7301 HARDESON RD 2019-01-11 - Laserfiche WebLink

vor PUBLIC WORKS accordance with the Soils Reports requirements per Section 3.1.1, Vol. I of the current SWMM (2016) for MR 1-9 sites. g. Section 8—Permanent Stormwater Control Plan o Provide documentation consistent with Section 3.1.5,Vol. I of the SWMM. h. Section 8.1 —Offsite Analysis o Section 2.6.2, Vol. I of the SWMM requires the off-site analysis to extend upstream to a point where any backwater effects created by the project cease. Confirm in the Drainage Report that the project does not create any backwater effects or update the text, as appropriate. o Downstream Analysis—Address the existing or potential impacts per Volume I, Section 2.6.2 of the SWMM. Include discussion of potential impacts associated with basin area diversions. i. Section 8.2—Pre-Developed Hydrology o Document pre-developed conditions in accordance with applicable Drainage Report submittal requirements. o Incorporate lot numbers in all discussion,tables, and graphics, to clarify the amount of lot drainage area tributary to the various pre-mining and post- developed basins. o Document TDA boundaries in the text and show them on relevant figures. j. Section 8.3 —Post-Developed Hydrology o Document post-developed conditions in accordance with applicable Drainage Report submittal requirements. o Include discussion of all creek basins affected by the project, not just Merrill and Ring Creek Basin. o Document TDA boundaries in the text and show them on relevant figures. o Incorporate lot numbers in all discussion, tables, and graphics,to clarify the amount of lot drainage area tributary to the various pre-mining and post- developed basins. o Document the basis for the assumption of 80% impervious are and 20% landscaped area. Address how this assumption relates to the proposed and future plans, and how it relates to applicable code requirements. Discuss the controls, if any,that would ensure that future tributary impervious area matched this design assumption, or the proposed adaptive management response if future development differed from this assumption. o An infiltration rate of 1.5 inches per hour(in/hr)was used,but the Infiltration Evaluation(GeoEngineers 2015)recommends design infiltration rates between 1 and 1.5 inches per hour, reduced to 0.8 inches per hour in consideration of possible silty layers. GeoEngineers recommends further Page5of9