WORK PLANS - Laserfiche WebLink

Home Browse Search

� v v 404001 Te Arks kc Page 3 L Additional Site Characterization Work Plan Project No. 724.2 June 27,2002 In order to investigate the lateral extent of thegroundwater plume, GTI proposes to install four separate sets of monitoring wells. Three sets: MW-8, 108, & 208; MW-9, 109, & 209; Land MW-10, 110, & 210, will be placed to the northeast, east and southeast, respectively, of the site. This placement is intended to define the down gradient extent of the plume. An additional set MW-11 & 111 will be placed up gradient of MW-3 to define the up gradient extent of the plume. L2.1 Soil Boring and Monitoring Well Installation Soil boring permits will be,secured as necessary and the local regulatory agency will be i notified 48 hours prior to commencing work. The subsurface will be cleared of L underground utilities by notifying Underground Service Alert. The boring for the wells will be drilled using an 8.00 inch outside diameter continuous flight hollow stem auger owned and operated by V&W Drilling (C57# 720904). Soil cuttings will be placed on plastic sheeting (and covered) on the adjacent site until their L removal can be arranged. A professional geologist under the supervision of a licensed registered geologist will direct all drilling and well construction. L2.1.1 Soil Sampling Procedure Soil samples will be collected for geological evaluation at five-foot intervals. A boring log providing sediment description using the USCS and field observations will be maintained by a professional geologist working under the supervision of a registered geologist. Soil samples will be collected using a 2.0-inch modified California split spoon sampler. LIn their April 24, 2002 correspondence the SJC/EHD concurred that the extent of the soil plume has been defined. Therefore, no soil sampling for laboratory analysis is proposed for this scope of work. B'tn"J /. '40,4or r.cid 2.1.2 Monitoring Well Construction L The monitoring wells will be constructed using 2.0-inch diameter PVC casing with flush threads. The filter pack will be surged during placement. A 2-foot retarded hydration weighted bentonite pellet transition seal will be installed and allowed to hydrate Lapproximately one half-hour. A surface seal will be achieved by pumping a neat cement grout (augmented with < 4% bentonite) via a tremie tube. The wells will be secured with locking watertight caps encased in flush mounted traffirerated well boxes. (See Figure 3 for La schematic of monitoring well construction). 2.1.3 Monitoring Well Development LAfter the well sealing materials have set (>24 hours) the wells will be developed (using mechanical surging and pumping methods) until a clear stream of water is obtained. The well will be purged and groundwater samples collected no sooner than 48 hours after well L