February 25, Mr. Wayne Loflin, Maintenance Director Winston-Salem/Forsyth County Schools PO Box 2513 Winston-Salem, NC

Transcription

1 February 25, 2015 Mr. Wayne Loflin, Maintenance Director Winston-Salem/Forsyth County Schools PO Box 2513 Winston-Salem, NC Subject: PRELIMINARY SYNOPSIS OF RESULTS VAPOR INTRUSION SAMPLING AND ASSESSMENT HANES-LOWRANCE MIDDLE SCHOOL 2900 INDIANA AVENUE WINSTON-SALEM, NORTH CAROLINA MID-ATLANTIC JOB NUMBER: 000R Dear Mr. Loflin: Mid-Atlantic Associates, Inc. (Mid-Atlantic) is pleased to provide this Preliminary Synopsis of Results for Vapor Intrusion Sampling and Assessment at the Hanes-Lowrance Middle School for your approval. This preliminary synopsis of field data and laboratory results is intended to provide initial guidance and information prior to delivery of the comprehensive vapor intrusion assessment report detailed in the February 9, 2015 work plan. SCOPE OF WORK On February 14 and 15, 2015, Mid-Atlantic mobilized to the Hanes-Lowrance middle school in order to collect data to provide multiple lines of evidence as to the vapor intrusion condition of buildings at the site. Mid-Atlantic conducted a building survey, collected indoor and outdoor air samples, and collected sub-slab soil gas samples. Indoor air, outdoor air and sub-slab samples were submitted for laboratory analysis of radon and volatile organic compounds (VOCs) and were collected in locations and by methods detailed in the February 9, 2015 Vapor Intrusion Sampling Plan with the following exceptions: Two VOCs: 1,1-dichloroethane (1,1-DCA); and 1,1,2-trichloroethane (1,1,2-TCA), were added to the list of analytes for all indoor air, outdoor air, and sub-slab soil gas sample analyses. These analytes were added because they were detected in the groundwater contamination plume on school grounds above North Carolina Department of Environment and Natural Resources (NCDENR) Department of Waste Management (DWM) residential vapor intrusion screening levels for groundwater;

2 Preliminary Synopsis Of Results Vapor Intrusion Sampling And Assessment February 25, 2015 Hanes-Lowrance Middle School Page 2 Winston-Salem, North Carolina The sub-slab VOC soil gas sample collected from room 208 was determined to be compromised (open valve) by the analytical laboratory and was not analyzed; One indoor air VOC sample was added to the proposed sample list described in the February 9, 2015 work plan and was collected in the office between room 108 and 110 (Figure 1); and Two ambient outdoor air VOC samples were added to the proposed sample list described in the February 9, 2015 work plan and were collected near the eastern school property boundary (Figure 1). Complete results of VOC analysis of indoor air, outdoor air and soil gas samples were received from the contracting laboratory on February 23. Radon analysis of sub-slab soil gas, outdoor air and indoor air were received on February 24. Results and interpretation of radon data will be provided in the comprehensive vapor intrusion assessment report. RESULTS Building Survey The building survey included inspection of the building, measurement of the building pressure, inspection of the heating, ventilating and air conditioning (HVAC) systems, collection of weather conditions during sampling, and VOC measurement with a photoionization detector (PID). Results of the building survey will be detailed in the final report for this assessment. Based on preliminary interpretation of the building survey data, it appears that near worst-case conditions for vapor intrusion were in place for this assessment for the following reasons: Samples were collected during the winter season; The building HVAC systems were operating during indoor sampling periods as they would when the school is in session; The maximum and minimum temperatures for both days of sampling were lower than the mean maximum and minimum for those dates; and Pressure differential monitoring suggests that the permanent buildings were depressurized relative to outdoors during the indoor air sampling period on February 14. Soil Gas, Indoor and Outdoor Air VOC sampling Results of VOC analysis of indoor air, outdoor air, and sub-slab soil gas samples is shown in Tables 1 and 2. Results are compared to screening levels published in NCDENR Division of Waste Management Residential Vapor Intrusion Screening Levels, June 2014 (DWM screening levels). The site-specific cancer risk, and non-cancer hazard

3 Preliminary Synopsis Of Results Vapor Intrusion Sampling And Assessment February 25, 2015 Hanes-Lowrance Middle School Page 3 Winston-Salem, North Carolina is calculated for each sample where at least one analyte was detected above the DWM default screening value at target cancer risk (TCR) of 1.0E-05 for sub-slab soil gas samples and TCR = 1.0E-06 for indoor/outdoor air samples, and hazard quotient (HQ) of 0.2 for soil gas and indoor/outdoor air samples. For sub-slab soil gas and indoor/outdoor air samples, the sample site-specific sum cancer risk and sum non-cancer hazard is compared to the DWM TCR of 1.0E-05 for sub-slab soil gas, TCR of 1.0E-06 for indoor/outdoor air, and target non-cancer hazard index (HI) of 1 for indoor air and soil gas. Sub-Slab Soil Gas Results Among the 31 sub-slab soil gas samples collected on February 14 and 15, 2015 and submitted for laboratory analysis of the target VOCs, tetrachloroethylene (PCE) was detected in 14 samples in concentrations that exceed DWM default residential soil gas screening levels (TCR=1.0E-05; HQ=0.2). No other target analytes were detected at concentrations that exceed the default screening levels. The sample sum target noncancer hazard index of 1 (HI=1), and the target cancer risk (1.0E-05) was not exceeded among all sub-slab soil gas samples with the exception of the sample collected in room 111; where the sample HI=1.53. Sub-slab soil gas VOC results are summarized in Table 1. Indoor Air Results Among 45 indoor air VOC samples collected on February 14, 2015 and submitted for laboratory analysis of the target VOCs, there were no exceedances of DWM default residential screening values (TCR=1.0E-06; HQ=0.2) for the target analytes. Accordingly, site-specific sum cancer risk and non-cancer hazard were not calculated for any of the indoor air VOC samples. Indoor air results are summarized in Table 2. Outdoor Air Results Outdoor air samples were collected on February 14, 2015 and submitted for laboratory analysis of the target VOCs. These outdoor sample locations were selected to measure background VOC concentrations that might impact indoor VOC concentrations. Additionally, two outdoor air samples were collected near the eastern school boundary in an attempt to measure the VOC influence on outdoor air from the groundwater treatment system operated on Kaba-Ilco property, across Indiana Avenue. Among the outdoor air samples, there were no exceedances of DWM default residential indoor air screening values (TCR=1.0E-06; HQ=0.2) for the target analytes. Outdoor air results are summarized in Table 2.

4

5 TABLES

6 TABLE 1 SUMMARY OF CHEMICAL CONSTITUENTS DETECTED IN SUB-SLAB SOIL GAS HANES-LOWRANCE MIDDLE SCHOOL WINSTON-SALEM, NORTH CAROLINA MID-ATLANTIC JOB NO. R CONCENTRATION (ug/m3) 1,1-Dichloroethane 1,1-Dichloroethene Tetrachloroethene 1,1,2-Trichloroethane Trichloroethene DWM Residential Vapor Intrusion Screening Levels HQ=0.2; TCR=1.0E-05 Laboratory Method Detection Limit Sample ID Location Date Time Sample Sum Cancer Risk Sample Cumulative Non-Cancer Hazard Index 104 SS VOC Room 104 2/15/ : E E SS VOC Room 105 2/15/ : SS VOC Room 106 2/15/ : E E SS VOC Room 108 2/15/ : E E SS VOC Room 109 2/15/ : E E SS VOC Room110 2/15/ : E E SS VOC Room 111 2/15/ : E E SS VOC Room 112 2/15/ : E E SS VOC Room 113 2/15/ : Fit SS VOC Fitness Room 2/15/ : SS VOC Room 203 2/15/ : SS VOC Room 206 2/15/ : SS VOC Room 207 2/15/ : SS VOC Room 211 2/15/2015 9: E E SS VOC Room 212 2/14/ : Z E E SS VOC Room 213 2/14/ : E E SS VOC Room 214 2/14/ : E E SS VOC Room 215 2/14/ : E E SS VOC Room 216 2/14/ : SS VOC Room 217 2/15/2015 9: SS VOC Room 218 2/14/ : SS VOC Room 219 2/14/ : SS VOC Room 220 2/14/ : SS VOC Room 221 2/14/ : SS VOC Room 222 2/14/ : SS VOC Room 223 2/14/ : SS VOC Room 224 2/15/2015 7: E E SS VOC Room 225 2/15/2015 8: E E SS VOC Room 231 2/15/ : Main SS VOC Main Office Hanes 2/15/2015 8: Media SS VOC Media Center 2/15/ : NOTES: -- = Not detected above the laboratory method detection limits. Values in Bold exceed the DWM Residential Soil Gas Screening Level at HQ=0.2; TCR=1.0E-05 Highlighted Sample Cumulative Cancer Risk or Sample Hazard Index Exceed Target Cancer Risk (TCR) = 1.0E-05 or Target Hazard Index (HI) =1 -

7 TABLE 2 SUMMARY OF CHEMICAL CONSTITUENTS DETECTED IN INDOOR AIR HANES-LOWRANCE MIDDLE SCHOOL WINSTON-SALEM, NORTH CAROLINA MID-ATLANTIC JOB NO. R CONCENTRATION (ug/m3) 1,1-Dichloroethane 1,1-Dichloroethene Tetrachloroethene 1,1,2-Trichloroethane Trichloroethene DWM Residential Indoor Air Screening Level TCR=1.0E-06; THQ= Laboratory Method Detection Limit Sample Sum Cancer Risk Sample Cumulative Non- Cancer Hazard Index Sample ID Location Date Time 104 IA VOC Room 104 2/14/ : IA VOC Room 105 2/14/ : IA VOC Room 106 2/14/ : J IA VOC Room 108 2/14/ : /110 Office IA VOC Room between Room 108 and 110 2/14/ : IA VOC Room 109 2/14/ : IA VOC Room110 2/14/ : IA VOC Room 111 2/14/ : IA VOC Room 112 2/14/ : IA VOC Room 113 2/14/ : J - - Fit IA VOC Fitness Room 2/14/ : IA VOC Room 203 2/14/ : J IA VOC Room 206 2/14/ : IA VOC Room 207 2/14/ : IA VOC Room 211 2/14/ : IA VOC Room 212 2/14/ : IA VOC Room 213 2/14/ : J IA VOC Room 214 2/14/ : IA VOC Room 215 2/14/ : IA VOC Room 216 2/14/ : J IA VOC Room 217 2/14/ : IA VOC Room 218 2/14/ : J IA VOC Room 219 2/14/ : J IA VOC Room 220 2/14/ : IA VOC Room 221 2/14/ : J IA VOC Room 222 2/14/ : IA VOC Room 223 2/14/ : J IA VOC Room 224 2/14/ : J IA VOC Room 225 2/14/ : IA VOC Room 231 2/14/ : Main IA VOC Main Office Hanes 2/14/ : J - - Media IA VOC Media Center 2/14/ : J IA VOC Room 601 Pod 2/14/ : J IA VOC Room 602 Pod 2/14/ : IA VOC Room 603 Pod 2/14/ : J IA VOC Room 604 Pod 2/14/ : J IA VOC Room 605 Pod 2/14/ : J IA VOC Room 606 Pod 2/14/ : J IA VOC Room 607 Pod 2/14/ : J IA VOC Room 608 Moble 2/14/ : J J IA VOC Room 609 Moble 2/14/ : IA VOC Room 610 Moble 2/14/ : J IA VOC Room 611 Moble 2/14/ : IV VOC Room 612 Moble 2/14/ : J IA VOC Room 613 Moble 2/14/ : Back OA VOC Outdoor Air 1, Background 2/14/ : J Plume OA VOC Outdoor Air 2, Plume 2/14/ : J - - OA-SE Outdoor Air - Southeast 2/14/ : OA-NE Outdoor Air - Northeast 2/14/ : J NOTES: -- = Not detected above the laboratory method detection limits. Values in Bold exceed the DWM Residential Indoor Air Screening Level at TCR=1.0E-06; HQ=0.2

8 DRAWINGS

9 BACK OA VOC OA-NE PLUME OA VOC OA-SE WB WS DN DN & WS