Pervious Pavement¶
Pervious paving systems are addressed in BMP Manual Chapter 9.6. In the live source corpus, the chapter distinguishes between systems designed to infiltrate into the subsoil and systems designed with underdrains, and that distinction controls how the BMP may be used for recharge and volume-reduction purposes.
Structured citation evidence for this page lives in the sibling claim manifest.
Chapter 9.6 describes pervious paving systems as a permeable surface course placed over a transition layer and open-graded aggregate storage bed. The chapter covers two main configurations:
- systems designed to infiltrate into the subsoil
- systems designed with underdrains
When designed in accordance with the chapter, the adopted total suspended solids removal rate is 80 percent.
The source-backed operational distinction is important. Only systems designed to infiltrate into the subsoil may be used to meet groundwater recharge requirements. Underdrained systems may still provide treatment and storage, but they are not the same as infiltrating systems for recharge purposes.
| Parameter | Source-backed requirement |
|---|---|
| Maximum additional inflow contributory drainage area ratio | 3:1 |
| Maximum drain time | 72 hours |
| Minimum tested subsoil permeability for infiltrating design | 1.0 in/hr |
| Minimum subsoil design permeability for infiltrating design | 0.5 in/hr after applying the Chapter 12 factor of safety |
| SHWT separation for underdrained design | 1 foot below the bottom of the storage bed |
| SHWT separation for infiltrating design | 2 feet below the bottom of the storage bed |
Chapter 9.6 also makes the underdrain distinction explicit in the worked examples: where the tested subsoil permeability is below the minimum for an infiltrating design, an underdrained system may still be used, but that configuration is not used to satisfy the recharge standard and the chapter's example states it cannot be used to reduce volume.
The source-backed siting review should focus on the actual Chapter 9.6 and NJAC constraints:
- verify Chapter 12 soil testing before crediting infiltration into subsoil
- use the 1-foot or 2-foot SHWT separation standard based on configuration
- assess hydraulic impacts on the groundwater table for infiltrating systems
- keep the system free from sediment during construction and avoid adjacent sediment sources
The live citations layer does not support a special NJAC mounding trigger such as > 3,000 ft² or < 4 ft to SHWT for pervious pavement. The governing trigger is the general hydraulic-impact requirement for infiltration BMPs.
Chapter 9.6 is unusually explicit about maintenance:
- the surface course must be vacuum swept, not power swept, at least four times per year
- the first annual maintenance must be performed in the spring
- each spring, after the last snow or ice event, the surface infiltration rate must be tested at multiple locations
That is a stronger requirement than the older shorthand summaries that reduced maintenance to "twice per year."
The most important page-level failure points in the live source set are:
- claiming infiltration credit without Chapter 12 support for the native soil profile
- confusing an underdrained system with an infiltrating system for recharge or volume-reduction purposes
- ignoring the hydraulic-impact review for systems that infiltrate into subsoil
- allowing sediment loading or poor maintenance to clog the surface course
Governing source chapters
- BMP Manual Chapter 9.6 for pervious paving systems
- BMP Manual Chapter 12 for soil testing criteria
- BMP Manual Chapter 13 for groundwater-mounding analysis
Governing NJAC sections
- N.J.A.C. 7:8-5.3 for green infrastructure table use
- N.J.A.C. 7:8-5.4 where infiltrating systems are used for groundwater recharge
- N.J.A.C. 7:8-5.2(h) for hydraulic-impact assessment where stormwater infiltrates into subsoil
Related Pages
Source Mapping¶
The live citations layer resolves this route directly to the following canonical source bundles.
- Route type:
canonical - 2023 source bundle: Chapter 9.6 (
2023_BMP_9_6) - Pervious Paving Systems - 2026 source bundle: Chapter 9.6 (
2026_BMP_9_6) - Pervious Paving Systems
Key verified claims already tied to this page manifest: - Chapter 9.6 distinguishes infiltrating and underdrained pervious paving systems. - Recharge use depends on the infiltrating configuration, not simply on the BMP label. - The main Chapter 9.6 thresholds are the 72-hour drain time, 1.0/0.5 permeability threshold, and the 1-foot or 2-foot SHWT separation. - Hydraulic-impact review applies, but the older numeric shortcut triggers are not source-backed.
Crosswalk Snapshot¶
The reconciled design criteria below come from the live crosswalk and page-level claim set, not from the older narrative snapshot.
| Parameter | 2023 source value | 2026 source value | Change |
|---|---|---|---|
| Storage void ratio | Storage aggregate (AASHTO No. 2): 40% voids; surface course (permeable asphalt or pervious concrete): 15-25% porosity | Storage aggregate: 40% voids; surface: 15-25% porosity | unknown |
| SHWT separation | Measured from static SHWT | Measured from static SHWT | unchanged |
Source-backed criteria that still control this route: - Chapter 9.6 distinguishes infiltrating and underdrained pervious paving systems. - Recharge use depends on the infiltrating configuration, not simply on the BMP label. - The main Chapter 9.6 thresholds are the 72-hour drain time, 1.0/0.5 permeability threshold, and the 1-foot or 2-foot SHWT separation. - Hydraulic-impact review applies, but the older numeric shortcut triggers are not source-backed. - Maintenance is at least four vacuum sweepings per year plus spring testing, not a twice-yearly shorthand.
Source Bundles¶
Use these source bundles when checking the live extracted text or paired OCR evidence:
- 2023 bundle: Chapter 9.6 (
2023_BMP_9_6) - Pervious Paving Systems - 2026 bundle: Chapter 9.6 (
2026_BMP_9_6) - Pervious Paving Systems