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Home My WebLink About12-01-09 Worksession Handouts FILE COPY k V�V4 CITY OF OAK PARK HEIGHTS I I Phase II Environmental Site Assessment Report Stillwater Motors Area 1 & 2 / Well and Tower 3 City of Oak Park Heights December 2009 Project Number 000055 - 09161 -0 * Bonestroo 3717 23rd Street S St. Cloud, MN 56301 Tel 320 - 251 -4553 Fax 320 - 251 -6252 www.bonestroo.com December 1, 2009 Bonestroo Eric Johnson, City Administrator City of Oak Park Heights 14168 Oak Park Boulevard North Oak Park Heights, MN 55082 Re: Phase II Environmental Site Assessment Stillwater Motors Area 1 & 2 / Well and Tower 3 Bonestroo File No.: 55- 09161 -0 Dear Mr. Johnson: In accordance with your authorization, Bonestroo conducted a Phase II Environmental Site Assessment at the proposed Well and Tower 3 site in the city of Oak Park Heights. The objectives of this assessment were to evaluate fill material apparently originating at the adjacent Stillwater Motors facility and sample groundwater from two nearby water wells to test for contamination. For a discussion of the methods and results of our assessment, please refer to the attached report. We appreciate the opportunity to provide professional services to you for this project. If you have any questions or comments regarding the contents of this letter or the attached report, please feel free to contact us at the number below. Sincerely, BONESTROO t 00' Clintort-Q. Jbrdahl, PG Christopher W. Long, PE Geologist Client Service Manager 320.229.5529 651.604.4808 , STILLWATER MOTORS AREA 1 &2 /WELL AND TOWER 3 Table of Contents Introduction.............................................................................................. ..............................1 Authorization........................................................................................ ..............................1 Projectbackground ............................................................................... ..............................1 Projectobjectives .................................................................................. ..............................1 Scopeof Services .................................................................................. ..............................1 ProjectResults .......................................................................................... ..............................2 TestPit Locations .................................................................................. ..............................2 SoilsEncountered ................................................................................. ..............................2 Soil Contamination Screening ................................................................ ..............................2 SoilSample Analysis .............................................................................. ..............................2 WellSample Analysis ............................................................................. ..............................3 Discussion and Conclusions ....................................................................... ..............................4 Assessment Limitations ............................................................................. ..............................5 STILLWATER MOTORS AREA 1 &2 /WELL AND TOWER 3 Introduction AUTHORIZATION In accordance with the authorization received from Mr. Eric Johnson of the City of Oak Park Heights (City), Bonestroo conducted a Phase II Environmental Site Assessment of approximately 2 1 /2 acres of land to be separated from Stillwater Motors Company for the construction of Well and Tower 3. A Site Location Map based on a 2006 aerial photograph is included as Figure 1 in Appendix A. PROJECT BACKGROUND A Phase I Environmental Site Assessment for the property that was recently completed by Bonestroo identified fill reportedly originating from the adjacent Stillwater Motors facility and apparently containing non -soil materials. The Stillwater Motors facility was identified as a leaking underground storage tank site and a review of the Minnesota Pollution Control Agency (MPCA) files suggests that significant levels of soil and groundwater contamination remain at the facility. Please refer to the Bonestroo report entitled Phase I Environmental Site Assessment, Areas 1 and 2, dated October 15, 2009, and a MPCA file review summary memo from Bonestroo to the City dated October 28, 2009 for a more detailed discussion of the site back ground information. PROJECT OBJECTIVES The objectives of the project were to evaluate the potential environmental hazards posed to the property by the presence of the fill material, and evaluate the uppermost bedrock aquifer(s) in the area for indications of gross contamination. SCOPE OF SERVICES The following work tasks were conducted as part of this assessment: • observation of three test pits excavated at the property by City personnel; • evaluation of soil samples collected from the test pits for obvious visual and incidental olfactory indications of contamination; • screening soil samples in the field for the presence and relative concentrations of organic vapors with a photoionization detector (PID); • laboratory chemical analyses of select soil samples collected from the test pits for the presence and concentrations of diesel range organic compounds (DRO), volatile organic compounds (VOCs), and the eight Resource Conservation and Recovery Act metals (8- RCRA metals); • laboratory chemical analysis of a groundwater samples collected from two nearby water wells for the presence and concentration of VOCs, nitrate and coliform bacteria; and • preparation of this report detailing the methods and results of our assessment. City of Oak Park Heights Page 1 Stillwater Motors Area 1&2 /Well and Tower 3, Bonestroo 000055- 09161 -0 STILLWATER MOTORS AREA 1 &2 /WELL AND TOWER 3 Project Results TEST PIT LOCATIONS Three test pits (TP -1 through TP -3) were dug at the property on November 10, 2009 by City personnel using a tracked mini - excavator. The test pit locations are shown on Figure 2 in Appendix A. Test pits TP -1 and TP -2 were excavated in a north -south trending berm of apparent fill material. Test pit TP -3 was excavated in an area where aerial photographs indicate materials and equipment were stored during the construction of additions to the Stillwater Motors facility. The location of TP -3 also appears to have been used as a concrete truck washout site. SOILS ENCOUNTERED The soils encountered in test pits TP -1 and TP -2 consisted of a very thin layer of turf grass and topsoil underlain by loamy fine sand fill material to the terminal depths of each test pit at 4 and 4 1 /2 feet. What appears to have been the original topsoil layer was encountered at the 4 1 /2 -f0ot terminal depth of TP -2. A few very minor solid waste inclusions were noted consisting of a few small fragments of PVC pipe and one piece of PVC electrical conduit, however in general, the fill material in the areas evaluated was comprised of "clean" mineral soil. The soils encountered at TP -3 consisted of a mixture of loamy sand, silt, and clay fill material to the terminal depth of 1 /2 feet. Aside from scattered concrete and reclaimed bituminous pavement on the surface, no indications of solid waste inclusions were noted in the soils excavated at the TP -3 location. SOIL CONTAMINATION SCREENING Soil samples retrieved from the test pits were examined visually for staining and other apparent signs of contamination. In addition, the soil samples were screened for the presence and concentrations of organic vapors with a photoionization detector (PID) using a polyethylene -bag headspace procedure recommended by the MPCA. The PID was equipped with an 10.6 electron - volt lamp and calibrated to an isobutylene standard to provide direct readings of relative organic vapor concentrations in parts per million. The polyethylene -bag headspace analytical procedure consisted of half - filling a new one -quart self - sealing bag with a soil sample. The bag was quickly sealed and headspace was allowed to development for at least 10 minutes. The bag was shaken vigorously for 15 seconds, both at the beginning and the end of the headspace development period. After headspace development, the PID probe was inserted through the top of the bag to one -half the headspace depth. The highest reading observed on the PID was then recorded. No unusual odors or obvious soil staining were noted in any of the other soil samples retrieved from the test pits conducted at the site. In addition, no elevated organic concentrations were detected emanating from any of these soil samples when they were screened with the PID. SOIL SAMPLE ANALYSIS Soil samples for laboratory chemical analyses were collected from each of the test pits conducted at the site. Since no field indications of contamination were noted in any of the samples retrieved from the test pits, the soil samples collected from TP -1 and TP -2 were taken from a depth of about 4 feet, which appears to be within the bottom foot of the fill material. The sample from test pit TP -3 was taken from the terminal depth of 1 12 feet. City of Oak Park Heights Page 2 Stillwater Motors Area 1&2 /Well and Tower 3 Bonestroo 000055- 09161 -0 The samples collected for DRO and metals analyses were placed in glass 4 oz chemical - sample jars with TeflonNined lids. The soil samples collected for volatile analysis were collected in 40 ml vials and preserved in the field with methanol in accordance with Wisconsin Department of Natural Resources Modified GRO analytical procedures. The jars were labeled in the field and transported to the laboratory on ice using standard chain -of- custody procedures. The soil samples were submitted to the Pace Analytical Services and analyzed for the presence and concentrations of DRO, VOCs and the 8 -RCRA metals. DRO was detected in the soil sample collected from TP -1 at a concentration of 15.9 mg /kg (parts per million), but was not detected in either of the remaining samples. None of the targeted VOC parameters were detected in any of the samples collected at concentrations greater than or equal to their laboratory detection limits. Arsenic, barium, chromium and lead were detected in each of the soil samples analyzed; however, the reported concentrations of these metals were below applicable risk and cleanup standards and their presence is not indicative of contamination. Specific laboratory analytical results are presented in the laboratory reports included in Appendix B. WELL SAMPLE ANALYSIS Water samples were collected from two water wells near the property. The wells sampled were Minnesota Department of Health (MDH) unique numbers 517024 and 561770 and their locations are shown on Figure 1 in Appendix A. Well #517024 is reportedly 121 feet deep and completed in the Prairie Du Chien Group. Well #561770 is reportedly 285 feet deep and completed in the Jordan Sandstone, which would be the target aquifer for the proposed municipal well 3. Untreated water samples were collected from outside taps after following a run time sufficient to evacuate the stagnant water column from the wells. The water samples were placed on ice and transported to Pace Analytical Services following standard chain -of- custody procedures. The samples submitted to the laboratory were analyzed for the presence and concentration of VOCs, nitrate and coliform bacteria. None of the targeted VOC parameters were detected in either of the water well samples at concentrations greater than or equal to their laboratory detection limits. The laboratory also reports that coliform was "absent" in both samples. The sample collected from well #517024 contained nitrates at a concentration of 2.7 mg /L, which is well below the maximum concentration limit of 10 mg /L that is applicable to municipal water supplies. Detectable nitrate was not present in the water sample collected from well #561770. City of Oak Park Heights Page 3 Stillwater Motors Area 1&2 /Well and Tower 3 Bonestroo 000055- 09161 -0 STILLWATER MOTORS AREA 1 &2 /WELL AND TOWER 3 Discussion and Conclusions Our observations of the materials encountered in the test pits excavated at the site suggest that there is not a significant amount of non -soil material incorporated in the fill material located at the site. With the exception of thin layer of reclaimed bituminous pavement that appears to have been placed as driving surfacing, the bulk of the fill material at the site appears to be mineral soil. DRO was detected in one of the soil samples collected from one of the test pits excavated at the site at a low concentration. The source of the DRO contaminated soil is not known, but it appears likely that it came to the site as excess fill removed from the adjacent Stillwater Motors facility during the construction of a building addition in about 2006. The DRO concentration detected (15.9 mg /kg) is low enough that it would not normally elicit cleanup action or further investigation if it were brought to the attention of the MPCA and known to be the maximum concentration present at the site. However, it is not known to be the maximum concentration present at the site and under such circumstances the MPCA's guidance would suggest that a reporting requirement exists. We therefore recommend that the situation be reported to the State Duty Officer. With respect to the acquisition of the property, we recommend that the City have Stillwater Motor Company remove the impacted soil from the site or secure the approval of the MPCA to allow it to remain. The results of the well sampling should be taken in the context. The absence of detectable contamination in the aquifer(s) is no guarantee that a new municipal well at the proposed site won't pull in contaminants from the Stillwater Motors property. It simply demonstrates that any contaminants from that property have not yet migrated to the wells we tested. To some degree, this was expected since reported regional groundwater flow direction is thought to be to the east or northeast (towards the river) in the area. City of Oak Park Heights Page 4 Stillwater Motors Area 1&2 /Well and Tower 3 Bonestroo 000055- 09161 -0 STILLWATER MOTORS AREA 1 &2 /WELL AND TOWER 3 Assessment Limitations The analyses and conclusions submitted in this report are based on our field observations and the results of laboratory chemical analyses of soil samples collected from the test pits completed for this project. In performing its services, Bonestroo used that degree of care and skill ordinarily exercised under similar circumstances by reputable members of its profession practicing in the same location. No other warranty is made or intended. City of Oak Park Heights Page 5 Stillwater Motors Area 1 &2 /Well and Tower 3 Bonestroo 000055- 09161 -0 Appendix A Figures City of Oak Park Heights Stillwater Motors Area 1&2/Well and Tower 3 Bonestroo 000055 - 09161 -0 boundary jr * It t Propose Well No. 3 0 , Y _ I y + 517024 r ♦ s r , w 561.770 le IP tv AV e 40 OF Alt IV } r t � Y q x- X f - w .dW dt 0 f 9r . e Site Location Map Figure 1 City of Oak Park Heights N December 2009 100 0 zoo Feet A 2006 USGS AERIAL PHOTO K: \55\55091610 \6I5 \Projects \Fgure 01 - Site Locadon.rrud w a . i - f, ' w rW x'' t 1 iqh Proposed Well No: 3, It bit y If IMP y - � TP =1 � 40 7 .► . o f TP ------- - - - - -- -- - -- A--------- - - - - -- � - -- - -- 4 b R T y Iw I I ;+y y , Test Pit Location Map Figure 2 City of Oak Park Heights N loo 0Feer A 2006 USGS AERIAL PHOTO December 2009 K: \55 \55091610 \GIS \Projects \Figure 01 - Site Lo bon.mxd IL Appendix B Laboratory Reports City of Oak Park Heights Stillwater Motors Area 1&2 /Well and Tower 3 Bonestroo 000055- 09161 -0