COMPLIANCE INFO - Laserfiche WebLink

Home Browse Search

AGE Standard Operating i.ocedures AdvancedGeo Geoprobe Soil Borings Environmental Page 4 of 6 Soil-Vapor Sampling The following procedures apply to soil-vapor samples collected using temporary soil- vapor wells. For installation of the soil-vapor well, a temporary/disposable vapor-tip and %-inch Teflon tubing will be lowered to the base of the borings; two feet of tubing will remain outside the borehole for vapor sample collection. Once the tubing and vapor-tip are in place, a filter pack of #3 sand will be placed from the bottom of the borehole to one-foot above the vapor tip. Following placement of the filter pack, dry bentonite crumbles will be placed atop the filter pack. Thereafter, bentonite will be placed and hydrated to near surface grade to seal the vapor well from ambient air intrusion. Once vapor wells are set, a 30- minute equalization time will be observed prior to sampling. Each soil-vapor boring location will be isolated from ambient air by enclosing the borehole, tubing and sample bag in a plastic shroud, which will be weighted at the surface. Isopropyl alcohol (IPA) as a liquid will be placed in a stainless steel bowl within the plastic structure and allowed to volatilize into the air enclosed within the plastic structure surrounding the borehole, tubing and sample bag. Prior to sample collection, approximately three to five well volumes of soil-vapor will be purged from the vapor sampling assembly and soil-vapor wells prior to obtaining a sample in a 1-liter Tedlar bag; Once the purging is complete a sample will be collected into a 1- liter Tedlar bag using a peristaltic pump or vacuum pump calibrated to 200 milliliters per minute. After sample collection, each Tedlar bag will be labeled and stored in a dry container. Additionally, soil-vapor samples may be field-screened for the presence of volatile organic compounds using an organic vapor meter (OVM), equipped with photo- ionization detector (PID) pre-calibrated to isobutylene. Soil-vapor samples will be collected from the vapor wells using Summa canisters. For this method, one 6-liter Summa canister will be utilized for purging and each soil-vapor sample will be collected in a 1-liter Summa canister. The sampling and purge canisters will be connected together with a dedicated and serialized sampling inlet manifold. The sampling inlet manifold will consist of a vapor-tight valve; a particulate filter; a calibrated flow restrictor, calibrated to 200 milliliters per minute (ml/min); a stainless steel tee-fitting; two vacuum gauges at either end of the flow controller and connections for both purge and sampling canisters (manifold assembly). The manifold assembly will be attached to the %-inch Teflon® tubing from the vapor sampling locations. The purge canister will be attached to the end of the sampling manifold while the sample canisters will be attached to the tee-fitting between the tubing and purge container.