CORRESPONDENCE_2017 - Laserfiche WebLink

Home Browse Search

indicate only indicate geophysical anomalies suggestive of waste disposal or other subsurface features which would subsequently need to be determined with a subsurface investigation. A set of trenches(later in August and throughout early September 2015) at the southwest boundary of the property(south cell T46, T48, T50, T58 and T59 and north cell T64, T65, T70) evaluated and also demonstrated a differing thickness (topology) of the potentially buried waste. The waste strata over native soil ranged from 18 inches at trench T46 to 10 feet deep at trench T58(south waste cell)and to 13 feet deep at trench T65 (north waste cell) areas. Comments: are the terms "south cell' and "north cell'and "south waste cell'and"north waste cell'and "deep excavation"the same?What are"A set of trenches?Are they exploratory trenches at locations of wastes? Two waste cells of approximately 2,000 square feet of area each (30 to 35 feet north-south to soil and 65-70 feet east-west) "had demonstrated "some" waste glass and debris, with a variable thickness. The southern cell was approximately eight feet deep and the northern cell was approximately thirteen feet thick. Comments: The term "two waste cells," does this mean the north and south waste cells and/or north cell and south cell (referenced above)? Please define what these are.Are they two locations where the trench and fill method was used to dispose of wastes or two areas excavated during remedial action? Please define "had demonstrated," this term is confusing. The statement that "some" waste glass and debris does not provide enough information. There should instead be a sentence indicating the depths and locations and range of thicknesses that glass and debris were encountered and does this correspond to the dimensions of the wastes cells?Are the two waste disposal "cells"the south waste cell and north waste cell discussed in the previous paragraph?Terminology should be consistent to avoid confusion. Remediation at this location[s] (late September 2015) involved the use of the excavator, which trenched down to native soil beneath any waste discovered(the current soil cap was set aside for segregation and reuse). The majority of waste stream was comprised of steel parts or window components (rusted), glass, and minor plastics. Comments: Was the remediation/waste excavation conducted in accordance with a regulatory-agency approved remedial action plan (RAP)? Was the remedial action conducted at the north and south waste disposal cells? This is not stated and the first sentence implies only one location was remediated. Documentation to confirm the adequacy of waste removal was not provided. Was the waste excavated based on visual observations (e.g., until soils and no wastes were observed) and then confirmation samples collected to confirm the adequacy of waste removal?Without confirmation samples and analytical testing, it is not known whether the wastes were adequately removed. In addition, the previous paragraph states "some" waste glass and debris were encountered and this paragraph (of the assumed same north and south waste cells) describes the wastes differently, once again, consistency. There should also be daily field documentation of the waste excavation activities, locations of confirmation samples, records of daily air and perimeter monitoring readings, photographs from the field followed by preparation of a waste excavation/remedial action report accompanied by documentation, locations of confirmation samples indicated on a figure/cross sections, summary of confirmation analytical data, laboratory analytical reports and waste manifests. This information needs to be provided to evaluate the adequacy of the waste excavation/remedial action. Excavations removed the waste from the waste cells and adequately defined the horizontal and vertical extent of the buried waste on the property to the western boundary. Excavation was required to a depth of 13 feet bsg at some locations (north cell), through the use of an excavator (removing the encountered waste) to reach native soil. Comments: please see above comments indicating that information/documentation to substantiate this statement and to confirm the adequacy of waste removal was not provided and it appears that confirmation samples were not collected and analyzed. Standard of care requires collection of confirmation samples to confirm wastes were adequately removed, otherwise it could be assumed wastes were not completely Ninyo&Moore 1 500 E.Louise Avenue,Lathrop,San Joaquin County,California 1 104690095 1 August 11,2017 52