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y . <br /> peak flow directed to each system. In all cases the length of the trench has been rounded <br /> up to the next 10' length to help remain conservative. <br /> The detention mitigation for this project in the east basin will be done via a detention vault. <br /> This vault is downstream of the treatment filters and will connect to SDMH #1 the control <br /> structure for the project before being released to the downstream system within the 16th <br /> Ave SE R.O.W. at the southeast corner of the site. <br /> The following table summarizes the areas input into the WWMH3 software for the drainage <br /> analysis for the east basin. <br /> Sub-Basin Impervious (ac) Pervious (ac) Total (ac) <br /> Vault 1.34 0.77 2.11 <br /> For this basin the total area to be disturbed is 2.11 acres and as noted above a <br /> comparable off-site area is being collected to account for the small on-site bypass areas <br /> that cannot be collected due to grade constraints. Refer to Developed Basin Map, Figure <br /> 3. <br /> The vault was analyzed and sized using WWHM3. The calculations for the sizing of the <br /> vault are included in Appendix A. <br /> 10. WETLAND PROTECTION <br /> The runoff from this site directed to the wetlands to the west will be maintained by allowing <br /> the proposed improvements within the NW and SW basins to sheet flow west and into one <br /> of the two existing wetlands. In addition, footing drains for those buildings fronting the <br /> critical area buffer will be directed to the west as well. Finally, a large portion of the site <br /> has been set aside west of the wetland to remain buffer as well. <br /> 11. OPERATION AND MAINTENANCE MANUAL <br /> The Property Owners/HOA will be responsible for maintaining the stormwater and <br /> landscaping facilities within this development. Included in this manual are checklists for <br /> each feature specific to this project. Copies should be made of the checklists as <br /> necessary during routine inspections and required maintenance. Specific problems can <br /> be recorded along with the appropriate action taken. <br /> These checklists are a guide for inspections and maintenance. The frequency of the <br /> inspections/maintenance should twice a year in the spring and fall until the maintenance <br /> routine of the different facilities are determined. <br /> Routine inspections and maintenance will improve the long-term performance of the <br /> stormwater facilities. If at any time you are unsure if a problem exists or how to address a <br /> specific problem contact a Professional Engineer. <br /> Refer to Appendix A for a list of each facility to be maintained and the appropriate <br /> maintenance checklist. <br /> Northlake Court Townhomes 13-0609 <br /> May,2014 Page 13 <br />