FIELD DOCUMENTS - Laserfiche WebLink

Home Browse Search

LIGHT, AIR & SPACE CONSTRUCTION ENVIRONMENTAL SERVICES COMPANY State Contractor's License Number 445403 Stale GPA R.E.A.Number 04072 Office 408-979-0661 contamination and tampering, and an at-grade well completion used with a traffic-rated well box noted as "monitoring well." 3.1 Monitoring Well Development Each well was developed until the water is relatively free of fine grained sediments and sand pumping was minimal and/or until field measurements of pH, and electrical conductivity appeared to have stabilized. The actual number of volumes withdrawn for development is well dependent and based on the field judgment and are well-dependent. Duration of development was specific for each well and site aquifer conditions and continued until the water turbidity decreases and fine sand content decreases or is minimal. Well development notes were kept including quantity of water removed, and some general observations of turbidity, sand yield and well recharge. The well development field notes are attached. 3.2 Monitoring Well Elevation Surve The new monitoring well casings were surveyed a known City of Manteca (monument in center of road lanes at corner of McKinley Avenue and Bronzan Road, 16.70 feet above NGVD) elevation datum for groundwater level measurements. 3.3 Monitoring Well Sampling and On-site Drinking Water Well Sampling All sampling equipment was pre-cleaned prior to arriving on-site, decontaminated following each sampling event, prior to use the next monitoring well and prior to leaving the site. Depth to groundwater was measured to the nearest 0.01 foot, and the well checked for presence of separate phase product; no separate phase product was observed in any well. Each standing well volume was calculated, and well volumes were purged from the well prior to sampling depending on well performance and yield (LA&S used USEPA sampling guidance and the number of purge volumes are related to aquifer strata and specific to each well). Measurements of aquifer parameters (conductivity, temperature and the pH, turbidity, dissolved oxygen and salinity) of the water were taken with a Horiba U-1 meter calibrated on the day of use to the manufacturers specifications. Purge volumes were removed until parameters have stabilized to indicate that aquifer water is entering the well over at least two purge volumes. Aquifer water is assumed to be entering the well when these parameters are measured within a 10% range of the previous measurements. The sample was collected when the well recovers to within 80% of the original depth to water measurement (see attached Well Sampling Forms). The groundwater samples were collected using a Teflon® or PVC disposable bailer. One water sample was collected from the on-site drinking water well. The sample was collected from a nearby faucet. The faucet was opened and allowed to run for about 5 minutes, and then one sample was collected using the procedure described below. January 5, 2009 _ Page 4 of 12 MAIN OFFICE • 1707 LITTLE ORCHARD STREs'r, SUITE A •SAN JOSE•CA •95125 MAILING ADDRESS a P.O.BOX 36303 a SAN JOSE:a CA a 95158-6303 a 408/979-0661 •408/979-0621 FAX•i I;u._kOl E(Al E-MAIL GENERAL AND ENGINEERING CONTRACIOR•HAZARDOUS SUBSTANCE:REMOVAL CONTRACTOR•SITE ENVIRONMENTAL AssEsSMhNrS WETLAND AND RIPARIAN HABITAT—ASSESSMENT—DEiSiGN—RESTORATION—CONSTRUCTION—MITIGATION MONITORING