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SynC · Editorial revision

Permeable Paving

Revision4
EditedOct 17, 2026
StatusCurrent
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Current revision. This is editorial revision 4, 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 23: rewritten from scratch under the authoring cheatsheet with datasheet constraints; scope boundaries restated against the remade neighbors

1 Scope

NOTE This standard governs the materials, construction, testing, and acceptance of a permeable pavement section from the accepted infiltration subgrade or liner upward: the reservoir stone, the choker, base, and bedding courses, the surface course, the underdrain and its outlet within the section, the edge restraints, and the observation and cleanout provisions through which the Owner will maintain it. (1.1)
NOTE The four surface systems covered are listed below. Each is a different product placed by a different trade, and each sits on the same open-graded reservoir, so this standard carries one set of articles for the section beneath the surface and a conditional article for each surface. (1.2)
  • Pervious concrete, a no-fines portland cement concrete with a connected void structure, placed and compacted in place without finishing tools
  • Porous asphalt, an open-graded asphalt wearing course with a modified binder, placed and rolled without vibration
  • Permeable interlocking concrete pavers, solid concrete units set on an open-graded bedding course with the water passing through aggregate-filled joints
  • Concrete grid pavers, open-celled concrete units whose cells are filled with aggregate or turf, carrying intermittent loads on fire lanes and overflow parking
NOTE A permeable pavement is a stormwater facility that is driven on. It is credited in the stormwater permit with a storage volume and an infiltration or release rate, and it is accepted on the surface rate at which water enters it; its service life is set by sediment, not by wheel loads. Every construction rule in this standard follows from one fact: a void that is filled with fines during construction never drains again, and no repair short of removal recovers it. (1.3)
NOTE The following are outside this standard and are governed elsewhere. (1.4)
  • Conventional dense hot-mix asphalt pavement, under Asphalt PavingAsphalt PavingResolves to the current adopted revision.sync/asphalt-paving
  • Conventional concrete pavement, and the cast-in-place or precast curb that restrains a paver edge, under Concrete PavingConcrete Paving, Curbs, and SidewalksResolves to the current adopted revision.sync/concrete-paving
  • The dense aggregate base beneath a conventional pavement, under Aggregate Base CourseAggregate Base CourseResolves to the current adopted revision.sync/aggregate-base-course
  • Detention and retention basins, bioretention, swales, underground storage, and the outlet structure of the site stormwater facility, under Stormwater Management SystemsStormwater Management and Detention SystemsResolves to the current adopted revision.sync/stormwater-management-systems
  • The storm sewer, inlets, and manholes the underdrain discharges to, under Storm DrainageStorm DrainageResolves to the current adopted revision.sync/storm-drainage
  • Mass excavation to within 12 in. of the reservoir subgrade, structural fill, and the proof rolling of a subgrade beneath a no-infiltration section, under EarthworkEarthworkResolves to the current adopted revision.sync/earthwork
  • The property class, certified test reports, and conformance of the geotextile, under GeosyntheticsGeosynthetics and GeotextilesResolves to the current adopted revision.sync/geosynthetics
  • Subgrade instruments, under Geotechnical Instrumentation And MonitoringGeotechnical Instrumentation and MonitoringResolves to the current adopted revision.sync/geotechnical-instrumentation-and-monitoring
  • Markings and signs on the finished surface, under Pavement MarkingsPavement Markings and Site SignageResolves to the current adopted revision.sync/pavement-markings
  • The storage volume, the design storms, and the release rate of the reservoir, which are set by the stormwater permit and the governing stormwater design manual and recorded in the stormwater management report
NOTE Solid-jointed unit pavers on a sand or mortar setting bed are a different pavement that passes no water, and no standard in this library currently covers them; a project that uses both places the solid pavers under a project-specific specification and the permeable pavers under this standard. (1.5)
1.6 The reservoir depth, the underdrain and outlet elevations, the surface grades, and the limits of each pavement cell shall be as shown in the Contract Documents, and the Contractor shall not alter them to suit field conditions without the written direction of the Engineer of Record.
1.7 Where this standard and the stormwater management report conflict, the report shall govern for the storage volume, the hydrologic mode, the reservoir depth, and the outlet elevations, and this standard shall govern for materials, procedure, testing, and acceptance, unless the Engineer of Record directs otherwise in writing.
1.8 Where the governing stormwater design manual or the stormwater permit sets a requirement more stringent than this standard, the more stringent requirement shall govern.
1.9 The Contractor shall report to the Engineer of Record any condition that prevents the section from being built as drawn, including groundwater, bedrock, or a soil at the subgrade that differs from the geotechnical investigation report, a utility within the reservoir, and an underdrain invert that does not meet the connecting storm sewer.
1.10 The Contractor shall coordinate work under this standard with EarthworkEarthworkResolves to the current adopted revision.sync/earthwork for the excavation above the reservoir subgrade and for the subgrade beneath a no-infiltration section; with Erosion And Sediment ControlErosion and Sediment ControlResolves to the current adopted revision.sync/erosion-and-sediment-control for the diversion of runoff around the cell until the contributing area is stabilized; with Storm DrainageStorm DrainageResolves to the current adopted revision.sync/storm-drainage for the inlet or manhole the underdrain discharges to and its invert; with Stormwater Management SystemsStormwater Management and Detention SystemsResolves to the current adopted revision.sync/stormwater-management-systems where the reservoir drains to a downstream facility; with Concrete PavingConcrete Paving, Curbs, and SidewalksResolves to the current adopted revision.sync/concrete-paving for the curb that restrains a paver edge and the sequence of curb and pavement; with GeosyntheticsGeosynthetics and GeotextilesResolves to the current adopted revision.sync/geosynthetics for the geotextile furnished by reference; with Landscape IrrigationLandscape IrrigationResolves to the current adopted revision.sync/landscape-irrigation so that no irrigation head discharges onto the permeable surface; and with Pavement MarkingsPavement Markings and Site SignageResolves to the current adopted revision.sync/pavement-markings for the age and condition of the surface at the time it is marked.

2 Referenced Standards

2.1 Materials, mixture design, testing, and execution 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
ASCE 68 Permeable Interlocking Concrete Pavement
ACI 522R Report on Pervious Concrete
ACI 522.1 Specification for Pervious Concrete Pavement
ASTM C936/C936M Solid Concrete Interlocking Paving Units
ASTM C1319 Concrete Grid Paving Units
ASTM C1645/C1645M Freeze-thaw and De-icing Salt Durability of Solid Concrete Interlocking Paving Units
ASTM C1688/C1688M Density and Void Content of Freshly Mixed Pervious Concrete
ASTM C1701/C1701M Infiltration Rate of In Place Pervious Concrete
ASTM C1747/C1747M Determining Potential Resistance to Degradation of Pervious Concrete by Impact and Abrasion
ASTM C1754/C1754M Density and Void Content of Hardened Pervious Concrete
ASTM C1781/C1781M Surface Infiltration Rate of Permeable Unit Pavement Systems
ASTM C33/C33M Concrete Aggregates
ASTM C88/C88M Soundness of Aggregates by Use of Sodium Sulfate or Magnesium Sulfate
ASTM C117 Materials Finer than 75-μm (No. 200) Sieve in Mineral Aggregates by Washing
ASTM C131/C131M Resistance to Degradation of Small-Size Coarse Aggregate by Abrasion and Impact in the Los Angeles Machine
ASTM C136/C136M Sieve Analysis of Fine and Coarse Aggregates
ASTM C150/C150M Portland Cement
ASTM C595/C595M Blended Hydraulic Cements
ASTM C260/C260M Air-Entraining Admixtures for Concrete
ASTM C494/C494M Chemical Admixtures for Concrete
ASTM C94/C94M Ready-Mixed Concrete
ASTM D448 Sizes of Aggregate for Road and Bridge Construction
AASHTO M 43 Sizes of Aggregate for Road and Bridge Construction
ASTM D5821 Determining the Percentage of Fractured Particles in Coarse Aggregate
ASTM D3385 Infiltration Rate of Soils in Field Using Double-Ring Infiltrometer
ASTM D5084 Measurement of Hydraulic Conductivity of Saturated Porous Materials Using a Flexible Wall Permeameter
AASHTO M 320 Performance-Graded Asphalt Binder
AASHTO M 332 Performance-Graded Asphalt Binder Using Multiple Stress Creep Recovery (MSCR) Test
ASTM D7064/D7064M Open-Graded Friction Course (OGFC) Mix Design
ASTM D6390 Determination of Draindown Characteristics in Uncompacted Asphalt Mixtures
ASTM D979/D979M Sampling Asphalt Mixtures
NAPA IS 131 Porous Asphalt Pavements for Stormwater Management
AASHTO M 252 Corrugated Polyethylene Drainage Pipe
AASHTO M 294 Corrugated Polyethylene Pipe, 300- to 1500-mm (12- to 60-in.) Diameter
ASTM D2729 Poly(Vinyl Chloride) (PVC) Sewer Pipe and Fittings
ASTM D3034 Type PSM Poly(Vinyl Chloride) (PVC) Sewer Pipe and Fittings
AASHTO M 288 Geosynthetic Specification for Highway Applications
GRI GM13 Test Methods, Test Properties and Testing Frequency for High Density Polyethylene (HDPE) Smooth and Textured Geomembranes
GRI GM17 Test Methods, Test Properties and Testing Frequency for Linear Low Density Polyethylene (LLDPE) Smooth and Textured Geomembranes
ASTM D7176 Non-Reinforced Polyvinyl Chloride (PVC) Geomembranes Used in Buried Applications
ASTM D5820 Pressurized Air Channel Evaluation of Dual Seamed Geomembranes

3 Submittals

3.1 Action Submittals

3.1.1 The Contractor shall submit the following for the Engineer of Record's review before any surface course material, paving unit, aggregate, geotextile, liner, or pipe is delivered to the site:
  • Product data for each paving unit, grid unit, edge restraint, underdrain pipe and fitting, geotextile, liner, observation well, and cleanout, identifying the product standard it is furnished to satisfy
  • Pervious concrete mixture design under ACI 522.1, stating the cementitious materials and content, the aggregate source and gradation, the water-cementitious materials ratio, each admixture and its dosage, the design void content, the design fresh density, and the results of the trial batch
  • Porous asphalt job-mix formula stating the aggregate sources and combined gradation, the binder grade and source, the design binder content, the modifier and fiber and their dosages, the design air void content, and the draindown test result
  • Aggregate test reports for each bedding, joint fill, choker, base, and reservoir source, reporting the gradation per ASTM C136/C136M, the fines per ASTM C117, the fractured particles per ASTM D5821, the Los Angeles abrasion per ASTM C131/C131M, the soundness per ASTM C88/C88M, and the measured void ratio of the reservoir stone
  • Paving unit test reports for compressive strength and absorption per ASTM C936/C936M or ASTM C1319, and freeze-thaw durability per ASTM C1645/C1645M where this standard requires it
  • Shop drawings showing the pavement section for each cell, the thickness of each layer, the reservoir bottom elevation and any terrace or check dam, the liner extent, the underdrain layout with inverts and the outlet elevation, the cleanouts and observation wells, the edge restraints, and the paver laying pattern
  • Geotextile product data and certified test report under GeosyntheticsGeosynthetics and GeotextilesResolves to the current adopted revision.sync/geosynthetics for the separation function
  • Installer qualifications under the Quality Assurance section of this standard
Action Submittals Requiredcheckbox
☑ Product data for units, restraints, pipe, geotextile, liner, and access provisions
☐ Pervious concrete mixture design with trial batch
☐ Porous asphalt job-mix formula with draindown result
☑ Aggregate test reports for each layer and source
☐ Paving unit strength, absorption, and freeze-thaw reports
☑ Shop drawings with section, underdrain, outlet, and access provisions
☐ Geotextile product data and certified test report
☑ Installer qualifications
3.1.2 No surface course shall be placed until the mixture design or the paving unit submittal for that surface has been reviewed and returned.
3.1.3 Review of a submittal does not relieve the Contractor of responsibility for compliance with the Contract Documents.

3.2 Informational Submittals

3.2.1 The Contractor shall submit the following for the record as each becomes available:
  • The subgrade infiltration test report, identifying the method, the test locations and depths relative to the reservoir bottom, the measured rates, and the design rate derived from them
  • The construction sequence and sediment protection plan for each pavement cell, showing the diversion of runoff, the equipment routes, and the stage at which the surface course is placed
  • The subgrade acceptance record for each cell, showing the date of the hold-point release and the date the geotextile or reservoir stone was placed
  • The mock-up acceptance record
  • Aggregate delivery tickets for each layer, identified to the source and the test report
  • Pervious concrete delivery tickets showing the batch time and the time of discharge, and porous asphalt delivery records showing the mixture temperature at delivery
Informational Submittals Requiredcheckbox
☑ Subgrade infiltration test report
☑ Construction sequence and sediment protection plan
☑ Subgrade acceptance record per cell
☐ Mock-up acceptance record
☐ Aggregate delivery tickets
☐ Surface course delivery tickets and temperature records

3.3 Closeout Submittals

3.3.1 The Contractor shall deliver the following before substantial completion:
  • Surface infiltration test reports for every test location, passing and failing, identified to the cell and the location
  • Pervious concrete fresh density records and core reports for thickness, density, and void content
  • The drawdown observation record for each cell with an observation well
  • Record drawings showing the as-built layer thicknesses, the reservoir bottom elevation, the underdrain inverts and the outlet elevation, and the location of every cleanout and observation well
  • The operation and maintenance manual required by the Maintenance Turnover section of this standard
  • The maintenance agreement or covenant the stormwater permit requires for the pavement, executed and recorded where recording is required
  • Warranty documentation under this standard
  • Receipt for the attic stock delivered under this standard
Closeout Submittals Requiredcheckbox
☑ Surface infiltration test reports, passing and failing
☐ Pervious concrete density and core reports
☐ Drawdown observation record
☑ Record drawings with as-built layers, inverts, and access locations
☑ Operation and maintenance manual
☐ Recorded maintenance agreement or covenant
☑ Warranty documentation
☐ Attic stock receipt

4 Quality Assurance

4.1 Installer Qualifications

4.1.1 Pervious concrete shall be placed by a crew qualified on the basis indicated in the datasheet.
Pervious Concrete Installer Qualification Basisradio
● A technician holding a current pervious concrete craftsman or installer certification from a national ready-mixed concrete industry program present at every placement
○ Documented completion of not fewer than three pervious concrete placements of comparable area within the preceding five years
NOTE Pervious concrete is placed at near-zero slump, struck and compacted in minutes, and covered before it dries, and none of that resembles conventional flatwork; the certification program tests the crew on exactly those steps, while the experience basis admits a crew that has learned them on earlier work and depends on the Engineer of Record checking the references. (4.1.2)
4.1.3 Permeable interlocking concrete pavers shall be installed by a contractor qualified on the basis indicated in the datasheet.
Paver Installer Qualification Basisradio
○ A foreman holding a current permeable interlocking concrete pavement installer certification from the concrete paver industry association present at every placement
○ Documented completion of not fewer than three permeable interlocking concrete pavement installations of comparable area within the preceding five years
4.1.4 Porous asphalt shall be produced by a plant that has produced an open-graded mixture within the preceding two years and placed by a crew that has placed porous asphalt or an open-graded friction course on not fewer than two projects.
4.1.5 The installing foreman for each surface type shall be present whenever that surface is being placed.

4.2 Testing Agency

4.2.1 Acceptance testing for surface infiltration, pervious concrete density and void content, and aggregate conformance shall be performed by a testing agency retained as indicated in the datasheet.
Permeable Pavement Testing Agency Retained Byradio
● Owner
○ Contractor, with results reported directly to the Owner
4.2.2 The subgrade infiltration test shall be performed by or under the supervision of the geotechnical engineer of record.
4.2.3 The producer's quality-control tests do not substitute for the acceptance tests of this standard, and acceptance tests shall be taken at locations the testing agency selects.

4.3 Pre-Installation Conference

4.3.1 Before the reservoir subgrade of the first cell is excavated, the Contractor shall convene a conference attended by the Contractor's superintendent, the earthwork subcontractor, the installer of each surface type, the aggregate supplier, the testing agency, the geotechnical engineer of record, the civil engineer of record, and the Authority Having Jurisdiction's inspector where the stormwater permit requires attendance.
4.3.2 The conference shall review the construction sequence relative to stabilization of the contributing area, the protection of the subgrade from compaction and sediment, the hold points, the aggregate sources and their delivery and stockpiling, the mixture designs, the mock-up, the surface infiltration acceptance test and its frequency, the procedure for a failing test, and the turnover cleaning.

4.4 Mock-Up

4.4.1 A mock-up of each surface type shall be constructed as indicated in the datasheet, on the project reservoir section, with the project materials, equipment, and crew.
Surface Course Mock-Upradio
● Required for each surface type
○ Not required
4.4.2 Where a mock-up is required, it shall be not less than 225 ft² for pervious concrete and porous asphalt and not less than 100 ft² for pavers, and it shall be tested for surface infiltration by the method and at the rate this standard requires before any production surface is placed.
4.4.3 The mock-up shall establish the surface texture, the joint fill level, the compaction equipment and passes, and, for pervious concrete, the placement rate and the curing procedure, and the accepted mock-up shall be the standard of comparison for the production work.
4.4.4 A mock-up that meets every requirement of this standard may remain as part of the work, and a mock-up that does not shall be removed and replaced at the Contractor's expense.

4.5 Inspection Hold Points

4.5.1 The Contractor shall give the Engineer of Record and the Authority Having Jurisdiction's inspector not less than 24 hours' notice before each hold point listed below, and shall not proceed past a hold point until the inspection has been performed and released in writing:
  • The excavated reservoir subgrade of each cell, after the subgrade infiltration test where one is required on the finished subgrade, and before any geotextile, liner, or stone is placed
  • The liner, after seam testing and before the cushion geotextile and stone are placed over it
  • The underdrain, with its inverts surveyed, before it is covered with stone
  • The completed reservoir and choker or base course, before the bedding or the surface course is placed
  • The surface infiltration test at each location
4.5.2 Where an inspection is not performed within 24 hours of the scheduled time through no fault of the Contractor, the Contractor may proceed after notifying the Engineer of Record in writing, and the Owner shall bear the cost of any later uncovering required to inspect that work.

5 Design Basis and Site Conditions

5.1 Surface Type

5.1.1 The permeable pavement surface type shall be as indicated in the datasheet.
Permeable Pavement Surface Typeselect
Pervious concrete
Porous asphalt
Permeable interlocking concrete pavers
Concrete grid pavers
NOTE Pervious concrete carries the heaviest sustained loads of the four, needs no edge restraint, and is placed by a specialty crew whose availability sets the schedule; its surface ravels under snowplow blades and turning trucks where the crew compacted it short, and it is the surface most often lost to surface clogging because its voids are smallest. Porous asphalt is placed by an ordinary paving crew from a plant that has produced an open-graded mixture, costs the least per square foot, and depends on a modified binder and fibers to hold the voids open through a hot summer; it is the surface that closes first where a sealcoat or a conventional overlay is mistakenly applied in service. Permeable pavers infiltrate through joints that a vacuum sweeper can clean and a crew can refill, carry truck loads on an 80 mm unit with a herringbone pattern, can be lifted and relaid over a utility repair, and cost the most per square foot in material and labor; their joints are the opening a pedestrian notices and the dimension an accessible route is checked against. Concrete grid pavers leave most of their area open to aggregate or turf, carry the intermittent loads of a fire lane or overflow parking, and rut under daily traffic. (5.1.2)
5.1.3 Where more than one surface type is used on the project, the limits of each shall be as shown on the paving plan.

5.2 Hydrologic Mode

5.2.1 The hydrologic mode of the section shall be as indicated in the datasheet.
Hydrologic Moderadio
○ Full infiltration, all stored water infiltrates the subgrade
○ Partial infiltration, an underdrain with a raised outlet releases what the subgrade has not infiltrated
○ No infiltration, a liner isolates the reservoir and the underdrain releases all stored water
NOTE Full infiltration removes the stored volume from the surface system altogether, which earns the highest credit under a retention or recharge criterion, and it is available only where the subgrade drains fast enough to empty the reservoir within the drawdown time, the groundwater is far enough below, and the pavement is outside every setback that protects a foundation or a well. Partial infiltration holds a chosen depth of water against the subgrade through a raised outlet and releases the rest through the underdrain, which is the mode for a slow subgrade that still infiltrates something, and the one most design manuals assign where the measured rate falls between the floor for infiltration credit and the rate that empties the reservoir unaided. No infiltration lines the reservoir and routes every drop through the underdrain, which converts the pavement into detention with a water-quality benefit, and is the mode over a contaminated site, an expansive or collapsible soil, a fill, within a well setback, or where the design manual classifies the surface as a hotspot. (5.2.2)
5.2.3 Requirements in this standard that apply to an infiltration subgrade apply where full or partial infiltration is selected, and requirements that apply to a lined section apply where no infiltration is selected.

5.3 Subgrade Infiltration Rate

5.3.1 The infiltration rate of the subgrade at the reservoir bottom shall be measured in the field by the method indicated in the datasheet, at not fewer than one test per pavement cell and not fewer than one test for each 7,000 ft² of pavement, at the elevation of the reservoir bottom.
Subgrade Infiltration Test Methodselect
Double-ring infiltrometer per ASTM D3385
Test pit falling-head or constant-head test per the governing stormwater design manual
Borehole percolation test per the governing stormwater design manual
Laboratory hydraulic conductivity of undisturbed samples per ASTM D5084
NOTE A double-ring infiltrometer measures the rate on a prepared horizontal face at the reservoir bottom and is the method most design manuals name for a pavement; a test pit wets the full excavation depth and suits a layered soil; a borehole test reaches depth quickly and overstates the rate where the hole crosses a permeable seam; and a laboratory test on an undisturbed sample gives a controlled value for a cohesive soil but misses the fissures and root channels that carry most of the flow in the field. Many design manuals accept only one or two of these for infiltration credit, and that acceptance decides the method more often than the soil does. (5.3.2)
5.3.3 The design infiltration rate of the subgrade shall be as indicated in the datasheet.
Design Subgrade Infiltration Raterange
in/hr
020
Per drawings — the infiltration test results in the geotechnical investigation report (deferred by default)
5.3.4 The design infiltration rate shall be the measured rate divided by the factor of safety the governing stormwater design manual applies to the test method used, and where the manual states no factor, by 2.
5.3.5 Where the design infiltration rate falls below the minimum rate the governing stormwater design manual accepts for infiltration credit, full infiltration shall not be constructed, and the Contractor shall report the result to the Engineer of Record before the hydrologic mode is confirmed.
NOTE A rate taken from a soil survey texture class rather than measured at the reservoir bottom is the most common cause of a permeable pavement that holds water for days and of a permit certification the Authority Having Jurisdiction refuses; a clay subgrade tested at the surface, where roots and desiccation cracks carry water, reads several times faster than the same clay two feet down where the reservoir sits. (5.3.6)

5.4 Groundwater, Bedrock, and Setbacks

5.4.1 The reservoir bottom shall be separated from Seasonal High Groundwater ElevationSeasonal High Groundwater ElevationParameterEach project supplies its own value.seasonal-high-groundwater-elevation by not less than the vertical distance indicated in the datasheet.
Vertical Separation from Seasonal High Groundwater to the Reservoir Bottomrange
Not less than
ft
123456810
Derived — the hydrologic mode and the separation the governing stormwater design manual requires for that mode (by default)
NOTE Separation is what the design manual trades for infiltration credit: an infiltrating reservoir needs unsaturated soil beneath it to drain into and to treat through, and a lined section needs none beyond what keeps the liner from floating. Groundwater that rises into the stone takes the storage it occupies, and the elevation that governs is the seasonal high, not the level on the day of the boring. (5.4.2)
5.4.3 The reservoir bottom of an infiltrating section shall be separated from bedrock by not less than the distance the governing stormwater design manual requires, and the geotechnical investigation report shall confirm the bedrock elevation at each cell.
5.4.4 An infiltrating section shall be set back from every building foundation by not less than the horizontal distance indicated in the datasheet, or shall be lined where it lies closer.
Horizontal Setback of an Infiltrating Section from a Building Foundationrange
Not less than
ft
510152025
Derived — the setback the governing stormwater design manual requires for an infiltrating practice beside a foundation (by default)
5.4.5 The section shall be kept outside the sanitary setback and the wellhead protection area of every water supply well shown on the well plan and the site utility plan, and where a permeable pavement is shown within that setback it shall be a lined, no-infiltration section.
NOTE Infiltration beside a foundation saturates the bearing soil and the backfill against the wall, and infiltration up-gradient of a well delivers the de-icing salt, the oil, and the dissolved load of the pavement to the aquifer the well draws from; the well construction code and the design manual set the distances, and the well plan is where the Engineer of Record reconciles them. (5.4.6)

5.5 Design Traffic Class

5.5.1 The design traffic class of the pavement shall be as indicated in the datasheet.
Design Traffic Classselect
Pedestrian and bicycle
Passenger vehicles in parking stalls and drive aisles
Light trucks, delivery vehicles, and emergency apparatus
Heavy trucks and loading areas
NOTE The traffic class sets the surface thickness, the paver thickness and laying pattern, the structural depth of the base, and the aggregate angularity, and each surface type carries a ceiling: grid pavers stop at intermittent emergency and overflow use, pavers and porous asphalt carry delivery trucks on an 80 mm unit or a thickened course, and pervious concrete and 100 mm pavers on a deep base reach the loading class, where the structural layer is designed as a pavement and the reservoir is sized to the thicker of the structural and the hydrologic demand. (5.5.2)
5.5.3 The structural depth of the section for the design traffic class shall be as stated in the pavement design in the geotechnical investigation report, and where that depth exceeds the reservoir depth the stormwater management report requires, the greater depth shall be built.

5.6 Run-On and Pretreatment

5.6.1 The ratio of the impervious area draining onto the permeable surface to the area of the permeable surface shall not exceed the value indicated in the datasheet.
Run-On Area Ratio, Impervious Area to Permeable Pavement Arearange
Not more than
to 1
0.51235
NOTE A pavement that receives only the rain that falls on it clogs at the rate its own traffic delivers sediment; every square foot of roof, drive, or landscape routed onto it adds that area's load to the same voids and shortens the sweeping interval in proportion. Most design manuals cap the ratio between 2 and 3 to 1, a roof with no sediment is counted more generously than a landscape bed, and a ratio above the cap is a design decision the manual asks the engineer to justify. (5.6.2)
5.6.3 Run-on from a contributing area shall pass through the pretreatment indicated in the datasheet before it reaches the permeable surface.
Run-On Pretreatmentselect
Vegetated filter strip along the receiving edge
Gravel diaphragm or stone trench along the receiving edge
Sumped inlet or forebay at the point of concentrated entry
None, the pavement receives direct rainfall only
NOTE A filter strip settles sheet flow across a grass width before it reaches the pavement and needs mowing and an edge that stays level with the pavement; a gravel diaphragm spreads concentrated flow into sheet flow and traps the coarse load where a shovel can reach it; a sumped inlet or forebay is the device for a pipe or a swale that enters at one point and is cleaned by a vacuum truck; and no pretreatment is the case for a pavement with no run-on, which is the condition the stormwater credit is simplest to defend for. (5.6.4)
5.6.5 Landscape beds, lawns, and bare soil adjoining the permeable surface shall be graded so that they do not drain onto it, or shall be separated from it by a curb or a pretreatment edge.

5.7 Freeze-Thaw and Winter Service

5.7.1 Where Frost DepthFrost DepthParameterEach project supplies its own value.frost-depth is greater than zero, permeable interlocking concrete pavers shall be qualified by test in accordance with ASTM C1645/C1645M with a mass loss not exceeding 1 percent after 50 cycles in the saline solution.
5.7.2 Where Frost DepthFrost DepthParameterEach project supplies its own value.frost-depth is greater than zero, pervious concrete shall contain an air-entraining admixture at the dosage stated in the mixture design.
NOTE An open-graded reservoir drains freely and does not heave, which is why a permeable pavement in a cold climate is built on the same reservoir as one in a warm climate; the surface course is what the freeze-thaw cycle attacks, through the de-icing salt that collects in the voids and the joints, and the paver test and the entrained air are what resist it. (5.7.3)
5.7.4 The operation and maintenance manual shall state that sand and other abrasives shall not be applied to the permeable surface for winter traction, and that any abrasive applied shall be removed by vacuum sweeping before the next thaw.
NOTE Winter sand is the single largest source of the fines that close a permeable surface, and a season of sanding undoes a year of sweeping; a permeable surface drains the meltwater that would otherwise refreeze, so it needs less de-icing than the conventional pavement beside it. (5.7.5)

6 Pervious Concrete

6.1 Requirements in this article apply where pervious concrete is selected as the surface type.

6.2 Pervious Concrete Mixture

6.2.1 Pervious concrete shall be designed under ACI 522.1 to the design void content indicated in the datasheet, verified on the trial batch in accordance with ASTM C1688/C1688M.
Pervious Concrete Design Void Contentrange
%
1530
Default: 20 %
NOTE Void content is the property that sets both the infiltration rate and the strength, in opposite directions: at 15 percent the voids barely connect and the surface clogs within a season, and above 25 percent the paste bridges between the aggregate particles thin to the point that the surface ravels under a turning tire. Twenty percent is the value most mixture designs land on and most acceptance ranges center on; a lower target is set for a loading area where strength governs, and a higher target where the design manual credits the surface rate and the traffic is light. (6.2.2)
6.2.3 The cementitious materials shall be portland cement conforming to ASTM C150/C150M or blended cement conforming to ASTM C595/C595M, with or without supplementary cementitious materials, at the content the mixture design states.
6.2.4 The coarse aggregate shall conform to ASTM C33/C33M and shall be a single-size or narrowly graded aggregate of 3/8 in. or 1/2 in. nominal maximum size, and fine aggregate, where any is used, shall not exceed the proportion the mixture design states.
6.2.5 Admixtures shall conform to ASTM C260/C260M or ASTM C494/C494M, and a hydration-stabilizing admixture shall be used where the time from batching to discharge exceeds 60 minutes.
6.2.6 The water-cementitious materials ratio shall be as stated in the mixture design, and water shall not be added at the site beyond the quantity the mixture design permits for the measured moisture of the aggregate.
NOTE Pervious concrete has no slump to measure and is judged at the chute by the sheen of the paste: a mixture too dry crumbles and bonds nowhere, a mixture too wet lets the paste run to the bottom and seal the voids, and the margin between the two is a few gallons per cubic yard, which is why the water is controlled at the plant and not at the truck. (6.2.7)
6.2.8 The fresh density of the delivered concrete, determined in accordance with ASTM C1688/C1688M, shall be within 5 lb/ft³ of the design fresh density, and a load outside that range shall be rejected.
NOTE The compressive strength of pervious concrete is reported in the mixture design for information and is not an acceptance criterion of this standard; acceptance rests on the fresh density, the hardened void content, the thickness, and the surface infiltration rate, because a strength cylinder of a no-fines mixture does not represent the compaction the surface receives in place. (6.2.9)

6.3 Pervious Concrete Thickness and Joints

6.3.1 The thickness of the pervious concrete surface course shall be as indicated in the datasheet.
Pervious Concrete Thicknessrange
Not less than
in
412
Per drawings — the pavement section details on the civil drawings (deferred by default)
6.3.2 Contraction joints shall be formed by the method indicated in the datasheet, at a spacing not exceeding 20 ft, to a depth not less than one quarter of the thickness.
Pervious Concrete Contraction Joint Methodradio
○ Rolled into the plastic concrete with a joint roller
○ Sawed after curing
○ No contraction joints
NOTE A rolled joint is formed minutes after compaction with the same crew and leaves a clean, open groove, and it must be struck before the surface stiffens; a sawed joint is cut after the cure, which spalls the void walls along the cut and leaves slurry in the voids unless the cut is vacuumed, and it is used where the placement is too large to joint by hand; omitting joints is the practice of many placements, because a no-fines mixture shrinks little and cracks that form in it stay tight and pass water, and it is accepted where a random crack is not an appearance defect. (6.3.3)
6.3.4 Isolation joints shall be provided where the pervious concrete abuts a structure, a conventional pavement, or a curb, and the joint filler shall not be a material that migrates into the voids.

6.4 Pervious Concrete Placement and Curing

6.4.1 The choker or reservoir surface shall be wetted before placement so that it does not draw water from the mixture, and no standing water shall remain on it.
6.4.2 Pervious concrete shall be discharged within 60 minutes of batching, or within 90 minutes where a hydration-stabilizing admixture is used, and a load not discharged within that time shall be rejected.
6.4.3 Pervious concrete shall be placed with a mechanical screed and compacted with a roller or a vibratory screed to the thickness and density the mock-up established, and shall not be finished with a float or trowel.
NOTE A troweled or over-worked surface closes the voids at the exact face through which the water enters, and the pavement beneath it is then a dense slab over a reservoir it cannot reach. (6.4.4)
6.4.5 Each placement shall be covered with polyethylene sheeting within 20 minutes of compaction and shall remain covered for the curing period indicated in the datasheet, with the sheeting held down continuously along every edge.
Pervious Concrete Covered Curing Periodrange
Not less than
days
71014
NOTE A no-fines mixture has a paste film a fraction of a millimeter thick on every particle and no body of concrete to hold moisture, so it dries from every void at once; seven days under sheeting is the curing period ACI 522.1 requires and the one that stops the surface from raveling, and a longer period is set for a hot, windy, or low-humidity site where the sheeting alone is marginal. (6.4.6)
6.4.7 No vehicle shall drive on pervious concrete until the curing period has ended, and no truck until 14 days after placement.

7 Porous Asphalt

7.1 Requirements in this article apply where porous asphalt is selected as the surface type.

7.2 Porous Asphalt Mixture

7.2.1 Porous asphalt shall be designed as an open-graded mixture in accordance with ASTM D7064/D7064M and NAPA IS 131 to the design air void content indicated in the datasheet.
Porous Asphalt Design Air Void Contentrange
%
1624
Default: 18 %
NOTE Eighteen percent air voids is the level at which the voids of an open-graded mixture connect reliably and the mixture still holds its stone skeleton under a steel-wheel roller; a lower target is accepted where a thin choker and a heavy binder make the surface tighter than the hydrology needs, and a higher target is set where the design manual credits the surface rate directly, at the cost of a mixture that drains binder in the haul truck unless the fibers and modifier hold it. (7.2.2)
7.2.3 The nominal maximum aggregate size of the mixture shall be as indicated in the datasheet.
Porous Asphalt Nominal Maximum Aggregate Sizerange
mm
9.512.519
7.2.4 The coarse aggregate shall be crushed stone with not less than 90 percent of particles having two or more fractured faces per ASTM D5821, a Los Angeles abrasion loss not exceeding 40 percent per ASTM C131/C131M, and a sodium sulfate soundness loss not exceeding 12 percent per ASTM C88/C88M.
7.2.5 The binder performance grade shall be as indicated in the datasheet.
Porous Asphalt Binder Performance Gradeselect
PG 58-28
PG 64-22
PG 64-28
PG 70-22
PG 70-28
PG 76-22
PG 76-28
PG 82-22
Per drawings — the pavement design in the geotechnical investigation report (deferred by default)
7.2.6 The binder shall be modified or stabilized as indicated in the datasheet.
Porous Asphalt Binder Modificationselect
Polymer-modified binder
Cellulose or mineral fiber stabilizer in the mixture
Polymer-modified binder and fiber stabilizer together
NOTE An open-graded mixture carries a thick binder film on a few points of contact and has no fine aggregate to hold the binder in place, so a neat binder drains to the bottom of the haul truck and the bottom of the mat; a polymer-modified binder is stiff enough at haul temperature to stay on the stone and is the modification every porous asphalt placed under truck traffic carries; fibers hold the binder by absorption and are the lower-cost answer on a parking lot in a mild climate; and the two together are specified where the grade is two steps above the climate grade and the haul is long. (7.2.7)
7.2.8 The binder content of the mixture shall be not less than the value indicated in the datasheet.
Porous Asphalt Binder Contentrange
Not less than
% of mixture
57.5
Default: 6 % of mixture
7.2.9 The draindown of the mixture, determined in accordance with ASTM D6390 at the production temperature, shall not exceed 0.3 percent.
NOTE A porous asphalt mixture is richer in binder than a dense mixture of the same stone, because durability in an open-graded mixture comes from the thickness of the film and not from the density of the mat; a mixture designed lean to save binder ravels at the surface in its first winter and is the porous asphalt that gave the material its early reputation. (7.2.10)

7.3 Porous Asphalt Thickness and Placement

7.3.1 The compacted thickness of the porous asphalt surface course shall be as indicated in the datasheet.
Porous Asphalt Compacted Thicknessrange
Not less than
in
26
Per drawings — the pavement section details on the civil drawings (deferred by default)
7.3.2 Porous asphalt shall be placed on a choker course of the gradation indicated in the Bedding and Choker Courses section of this standard, and no prime coat or tack coat shall be applied to the choker.
7.3.3 Porous asphalt shall be delivered and placed within the temperature range the job-mix formula states, and shall not be placed when the air temperature is below 50°F or on a wet or frozen choker.
7.3.4 Porous asphalt shall be compacted with static steel-wheel rollers in not more than the number of passes the mock-up established, and vibratory compaction shall not be used.
NOTE Vibration and excess rolling crush the stone-on-stone contacts and close the voids the mixture was designed to hold; the mat reaches its density in two to four static passes while it is still above the binder's compaction temperature, and a roller that keeps working after that is sealing the surface. (7.3.5)
7.3.6 No vehicle shall drive on porous asphalt until the mat has cooled to ambient temperature, and no truck until 24 hours after placement.
7.3.7 A sealcoat, a slurry seal, a fog seal, or a dense overlay shall not be applied to porous asphalt, and the operation and maintenance manual shall state that prohibition.

8 Permeable Interlocking Concrete Pavers

8.1 Requirements in this article apply where permeable interlocking concrete pavers are selected as the surface type.

8.2 Paver Units

8.2.1 Paving units shall conform to ASTM C936/C936M, with a compressive strength not less than 8,000 psi and an absorption not exceeding 5 percent, and shall be formed with spacer bars or a profile that holds the joint opening this standard requires.
8.2.2 The paver thickness shall be as indicated in the datasheet.
Paver Thicknessrange
Not less than
mm
6080100120
Derived — the design traffic class under ASCE 68, 80 mm where any vehicle uses the pavement (by default)
8.2.3 Pavers in a pavement that carries vehicles shall be not less than 80 mm thick, and 60 mm pavers shall be used only where the design traffic class is pedestrian and bicycle.
8.2.4 The joint opening between adjacent pavers shall be as indicated in the datasheet.
Paver Joint Openingrange
in
0.18750.250.31250.3750.5
NOTE The joint is the whole infiltration path of a paver pavement, and its width is a product dimension set by the spacer bars: a narrow joint holds a small stone, infiltrates less, and is the opening an accessible route tolerates; a wide joint infiltrates more, takes a larger stone that resists being vacuumed out, and reaches the 1/2 in. that the accessibility standard sets as the limit for an opening in an accessible route. (8.2.5)
8.2.6 The color, texture, and shape of the paving units shall be as shown on the paving plan and the finish schedule.

8.3 Joint Fill and Laying Pattern

8.3.1 Joints shall be filled with washed stone of the gradation indicated in the datasheet, swept and vibrated into the joints until they are full, and topped up after the final compaction so that the fill is flush with the chamfer.
Paver Joint Fill Gradation per ASTM D448select
No. 8
No. 89
No. 9
NOTE No. 8 stone is the fill for a joint of 3/8 in. and wider and the gradation most paver manufacturers and the ASCE 68 design method assume; No. 89 enters a 1/4 in. joint and holds its position under a vacuum sweeper better than the finer stone; and No. 9 is the fill for a joint narrower than 1/4 in., where it is the only stone that enters, and it is the fill a sweeper set too aggressively removes. The fill gradation and the joint opening are selected together, and a fill that will not enter the joint leaves the surface unfilled and the pavers free to creep. (8.3.2)
8.3.3 Sand, stone dust, and polymeric joint sand shall not be used as joint fill or as bedding in any layer of a permeable pavement.
8.3.4 Pavers in a pavement that carries vehicles shall be laid in a herringbone pattern at 45 or 90 degrees to the direction of travel, and the pattern in a pedestrian pavement shall be as shown on the paving plan.
NOTE A herringbone pattern locks every unit against its neighbors in both directions, so a braking or turning wheel cannot shove a row; a running bond or a stack bond carries the same load but creeps in the direction of its continuous joints under traffic, which is why ASCE 68 limits those patterns to pedestrian use. (8.3.5)
8.3.6 Cut units along an edge in a pavement that carries vehicles shall be not smaller than one third of a full unit, and smaller spaces shall be filled by adjusting the pattern or with a concrete infill of the same thickness.
8.3.7 After the joints are filled, the pavement shall be compacted with a plate compactor of not less than 5,000 lbf centrifugal force, fitted with a protective pad, in not fewer than two passes, until the units are seated in the bedding and the joints are full.
8.3.8 The finished paver surface shall not deviate from a 10 ft straightedge by more than 3/8 in., and the lippage between adjacent units shall not exceed 1/8 in.

9 Concrete Grid Pavers

9.1 Requirements in this article apply where concrete grid pavers are selected as the surface type.
9.2 Grid paving units shall conform to ASTM C1319, with a compressive strength not less than 5,000 psi, and shall be not less than 3-1/8 in. thick.
9.3 The cells of the grid units shall be filled as indicated in the datasheet.
Grid Paver Cell Fillradio
○ Washed stone of the joint fill gradation
○ Topsoil and turf over a stone bedding
9.4 Where the cells are filled with topsoil and turf, the topsoil shall be a sandy growing medium placed to 1/2 in. below the top of the unit, and the turf shall be established and mowed twice before the pavement is placed in service.
9.5 Grid pavers shall be set on the bedding course this standard requires for pavers, shall be laid tight against one another, and shall be restrained at every edge.
9.6 Grid pavers shall not be used where the design traffic class is heavy trucks and loading areas, and a grid pavement used as a fire lane shall be marked as the fire code official requires under Pavement MarkingsPavement Markings and Site SignageResolves to the current adopted revision.sync/pavement-markings.

10 Bedding and Choker Courses

10.1 The bedding course beneath pavers and grid pavers shall be 2 in. of washed No. 8 stone per ASTM D448, screeded to grade over the base course and not compacted before the units are set.
NOTE A No. 8 bedding is the one layer every paver manufacturer, ASCE 68, and the paver industry design method agree on, because it is the largest stone that screeds true under a 2 in. depth and the smallest that passes water as fast as the joints deliver it; a sand bedding is the single most common defect in a permeable paver pavement, and it turns the section into a conventional one that drains nowhere. (10.2)
10.3 The choker or base course between the surface course and the reservoir shall be of the gradation indicated in the datasheet.
Choker or Base Course Gradation per ASTM D448select
None, the surface course or bedding placed directly on the reservoir stone
No. 57
No. 67
NOTE A choker course of No. 57 stone keys into the top of a large reservoir stone to make a surface that a paver screed, a pervious concrete screed, or an asphalt paver can run on without the surface material falling into the voids below, and in a paver section it is the 4 in. base course ASCE 68 names between the bedding and the subbase; No. 67 chokes a No. 3 or No. 4 reservoir more tightly where the surface is porous asphalt placed in a thin lift; and no choker is the section where the reservoir itself is No. 57 stone and the pervious concrete or the bedding is placed on it directly. (10.4)
10.5 The thickness of the choker or base course shall be as indicated in the datasheet.
Choker or Base Course Thicknessrange
Not less than
in
08
Per drawings — the pavement section details on the civil drawings (deferred by default)
10.6 Choker and base stone shall meet the washed-stone, fines, and fractured-face requirements of the Reservoir Aggregate section of this standard, shall be placed in one lift, and shall be compacted with a vibratory plate or roller until the surface is firm and the stone does not move under foot.

11 Reservoir Aggregate

NOTE The reservoir performs two jobs at once, it carries the traffic load to the subgrade and it stores the stormwater the permit credits, and its depth is set by the thicker of the two demands. The storage is in the voids between the stones, so every property of the reservoir stone serves the voids: it is single-sized so the small particles do not fill the gaps between the large ones, it is washed so there are no fines to carry down into the subgrade, and it is crushed so the angular faces lock and the stone does not consolidate under load. (11.1)

11.2 Reservoir Gradation and Quality

11.2.1 Reservoir stone shall be washed, crushed, angular stone of the gradation indicated in the datasheet.
Reservoir Aggregate Gradation per ASTM D448select
No. 2
No. 3
No. 4
No. 57
No. 67
NOTE The larger gradations store the most water per cubic foot, let it move through the reservoir to the underdrain fastest, and are the subbase ASCE 68 names beneath a paver base course; they are also the hardest to place to a level bed and need a choker before any surface can be placed on them. No. 57 stone is the reservoir most pervious concrete is placed on directly and the base course of a paver section, with a void ratio a few points lower and a surface a screed can run on; No. 67 is used where a thin reservoir under a pedestrian pavement does not justify a two-stone section. A reservoir deeper than about 12 in. is usually built of the large stone with a choker, and a shallow one of No. 57 alone. (11.2.2)
11.2.3 Reservoir stone shall have not more than 2 percent by mass passing the No. 200 sieve per ASTM C117, not less than 90 percent of particles with two or more fractured faces per ASTM D5821, a Los Angeles abrasion loss not exceeding 40 percent per ASTM C131/C131M, and a sodium sulfate soundness loss not exceeding 12 percent per ASTM C88/C88M.
11.2.4 Recycled concrete aggregate, slag, rounded gravel, limestone screenings, and any aggregate with a fines content above the limit shall not be used in any layer of the section unless the Engineer of Record permits it in writing for the project.
NOTE Recycled concrete releases lime into the water that passes through it, which raises the pH of the discharge and cements the fines at the reservoir bottom, and rounded gravel neither locks to carry the load nor holds the void ratio the credit assumes. (11.2.5)

11.3 Reservoir Depth and Void Ratio

11.3.1 The depth of the reservoir shall be as indicated in the datasheet.
Reservoir Depthrange
Not less than
in
648
Per drawings — the stormwater management report and the pavement section details on the civil drawings (deferred by default)
11.3.2 The storage volume credited to the reservoir shall be computed with the void ratio indicated in the datasheet, and the Contractor shall furnish reservoir stone whose measured void ratio is not less than that value.
Design Void Ratio of the Reservoir Aggregaterange
Not less than
%
2545
Default: 40 %
NOTE Forty percent is the void ratio the industry attributes to clean, crushed, single-sized stone and the value most design manuals cap the credit at; a rounded gravel or a graded stone falls short of it, and a reservoir credited at 40 percent and built with stone that yields 30 stores a quarter less than its permit assumes. (11.3.3)
11.3.4 Where the reservoir bottom slopes, the reservoir shall be terraced with check dams or berms at the spacing and to the heights shown on the pavement section details and the reservoir grading plan, so that the stored water is held across the cell rather than draining to its low end.
NOTE A reservoir built on a 2 percent subgrade slope holds its design depth at the downhill edge and nothing at the uphill edge, and the surface rate is then tested on a pavement whose storage is a fraction of the volume credited; the terraces are what make the plan-area storage real. (11.3.5)

11.4 Reservoir Placement

11.4.1 Reservoir stone shall be placed from the edge of the cell inward, or from stone already placed, and no equipment shall operate on an infiltration subgrade.
11.4.2 Reservoir stone shall be placed in lifts not exceeding 8 in. in loose thickness and compacted with a vibratory plate or roller in not fewer than two passes per lift, until the stone does not move under the compactor and the surface is firm.
11.4.3 Density of the reservoir shall not be specified or accepted on a moisture-density relationship, and no proctor-based acceptance shall be applied to a single-sized stone.
NOTE A moisture-density test assumes a continuous gradation that packs tighter with water and effort, and a single-sized stone has neither; it seats under a few passes to a density the compactor cannot change, and the acceptance that means anything is the stone source, the washed-stone certification, and the compaction passes the mock-up established. (11.4.4)
11.4.5 Stone shall not be dumped in piles on the subgrade and spread by pushing, and the exposed subgrade shall be covered with geotextile or stone within the same working day it is excavated to grade.

12 Separation Geotextile

12.1 The geotextile at the reservoir boundary shall be as indicated in the datasheet.
Separation Geotextile at the Reservoir Boundaryradio
○ Nonwoven geotextile on the sides of the excavation and across the full reservoir bottom
○ Nonwoven geotextile on the sides of the excavation only
○ No geotextile at the reservoir boundary
NOTE A geotextile on the sides of the excavation keeps the adjoining soil from washing into the stone through the excavation face, and nearly every manufacturer and design manual calls for it. The bottom is the decision: a geotextile across the reservoir bottom separates the stone from a subgrade that would pump fines up into it, and it is also the plane on which the sediment that reaches the bottom of the reservoir collects, so a bottom fabric is the layer that blinds first on an infiltration subgrade and is the one most paver-industry guidance omits where the subgrade is sand or gravel. Omitting the geotextile altogether is the case for a clean granular subgrade in an excavation that will be stoned the day it is cut, and for a lined section where the cushion geotextile does the job. (12.2)
12.3 Where a geotextile is placed across the bottom of an infiltrating section, the geotextile shall be a nonwoven needle-punched geotextile furnished under GeosyntheticsGeosynthetics and GeotextilesResolves to the current adopted revision.sync/geosynthetics for the separation function, and a woven slit-film geotextile shall not be used.
12.4 Geotextile panels shall overlap not less than 12 in. at every seam, with the upslope panel lapped over the downslope panel, and shall be turned up the excavation face to the underside of the surface course.
12.5 No geotextile shall be placed between the surface course and the reservoir, between the bedding and the base, or within the reservoir, where it would collect sediment and stop the vertical flow of water.
12.6 A geotextile torn or punctured during stone placement shall be patched with a panel of the same material extending not less than 24 in. beyond the damage in every direction.

13 Impermeable Liner

13.1 The reservoir shall be lined as indicated in the datasheet.
Impermeable Linerradio
○ Geomembrane liner across the reservoir bottom and up the sides of the excavation
○ No liner
Derived — the hydrologic mode, a liner where no infiltration is selected and none otherwise (by default)
13.2 Requirements in the remainder of this section apply where a liner is selected.
13.3 The liner material shall be as indicated in the datasheet.
Liner Materialselect
High-density polyethylene geomembrane per GRI GM13
Linear low-density polyethylene geomembrane per GRI GM17
Polyvinyl chloride geomembrane per ASTM D7176
Reinforced polypropylene geomembrane
NOTE HDPE is the stiffest and the most chemically resistant of the four and the least forgiving of a rough subgrade or a tight corner, so it is fusion-welded by a specialty installer and specified where the discharge is regulated; LLDPE conforms to the excavation and the underdrain trench and is seamed in the field with the same equipment at a lower stiffness; PVC conforms best and seams with solvent or heat by a general crew, with a lower resistance to hydrocarbons from the pavement above; and reinforced polypropylene carries a scrim that resists the puncture of the stone placed on it and is specified where the cushion geotextile alone is judged marginal. (13.4)
13.5 The liner thickness shall be as indicated in the datasheet.
Liner Thicknessrange
Not less than
mil
20304060
13.6 The liner shall be protected by a cushion geotextile furnished under GeosyntheticsGeosynthetics and GeotextilesResolves to the current adopted revision.sync/geosynthetics on each face where reservoir stone bears on it, and the subgrade beneath it shall be free of stones larger than 3/8 in., roots, and sharp projections.
13.7 The liner shall extend up the excavation face to the elevation shown on the pavement section details and shall be sealed to the underdrain outlet pipe and to every other penetration with the manufacturer's pipe boot or a mechanical batten with a gasket.
13.8 Field seams shall be made by the method the liner manufacturer publishes for the material, every seam shall be tested nondestructively over its full length by air pressure per ASTM D5820 for a dual-track fusion seam or by vacuum box for every other seam, and a seam that fails shall be repaired and retested before the cushion geotextile is placed.
13.9 A lined reservoir below Seasonal High Groundwater ElevationSeasonal High Groundwater ElevationParameterEach project supplies its own value.seasonal-high-groundwater-elevation shall not be left empty before the reservoir stone is in place, and the Contractor shall maintain dewatering under EarthworkEarthworkResolves to the current adopted revision.sync/earthwork until it is.
NOTE A lined reservoir weighs almost nothing when it is empty, and a liner that floats before the stone is placed folds, tears at its seams, and has to be removed; the stone is the ballast, and the sequence that places it the same day the liner is tested is what keeps the liner down. (13.10)

14 Underdrains and Outlet Control

14.1 An underdrain shall be provided within the reservoir as indicated in the datasheet.
Underdrain within the Reservoirradio
○ Perforated underdrain in the reservoir bottom
○ No underdrain
Derived — the hydrologic mode, an underdrain where partial or no infiltration is selected and none where full infiltration is selected (by default)
14.2 Requirements in the remainder of this section apply where an underdrain is provided.

14.3 Underdrain Pipe

14.3.1 Underdrain pipe shall be perforated pipe of the material indicated in the datasheet, laid in the reservoir stone with the perforations down and without a pipe sock or a filter wrap.
Underdrain Pipe Materialselect
Perforated corrugated polyethylene per AASHTO M 252 or AASHTO M 294
Perforated PVC drain pipe per ASTM D2729
Perforated PVC sewer pipe per ASTM D3034
NOTE Corrugated polyethylene is the lightest, the cheapest, and the easiest to lay in a stone bed, and its corrugated interior holds sediment and resists a jetting nozzle; ASTM D2729 PVC is a thin-walled smooth pipe that cleans easily and is the drain pipe most paver-industry guidance names; and ASTM D3034 PVC is a sewer-wall pipe specified where the underdrain runs under a truck loading area, where it is jetted on a schedule, or where the local sewer authority's standard details call for it. (14.3.2)
14.3.3 The underdrain diameter shall be as indicated in the datasheet.
Underdrain Pipe Diameterrange
in
4681012
Per drawings — the underdrain plan and profile on the civil drawings (deferred by default)
14.3.4 Underdrain layout, inverts, and slopes shall be as shown on the underdrain plan and profile, and the Contractor shall survey the inverts before the pipe is covered.
14.3.5 A cleanout shall be provided at the upstream end of every underdrain run and at every change of direction, extended to the finished surface with a cap set flush, so that the run can be rodded or jetted from the surface.
14.3.6 The underdrain shall discharge to the storm sewer, inlet, or downstream stormwater facility shown on the drawings through the connection and the invert specified under Storm DrainageStorm DrainageResolves to the current adopted revision.sync/storm-drainage.

14.4 Raised Outlet and Drawdown

14.4.1 Where the hydrologic mode is partial infiltration, the underdrain outlet shall be raised so that water is held in the reservoir above the subgrade to the height indicated in the datasheet before it discharges.
Raised Outlet Height above the Reservoir Bottomrange
in
024
Per drawings — the stormwater management report and the outlet detail on the civil drawings (deferred by default)
14.4.2 The raised outlet shall be formed by an upturned elbow or a weir in an accessible outlet structure, and not by a bend buried in the stone.
NOTE The raised outlet sets the depth of water that waits on the subgrade and the depth that leaves through the pipe, so it is the dimension that divides the storm between infiltration and release; an outlet formed in a buried bend cannot be inspected, adjusted when the measured rate differs from the design, or cleaned, and every design manual that credits partial infiltration asks to see it. (14.4.3)
14.4.4 The reservoir shall drain from full to empty, through infiltration and the underdrain together, within the time indicated in the datasheet.
Reservoir Drawdown Timerange
Not more than
hr
244872
Derived — the drawdown time the governing stormwater design manual requires for a permeable pavement (by default)
NOTE A reservoir that has not emptied before the next storm stores only the part of its volume that is empty, and a subgrade that stays saturated loses the bearing the structural design counted on; the drawdown time is a firm limit in every design manual, and the raised outlet height, the orifice, and the subgrade rate are what the civil engineer of record adjusts to meet it. (14.4.5)
14.4.6 Where an overflow or a bypass is shown for the pavement cell, it shall be set at the elevation shown on the drawings and shall discharge to the storm sewer under Storm DrainageStorm DrainageResolves to the current adopted revision.sync/storm-drainage.

15 Edge Restraints

15.1 Every edge of a paver or grid paver pavement shall be restrained as indicated in the datasheet, and the restraint shall bear on the base course and not on the bedding.
Paver Edge Restraintselect
Cast-in-place concrete curb or curb and gutter
Precast concrete curb
Cut stone curb
Metal or plastic edge restraint spiked into the base course
Existing structure, wall, or pavement edge
NOTE A cast-in-place curb is the restraint of nearly every vehicular paver pavement, because it is placed before the base and the pavers are laid against it, and it is built under the concrete paving standard; a precast curb is set on a concrete haunch and suits a site that cannot wait for a cast-in-place cure; a cut stone curb is the restraint where the finish schedule calls for it; a spiked metal or plastic restraint holds a pedestrian pavement and is the only restraint that can follow a curve tightly, and it is lifted by frost and by a wheel that rides over the edge, so ASCE 68 keeps it off vehicular work; and an existing structure or pavement edge restrains where the pavers meet one. (15.2)
15.3 Where the restraint is a concrete curb, the curb shall be constructed under Concrete PavingConcrete Paving, Curbs, and SidewalksResolves to the current adopted revision.sync/concrete-paving with its back face vertical for the full depth of the bedding and surface course, and the gap between the curb and the first paver shall not exceed the joint opening.
15.4 Pervious concrete and porous asphalt need no edge restraint for their own stability, and an edge against landscape shall be formed with a thickened edge or a curb as shown on the pavement edge details, so that the adjoining soil does not wash into the voids.

16 Inspection and Maintenance Provisions

16.1 The pavement shall be furnished with the inspection and maintenance provisions indicated in the datasheet.
Inspection and Maintenance Provisionscheckbox
☑ Observation well to the reservoir bottom in each pavement cell
☑ Cleanout at each underdrain run
☐ Access cover on the outlet structure
☐ Permanent marker or sign identifying the permeable pavement and the maintenance it requires
NOTE An observation well is a perforated riser standing on the reservoir bottom and capped flush with the surface, through which the Owner reads how far the reservoir has drained a day after a storm; it is the only instrument that distinguishes a clogged surface from a clogged subgrade, and most stormwater permits require one per cell. The sign is the device that stops a future contractor from sealcoating the surface or a future owner from sanding it. (16.2)
16.3 Each observation well shall be a perforated pipe not less than 4 in. in diameter, set vertically on the reservoir bottom, with a lockable cap set flush with the finished surface and its location recorded on the record drawings.
16.4 The locations of observation wells, cleanouts, and the outlet structure shall be as shown on the underdrain plan.

17 Installation

17.1 Sequencing and Sediment Protection

17.1.1 A permeable pavement cell shall not be excavated to the reservoir subgrade until every area that drains to it has been permanently stabilized, or until the runoff from every unstabilized area has been diverted around the cell under Erosion And Sediment ControlErosion and Sediment ControlResolves to the current adopted revision.sync/erosion-and-sediment-control.
17.1.2 The surface course shall be placed as the last paving operation in the area it serves, after the adjoining pavements, curbs, utilities, and landscape grading are complete, unless the Engineer of Record accepts a different sequence in writing with the protection it requires.
17.1.3 Where a completed reservoir or surface must remain exposed before the contributing area is stabilized, the Contractor shall protect it from sediment-laden runoff with a diversion berm, a silt fence set outside the edge restraint, or a geotextile cover over the reservoir, and shall remove the protection only when the contributing area is stabilized.
17.1.4 Construction equipment, haul trucks, and material deliveries shall not cross the completed surface, and no soil, mulch, or construction material shall be stockpiled on it.
17.1.5 Sediment-laden runoff that reaches a completed reservoir before the surface is placed shall be removed, and where the stone has been contaminated the Contractor shall remove and replace the contaminated stone at the Contractor's expense.
17.1.6 Sediment that reaches a completed surface before acceptance shall be removed by vacuum sweeping before it is tracked into the voids, and the surface shall be tested again for infiltration where the Engineer of Record directs.
NOTE The reservoir is open storage for the whole period it is exposed, and the construction site around it is the dirtiest its contributing area will ever be; a permeable pavement built first and used as the haul road is clogged before the certificate of occupancy, and the failure is charged to the product. (17.1.7)

17.2 Subgrade Excavation and Protection

17.2.1 Excavation to within 12 in. of the reservoir subgrade elevation shall be made under EarthworkEarthworkResolves to the current adopted revision.sync/earthwork, and the final 12 in. shall be excavated under this standard, with equipment working from outside the cell or from stone already placed, immediately before the geotextile, liner, or reservoir stone is placed.
17.2.2 An infiltration subgrade shall not be proof-rolled, compacted, or driven on by rubber-tired or tracked equipment, and the proof rolling and compaction that EarthworkEarthworkResolves to the current adopted revision.sync/earthwork requires of a pavement subgrade shall not be applied to it.
17.2.3 Where the hydrologic mode is no infiltration, the subgrade beneath the liner shall be compacted and proof-rolled as a pavement subgrade under EarthworkEarthworkResolves to the current adopted revision.sync/earthwork before the liner is placed.
17.2.4 Where an infiltration subgrade has been smeared, compacted, or sealed by equipment or by rain, the surface shall be scarified to a depth of 3 in. with a toothed bucket or a rake and the loosened soil left in place before the stone is placed.
NOTE The subgrade is prepared to pass water, not to carry a roller: a clay subgrade smeared by a bucket or rolled by a loaded truck closes to a fraction of its measured rate, and the pavement built on it then behaves as a lined section with no outlet. (17.2.5)
17.2.6 The excavated subgrade shall be released at the hold point before any geotextile, liner, or stone is placed, and where a subgrade has stood exposed for more than one working day, or has received runoff, the Engineer of Record may require the infiltration test to be repeated at the Contractor's expense before release.
17.2.7 Where the finished subgrade of an infiltrating section fails the infiltration rate the design rests on, the Contractor shall report the result to the Engineer of Record, and the Engineer of Record shall direct remediation, conversion to partial or no infiltration, or a revised reservoir, with the cost borne by the Contractor where the failure results from compaction or contamination of the subgrade during construction.

17.3 Surface Grades and Slopes

17.3.1 The finished surface shall be graded to the elevations and slopes shown on the grading plan, and shall not slope more than 5 percent unless the reservoir beneath it is terraced as this standard requires.
17.3.2 The finished surface shall drain to its own voids and joints, and no area shall hold water deeper than 1/4 in. an hour after rain, and no area of ponding shall occur within an accessible parking space, access aisle, or accessible route.
17.3.3 Accessible parking spaces, access aisles, and accessible routes across the pavement shall be finished within the slope limits of the adopted accessibility standard, and the Contractor shall verify the finished slopes at each space and aisle before the surface is released for marking.
17.3.4 The finished surface shall be flush with every adjoining pavement, curb, drainage structure, and cleanout cap, within 1/4 in., so that a vacuum sweeper passes over the edge without lifting.

18 Testing and Acceptance

18.1 Surface Infiltration

18.1.1 The surface infiltration rate of the completed pavement shall be measured in accordance with ASTM C1701/C1701M for pervious concrete and porous asphalt, and in accordance with ASTM C1781/C1781M for permeable interlocking concrete pavers and grid pavers, and shall be not less than the rate indicated in the datasheet at every test location.
Surface Infiltration Acceptance Raterange
Not less than
in/hr
50100150200300500
NOTE A new permeable surface infiltrates at several hundred inches per hour, and the acceptance rate is set well below that, because the surface rate is the property that falls in service and the number in the datasheet is the margin the Owner starts with; 100 in/hr is the acceptance most design manuals and manufacturers name and is an order of magnitude above any rainfall, a lower rate is accepted for a grid or turf surface, and a higher rate is set where the design manual tests the surface at acceptance against the rate it credits and the Owner wants the sweeping interval to start long. (18.1.2)
18.1.3 Surface infiltration tests shall be performed at not fewer than one location for each area of pavement indicated in the datasheet, at not fewer than three locations in each cell, at locations the testing agency selects and distributes across the cell, after the pavement is complete and before it is opened to traffic.
Pavement Area per Surface Infiltration Testrange
Not more than
ft²
25005000100001500025000
NOTE A closer test spacing finds the low corner of a cell that a single test in the middle of it misses, at the cost of a technician's day per cell; one test per 5,000 to 10,000 ft² is the usual setting on site work, the close interval is set where the pavement is small and the whole of it is a few tests, and the wide interval where the state design manual sets its own sampling and that sampling applies. (18.1.4)
18.1.5 Where a test location fails the acceptance rate, the Contractor shall vacuum-sweep the area around it, the location shall be retested at the Contractor's expense, and a location that fails the retest shall be removed and replaced to the limits the Engineer of Record directs, at the Contractor's expense.
18.1.6 The testing agency shall record the location, the method, the water volume, the time, and the computed rate of every test, passing and failing, and the Contractor shall not replace a failing report with the report of a later passing test.

18.2 Pervious Concrete Density, Void Content, and Thickness

18.2.1 The fresh density of pervious concrete shall be tested in accordance with ASTM C1688/C1688M on the first three loads of each placement day and on every fifth load thereafter.
18.2.2 Not fewer than three cores shall be taken from each 5,000 ft² of pervious concrete, or fraction of it, placed on a day, not sooner than 7 days after placement, and tested in accordance with ASTM C1754/C1754M for hardened density and void content and measured for thickness.
18.2.3 The average void content of each set of cores shall be within 3 percentage points of the design void content, and the thickness of each core shall be not less than the thickness in the datasheet less 1/4 in.
18.2.4 A placement whose cores fall outside the void content tolerance or below the thickness limit shall be evaluated by the Engineer of Record, who may accept it at an adjusted price, require additional cores at the Contractor's expense to bound the deficient area, or require removal and replacement.
18.2.5 Core holes shall be filled with pervious concrete of the project mixture the same day the core is taken.

18.3 Drawdown Observation

18.3.1 Where an observation well is provided, the Contractor shall record the water level in each well at 24 hours and at 48 hours after the first storm of 0.5 in. or more that follows completion, and the reservoir shall have drained to the raised outlet elevation, or to empty where there is none, within the drawdown time in the datasheet.
18.3.2 Where the reservoir has not drained within the drawdown time and the surface infiltration tests have passed, the Contractor shall report the condition to the Engineer of Record, who shall determine whether the cause is the subgrade, the outlet, or construction, and the cost of the correction shall be borne by the Contractor where the cause is compaction or contamination of the subgrade or a defect in the underdrain or outlet.

18.4 Final Acceptance of the Pavement

18.4.1 Final acceptance of the permeable pavement shall require passing results at every surface infiltration test location, pervious concrete cores within tolerance where that surface is used, the drawdown observation where an observation well is provided, the record drawings, the operation and maintenance manual, the turnover cleaning, and the recorded maintenance agreement where the stormwater permit requires one.
18.4.2 Acceptance shall not waive the Contractor's warranty obligations or the Contractor's liability for latent defects.

19 Maintenance Turnover

19.1 The permeable surface and the joints shall be vacuum-swept, every cleanout and observation well shall be flushed and capped, and the outlet structure shall be cleaned of construction sediment before the surface infiltration acceptance tests are performed and again at turnover where the pavement has been in use between the two.
19.2 The operation and maintenance manual shall state a vacuum sweeping schedule of not fewer than two sweepings per year, one after the winter season and one after leaf fall, with a regenerative-air or vacuum sweeper and not a mechanical broom sweeper, and additional sweepings wherever the observation well or a surface test shows the rate falling.
19.3 The operation and maintenance manual shall state the observation well reading procedure and the drawdown time, the surface infiltration retest method and the rate at which cleaning is triggered, the joint fill top-up procedure and gradation for a paver surface, the prohibition on sealcoating, overlay, sand, and abrasives, and the repair procedure for a utility cut through the section.
19.4 The Contractor shall record the surface infiltration rate at every acceptance test location and the observation well readings at turnover, and that record shall be the baseline from which the Owner's first cleaning interval is measured.
NOTE A permeable pavement is a stormwater practice with a maintenance obligation attached to the property, and the party that sweeps it is the party that keeps the permit; the manual is written for a maintenance crew that has never seen the section, and the baseline rate is what lets a reading a year later be judged. (19.5)

20 Delivery, Storage, and Handling

20.1 Washed stone for every layer shall be delivered from the certified source, shall be stockpiled on a clean, hard, drained surface separated from soil and from every other aggregate, and shall not be stockpiled on the subgrade or on a completed layer of the section.
20.2 A stockpile that has been contaminated by soil, by runoff, or by another aggregate shall not be used in the section, and the Engineer of Record may require a gradation and fines test on any stockpile before it is placed.
NOTE Washing removes the fines at the quarry, and a stockpile on bare ground or under a runoff path puts them back; aggregate cleanliness is the property most easily lost between the quarry and the reservoir and the one no later test on the completed pavement can restore. (20.3)
20.4 Paving and grid units shall be delivered banded on pallets, stored on a hard surface, and protected from soil, mortar, and mud before placement.
20.5 Geotextile and liner rolls shall be stored off the ground and covered where they will remain on site longer than the exposure period the manufacturer publishes, and shall be handled so that the rolls are not torn or punctured.
20.6 Pervious concrete shall be delivered in accordance with ASTM C94/C94M, with the batch time on every ticket, and porous asphalt shall be sampled in accordance with ASTM D979/D979M and delivered in covered trucks at the temperature the job-mix formula states.

21 Warranty

21.1 The Contractor shall warrant the permeable pavement against defects in materials and workmanship for the period indicated in the datasheet, beginning at substantial completion.
Permeable Pavement Warranty Periodrange
Not less than
years
1235
NOTE One year from substantial completion is the period most site civil work carries and the one in which a section built wrong shows it, through its first winter and its first wet season; a longer period is set where the stormwater permit or a municipality that will accept the pavement requires it, or where the Owner wants the installer answerable through the second season that a subgrade takes to prove its rate. (21.2)
21.3 The warranty shall cover raveling of pervious concrete or porous asphalt, loss of joint fill or creep of pavers beyond the lippage and straightedge limits of this standard, settlement of the surface over the reservoir or over the underdrain trench, displacement of an edge restraint, a liner that leaks, an underdrain or outlet that does not drain, and a surface infiltration rate at any acceptance test location that falls below the acceptance rate in the datasheet within the warranty period where the Owner has performed the sweeping the operation and maintenance manual requires.
21.4 The warranty shall not cover loss of infiltration attributable to sediment delivered from the contributing area after acceptance, to winter sand or abrasives, to a sealcoat or overlay applied by others, to a utility cut through the section after substantial completion, or to loads exceeding the design traffic class in the datasheet.
21.5 Where the parties disagree whether a loss of infiltration is attributable to construction or to a cause after acceptance, the Engineer of Record shall make the initial determination, and the observation well record and the baseline rate at turnover shall be the evidence considered first.
21.6 Where the Contractor repairs or replaces work under the warranty, the repaired work shall carry a warranty running from the date of the repair for the full warranty period or for the remainder of the original period, whichever ends later.
21.7 The Contractor shall bear the cost of the warranty repair, of the markings restored over it, and of the restoration of adjoining pavement and landscape disturbed by it.
21.8 The warranty does not limit the Owner's remedies for a sand bedding, a contaminated reservoir, a compacted subgrade, or an untested liner seam that is concealed by the surface course and discovered after the warranty period.

22 Spare Parts

22.1 For a paver or grid paver pavement, the Contractor shall deliver attic stock of full units of each type, color, and thickness used, in the quantity indicated in the datasheet, palletized and stored where the Owner directs.
Paver Attic Stockrange
Not less than
% of installed units
05
22.2 The Contractor shall furnish the attic stock indicated in the datasheet with the closeout submittals.
Attic Stock Furnishedcheckbox
☑ Paving or grid units of each type, color, and thickness
☑ Joint fill stone of the specified gradation, not less than 1 ton
☐ One spare cap for each observation well and cleanout
NOTE A utility cut through a paver pavement is repaired by lifting the units and relaying them, and the units lost to the saw are replaced from the attic stock in the same color run; a stock of the joint fill lets the Owner top up the joints after the first season's sweeping without finding a source for a ton of washed No. 8 stone. (22.3)

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