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#To avoid soil disturbance and compaction during construction, will the proposed infiltration area be clearly marked before any site work begins?
#To avoid soil disturbance and compaction during construction, will the proposed infiltration area be clearly marked before any site work begins?
#Do the plans include an appropriate cross-sectional detail for the permeable pavement?
#Do the plans include an appropriate cross-sectional detail for the permeable pavement?
==Design checklist==
Verify the drainage area directed to any proposed porous pavement. If DCIA runoff from other areas on-site, in addition to the direct (1:1) rainfall onto the porous pavement, is directed onto porous pavement, the porous pavement cannot be considered disconnected. It must instead be considered, and modeled as, a porous pavement structural SMP. The porous surface must be considered, and modeled as, DCIA. Porous pavement structural SMPs require infiltration testing. [Section 4.2.1]
For porous pavement structural SMPs, if infiltration is feasible, verify that the porous pavement design meets all Design Guidance Checklist design standards noted in Appendix F.10, Subsurface Infiltration. [Section 4.2.3, 2]
For porous pavement structural SMPs, if infiltration is infeasible, verify that the porous pavement design meets all Design Guidance Checklist design standards noted in Appendix F.14, Subsurface Detention. [Section 4.2.3, 3]
For porous pavement DIC systems:
Verify that the porous pavement DIC is installed on-site such that it does not create any areas of concentrated infiltration or discharge. [Section 4.2.3, 1a]
Verify that the surface slope in any direction across porous pavement does not exceed 5%. [Section 4.2.3, 1b]
Verify that the choker course depth is a minimum of two inches. [Section 4.2.3, 1c]
If an underdrain is proposed, verify that the first 1.5 inches of runoff are stored below the lowest invert of the underdrain. [Section 4.2.3, 1d]
Verify that an appropriate porous pavement curve number value is used when performing Flood Control calculations. [Section 4.2.3, 1e]
Verify that the stone storage bed depth is a minimum of eight inches, except when located beneath walkways or play surfaces, for which a depth of four inches is allowable. [Section 4.2.3, 6a]
Verify that stone is separated from soil media by a geotextile or a pea gravel filter to prevent sand, silt, and sediment from entering the system. [Section 4.2.3, 6b]
Verify that the stone storage system has a level bottom. Terraced systems may be used to maintain a level infiltration interface with native soil while accommodating significant grade changes. [Section 4.2.3, 6c]
Verify that pretreatment is provided for all runoff entering the porous pavement, including pretreatment of runoff from all inlets. At a minimum, this can be achieved through the use of sumps and traps for inlets, sump boxes with traps downstream of trench drains, and filter strips for overland flow. [Section 4.2.3, 4]
Verify that, when SMPs are used in series, the storage areas for all SMPs provide cumulative static storage for the WQv. [Section 4.2.3, 9]
Verify that any impervious liner, if necessary, is not interrupted by structures within the basin footprint. The plans must indicate that the impervious liner is to be continuous and extend completely up the sides of any structures that are located within the lined basin footprint to the ground surface. If additional liner material must be added to extend up the structures, the additional liner sections are to be joined to the rest of the liner with an impervious seam per the manufacturers’ recommendations. [Section 4.2.3, 10]
Verify that underdrains, if proposed for porous pavement DIC systems, meet the following requirements:
Underdrains must be surrounded by a sand or stone layer to filter sediment and facilitate drainage. [Section 4.2.3, 11a]
The minimum allowable thickness of a sand or stone filter layer is six inches both above and beneath the underdrain. [Section 4.2.3, 11b]
To prevent clogging, underdrain pipes must be surrounded by a geotextile fabric if a sand layer is used. [Section 4.2.3, 11c]
Verify that an adequate number of appropriately placed cleanouts, manholes, access panels and other access features are provided to allow unobstructed and safe access to the porous pavement structural SMP for routine maintenance and inspection of inflow, outflow, underdrains, and storage systems. [Section 4.2.3, 13]
Verify that an observation well is provided for a storage system that includes stone storage and that it meets the following requirements:
The observation well must be placed at the invert of the stone bed. [Section 4.2.3, 14a]
An observation well must be located near the center of the stone bed system to monitor the level and duration of water stored within the SMP (drain down time). [Section 4.2.3, 14b]
Adequate inspection and maintenance access to the observation well must be provided. [Section 4.2.3, 14c]
A manhole may be used in lieu of an observation well if the invert of the manhole is installed at or below the bottom of the SMP and the manhole is configured in such a way that stormwater can flow freely between the SMP and the manhole at the SMP’s invert. [Section 4.2.3, 14d]
Verify that access features are provided for all underground storage systems that are not stone storage beds. [Section 4.2.3, 15a]
Verify that a sufficient number of access points in the system are provided to efficiently inspect and maintain the infiltration area. [Section 4.2.3, 15b]
For cast-in-place vault systems, verify that access features consist of manholes or grated access panels or doors. Grated access panels are preferred to maintain airflow. [Section 4.2.3, 15c]
For grid storage or other manufactured systems, verify that the manufacturer’s recommendations are followed. [Section 4.2.3, 15d]
Verify that ladder access is proposed for vaults greater than four feet in height. [Section 4.2.3, 15e]
Verify that header pipes, at minimum 36-inch diameter, connected to manholes at each corner of the subsurface system are provided. Alternatively, smaller header pipes may be used if cleanouts are provided on every second manifold pipe/header pipe junction, on alternating sides of the SMP. [Section 4.2.3, 15f]
https://www.pwdplanreview.org/manual/appendices/f.-design-guidance-checklist/f.8-porous-pavement
[[category: Planning]]