COMPLIANCE INFO_2011-2012 - Laserfiche WebLink

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California Water Service Co any Final Closure Report for Underground Storage Tank Removal 1602 E. Lafayette St., Stockton, CA larger diameter pipes, and physical pot-holing along the pipelines, the location of these pipelines associated with the USTs were identified up to where they entered the foundation of the adjacent building. These three larger pipelines ran together straight from the former UST location approximately 45 feet, then turned south and headed approximately 25 feet into the building. Pot-holes were excavated at approximately 22 feet west of the end of the excavation at the curb line and a break in the pipelines approximately 20 feet further west, at the 90 degree turn where the pipelines head south, and at the face of the building where these pipelines and several other pipelines not associated with the USTs entered the building. On December 19, 2011, five (5) confirmation soil samples were collected from pot-holes in the floor of the main pipeline trench. Soil samples were collected beneath the 3-inch piping in three places: approximately 20 feet and 42 feet west of the curb line and at the building foundation (2 samples were collected at the building foundation, 2 feet and 4 feet below the piping, samples 12-PH and 13-PH respectively). These samples were analyzed for TPHg, TPHd, VOCs, PCBs, LUFT metals, and Cr VI, and the results are shown in the attached table entitled: "Summary of Sample Results". The 1%-inch line was extracted from the ground in two locations: at the end of the trench excavation near the curb line and at the 90 degree turn where the pipelines turned south toward the building. This piping was cut and disposed of as hazardous waste. The %-inch line was observed to be deteriorated with advanced corrosion. Pieces of the %-inch line were extracted from the curb line and farther west. The two 3-inch lines were discovered to be broken or cut previously approximately 20 feet from the curb line, forming a "break" in the lines. These two lines were cut at the building foundation and removed entirely from the building foundation to the open trench for disposal as hazardous waste. The associated pipelines underneath the building foundation were closed in place under a separate permit (see Section 2.4). In the southern trench, three (3) pipelines were discovered: a 1%-inch, a two-inch and a three-inch pipeline, at approximately two feet below ground surface. The 1%-inch line had residual heavy petroleum hydrocarbons. The pipelines ended at the curb line. An excavation was performed by hand beyond the curb line and under the asphalt to determine whether the three pipes continued beyond the curb line. The excavation was 3 feet deep horizontally and no pipes were discovered. Since the pipes were not found, no additional excavation was warranted. On December 15, 2011, confirmation soil samples 4E and 5W were collected from approximately two feet deep in the floor of the southern trench. Confirmation samples 6E, 7M, and 8W were also collected beneath a 4-inch line uncovered on the south side of the northern trench. The line ' is believed to be a former water line. The laboratory results are shown in the table entitled "Summary of Sample results". CHOW ENGINEERING INC. 3