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September 11. 2008 <br /> (-[WA Project No. 2008 094 <br /> Underground Utilities. HATA will call the Utilities Underground Location Center and <br /> have the underground utilities best located before drilling. HWA will also subcontract a <br /> private locating service to best locate and mark underground utilities at proposed <br /> exploration locations. PVC and concrete utilities can not be located. <br /> • Mapping existing data. HWA will coordinate with the City and their <br /> subcontracted surveyors to produce a GIS base map showing: accurate property <br /> boundaries for the property. the 36th Street ROW. adjacent areas where the plume <br /> may be located, existing sampling locations, and additional sampling data <br /> collected as part of Task 3. The base map wilt be capable of being edited/revised <br /> by City GIS staff. <br /> • Access. This proposal assumes EIWA will have access to the site. The <br /> explorations will require access for a track and truck-mounted drilling equipment <br /> to selected portions of the site. <br /> TASK 2 —EXPLORATIONS <br /> We anticipate two rounds of exploration: one to two days of direct push(e.g. <br /> Geoprobe)drilling to establish the limits of soil and ground water impacts, followed <br /> by installation of four permanent ground water monitoring wells via hollow-stem <br /> auger drilling.The direct push explorations will include collection and analysis of soil <br /> and ground water samples.Ground water samples will be collected from temporary <br /> well points. Depths and locations of the direct push explorations will be determined <br /> after the data review. The ground water monitoring wells will allow collection of <br /> multiple, representative ground water samples,and accurate measurement of ground <br /> water levels. Depths and locations of the monitoring wells will be determined after <br /> the direct push explorations. All subsurface explorations will be completed by <br /> Washington state-licensed drilling contractors under subcontract to HWA. • <br /> • Property boundary staking. City will have it's surveyor stake property at <br /> appropriate locations to indicate boundaries of the GTS Drywall property and 36th <br /> Street ROW. <br /> • Geophysical Reconnaissance. A geophysical subconsultant to HWA will <br /> conduct geophysical investigations in selected areas to search for abandoned <br /> USTs. Geophysical methods may include 1) a magnetic gradiometer, which is <br /> used to detect buried ferrous metal objects, and 2) ground penetrating radar <br /> (GPR). GPR is a geophysical method in which a high frequency electromagnetic <br /> signal is emitted into the ground during a linear traverse. Reflections of this <br /> signal are recorded and processed to yield a visual image(cross-section) of the <br /> subsurface. GPR is a useful tool for determining depth,shape and orientation of <br /> buried objects and subsurface features based on density differences. <br /> • Advance and sample direct push soil probes. HWA will employ a <br /> subcontracted mobile drive point sampling device(e.g.,Geoprobe) to collect soil <br /> and ground water samples. The device consists of a hydraulic/pneumatic drive <br /> Drywall GTS HWA SOW Exhibit A 9 17 08.doc 3 HWA GEOSCIENCES INC. <br /> 1J <br /> 3 <br />