Laserfiche WebLink
- s <br /> r <br /> lv <br /> j )'Axe J <br /> 15,.,,,,,r•S L��ter lryfi,rat <br /> "A 3.0 (T1t0lJNl)WA'lTI:R CONTAMINA'1'lON ASSMSSMENT <br /> 3.1 flan <br /> The existing gra'.+nd,vat:r monitoring wells on-site have been evaluated to determine groundwater <br /> t=t (low direction. -fllis background rata will be qualified and has been used to develop a monitoring <br /> program to assess the full extent of site contamination using additional monitoring wells as <br /> indicated diagrammatically Mn figure 2. "1'he borehole and monitor well location may be modified <br /> fallo%ving review by and discussion svitll Public Health Services representatives. During this phase <br /> of work,groundwater samples will not be collected from any wells having floating free product. <br /> t_ Geologic supervision during drilling will minimize the potential for penetration of any confined <br /> aquifers. <br /> 3.2 Drilling Method <br /> The monitoring weil will be installed ten feet into the groundwater aquifer. Based on previous <br /> F consultants investigations during the period March-August 1985,groundwater is greater than 20 <br /> i ; <br /> feet below ground surface. A drilling schedule will be finalized upon approval of this wort:plan. <br /> Figure 3 illustrates the proposed monitoring well construction detail:. The screened interval will <br /> t schedule 40 PVC 4-inch diameter 0.02 factory-slotted casing installed from the end of(tole to 4 <br /> feet about the groundwater surface. 'The remainder will be blank casing. The annular space from <br /> the bottom of the bore to 3 feet above the screened interval will be filled with #2 grade sands. <br /> A 2-foot bentonite seal v,ill be placed above the sand. <br /> t ' <br /> i = Grout composed of Portland cement and 4 percent bentonite will fill the annular space to grade. <br /> Locking well caps and a traffic-bearing well boa set to grade will then be set over each well head <br /> in a traffic zone. <br /> 3.3 Development Method <br /> The wells will be developed by surging with a surge block and removing at least 6 to 10 well <br /> casing volumes. All development water and cuttings will be labeled and stored in DOT approved <br /> " drums on-site for proper disposal by the client. <br /> 3.4 Groundwater Sampling <br /> _climin-try Testing <br /> Thickness of floating free product, if any, will be measured with an oil/water interface probe. <br /> -- - -- -Well purging and sampie collection procedures will follow normal groundwater satnpling protocol <br /> as described below. Water samples will be analyzed for the BXTE, TPH G, and total-lead.- <br /> Following installation of the monitoring wells,the top-of-casing(TOC)elevations will be surveyed <br /> relative to an arbitrary datum. At least 24 hours after the development of wells;water depth will <br /> be measured and plotted relative to the datum. <br /> - � - - -6idfen RoLert,on+n6 Kin7te - - <br /> - '-_ it w..�.rwr.•..�.rr - <br />