTE A quarter inch on a weir crest changes the release rate the stormwater report certifies by a measurable fraction on a small storm, while an inch on a pipe invert in a junction chamber is within what the pipe laying can absorb; the tolerance is set to the function of the elevation, tight on a control structure and loose on a chamber that only turns the flow. The outlet dimensions are measured again at acceptance under Stormwater Management SystemsStormwater Management and Detention SystemsResolves to the current adopted revision.sync/stormwater-management-systems against the tolerance its detail states. (14.5)
14.6 The top slab of each chamber and vault shall be as indicated in the datasheet.
Top Slab of Chambers and Vaultsradio
○ Cast-in-place top slab with the frame seat formed in it
○ Precast top slab set on the cast-in-place walls
○ Removable cover panels in a cast-in seat
NOTE A cast-in-place top slab makes the structure monolithic and is formed over a deck that is stripped through the access opening, which fixes the opening at a size a person and a form panel can pass; a precast top slab is set the day the walls are stripped and lets the walls be backfilled without waiting for a slab to cure, at the cost of a joint around the perimeter that is sealed and a lifting operation; removable cover panels, of precast concrete or steel-framed plate under Metal Gratings And Floor PlatesMetal Gratings and Floor PlatesResolves to the current adopted revision.sync/metal-gratings-and-floor-plates, are the top of a vault whose contents are serviced from above and of a chamber whose weir plates are changed. (14.7)
14.8 Where a precast top slab or removable panels are used, the bearing seat shall be formed level, the panels shall bear on a full mortar bed or an elastomeric gasket under ASTM D1056, and the perimeter joint of a precast slab shall be sealed on the inside face.
14.9 A top slab in a vehicular area shall be designed for the vehicle load of this standard and shall be identified on the record drawings with that load.

15 Cast-in-Place Utility Vaults

NOTE A cast-in-place electrical or communications vault is a precast handhole that would not fit, and everything a precast vault carries as a factory item is cast in here by the concrete trade from an electrical drawing. The items are decided under Utility Manholes And HandholesUtility Manholes and HandholesResolves to the current adopted revision.sync/utility-manholes-and-handholes for a precast unit; for a cast-in-place vault they are decided here, against the same list. (15.1)
15.2 The items cast into each utility vault shall be as indicated in the datasheet.
Items Cast Into Utility Vaultscheckbox
☐ Pulling irons opposite each conduit entry
☐ Cable rack inserts or channel on the walls
☐ Ground rod sleeve through the floor
☐ Grounding electrode conductor or ground bus insert
☐ Conduit end bells or terminators at each entry
☐ Lifting inserts in a precast or removable top
☐ Sump pocket in the floor
☐ No items cast in beyond the conduit entries
15.3 Pulling irons, inserts, and sleeves shall be set in the forms before placement at the locations on the electrical vault details, secured against displacement, and positioned so that the cable bending radius at each entry is not violated by the iron opposite it.
15.4 Grounding provisions cast into a vault shall conform to Grounding And BondingGrounding and Bonding for Electrical SystemsResolves to the current adopted revision.sync/grounding-and-bonding and NFPA 70 Article 250, and the ground rod sleeve shall pass through the floor clear of the reinforcement.
15.5 The floor of each vault shall be sloped to the sump or drain, and the sump shall be as indicated in the datasheet.
Vault Floor Sumpradio
○ Formed sump pocket with a drain connection to the storm system
○ Formed sump pocket for a portable pump
○ Floor sloped to a drain without a sump pocket
○ No sump or drain
NOTE A sump drained to the storm system keeps the vault dry without a visit, and it is also a path by which a storm surcharge enters the vault, which is why a backwater valve goes on that drain; a sump for a portable pump collects the water and waits for the maintenance crew, and it is the sump of a vault where there is no storm system below the floor; a sloped floor to a drain is the arrangement where the water comes from condensation and washdown rather than infiltration; no sump is the floor of a vault above groundwater in a dry climate, or of one that is accepted to hold water between visits. (15.6)
15.7 Where the sump drains to the storm system, the drain shall carry a backwater valve and shall discharge above the storm system's design water surface where one is shown.

16 Collars, Adjustment Rings, and Base Slabs on Precast Units

NOTE Cast-in-place concrete is placed on, under, and around precast units more often than it is placed as a structure of its own: the collar that brings a precast inlet to a grade the rings cannot reach, the adjustment that fills a gap under a frame, the base slab beneath precast risers where the precaster's monolithic base is not used. Each is a cast-in-place element whose other half is precast, built to two sets of requirements. (16.1)
16.2 A cast-in-place collar or adjustment on a precast unit shall bear on the precast unit's prepared top, shall be reinforced as the structure details show, and shall be doweled to the unit or keyed into it as shown, with the precast unit's surface roughened and cleaned before the collar is placed.
16.3 A cast-in-place base slab beneath precast risers shall be placed on the granular foundation course that Storm DrainageStorm DrainageResolves to the current adopted revision.sync/storm-drainage or Sanitary Sewer SystemsSanitary Sewer Systems (Site)Resolves to the current adopted revision.sync/sanitary-sewer-systems requires, with the first riser's joint seated as that standard requires and with the pipe openings formed before the risers are set.
16.4 A collar or adjustment on a precast unit in a vehicular area shall be not less than 4 in. thick and shall extend over the full wall thickness of the precast unit.
NOTE A thin collar poured on a precast top to catch a grade is the adjustment that works loose first under traffic, because it has no mass to hold the frame and no reinforcement to hold itself; the collar is a structural element bearing on the unit, not a mortar bed that grew. (16.5)

17 Pole, Post, and Sign Bases

NOTE Requirements in this article apply only to a base whose pole, post, or sign is furnished under a standard that does not govern its base; light pole foundations are governed by Exterior LightingExterior and Site LightingResolves to the current adopted revision.sync/exterior-lighting, flagpole foundations by FlagpolesFlagpolesResolves to the current adopted revision.sync/flagpoles, fence post footings by Fencing And GatesFencing and GatesResolves to the current adopted revision.sync/fencing-and-gates, bollard footings by Site Furnishings And BollardsSite Furnishings and BollardsResolves to the current adopted revision.sync/site-furnishings-and-bollards, and sign footings by Exterior SignageExterior SignageResolves to the current adopted revision.sync/exterior-signage with the design basis it cites. (17.1)
17.2 Where a base is governed by this article, its dimensions, depth, and reinforcement shall be as indicated on the site details for the item the base supports.
17.3 The form of each base governed by this article shall be as indicated in the datasheet.
Form of Pole and Post Basesradio
○ Drilled pier cast against the drilled hole
○ Round base cast in a tube form
○ Rectangular formed base
NOTE A drilled pier cast against the hole is the base of most posts and small poles, because the auger is the form and the soil holds the concrete; it depends on a soil that stands and gives a base whose surface is whatever the auger left. A tube form gives a round base with a finished face above grade and a known diameter below, at the cost of a hole dug oversize and backfilled; a rectangular formed base is the base of a sign or a post whose plate or embedment is rectangular, or whose face is seen. (17.4)
17.5 The projection of the top of the base above the adjacent finished grade or paving shall be as indicated in the datasheet.
Base Projection Above Finished Grade or Pavingrange
in
2461218243036
NOTE A base flush with the grade is the base in a lawn that is mowed over and in a walk that is tripped over otherwise; a base 2 to 6 in. above grade keeps the post base and its anchor bolts out of standing water; a base 24 to 36 in. above a parking lot is the base that takes the bumper instead of the pole, where a bollard is not provided. (17.6)
17.7 Anchor bolts in a base governed by this article shall be set to the template furnished with the pole, post, or sign, shall conform to ASTM F1554, and shall be held by the template through placement.
17.8 Raceway and grounding provisions through a base shall be as the standard furnishing the item requires, and shall be cast in before placement.
17.9 The top of each base shall be finished with its edges chamfered or tooled, and the surface sloped to shed water away from the post.

18 Surface Finish and Protection

18.1 Finishing of unformed surfaces shall be performed in accordance with Concrete Curing And FinishingConcrete Curing and FinishingResolves to the current adopted revision.sync/concrete-curing-and-finishing.
18.2 The tops of walls, headwalls, and wingwalls shall receive a float finish with the edges tooled or chamfered, and aprons, channel linings, and every surface a person walks on shall receive a broom finish.
NOTE A troweled finish on an apron is a surface a person slides on when it is wet or iced, which is every day it is in use; the broom is the finish of every exterior surface that carries foot traffic, under this standard as under Concrete PavingConcrete Paving, Curbs, and SidewalksResolves to the current adopted revision.sync/concrete-paving. (18.3)
18.4 The surface treatment applied to the exposed faces of site structures after curing shall be as indicated in the datasheet.
Surface Treatment of Exposed Facesselect
None
Penetrating silane or siloxane sealer
Film-forming acrylic sealer
Coating system under the high-performance coatings standard
NOTE Most site structures receive no treatment and depend on the air entrainment and low permeability their exposure class gives them, which is what the exposure class is for; a penetrating silane or siloxane sealer soaks in and repels water without changing the appearance, and it is applied where the structure is class F3 and the deicer exposure is heavy, or where a headwall face in public view is to be kept free of efflorescence; a film-forming acrylic sealer darkens the surface and wears off a walking surface within a few seasons, and it is the treatment of a wall face that is seen and not walked on; a coating under High Performance CoatingsHigh-Performance CoatingsResolves to the current adopted revision.sync/high-performance-coatings is the treatment of a structure in chemical or wastewater service, which is rarely a structure of this standard. (18.5)
18.6 A surface treatment shall not be applied until the curing period under Concrete Curing And FinishingConcrete Curing and FinishingResolves to the current adopted revision.sync/concrete-curing-and-finishing is complete and the surface has dried to the moisture condition the treatment manufacturer publishes.
18.7 A curing compound shall not be applied to a surface that will receive a sealer or coating unless the compound is demonstrated to be compatible with it or is fully removed before it.

19 Curing of Site Structures

19.1 Site structures shall be cured in accordance with Concrete Curing And FinishingConcrete Curing and FinishingResolves to the current adopted revision.sync/concrete-curing-and-finishing, including the curing of formed faces after stripping.
NOTE A wall stripped at a day old on a windy site and left bare loses its surface water before the cement has used it, and the face that results is the one that scales first; the curing of a formed face is the part of curing that site work skips, because the wall is about to be buried. (19.2)
19.3 Curing shall continue on a face that will be backfilled until the backfill covers it or the curing period is complete, whichever is first.

20 Dewatering, Flotation, and Backfill

20.1 Dewatering at Placement

20.1.1 Groundwater control in the excavation shall be performed under EarthworkEarthworkResolves to the current adopted revision.sync/earthwork where sump pumping suffices, and under Excavation Support And DewateringExcavation Support and DewateringResolves to the current adopted revision.sync/excavation-support-and-dewatering where an engineered system is required, and the excavation shall be free of standing water when the bearing surface is accepted and when concrete is placed.
20.1.2 Dewatering shall continue without interruption until the structure has reached the strength required for backfill and the backfill has been placed to the elevation at which the structure's weight and the backfill resist uplift.
NOTE A sump pump switched off the evening the walls are stripped lets the groundwater back into an excavation holding a hollow concrete box that weighs less than the water it displaces, and the box rises. The check is the same one Stormwater Management SystemsStormwater Management and Detention SystemsResolves to the current adopted revision.sync/stormwater-management-systems makes for its facilities: the dry weight of the structure, plus the backfill on its footing projections, against the uplift at Seasonal High Groundwater ElevationSeasonal High Groundwater ElevationParameterEach project supplies its own value.seasonal-high-groundwater-elevation. (20.1.3)
20.1.4 Where the structure details show a flotation check, the Contractor shall not reduce the backfill, remove the dewatering, or leave the structure empty in a condition the check did not assume without the Engineer of Record's written direction.

20.2 Backfill Against Structure Walls

20.2.1 Backfill shall not be placed against the walls of a structure until the concrete of those walls has attained the fraction of its specified compressive strength indicated in the datasheet.
Fraction of Specified Compressive Strength Before Backfill Against Wallsrange
Not less than
%
2550607075808590100
NOTE A wall that is backfilled early takes the lateral load of the fill and the compactor before it has the tensile strength to span between its footing and its top slab, and a wall that cracks then stays cracked under the backfill forever. Most site specifications release backfill at 70 to 75 percent of the specified strength, which a normal mixture reaches in a week of warm weather and in a fortnight of cold; a vault whose walls span to a top slab that is not yet placed is released only when that slab exists, whatever the fraction says. (20.2.2)
20.2.3 The attainment of the strength before backfill shall be demonstrated on the basis indicated in the datasheet.
Basis for Release of Backfill Against Wallsradio
○ Field-cured cylinders cast from the wall placement
○ Maturity method calibrated for the mixture
○ Minimum age in days with the standard-cured strength record of the mixture
NOTE Field-cured cylinders tell what the wall has actually reached in the weather it has had, and they are what most site work breaks; the maturity method reads the wall's own temperature history and releases it the hour it qualifies, which pays where the schedule turns on the backfill; a minimum age with the mixture's strength record is the simplest basis and the one that is wrong in cold weather, because the record was made at 73 degrees and the wall was not. (20.2.4)
20.2.5 Where a wall is designed to span to a top slab, backfill shall not be placed against it until the top slab has been placed and has reached the strength this article requires, or until the wall is braced as the structure details show.
20.2.6 Backfill against structure walls shall be placed, compacted, and brought up in balanced lifts under EarthworkEarthworkResolves to the current adopted revision.sync/earthwork, and the heavy equipment setback and the hand-compacted zone adjacent to the walls shall be as that standard requires.
20.2.7 No load from construction equipment, stockpiled material, or vehicles shall be placed over a top slab until the slab has attained its specified compressive strength and its shoring has been removed under Concrete FormworkConcrete Formwork and AccessoriesResolves to the current adopted revision.sync/concrete-formwork.
20.2.8 The backfill release record for each structure shall state the basis on which the walls were released, the strength or age demonstrated, and the date backfill began.

21 Tolerances for Site Structures

21.1 Dimensional tolerances not stated in this standard shall be as specified in ACI 117 for the member type.
21.2 The plan location of each structure shall be within 2 in. of the location shown, and the top elevation of each wall and slab shall be within 1/2 in. of the elevation shown, except that a rim elevation at a frame shall be set to the pavement or grade it meets.
21.3 The elevations of weirs, orifices, and inverts shall be within the tolerance of this standard for them, and the mounting face for a gate shall be within the tolerance the gate manufacturer publishes under Slide Gates And Stop LogsSlide Gates and Stop LogsResolves to the current adopted revision.sync/slide-gates-and-stop-logs.
21.4 The position of each pipe opening, conduit entry, and cast-in item shall be within 1/2 in. of its position on the reconciled layout, measured to the centerline of an opening and to the face of an item.
NOTE ACI 117 tolerances were written for the frame of a building, where an inch in the location of a wall is absorbed by the finishes; a site structure is located by the pipe that enters it and the pavement that meets its rim, and neither absorbs anything. The tolerances here are the ones those interfaces can take. (21.5)

22 Testing of Site Structures

22.1 Field testing of the fresh and hardened concrete of site structures shall be performed under Cast In Place ConcreteCast-in-Place ConcreteResolves to the current adopted revision.sync/cast-in-place-concrete, at not less than one strength test for each structure type on each day it is placed.
22.2 Strength test reports shall be indexed to the structures each placement served.
22.3 Leakage testing of a cast-in-place storm drainage structure, where the system watertightness selected under Storm DrainageStorm DrainageResolves to the current adopted revision.sync/storm-drainage requires one, shall be performed under that standard, and a vacuum test of a cast-in-place structure shall be performed in accordance with ASTM C1244.
22.4 A storage structure designed under ACI 350 to contain water is tested under Water Retaining Concrete StructuresWater-Retaining Concrete StructuresResolves to the current adopted revision.sync/water-retaining-concrete-structures, and no hydrostatic tightness test is required of a structure of this standard.
NOTE Site structures are not leak tested as a class because they are not built to hold water; the exceptions are the storm structures whose watertightness class was selected under Storm DrainageStorm DrainageResolves to the current adopted revision.sync/storm-drainage, and those are tested as that standard requires with the vacuum test as the method for a structure. (22.5)

23 Delivery, Storage, and Handling

23.1 Reinforcement, waterstops, form ties, anchor bolts, and curing materials shall be delivered, stored, and handled in accordance with the standards that furnish them.
23.2 Steps, ladders, inserts, pulling irons, frames, and gate templates shall be delivered before the structure they are cast into is formed, stored off the ground, and identified by the structure they serve.
23.3 Resilient connectors, modular seals, hydrophilic strips, and sealers shall be stored within the temperature limits their manufacturers publish and shall not be incorporated after their published shelf life has expired.

24 Warranty

24.1 The Contractor shall warrant the structures constructed under this standard against defects in materials and workmanship for the period indicated in the datasheet, running from the date of substantial completion, in addition to the warranties of the material standards this standard is read with.
Site Structure Warranty Periodrange
Not less than
years
1235
24.2 The warranty shall cover cracking beyond the acceptance criteria of Concrete Repair And RestorationConcrete Repair and RestorationResolves to the current adopted revision.sync/concrete-repair-and-restoration, surface scaling, infiltration at a construction joint, a tie hole, or a pipe penetration, displacement or loosening of a frame, a step, or an anchor, separation of a collar or apron from the unit or wall it was tied to, and settlement or heave of the structure.
24.3 The warranty shall not cover damage caused by a load exceeding the design basis on the contract documents, by vehicle impact, by a flow exceeding the design discharge at an outfall, or by settlement of subgrade prepared under a scope other than the Contractor's.
24.4 Where the parties disagree whether a defect within the warranty period is a construction defect, a design matter, or the result of service beyond the design basis, the Engineer of Record shall make the initial determination.
24.5 Work repaired under the warranty shall carry a renewed warranty running from the date the repair is accepted, for the full original period or for the remainder of the original period, whichever ends later.
24.6 The Contractor shall bear the cost of a warranty repair, of the excavation and backfill needed to reach it, and of restoring the pavement, grade, and surface finishes disturbed by it to the condition recorded before the repair.
24.7 Infiltration at a penetration that was never sealed, a frame set on a seat formed to the wrong casting, and a wall backfilled before it reached its strength are nonconforming work whenever they are discovered, and the warranty period shall not limit the Contractor's liability for them.

Written and maintained by SynC. Licensed under CC BY 4.0.