Limited Site Investigation Report

Transcription

1 Limited Site Investigation Report Former Nightclub 8315 East Colfax Avenue Denver, Denver County, Colorado October 6, 2017 Terracon Project No Prepared for: City and County of Denver Denver, Colorado Prepared by: Terracon Consultants, Inc. Wheat Ridge, Colorado

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3 TABLE OF CONTENTS SITE DESCRIPTION... 1 SCOPE OF SERVICES Standard of Care Additional Scope Limitations Reliance... 2 FIELD INVESTIGATION Utility Clearance and Health and Safety Plan Preparation Soil Gas Sample Point Installation Soil Gas Sampling... 3 FIELD INVESTIGATION RESULTS... 4 SUMMARY OF ANALYTICAL RESULTS... 4 CONCLUSIONS... 4 RECOMMENDATIONS... 5 APPENDICES APPENDIX A EXHIBITS and TABLE Exhibit 1 Topographic Map Exhibit 2 Site Diagram Table 1 Detected Constituents in Soil Gas APPENDIX B TYPICAL SOIL GAS SAMPLE POINT CONSTRUCTION DETAIL APPENDIX C LABORATORY REPORT

4 LIMITED SITE INVESTIGATION FORMER NIGHTCLUB 8315 EAST COLFAX AVENUE DENVER, DENVER COUNTY, COLORADO Terracon Project No October 6, 2017 SITE DESCRIPTION The site is located at 8315 East Colfax Avenue and consists of an approximate 0.55 acre-tract of land, corresponding with Denver County Schedule No The site is improved with an approximate 7,590 square-foot building, which was constructed in The site is currently vacant and most recently occupied by PT s Nightclub. A topographic map with the site location is provided as Exhibit 1. It is Terracon s understanding that the City and County of Denver (CCoD, client) intends to redevelop the property with an affordable housing rental complex. SCOPE OF SERVICES The scope of work performed was in response to the results of Terracon s Environmental Site Assessment (ESA-Report No ) dated September 6, The ESA identified the following Recognized Environmental Condition (REC) in connection with the site: Historical presence of a filling station on the south adjoining and topographically up-gradient property, identified on Sanborn maps and city directories from 1951 through The objective of the LSI was to evaluate for the potential presence of select volatile organic compounds (VOCs) in soil gas above relevant laboratory reporting limits as a result of the identified REC. Per discussions with the client, the proposed redevelopment is not anticipated to use or come into contact with groundwater, which is estimated at 25 feet to 32 feet below ground surface (bgs). Therefore, this scope of work was limited to soil gas sampling and did not include groundwater sampling. 2.1 Standard of Care Terracon s services were performed in a manner consistent with generally accepted practices of the profession undertaken in similar studies in the same geographical area during the same time. Terracon makes no warranties, either express or implied, regarding the findings, conclusions, or recommendations. Please note that Terracon does not warrant the work of laboratories, regulatory agencies, or other third parties supplying information used in the preparation of the report. These LSI services were performed in accordance with the scope of work agreed with you, our client, as reflected in our proposal and were not restricted by ASTM E Responsive Resourceful Reliable 1

5 Limited Site Investigation Report 8315 East Colfax Avenue Denver, CO October 6, 2017 Terracon Project No Additional Scope Limitations Findings, conclusions, and recommendations resulting from these services are based upon information derived from the on-site activities and other services performed under this scope of work; such information is subject to change over time. Certain indicators of the presence of hazardous substances, petroleum products, or other constituents may have been latent, inaccessible, unobservable, non-detectable, or not present during these services. We cannot represent that the site contains no hazardous substances, toxic materials, petroleum products, or other latent conditions beyond those identified during this LSI. Subsurface conditions may vary from those encountered at specific borings or wells or during other surveys, tests, assessments, investigations, or exploratory services. The data, interpretations, findings, and our recommendations are based solely upon data obtained at the time and within the scope of these services. 2.3 Reliance This report was prepared exclusively for the use of the CCoD. Any authorization for use or reliance by any other party (except a governmental entity having jurisdiction over the site) is prohibited without the express written authorization of the CCoD and Terracon. Any unauthorized distribution or reuse is at clients sole risk. Notwithstanding the foregoing, reliance by authorized parties will be subject to the terms, conditions, and limitations stated in the proposal, LSI Report, and Terracon s 2015 Agreement with CCoD. FIELD INVESTIGATION 3.1 Utility Clearance and Health and Safety Plan Preparation A 48-hour notice-of-intent to advance the LSI borings was filed with the Utility Notification Center of Colorado to identify the public subsurface utilities at the site. Terracon conducted the field work under a health and safety plan developed specifically for this project. Work was performed using Occupational Safety and Health Administration Level D work attire consisting of hard hats, safety glasses, safety vests, protective gloves, and protective boots. 3.2 Soil Gas Sample Point Installation On September 28, 2017, utilizing direct-push drilling methods, Terracon installed three soil gas sample points (SG-01, SG-02, and SG-03) to a depth of 5 feet bgs (refer to Exhibit 2). The sample points, consisting of 6.0-inch long stainless steel screened points and Teflon tubing, were placed into each boring at an approximate depth of 5 feet bgs and backfilled with clean silica sand to approximately 6 inches above the top of the screen, followed by hydrated bentonite to near surface. A protective polyvinyl chloride (PVC) riser pipe and cap were placed at the top of the Responsive Resourceful Reliable 2

6 Limited Site Investigation Report 8315 East Colfax Avenue Denver, CO October 6, 2017 Terracon Project No soil boring, flush with the surface. The soil gas sampling point locations are provided on Exhibit 2 and a typical soil gas sample point construction detail is provided on Exhibit 3 in Appendix B. 3.3 Soil Gas Sampling Soil gas samples were collected for field screening and laboratory analysis approximately 24 hours following installation. Soil gas sampling was conducted within a polyethylene shroud placed over the sampling point. Extracted soil gas was screened in the field utilizing a MultiRae sixgas detector, which was calibrated prior to use in accordance with the manufacturer s specifications. The MultiRae six-gas detector was used to assess potential explosive gas (methane) and VOCs in the soil gas. Sample tubing was connected to the sampling point and routed to the exterior of the shroud. Leak detection was conducted by introducing helium tracer gas into the sampling shroud through a separate port prior to sampling and using a portable helium gas detector to monitor for potential leaks in the sampling train. A peristaltic pump was utilized to purge the sample train tubing prior to collecting the laboratory samples. Field measurements by the portable helium gas detector did not indicate leaks associated with the sampling train at the three soil gas sampling points. After purging the sampling point of approximately three sampling train volumes and observing the lack of detected leaks, a laboratory-supplied 6-liter summa canister was filled with soil gas for analysis. The canister was connected to the sampling point using dedicated nylon tubing and was equipped with a laboratory-supplied flow regulator allowing for sample collection at a lowflow rate (i.e. <200 ml/min). Upon completion of sample collection, the summa canister valve was closed, secured, and appropriately labeled with pertinent sample information. Canister pressures were recorded prior to and after sample collection. The sample canisters were placed into a shipping container and transported under chain-of-custody to Environmental Chemistry Services (ECS) of Castle Rock, Colorado for analysis of VOCs by US Environmental Protection Agency (US EPA) Method TO- 15. The TO-15 analyte list was limited to contaminants of concern commonly associated with filling stations for which regulatory standards have been established: Benzene, toluene, ethylbenzene, xylenes / methyl tert-butyl ether (BTEX/MTBE) Naphthalene 1,2,4-Trimethylbenzene 1,2-Dichloroethane Following collection of the soil gas samples the PVC piping and cap were removed and the boring backfilled with sand and the surface patched with asphalt. Responsive Resourceful Reliable 3

7 Limited Site Investigation Report 8315 East Colfax Avenue Denver, CO October 6, 2017 Terracon Project No FIELD INVESTIGATION RESULTS Field screening of the soil gas with the MultiRae six-gas detector did not detect the presence of explosive vapors or VOCs at the three sampling points. SUMMARY OF ANALYTICAL RESULTS VOC constituents detected in the soil gas samples were compared to the 2016 Colorado Department of Public Health and Environment (CDPHE) Indoor Air Screening Concentrations (ASC) Residential and Worker Remediation Goals, and the June 2017 US EPA Residential and Industrial Indoor Air Regional Screening Levels (RSLs), after applying a 3% attenuation factor for sub-slab soil gas per the US EPA Office of Solid Waste and Emergency Response (OSWER) Technical Guide for Assessing and Mitigating the Gas Intrusion Pathway from Subsurface Gas Sources to Indoor Air (OSWER Guidance, June 2015). Reference to the OSWER guidance is not meant to imply that the scope of this soil gas investigation was designed to include the guidance s subsurface characterization criteria or that Terracon conducted a detailed vapor intrusion risk assessment. Several VOCs were detected above the analytical method reporting limits in the soil gas samples. These reported detections were at concentrations that are calculated not to result in indoor air concentrations that would exceed US EPA RSLs or CDPHE ASCs, utilizing the OSWER attenuation factor. Reported concentrations are provided as Table 1 in Appendix A and the laboratory report is provided in Appendix C. CONCLUSIONS Based on the scope of services described in this report and subject to the limitations described herein, Terracon concludes the following: Three soil gas sampling points (SG-01 through SG-03) were installed at an approximate depth of 5 feet bgs on September 28, 2017, for field screening and to collect soil gas samples for laboratory analysis. Laboratory analysis of the three soil gas samples collected during this investigation detected the presence of VOCs. Utilizing the OSWER guidance method with a 3% attenuation factor for sub-slab soil gas, VOCs detected in the soil gas would not exceed US EPA RSLs or CDPHE ASCs. Responsive Resourceful Reliable 4

8 Limited Site Investigation Report 8315 East Colfax Avenue Denver, CO October 6, 2017 Terracon Project No RECOMMENDATIONS Based on the scope of services, limitations and conclusions of this assessment, it is Terracon s professional opinion that detected VOCs in soil gas at the site do not represent a vapor intrusion risk for the proposed redevelopment. Responsive Resourceful Reliable 5

9 APPENDIX A EXHIBIT 1 TOPOGRAPHIC MAP EXHIBIT 2 SITE DIAGRAM TABLE 1 DETECTED CONSTITUENTS IN SOIL GAS

10 APPROXIMATE SITE BOUNDARY TOPOGRAPHIC MAP IMAGE COURTESY OF THE U.S. GEOLOGICAL SURVEY QUADRANGLES INCLUDE: COMMERCE CITY, CO (1/1/1994), MONTBELLO, CO (1/1/1994), ENGLEWOOD, CO (1/1/1997) and FITZSIMONS, CO (1/1/1994). DIAGRAM IS FOR GENERAL LOCATION ONLY, AND IS NOT INTENDED FOR CONSTRUCTION PURPOSES Project Manager: KRS Drawn by: CPD Checked by: SBH Approved by: KRS Project No Scale: AS SHOWN File Name: EX.1 Date: W I 70 Frontage Rd N Ste 3 Wheat Ridge, CO TOPOGRAPHIC MAP FORMER NIGHTCLUB 8315 EAST COLFAX AVENUE DENVER, COLORADO EXHIBIT 1

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12 Table 1 Detected Constituents in Soil Gas Former Nightclub 8315 East Colfax Avenue, Denver, Colorado Terracon Project No Sample ID SG-01 SG-02 SG-03 Maximum Reported Conc. Calculated Indoor Air Conc. 1 Collection Date 9/29/2017 9/29/2017 9/29/2017 9/29/2017 9/29/2017 Parameter CDPHE Residential Industrial CDPHE Residential RSL RSL Worker ASC ASC µg/m 3 µg/m 3 µg/m 3 µg/m 3 µg/m 3 VOC (TO-15) Benzene Ethylbenzene < Toluene 5,200 22,000 5,200 22, < ,2,4-Trimethylbenzene NE NE m&p-xylene o-xylene ) As calculated using a 3% attenuation factor per the Office of Solid Waste and Emergency Response Technical Guide for Assessing and Mitigating the Vapor Intrusion Pathway from Subsurface Vapor Sources to Indoor Air (June 2015) and the maximum reported concentration RSL = United States Environmental Protection Agency (USEPA) Indoor Air Regional Screening Level (June 2017), µg/m 3 ASC = Colorado Department of Public Health and Environment (CDPHE) Air Screening Concentrations, Remediation Goals (January 2016), µg/m 3 ND = Not Detected NE = Not Established NA = Not Applicable Only detected analytes shown (detected concentrations are bold) Table.xlsx: Table 1 - Soil Gas Summary Page 1 of 1 10/6/2017

13 APPENDIX B TYPICAL SOIL GAS SAMPLE POINT CONSTRUCTION DETAIL

14 GROUND SURFACE 1' 2-INCH DIAMETER PVC CAP AND CASING NYLON TUBING 5' 3' HYDRATED BENTONITE 1' STAINLESS STEEL SCREENED POINT 10/20 SILICA SAND Project Mngr: Drawn By: Checked By: Approved By: KRS CPD SBH KRS Project No. Scale: File No. Date: N.T.S DWG Consulting Engineers and Scientists W I-70 FRONTAGE RD N., SUITE 3 WHEAT RIDGE, CO PH. (303) FAX. (303) TYPICAL SOIL GAS SAMPLE POINT CONSTRUCTION DETAIL FORMER NIGHTCLUB 8315 EAST COLFAX AVENUE DENVER, COLORADO EXHIBIT No. 3

15 APPENDIX C LABORATORY REPORT

16 Environmental Chemistry Services, Inc. 2 Oakwood Park Plaza; 100 Castle Rock, CO TEL: (303) FAX: (303) Website: October 03, 2017 Steven Hoffman Terracon Environmental, Inc W. I-70 Frontage Rd. North, Ste. 3 Wheat Ridge, CO TEL: (303) FAX (303) RE: Former Nightclub Order No.: Dear Steven Hoffman: Environmental Chemistry Services, Inc. received 3 sample(s) on 9/29/2017 for the analyses presented in the following report. There were no problems with the analytical events associated with this report, , unless noted in the Case Narrative. Quality control data is within laboratory defined or method specified acceptance limits except if noted. If you have any questions regarding these tests results, please feel free to call or . TEL: (303) ext:300 kris@ecs-corp.com Sincerely, Kris Mascarenas Director of Client Services 2 Oakwood Park Plaza; 100 Castle Rock, CO Original Page 1 of 7

17 Environmental Chemistry Services, Inc. 2 Oakwood Park Plaza; 100 Castle Rock, CO TEL: (303) FAX: (303) Website: Case Narrative WO#: Date: 10/3/2017 CLIENT: Project: Terracon Environmental, Inc. Former Nightclub WorkOrder Narrative: : This report in its entirety consists of the documents listed below. All documents contain the Environmental Chemistry Services, Inc. Work Order Number assigned to this report. 1. Paginated Report including: A Cover Letter, Case Narrative, Analytical Results, and Applicable Quality Control Reports. 2. Copies of the Chain of Custody Document(s) supplied with this sample set. 3. Electronic Data Deliverables (EDD) if requested. Samples were analyzed in accordance with "Compendium of Methods for the Determination of Toxic Organic Compounds in Ambient Air Second Edition." The method used is the Compendium Method TO-15 for the Determination of Volatile Organic Compounds (VOCs) in air collected in specially prepared canisters and analyzed by Gas Chromatography/Mass Spectrometry (GC/MS). REF: Center for Environmental Research Information Office of Research and Development U.S. Environmental Protection Agency Cincinnati, OH January 1999 Any comments or problems with the analytical events associated with this report are noted below. Original Page 2 of 7

18 Environmental Chemistry Services, Inc. Client: Terracon Environmental, Inc. Work Order: Project: Former Nightclub Lab ID: A Date: 03-Oct-17 Client Sample ID: SG-01 Canister ID: 0691 Collection Date: 9/29/2017 8:56:00 AM Matrix: AIR Analyses Result RL Qual Units DF Date Analyzed VOCS IN AIR BY TO-15 Method: TO-15 Analyst: TSM MTBE ND 1.1 µg/m³ 1 1,2-Dichloroethane Benzene Toluene Ethylbenzene m,p-xylene o-xylene 1,2,4-Trimethylbenzene Naphthalene Surr: 1,2-Dichloroethane-d4 Surr: Toluene-d8 Surr: 4-Bromofluorobenzene ND ND µg/m³ µg/m³ 1 11 µg/m³ µg/m³ µg/m³ µg/m³ µg/m³ µg/m³ %Rec %Rec %Rec 1 Qualifiers: B Analyte detected in the associated Method Blank D Dilution was required. DF Dilution Factor E Value above quantitation range H Holding times for preparation or analysis exceeded J Analyte detected above MDL below RL N Tentatively identified compounds (Valures are estimated) ND Not Detected at the RL R RPD outside accepted recovery limits R Percent Difference outside accepted limits Page 3 of 7

19 Environmental Chemistry Services, Inc. Client: Terracon Environmental, Inc. Work Order: Project: Former Nightclub Lab ID: A Date: 03-Oct-17 Client Sample ID: SG-02 Canister ID: 2689 Collection Date: 9/29/2017 9:54:00 AM Matrix: AIR Analyses Result RL Qual Units DF Date Analyzed VOCS IN AIR BY TO-15 Method: TO-15 Analyst: TSM MTBE ND 1.1 µg/m³ 1 1,2-Dichloroethane Benzene Toluene Ethylbenzene m,p-xylene o-xylene 1,2,4-Trimethylbenzene Naphthalene Surr: 1,2-Dichloroethane-d4 Surr: Toluene-d8 Surr: 4-Bromofluorobenzene ND ND µg/m³ µg/m³ 1 11 µg/m³ µg/m³ µg/m³ µg/m³ µg/m³ µg/m³ %Rec %Rec %Rec 1 Qualifiers: B Analyte detected in the associated Method Blank D Dilution was required. DF Dilution Factor E Value above quantitation range H Holding times for preparation or analysis exceeded J Analyte detected above MDL below RL N Tentatively identified compounds (Valures are estimated) ND Not Detected at the RL R RPD outside accepted recovery limits R Percent Difference outside accepted limits Page 4 of 7

20 Environmental Chemistry Services, Inc. Client: Terracon Environmental, Inc. Work Order: Project: Former Nightclub Lab ID: A Date: 03-Oct-17 Client Sample ID: SG-03 Canister ID: 2673 Collection Date: 9/29/ :52:00 AM Matrix: AIR Analyses Result RL Qual Units DF Date Analyzed VOCS IN AIR BY TO-15 Method: TO-15 Analyst: TSM MTBE ND 1.1 µg/m³ 1 1,2-Dichloroethane Benzene Toluene Ethylbenzene m,p-xylene o-xylene 1,2,4-Trimethylbenzene Naphthalene Surr: 1,2-Dichloroethane-d4 Surr: Toluene-d8 Surr: 4-Bromofluorobenzene ND 2.9 ND ND ND µg/m³ µg/m³ 1 11 µg/m³ µg/m³ µg/m³ µg/m³ µg/m³ µg/m³ %Rec %Rec %Rec 1 Qualifiers: B Analyte detected in the associated Method Blank D Dilution was required. DF Dilution Factor E Value above quantitation range H Holding times for preparation or analysis exceeded J Analyte detected above MDL below RL N Tentatively identified compounds (Valures are estimated) ND Not Detected at the RL R RPD outside accepted recovery limits R Percent Difference outside accepted limits Page 5 of 7

21 Environmental Chemistry Services, Inc. 2 Oakwood Park Plaza; 100 Castle Rock, CO TEL: (303) FAX: (303) Website: QC SUMMARY REPORT Work Order: Oct-17 Client: Terracon Environmental, Inc. Project: Former Nightclub BatchID: R3858 Sample ID: LCS SampType: LCS TestCode: TO15 Units: µg/m³ Prep Date: RunNo: 3858 Client ID: LCSW Batch ID: R3858 TestNo: TO-15 Analysis Date: 10/1/2017 SeqNo: Analyte Result PQL SPK value SPK Ref Val %REC LowLimit HighLimit RPD Ref Val %RPD RPDLimit Qual 1,1-Dichloroethene Benzene Trichloroethene Toluene Chlorobenzene Surr: 1,2-Dichloroethane-d Surr: Toluene-d Surr: 4-Bromofluorobenzene Sample ID: LCSD SampType: LCSD TestCode: TO15 Units: µg/m³ Prep Date: RunNo: 3858 Client ID: LCSS02 Batch ID: R3858 TestNo: TO-15 Analysis Date: 10/1/2017 SeqNo: Analyte Result PQL SPK value SPK Ref Val %REC LowLimit HighLimit RPD Ref Val %RPD RPDLimit Qual 1,1-Dichloroethene Benzene Trichloroethene Toluene Chlorobenzene Surr: 1,2-Dichloroethane-d Surr: Toluene-d Surr: 4-Bromofluorobenzene Qualifiers: B Analyte detected in the associated Method Blank D Dilution was required. H Holding times for preparation or analy ND Not Detected at the RL O RSD is greater than RSDlimit R RPD outside accepted recovery limits RL Reporting Limit S Spike Recovery outside accepted recovery limits W Sample container temperature is out o Page 6 of 7

22 Environmental Chemistry Services, Inc. 2 Oakwood Park Plaza; 100 Castle Rock, CO TEL: (303) FAX: (303) Website: QC SUMMARY REPORT Work Order: Oct-17 Client: Terracon Environmental, Inc. Project: Former Nightclub BatchID: R3858 Sample ID: MBLK SampType: MBLK TestCode: TO15 Units: µg/m³ Prep Date: RunNo: 3858 Client ID: PBW Batch ID: R3858 TestNo: TO-15 Analysis Date: 10/1/2017 SeqNo: Analyte Result PQL SPK value SPK Ref Val %REC LowLimit HighLimit RPD Ref Val %RPD RPDLimit Qual 1,1-Dichloroethene ND MTBE ND ,2-Dichloroethane ND Benzene ND Trichloroethene ND Toluene ND 11 0 Chlorobenzene ND Ethylbenzene ND m,p-xylene ND o-xylene ND ,2,4-Trimethylbenzene ND Naphthalene ND Surr: 1,2-Dichloroethane-d Surr: Toluene-d Surr: 4-Bromofluorobenzene Qualifiers: B Analyte detected in the associated Method Blank D Dilution was required. H Holding times for preparation or analy ND Not Detected at the RL O RSD is greater than RSDlimit R RPD outside accepted recovery limits RL Reporting Limit S Spike Recovery outside accepted recovery limits W Sample container temperature is out o Page 7 of 7

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