nR = porosity of reservoir fill; 0.35 may be assumed where other information is not available dR = depth of reservoir, ft If the area required is greater than the selected pavement area, adjust reservoir depth and recalculate required area until the required area is achieved. Configuration for Use in a Treatment Train Permeable pavement may be preceded in a treatment train by HSCs in the drainage area, which would reduce the runoff volume to be infiltrated by the permeable pavement Permeable pavement areas can be designed to be self-retaining to lessen the pollutant and volume load on downstream BMPs. Additional References for Design Guidance SMC LID Manual (pp 84): Los Angeles Unified School District (LAUSD) Stormwater Technical Manual, Chapter 5: City of Portland Stormwater Management Manual (Pervious Pavement, page 2-40) San Diego County LID Handbook Appendix 4 (Factsheets 8, 9 & 10): City of Santa Barbara Storm Water BMP Guidance Manual, Chapter 6: County of Los Angeles Low Impact Development Standards Manual, Chapter 5: INF-7: Underground Infiltration Underground infiltration is a vault or chamber with an open bottom that used to store runoff and percolate into the subsurface. A number of vendors offer proprietary infiltration products that allow for similar or enhanced rates of infiltration and subsurface storage while offering durable prefrabricated structures. There are many varieties of proprietary infiltration BMPs that can be used for roads and parking lots, parks and open spaces, single and multi-family residential, or mixed-use and commercial uses. Feasibility Screening Considerations Infiltration bains shall pass infeasible screening criteria to be considered for use. Underground infiltration galleries pose a potential risk of groundwater contamination; pretreatment should be used. Opportunity Criteria Soils are adequate for infiltration or can be amended to provide an adequate infiltration rate. Appropriate for sites with limited surface space. Can be placed beneath roads, parking lots, parks, and athletic fields. Potential for groundwater contamination can be mitigated through isolation of pollutant sources, pretreatment of inflow, and/or demonstration of adequate treatment capacity of underlying soils. Infiltration is into native soil, or depth of engineered fill is 5 feet from the bottom of the facility to ≤ native material and infiltration into fill is approved by a geotechnical professional.
nR = porosity of reservoir fill; 0.35 may be assumed where other information is not available dR = depth of reservoir, ft If the area required is greater than the selected pavement area, adjust reservoir depth and recalculate required area until the required area is achieved. Configuration for Use in a Treatment Train Permeable pavement may be preceded in a treatment train by HSCs in the drainage area, which would reduce the runoff volume to be infiltrated by the permeable pavement Permeable pavement areas can be designed to be self-retaining to lessen the pollutant and volume load on downstream BMPs. Additional References for Design Guidance SMC LID Manual (pp 84): Los Angeles Unified School District (LAUSD) Stormwater Technical Manual, Chapter 5: City of Portland Stormwater Management Manual (Pervious Pavement, page 2-40) San Diego County LID Handbook Appendix 4 (Factsheets 8, 9 & 10): City of Santa Barbara Storm Water BMP Guidance Manual, Chapter 6: County of Los Angeles Low Impact Development Standards Manual, Chapter 5: INF-7: Underground Infiltration Underground infiltration is a vault or chamber with an open bottom that used to store runoff and percolate into the subsurface. A number of vendors offer proprietary infiltration products that allow for similar or enhanced rates of infiltration and subsurface storage while offering durable prefrabricated structures. There are many varieties of proprietary infiltration BMPs that can be used for roads and parking lots, parks and open spaces, single and multi-family residential, or mixed-use and commercial uses. Feasibility Screening Considerations Infiltration bains shall pass infeasible screening criteria to be considered for use. Underground infiltration galleries pose a potential risk of groundwater contamination; pretreatment should be used. Opportunity Criteria Soils are adequate for infiltration or can be amended to provide an adequate infiltration rate. Appropriate for sites with limited surface space. Can be placed beneath roads, parking lots, parks, and athletic fields. Potential for groundwater contamination can be mitigated through isolation of pollutant sources, pretreatment of inflow, and/or demonstration of adequate treatment capacity of underlying soils. Infiltration is into native soil, or depth of engineered fill is ≤ 5 feet from the bottom of the facility to native material and infiltration into fill is approved by a geotechnical professional.
OC_TGD_Appendices_5-19-11.docx