COMPLIANCE INFO - Laserfiche WebLink

Home Browse Search

Proiect Number 2098RV45 November 30 2017 2.2 Groundwater Monitoring Well Installation For the purpose of this investigation addendum, the following are proposed: Four (4) groundwater monitoring wells (MW-1 through MW-4) will be advanced using a truck mounted hollow stem auger drill rig. The proposed depth for the wells is 40 feet bgs based on the expected depth to water at the site (A 12 September 2011 Semi- Annual Groundwater Monitoring and Remediation Progress Report prepared for the adjacent former ARCO Service Station No. 0548 indicated that the depth to groundwater was approximately 24 to 26 feet bgs based on monitoring well water level measurements (Arcadis, 2011). 2.2.1 Site Visit to Mark Locations and Locate Utilities E2C personnel will visit the Site to mark boring locations and locate utility lines. USA Underground will also be notified 72-hours before field work begins. Note: This work will be done in concert with a representative of the Client who is aware of potential subsurface utility lines. 2.2.2 Well Installations Every boring location will be hand-augered to five (5) feet in depth to clear for the potential presence of subsurface utility lines or other obstructions prior to advancing the borings by a drill rig. Each boring will be advanced to approximately 40 feet bgs using a truck-mounted hollow stem auger drilling rig with an 8-inch or larger diameter hollow-stem continuous flight auger in accordance with ASTM Method D 1452-80 for soil investigations and sampling by auger borings. The augers will be steam cleaned prior to drilling the boring. The lithology and other pertinent data will be recorded on a boring log in accordance with Method D 2488-17 for visual description and identification of soils in accordance with the Unified Soils Classification System (USCS). Soil samples will be collected at approximate target depths of 5, 10, 15, 20, 25, and 30 feet bgs using a split-spoon sampler containing three (3) brass or stainless steel sleeves. All sampling equipment will be cleaned in an Alconox solution and double- rinsed prior to each use. The proposed groundwater monitoring wells will be constructed with nominal 2-inch diameter Schedule 40 PVC casing with 20 feet of machine-slotted well screen at the bottom followed by blank casing to the surface. Filter pack sand will be emplaced by gravity feed in the annular space from the bottom to a point at least 1 feet above the screened interval to be followed by at least 3 feet of hydrated bentonite chips to seal the filter pack. Neat cement-bentonite slurry will fill the annular space to the surface. The wellhead will be equipped with a locking water-tight expansion cap and a traffic- rated box set in cement slightly above grade to complete the installation. See Figure 3 for a diagram showing the proposed groundwater monitoring well construction diagram. Field Screening of Soil Samples Drilling operations, soil sampling and field monitoring for the presence of chlorinated solvents will be performed by a field geologist or engineer under the supervision of a California-licensed Professional Geologist. A photoionization detector (PID) will be used during the drilling process to detect the presence of Chlorinated Volatile Organic EzC Remediation 5