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STATIC TEST FACILITY PRELIMINARY STORM DRAINAGE REPORT <br /> EVERETT,WASHINGTON <br /> Developed Conditions <br /> The proposal is to construct a 115,000sf, 120ft tall building and surrounding concrete paved surfaces and <br /> utilities. The building will house a not fueled 777-9X airplane,where a series of static tests on the airplane <br /> will be performed. Externally,the paved surfaces will be used to wheel the airplane from the flightline into <br /> the building, as well as, provide storage of raw materials (i.e. steel, aluminum, etc.) used for the <br /> manufacturing of fixtures and structures in support of the testing operations. Stormwater from the site will <br /> be collected by concrete swales and catch basins and conveyed in a pipe network. The stormwater will <br /> generally be conveyed in a northwest direction and discharged into the existing stormwater wetlands and <br /> Al ha o e main runway. Ultimately, the stormwa er a iese Gulch and <br /> discharges into Possession Sound. <br /> The stormwater vesting document for the site is the 1991 Environmental Impact Statement Facilit <br /> Expansion Everett Division Boeing and the Master Development Plan. The 1992 DOE Stormwater <br /> Management Manual is the vesting code for determining stormwater runoff from the site. The site will be <br /> modeled utilizing the SCS Type IA,24-hour hydrology modeling methodology for both quantity and er <br /> quality volumes. Basic Water Quality Treatment of the sites Stormwater will comply with the DOE <br /> -. <br /> STORM EVENT Precipitation Peak Runoff -06C c.( <br /> SCS Type 1A 24 hour (inches) (cfs) cls G/t�1 <br /> 6 month (72% of 2yr= 1.55") 1.12 1.84 <br /> 25 year 2.60 4.27 Je <br /> 100 year 3.20 5.25 <br /> Table 2: Storm Event precipitation and Peak Runoff c `emse�fi fi `S <br /> TOTAL ON-SITE <br /> DEVELOPED CONDITIONS Total Area=6.84 acres S ve5fi <br /> 17 t <br /> Building(test,office, etc) 2.74 <br /> Paving 4.14 C-e C's i U' <br /> Table 3: Total Developed Conditions Xacu 10 Cj fw C) /o <br /> DEVELOPED BASIN Total Area Percentage of 6 month Peak 25yr Peak 100yr Peak <br /> BREAKDOWN =6.84 acres the site(%) Runoff(cfs) Runoff(cfs) Runoff(cfs) <br /> NORTH BASIN 1.88 27 0.50 1.15 1.42 <br /> Building 1.24 <br /> Paving 0.64 <br /> SOUTH BASIN 4.96 73 1.34 3.12 3.83 <br /> Building 1.50 <br /> Paving 3.46 <br /> Table 4.Developed Conditions Breakdown—SCS Type IA, 24 hour <br /> CEI Project#141001 Pg. 8 <br />