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Project No.580804*-02 September�% .1.994 Page 5 bottom of the screen interval to an elevation of two feet above the screen zone. A. two foot thick seal consisting of hydrated bentonite chips will be plaice above the filter pack. ,;Above the seal a mixture of bentonite powder and cement willbeplaced to within two feet of grade I el. A minimum 14-inch diameter,.traffic-rated s�urity: wellhead cxrirer set in a concrete pad will be used to complete construction. V•Installation of Graun(water MaWlofing Wells • Install offsite groundwater monitoring wells MW4 and BCW-5'i th adjacent public right-of-ways a; the locations depicted on Figure 2., The wells vvilt be;installed to: depths of'Tf l;feet below the groundwater surface. The monitoring wells will be: constructed using 2-inc diameter poCyvin l chloride (PVC) casing 1`he lover portion of the w will be constructed using 2g tedi of 0 CdQi�d d6ttedl sheen. PVC casing. A ;fitter pack consisting of No. 3 Monterey, and will be trimmed around the screen from the bottom of the boring to an elevation of two feet above the screen zone. A two foot thick seal consisting of hydrated bentonite chips wfll be. placed above;the filter pack. Above the seal a mixture of bentonite powder and cement will be placed to within two feet of grade level. A minimum 14-inch diameter, traffic-rated security wellhead cover set in a concrete pad will be used to complete construction. • The top of using elevations for the new groundwatermonitoring wells will be surveyed relative to the designated temporary benchmark. Task 3a - Groundwater W Development. J"gfgiug and SaMWing No less than 448 hours after the completion of well construction,, develop the groundwater monitoring welts for approximately 10 minutes (or until turbidity stables)utilizing a surge block. No less than hours after the completion of well development the depth4ow groundwater will be:measured with a electronic water level meter. 'Ih+e water l meteor will be clearte l with liquinox solution and triple rinsed prior to introduction into a new well. Three to five rehole volumes of groundwater will be purged to attow formation water to infiltrate the wells. During purging, the pH; temperature, and: electrical conductivity of the groundwater will be measured. Fallowing -purging, water will be collected from each well. with a pre-cleaned' disposable bailer. The collected water will be decanted into appropriate sampling containers supplied by the analytical laboratory. Upon collections, the saw containers will be sealed, labeled and placed into an ice-chest coaled with blue pending delivery to the laboratory. Samples will be collected and transported under standard chain-of-custody documrentation.