4719 BELVEDERE AVE 2016-01-01 MF Import

}' � Junc 28, 20G David nnd Judy King LFcA Job No. 6AU7G Page 1 R line. Thc rcmaining trcnch may bc backfillcd with on-site impervious soils. Water collectcd by tl�e perimctcr footing subdrain system should bc tightlined, sepazalely from the roof and surface stermwatcr drain systems, to discharge into a stortn sewer or a suitablc stormwatcr disposal facility as rccommcndcd in this report. Sprcadcr Pipc Dispersiun Systcm Stormwatcr colicctcd ovcr impervious surfaces of the proposcJ new residence shoald be drained into u storm sewer, if there is one nvailablc nc:uby. Othcrwisc, stormwater may bc dispersed onto wcll-vegetatcd areas of the slope bclow the residence through sprender pipes. Water in the underground drain line systems of thc residence should be routed into a scdiment conUol structure/oil-watcr separator prior to bcing rcle.�.scd through the sprcader pipes. 71ie spreader pipcs should be constructcJ with minimum 4-inch-diameter, perforated, PVC pipes, supportcd on 2.5-inch galvanized stecl pipc pifcs at the spacing of 10 fect maximum on centers und driven into thc ground with at Ieast 5 fect of toe cmbcdment. Tlic PVC pipes should bc installed Ievcl at about 2 to 3 fect above the ground. 7�he Icngths of sprcadcr pipes should be based on 50 square fect of impervious surfacc per lincal foot of sprcader pipe. Rows of spreader pipcs should be set at 4 fcct minimum on centcrs. '17u sprcader pipes would allow dischurged water to be dispersed ovcr a large area witli low (low vclocity to not cause soil crosion problem. The dispersed water will mostly be evapor.ricd ancl/or absorbed by the root s}'stcros of vegetalion covering thr, gtound, with thc rcmaining watcr sceping into the ground und merge into the groundwater system under the sitc. The dispersion area should be ut lc.�tst 35% of lhe impervious surface over which t6e storm runofl� is collectcd nnd Jisposcd. R1SK EVALUATION STATEMENT 7'he sitc is undcrlain at rclativcly shallow depU� by dense Gsperance Sand soils znd hard Whidbey fomia�ion. '1'hcse soils are of high shcar strcngth in their undisturbed native swte. It is our LIU & ASSOCIATES, INC.