RecDoc 2016-104272 STMMA (849 Veterans)

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C . 3 STORMWATER TECHNICAL GUIDANCE • Minimum 2 and up to12 inches of water surface storage between the planting surface and crest of overflow weir. VEGETATION • Plantings should be selected for viability in a well-drained soil. See planting guidance in Appendix A. • Use integrated pest management (IPM) principles in the landscape design to help avoid or minimize any use of synthetic pesticides and quick-release fertilizer. Check with the local jurisdiction for any local policies regarding the use of pesticides and fertilizers. • Irrigation shall be provided, as needed, to maintain plant life. • Trees and vegetation do not block inflow, create traffic or safety issues, or obstruct utilities. INLETS TO TREATMENT MEASURE Flow may enter the treatment measure (see example drawings in Section 5.13): • As overland flow from landscaping (no special requirements) • As overland flow from pavement (cutoff wall required) • Through a curb opening (minimum 18 inches) it Through a curb drain • With drop structure through a stepped manhole (refer to Figure 5-3 in Chapter 5) • Through a bubble-up manhole or storm drain emitter • Through roof leader or other conveyance from building roof • Where flows enter the biotreatment measure, allow a change in elevation of 4 to 6 inches between the paved surface and biotreatment soil elevation, so that vegetation or mulch build-up does not obstruct flow. • Splash blocks, cobbles or rocks shall be installed to dissipate flow energy where runoff enters the treatment measure. • For long linear planters, space inlets to planter at 10-foot intervals or install flow spreader. SOIL CONSIDERATIONS SPECIFIC TO FLOW THROUGH PLANTERS • Waterproofing shall be installed as required to protect adjacent building foundations. • If site conditions permit infiltration to underlying soils, waterproofing is not required. • An underdrain system is generally required for flow through planters. Depending on the infiltration rate of in situ soils, the local jurisdiction may allow installation without an underdrain on a case-by-case basis. • Underdrain trench shall include a 12-inch thick layer of Caltrans Standard Section 68- 1 .025 permeable material Class 2, or similar municipality-approved material. A minimum 6-inch diameter perforated pipe shall be placed within the backfill layer. To help prevent clogging, two rows of perforation may be used.. • Planting soil shall have minimum percolation rate of 5 inches per hour and a maximum long-term percolation rate of 10 inches per hour. Soil specifications are provided in Appendix L. Check with municipality for additional requirements. • The biotreatment soil shall be at least 18 inches thick. • Provide 3-inch layer of mulch in areas between plantings. SOIL CONSIDERATIONS FOR ALL BIOTREATMENT SYSTEMS • Beginning December 1 , 2011 , soils in the area of inundation within the facility shall meet biotreatment soil specifications approved by the Regional Water Board (to be included in Appendix K), which will supersede other soil specifications. The minimum percolation CHAPTER 6 PAGE 75 ATTY/AGR.2016.231/849 Veterans RWC, LLC - STMMA