ARCHIVED REPORTS XR0012560 - Laserfiche WebLink

Home Browse Search

ey x�w '. •l.R=-r�'..�,J't ' Sf'si ".r U1 n 1.,.^' �.. .�} r. j1 ...pi S t ;;Ite Pssessment Report April 5, 1 Page 7 139 South Center,Stockton,CA ea well from the bottom of the well bore up to Meet above the top of the well screen. A 2-foot-thick layer p set of hydrated bentonite pellets was Placed above each sand fitter pack and a cement surfer seal v.as to grade level above the bentonite. A traffic-rated Qd400 Wheaton box was placed over the cap. The wellheads were sealed with locking plugs. Well oonstructlon d9wis are presented on the drill logs In Appendix B. Well iecation photographs are Presented as Figure 3. 1 Before the cement seal for mtinitoring well MW-4 had set completely,a gasoline delivery truck l passed over it and over the red warning cone that had been Plate atop the traffic cover. i.: Consequently,Groundwater Technology staff personnel had to return to the site and rebuild the surface r:d prctr c,Ion for this well. Mlonitarina Well pevefoo et Standard Groundwater Techneiogy well development �.. procedures require new wells to be devetaped using a combination of bailing,surging and pumping. Groundwater Technology empiL yed a truck-mounted surge block and ballet system to develop ti-a four new wells on March 8, 1991. Development of the monitoring wells entailer!the ex'laction of between 60 and 70D-gallons of well water. The well was sampled when the well volume had recovered to at least 80 i percent of Its original static water level. i t.; .� nhoring well MW-4 found to be bent slightly,so that During development,the casing for m. �., the metal surge block could not pass down IL Therefore,a F s/C bailer was used to develop this well. l r GROUNDWATER MONITORING AND SAMPLING = On February 15, 1991,monitoring wells MW-1,MW-2 and MW-3 were professionally surveyed to ;. a common datum to rtetermirw wellhead elevations. The depth-to-groundwater was then measured using an Interface Probe,to make a preliminary determination of the groundwater gradient direction Prior -4 near the waste oil tank.On the basis of this preliminay det:rmina�tlon of to the Installation of MW the 3 groundwater gradient direction, monitoring wellMW-4 was sited t0 the north ole oil tank,In a j.� downg adient direction from the waste-oil tank. On March 8, 1941,the elevation of the wellhead of MW-4 and the horizontal Position of the four monitoring wells were professionally surveyed referenced to a common United States Geological Survey dawn. p •GROUN©WATER i'TECHNOLOGY,INC. 111�a ....reAAa�IaC! flag^. _