ARCHIVED REPORTS_XR0005992 - Laserfiche WebLink

Home Browse Search

Quarterly Monitoring Report,Site Code 1203 Stockton Regional Wastewater Treatment Facilsty 2500 W Navy Dave,Stockton,CA August 6, 1992 Page 2 On October 16, and 17, 1989, five soil borings were drilled to depths ranging from 11 to 29 feet below grade (Figure 2) Four of the borings were completed as groundwater monitoring wells. No soil contamination was noted in any boring with the exception of SBI, which was located approximately 30 feet north of the former tank TPHD was detected at 378 parts per million in a sample collected from 10 feet below grade No volatile constituents (BTEX) were detected in the sample No soil impaction was evident above 10 feet below grade, based upon field observations (PID, visual) Field activities performed during the initial investigation are discussed in detail in WaterWork's Problem Assessment Report, dated January 15, 1990 FIELD ACTIVITIES Restoration of Monitoring Well MW4 During resurfacing of the area in 1990, monitoring well MW4 was inadvertently paved over with asphalt Several attempts had been made to locate the covered well During the week of June 13, 1992, MW4 was located by a City of Stockton Public Works crew The area in the vicinity of the well was excavated down to approximately 5 feet below grade The upper 4 to 4 5 feet of the 2" PVC well casing was removed The well had apparently been filled with sand prior to the resurfacing of the asphalt During the week of June 20, 1992, the 2" well casing was repaired by installing new casing to grade using set screws and a coupling No glue or solvents were used during the repair of the well The sandpack and bentonite seal remained undisturbed After discussions with Steve Schneider of PHS/EHD, the surface seal was restored by placing 8" PVC pipe from the bentonite seal (approximately 5 feet below grade) to ground surface to serve as a conductor casing Approximately one vertical foot of bentonite pellets were then placed in the newly created well annulus and hydrated to ensure the integrity of the well seal The 8" conductor casing was secured In-place at the base by cement The above work was-- observed by Mr Schneider Subsequent to securing the 8" conductor casing, the City crews backfilled the open area around the conductor casing, and the well annulus was sealed to ground surface with neat cement grout to restore the well seal A traffic rated well box was subsequently installed to grade to complete the well Restoration of the well seal was observed by Mr Schneider LR090392 1PL