Laserfiche WebLink
City of Otdxk) Public Works Deparfflwnt <br />Pn^ No. CMKX-93^163 <br />January 28, 1W4 <br />Pagc2 <br />A.Introduction <br />Additional remedial investigatton activitkt are necessary at the City of Orono proper,y located <br />ct 1285 Brown Road South (Figure 1 in Appendix A is a site location map) be^ure the fall <br />vertical and horizontal extern of soil contamination has not been defined for die area <br />surrounding a former 3,(XX>-gallon unleaded gasoline underground storage tank (UST) and the <br />suspr t' 1 leaking former 5S0~gallon diesel fuel UST. Braun Intertec observed the tank <br />removal and performed all the necessary sampling and analysis aaivitia. A remslial <br />investigation is also required to determine if the petroleum release may have impacted <br />groundwater. <br />B.Background <br />B.l UST Excavation <br />On November 1, 1993, Braun Intertec observed the removal of four USTs at the above- <br />mentioned property. A site map is provided as Figure 2 in Appendix A. The tanks were <br />removed by City of Orono personnd and the removal was supervised by an MPCA certified <br />tank .''.'•av^ting contractor. Griffen Service Station Equipment, Inc. Two USTs, historically <br />to have contained diesel fuel and having cqiacities of 560-galIons (Tank 1) and 3,0(X)-galIons <br />(Tank 3) exhibited no apparent signs of contamination in the respective excavations based on <br />field observations and soil chemied analysis. <br />One additional 560-gallon dimel UST (Tank 4) exhibited signs of a release, and excavation <br />activities including field screening, seemed successful in removing contaminated soil and <br />delineating the venical md horizontal extent of petroleum contamination. However, <br />laboratory analysis of basin soils from this tank excavation indicate that soil contamination <br />remains at the base of the excavation and within the south and west sidewalls of the <br />excavation. Because the vertical and horizontal extent of soil petroleum contamination was <br />not defined during field activities bas«I on soil analytical r«ults, additional remedial <br />investigation was required. <br />The remaining tank, a 3,000-gallon unleaded gasoline UST (Tank 2), was excavated, and <br />petroleum contaminated soil was detected tu a depth of 16 feet below grade where the <br />ere jvation was halted because the reach of the backhoe could go no further. An estimated 85 <br />cubic yards of petroleum contaminated soil was removed from this excavation, stockpiled on <br />site, and later transported to the City of Orono facility located at 27(X) Kelly Parkway. <br />MPCA verbal approval to transport the contaminated soil was given on November 2, 1993. <br />Soil sample laboratory analysis indicated that the vertical extent of soil contamination has been <br />delineated because of a non-de ’.xt reading of Gasoline Range Organics for the sample <br />retrieved beneath the UST. Soil analytical results of samples retrieved from the east sidewall <br />of the excavation indicated petroleum contamination. Because the horizontal extent of <br />petroleum contamination associated with this UST was not defined in this UST basin, a <br />remedial investigation was required by the MPCA. The release of petroleum was reported to <br />the MPCA on November 1, 1993, and the site was assigned MPCA Leak4'0(XX)6933.