SITE INFORMATION AND CORRESPONDENCE

Home Browse Search

Herman&Helen's Marina Status Report and Amendment to Work Plan July 24,2000 Page 2 It was proposed that at least one soil sample and one groundwater sample would be collected from each boring. The proposed borings were to be advanced down to groundwater,anticipated to be approximately six feet below ground surface(bgs). To address your concerns regarding the evaluation of the vertical extent of contamination in the study area, it is herein proposed that five of the nine borings be extended down to approximately 30 feet bgs. The four retraining borings will be advanced as originally proposed(six feet bgs). All of the borings,as originally proposed,will be continuously cored to evaluate the lithology and potential contaminant distribution. It is anticipated that Geoprobe refusal may occur at approximately 30 feet bgs. As previously described in the Work Plan dated May 27,2000, because the study area is essentially a peat bog that may be inaccessible to vehicles,installation of some of the borings may require hand-auger. Depending on the soil encountered,any borings that require hand-auger can potentially be advanced to approximately 20 feet bgs. One shallow water sample and one soil sample will be collected from each of the four shallow direct push borings (as originally proposed). One shallow water sample and as many as three soil samples,on average,will be collected from each of the five deep borings. In addition, if field observations during the deep borings indicate the potential for contaminants in lower soil strata,a Simulprobe sampler will be advanced with an auger drill rig(if it can gain access)to collect discreet water samples from horizons that are suspected to contain contaminated groundwater. The Simulprobe borings will be advanced directly adjacent to as many as three deep direct push borings that may have encountered deep contamination. The general methodology for vertical investigation at the site,therefore,will consist of identifying sensitive sail horizons with the continuous coring of the direct push borings and then collecting a groundwater sample from the horizons with the Simulprobe. This procedure will assist in collecting groundwater samples from discrete horizons containing groundwater that has not mixed with groundwater from overlying strata. For the purposes of estimating the scope of work, it is anticipated that three Simulprobe borings will be advanced at the site and three groundwater samples will be collected from each Simulprobe boring. The locations of the shallow,deep,and Simulprobe borings are shown in Figure I, attached. As requested in your letter dated June 30,2000, laboratory analyses of samples collected during the additional groundwater investigation will include EDB and 1,2-DCA in addition to the analytes originally proposed in the Work Plan. If you have any questions or need any additional information please call us at(209)234-0518. Respectfully submitted, CONDOR EARTH TECHNOLOGIES,INC D GEF. p Donald F. KresseM Todd C. Hafner California Registered ; �Q Senior Geologist Geologist#6430 �F CA��E00 PAI432 H&Helen's\Work Plans\WPlanAmendLV.doc h• tI CONDOR