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� KA No.C92-06160 <br /> Octobcr 25,2006 <br /> Pagc 6_ <br /> Erosioo ConceraMazard <br /> Erosion and sediment control (ESC) is csed to minimize the transportation of scdimcnt to wetlands, <br /> streams, lakes,drainage systems, and zcljnccnt properties. Erosion and sediment control measures should <br /> be takcn and Ihese measures shou:d be in general accordance with local regulations. At a minimum, the <br /> following basic rccommendations should be incorporatcd into the dcsign of the erosion and sediment <br /> control features of the site: <br /> 1} Phasc thc soil, foundation, utility, and other work rcquiring cxcavation or the disturbance of the <br /> site soils, to take placc during the dry season (gcnerally May through Septcmber). However, <br /> provided precautions are takcn using Best Management Practices(BMP's),grading activitics can <br /> be uttdertaken during the wet scason (gcncrally October through April), but it should also bc <br /> known that this may increase the ovcrall cost of the projeci. <br /> 2) All site work should he complctcd and stabilized as quickiy as pcss�ble. <br /> 3) Additional perimctcr erosion and sediment control fcatures may be required to reduce the <br /> I possibility of scdimcnt entcring the surface water. This may includc additional silt fences, silt <br /> fences witlr a highcr Apparcnt Opening Size (AOS), construction of a bcrm, or other filtration <br /> systems. <br /> 4) Any runoff gencratcd by dewatering dischargc should be treated through construction of a <br /> sedimcnt trap if thcre is suf6cient space, if spacc is limited other filtration methods will need to <br /> bc incorporatcd. <br /> Groundwater influcnce on Structures/Construction <br /> Groundwatcr was not encountered in thc cxploratory test pits during our field exploration work. If <br /> groundwater is encauntereJ during the construction work, tlie groundw:tter is most likely perched. This <br /> perchcd groundwater develops where vcrtical infiltration of surface precipitation is impedcd by a <br /> rclatively impe:meable soil layer, resulting in horizontal migration of d�e groundwater within overlying <br /> morc permeable soils. If groundwatcr is encountered during construction, wc should observe the <br /> conditions to detertnir,e if de-watcring w�ill be needed. Design of temporary dcwatcring systems to <br /> rcmove groundwater should be thc responsibiliry of the contractor. <br /> if earthwork is performed during or soon aiicr periods of prer,�pitation, the subgrade soils may becomc <br /> saturated. Thcse soils may "pump;' and the materials may n�t respond to densification techniqucs. <br /> Typical rcmcdial mcasures inciude: discing and acrating thc soil during dry weather;mixing the soil with <br /> drier malerials; ancUor removing and replacing the soil with an approved fill material. A qualified <br /> geotechnical enginccring firtn should be consultr.d prior to implemcnting remedial measures to observe <br /> the mutable sub6rade conditions and provide appropriate recommendations. <br /> Krezun&Assocletes,Inc. �� <br /> Officcs Scrving The Westem UniMd States '� <br />