SITE INFORMATION AND CORRESPONDENCE

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94/23/2963 15:41 26983259 WRIGHT ENVIRQNMEh' PAGE 06 Wright has consulted drilling contractors who have previously worked at the site. Tbc sub.,uxface area of investigation is known to have severe flowing conditions at depth. Flowing conditions create great difficulty when drilling with hollow stern auger's. Severe flowing conditiiow cause sediment to effectively liquefy locally at the borehole and make monitoring well completion very difficult and affect overall construction and well performance. For these reasons, 'Wright proposes to use mud rotary drilling for all well installations to address this subsurface pr6blem. Mud rotary drilling will stabilize the borehole walls sealing them to prevent both cross contamination and borehole wall collapse. These two-inch diameter wells placed to 60 feet will be drilled to their completion depth(estimated to be no deeper than 65 feet)and completed. The well bwallation to 114-119 feet will require placing a conductor casing to 65 feet to s A out the higher contazrfua o zones. The conductor will be drilled into place using mud otary- Following bailing out the drilling muck and a seal leak check,the borehole will be advanced to the well completion depth (estimated to be about 11.5 feet) and the well constructed. Due to the depth of this well completion, Wright will install afour-inch diameter well casing. Field Methods-Exploratory Borings USA Clearance and Access Agreements or Encroachment Permit Access Wright will install these wells under approved well installation permits from PHS F-M;''. An underground service alert (USA) call will be made to clear underground utilities prior to 011ing. Aerial utilities are present on either side of East Charter Way, so boreholes will have to be adjusted to accessible locations. At least two monitoring wells are to be placed off-site so access agreemcuts or public encroachment permits will have to be secured prior to drilling- those locations. Wright will contact the adjacent property owners to ascertain access requiremei Lts and will move to secure encroachment permits at the same time so some flexibility for drilling..exists. However, the length of time to secure privately owned access is unknown at this time. Wright and PHS EM will need to work together informing property owners of importance of allowi-* this work to proceed without uoreasonable demands for access by off site property owners. Decontamination The drilling rig and rods, samplers and cables will be decontaminated prior to arriving at the site, between each borehole and prior to leaving the site. The equipment will be washed with pa"essure washers and soapy water and sampler gear will be hwd washed w soapy water uaing a triphosphate soap. The decontamination water will be stored in closed top drums and temporarily stored on-site. Page 4 of 4