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RCWDPermitNumber14-105 <br />Soilsonsiteareprimarilysiltysand (HSGB) topsoil, underlainbysandyleanclays (HSGD) soils. <br />Thus, infiltration isnotconsideredfeasibleandfiltrationisacceptabletomeetthewaterquality <br />requirement. PerRuleC.6(c)(1), theWaterQualityrequirement is2.2-inchesoverthe <br />new/reconstructedarea (35,000± SF) foratotalrequirementof6,417± cubicfeet. Runofffromthe <br />drivewaysisroutedtodepressionalareasinthefrontandcollectedviadraintiletoafiltration <br />trenchinthebackyard, whichwillalsocatchsheetflowfromtherearroofs. Eachlothasa <br />separatetrenchanddrain-tilesystem. Thisprovidesadequatepre-treatment. Thetrenchesare <br />expectedtodraw-downwithin48-hours. Thetrencheshaveprovided3-feetoffiltermaterial <br />abovethedraintile. Groundwaterwasnotencountered. Approximately90% oftheprojectarea <br />hasbeentreated. AdditionaltreatmentorTSSremovalisnotfeasible. Thustheapplicanthas <br />compliedwiththeRuleC.9(c) designrequirementsandprovidedadequatevolumetomeetthe <br />RuleC.6WaterQualityRequirement. <br />2-year (cfs) 10-year (cfs) 100-year (cfs) DrainageArea Existing Proposed Existing Proposed Existing Proposed <br />Westernpropertyline 2.94 0.34 5.22 0.80 10.72 1.99 <br />Eastandsouthern 4.22 1.71 8.04 4.96 17.41 19.88propertyline <br />Totals 7.16 2.05 13.26 5.76 28.13 21.87 <br />10.61 22.5080% ofExisting 5.73 <br />TheprojectislocatedwithintheFloodManagementZone. AsallthedrainageflowstoFarrel’s <br />wetland, theincreaseshownatthe100-yearattheeastern/southernpropertylinewillnothavean <br />adverseimpact. TheprojecthascompliedwiththeRuleC.7requirements. Theprojectwillnot <br />haveameasurableeffectontheFarrel’swetlandcomplex, whichcomplieswiththebounceand <br />inundationcriteriaofRuleC.8. TheprojectcomplieswiththefreeboardrequirementsofRule <br />C.9(g). <br />3. Wetlands – Awetlanddelineationwithboundaryapprovalwasconductedforthesiteunder <br />reviewfile14-169R. Theprojectwillnotimpactanywetlands. <br />4. Floodplain – Theregulatory floodplainelevationfortheFarrel’swetlandcomplexis878.5 <br />NAVD88). Theprojectwillnotimpacttheregulatoryfloodplain. <br />5. ErosionControl – Proposederosioncontrolmethodsincludesiltfence, arockconstruction <br />entrance, inletprotectionandriprap. AnNPDESpermitisrequiredfortheproject. The <br />informationlistedundertheErosionandSedimentationControlRecommendationsmustbe <br />submitted. Otherwise, theprojectcomplieswithRCWDRuleDrequirements. <br />6. DocumentingEasementsandMaintenance Obligations – Applicantmustprovidedraftdrainage <br />andflowageeasements (ifrequiredbytheCity), andadraftmaintenance declarationforreview, <br />andreceiptshowingrecordationonceapproved. <br />7. PreviousPermitInformation – Awetland delineationwasconductedforthesiteunderreview <br />file14-169R. <br />HoustonEngineering Inc Page4of4 2/25/2015