ARCHIVED REPORTS XR0010498 - Laserfiche WebLink

Home Browse Search

Pl-OP05hD WORK PLAN Sr opi- of Mork 1'he hor i !nnt-a 1 and ryrert3-cal extent of the contaminated area rust be defined, and the ground water must be measured for contamination and its gradient A rF=mediation plan is necessary to mita ate the opill area ;fie propose to drill 3 monitoring wells at the site, one within 10 feet of the tank excavation pit Two other monitoring wells are Lo lie drilled and developed on the site, their location is based upon the electromagnetic survey These wells will be driiled to a depth of aproximately 50 feet, completed and sampled according to the guidelines of the Tri-Regional Recommendations revised April 3 , 1989 The monitoring wells will supply data to calculate the site specific hydraulic gradient plus the geology, vadose contamination and ground water contamination If time permits two or three exploratory wells will also be drilled at the time of the monitoring wells These wells will not be completed into the water table, but will be used for data gathering and completed for possible use as remediation wells for vapor extraction during the next phase of the project The location of these exploratory borings will be decided upon after the monitoring wells are drilled and assessed Well Drilling and Desinn The wells will be drilled using a hollow stem auger with the ability to sample with a Shelby Tube or Split Spoon The well diameter will be about 8 inches and soil samples will be taken at 5 foot intervals with one sample taken in the capillary fringe The well will be logged by our geologist who is registered in the State of California The monitoring wells will be completed using Sch 40 PLIC pipe 2 in diameter with flush threaded joints Slotted casing will be run from the bottom of the well to a point aproximately 5 feet above the water table Number 3 sand will be used to pack the annulus opposite the slotted liner Above the sand will be placed a two foot bentonite seal and the remainder of the well annulus will be sealed with concrete The casing will be capped with a watertight plug and the well head will be within a security vault 2 feet square concreted in the surrounding Pavement and covered The wells will be developed by bailing several volumes of water until the return is clear and free of sediment. Water table measurements will be done at least 48 hours after the well is developed Bailed water will be placed in drums until lab analysis is completed If they contain hazardous materials they will be sent to a class #1 dump site.