COMPLIANCE INFO_1986-1997 - Laserfiche WebLink

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October 20, 1993 Page Two San Joaquin County Motor Pool Earl Gilford With reference to the negative results shown on page one for the 12,000 gallon West U/L Premium fuel storage tank system there always exists the possibility that the loss rate was being caused by entrapped vapors collapsing and causing a false leak rate. However, because the standpipe test vessel emptied within two hours after all above grade exit points were flooded and sealed, we believe that the is a fuel exit point in the tanks system. We can not state with any degree of accuracy were the exit point exists. The tank was full to within 20 inches of grade at the fill when we arrived at the site. Based upon this we believe that the exit point is in one of the lines above the top of the tank. The tank top is 47.5 inches below grade at the fill. If we are correct then the area of concern would be in one of the following lines: The vent line, the phase 11, vapor lines, the suction lines, the abandoned second point phase one vapor return riser, or in the fill riser. During our testing we did locate one area of leakage, the vertical check valve located just below the Southwest pump. The valve was seeping rather that leaking and would not account for the amount of decrease in our standpipe. This pump was taken out of service, the seeping valve was removed and the suction stub was capped by Stockton Service Station Equipment. We also conducted a suction line test on this line but the results were not conclusive as upon applying pressure the product in the line was pushed back into the tank chamber. As you are aware, you have a responsibility to advise the County Health of the failed annual precision test. At the same time you need to advise them of action you are going to take to locate the product exit point(s) and to remedy the situation. One remedy is the conduct another full system precision test, with the idea in mind that we did not test properly. Other leak location remedies available are: Uncover the various lines connected to the tank, disconnect them from the tank, pressure test each line, and conduct an isolated tank only test with the tank filled to it's full capacity. Conduct a helium test of the lines and tank to determine where the exit point exists. Then excavate only the area where helium is found to be exiting the asphalt or concrete to effect repairs. The helium test will also indicate if a problem exist with the tank chamber. We can conduct the helium test and the cost would be about $800.00. Firms such as: Stockton Service Station Equipment, Oil Equipment Service, or Banks and Company would be our choice to excavate and repair. Which ever company you may choose to select will receive our cooperation and we will pa,ss on all the information we have regarding your system. Please advise if you have any questions or would like us to assist you in any way.