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HomeMy WebLinkAbout2004-11-04 All Phase - Utility Trench Excavation OversightAllPhase Companies, Incorporated 404-A St. Croix Trail North, Lakeland, MN 55043 Phone: 651-436-2930 Fax: 651-436-3918 November 4, 2004 Mr. Joel Martin BAHR Construction, L.L. C. 11550 Stillwater Boulevard Stillwater, MN 55082 RE: Utility Trench Excavation Oversight Vacant Property 15431 N. 58 Street, Oak Park Heights, Minnesota 55082 All Phase #1460-04B-E Dear Mr. Martin: All Phase Companies, Incorporated, was on site for the utility trench excavation on November 2, 2004. We collected some soil samples for in-field screening for organic vapors and observed the soils for staining and detectable odors. Based on the screening results and our observations there does not appear to be contamination at the utility trench from petroleum or its derivatives except for an inconsequential volume of soil with organic vapors screened below regulatory action levels. However, it should be noted that the investigation does not guarantee that contamination is or is not present at other locations on the subject site due to the limited amount of evaluation on the subject site. Our evaluation is based solely on the investigated locations and the soils collected for screening of organic vapors. Should you have any questions regarding the contents of this report, or if we can be of further service, please call us at your convenience at (651) 436-2930. Cordially, David S. Jenkin, P.G. Environmental Consultant Encl. : Eric Johnson, City of Qak Park Heights, 14168 Oak Park Blvd N., Oak Park Heights, MN 55082 UTILITY TRENCH EXCAVATION OVERSIGHT Vacant Property 15431 58 Street, MN Oak Park Heights, MN 55082 AllPhase Companies, Incorporated #1460 -04B -E Reported To BAHR Construction L.L.C. Stillwater, MN November 4, 2004 AllPhase Companies, Incorporated 404 -A St. Croix Trail North, Lakeland, MN 55043 Phone: 651-436-2930 Fax: 651- 436 -3918 INTRODUCTION AllPhase Companies, Incorporated, (AIIPhase) was retained by Bahr Construction, L.L.C. (Bahr) to observe excavation activities, screen for organic vapors and manage petroleum - contaminated soils, if encountered, for a utility trench at 15431 North 58 Street, Oak Park Heights, Minnesota hereafter referred to as the subject site (Figure 1). The subject site used to be a small commercial site for automobile repair. The excavation commenced and finished on November 2, 2004, and consisted of one trench from the water shutoff to the eastern wall of the house (Figure 2). BACKGROUND UTILITY TRENCH EXCAVATION OVERSIGHT Five buildings that had existed on the subject site were removed earlier in the year. There were reported observations of the dumping of automobile fluids and the piling of automobile engines on the ground. People familiar with the subject site identified three areas of concern. AllPhase conducted three test pits within the identified zones on August 18, 2004. Contaminated soil was encountered at Test Pit 2, 1.5 ft below grade (bg)-- Diesel range organics (DRO) were detected at 160 milligrams per kilogram (mg/kg). During the excavation of the basement area for the home that was being moved on site, three areas of contaminated soil were encountered. The first was a zone of stained soil with chemical odor located immediately adjacent to Test Pit 2. Its dimensions were approximately 4 ft in diameter and 6 ft bg. These soils were removed and thermally treated. The other two areas were near - surface layers of both minor odor and minor in-field screening measurements of organic vapors. They were located at the center of the subject site and the center of the basement excavation. These soils were also removed for thermal treatment. Remaining soils adjacent to the excavated areas were determined to be below regulatory action levels and were handled in the same manner as other on -site soils. METHODOLOGY A HNu PID organic vapor meter with a 10.2 eV lamp source was used to field screen soils for total organic vapors. Soil samples were collected from freshly exposed surfaces. The soil samples were placed in re- sealable bags and allowed to warm prior to screening the sample air space for organic vapors. The soil screenings were performed in accordance with the MPCA - approved protocol for this procedure. FINDINGS The utility trench excavation began at the water shut-off and proceeded west, then angled north-northwest, then west again up to the basement wall (Figure 2). The sewer stub was found directly beneath the water shut -off. The excavation extended to approximately 9 ft bg near the road and was at approximately 6 ft bg at the basement wall. Soils ranged in texture from gravelly clay to sandy gravel to sand. The sand unit was encountered at approximately 9 ft bg. In general, excavated soils were not stained and did not have detectable odors or organic vapors. Soils from Locations 21 through 24 were collected for in-field screening of organic vapors. Location 22 was the only soil that screened above background but only slightly, remaining near 1 part per million (ppm). Screening results and other field observations are summarized in Table 1. A more detailed description of this area follows. As the trench proceeded west then north - northwest, fill was encountered approximately 15 ft east of the house and in the upper two feet. The fill consisted of sand underlain by black sandy silt. The black unit was not the A horizon of nearby native soils, but was previously disturbed soils with organics, containing minor scattered glass, scrap metal, miscellaneous debris. This same black unit was encountered during the previous basement excavation and did not have detectable organic vapors or detectable petroleum or chemical odors. Of the two samples collected in the black sediment during the trench excavation, Location 22 had a mild chemical odor and screened near 1 ppm. The area that had odor was within an approximate 5 - foot diameter, and the black unit was generally Less than 1.5 feet thick. Based on the small volume (perhaps up to one cubic yard), the minor level of detectable organic vapors, and the analytical results of previous on-site sampling, the soil was not excavated and stockpiled. Utility Trenc h Excavation Overs 1 5431 N. 58th St., Oak Park sleigh,,, MN 55082 AliPhase Project #1460• -04 --E ppm = parts per million <1 ppm is considered background SUMMARY AND RECOMMENDATIONS Based on the screening results and our field observations, soils in and adjacent to the utility trench appear to be uncontaminated by petroleum, or other products that produce organic vapors, with the exception of up to one cubic yard of soil that had screening results slightly above background levels and well below regulatory action levels. Fill from the previous basement excavation extended 10 ft east of the house. The older fill with the black sediment in discussion was approximately 5 feet wide and extended to 15 ft east of the basement wall. This area of negligible contamination did not extend beyond the limits of the utility trench excavation. The excavated soils were used as backfill after utilities were installed. Our evaluation is based solely on the locations investigated at the subject site and the results from the screening of soils for organic vapors. If further excavation takes place on the property, we recommend environmental oversight as conducted with this project and that of the house basement. STANDARD OF CARE The recommendations and opinions presented by AllPhase Companies, Incorporated, are based solely on information collected during the performance of the site assessment and/or information provided by individuals with knowledge of the subject site. Assessor: Cijek Report Review Rennie Smith, P.G. Environmental Consultant David S. Jenkin, P.G. Environmental Consultant Table 1 Screening Results LI Date: 0 Date: Location 21 1.5' Location 22 1.5' Location 23 2.5' Location 24 3.5' OVM Reading < 1 PPm 1 PPm Detected < 1 ppm None < 1 PPm None Odor None Notes Fill Associated with minor waste in fill Native soils Native soils Utility Trenc h Excavation Overs 1 5431 N. 58th St., Oak Park sleigh,,, MN 55082 AliPhase Project #1460• -04 --E ppm = parts per million <1 ppm is considered background SUMMARY AND RECOMMENDATIONS Based on the screening results and our field observations, soils in and adjacent to the utility trench appear to be uncontaminated by petroleum, or other products that produce organic vapors, with the exception of up to one cubic yard of soil that had screening results slightly above background levels and well below regulatory action levels. Fill from the previous basement excavation extended 10 ft east of the house. The older fill with the black sediment in discussion was approximately 5 feet wide and extended to 15 ft east of the basement wall. This area of negligible contamination did not extend beyond the limits of the utility trench excavation. The excavated soils were used as backfill after utilities were installed. Our evaluation is based solely on the locations investigated at the subject site and the results from the screening of soils for organic vapors. If further excavation takes place on the property, we recommend environmental oversight as conducted with this project and that of the house basement. STANDARD OF CARE The recommendations and opinions presented by AllPhase Companies, Incorporated, are based solely on information collected during the performance of the site assessment and/or information provided by individuals with knowledge of the subject site. Assessor: Cijek Report Review Rennie Smith, P.G. Environmental Consultant David S. Jenkin, P.G. 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