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Home My WebLink AboutWI0400198_DEEMED FILES_20201028A ARCADIS! �;-ir� t Mr. Michael Rogers UIC Program Manager NCDEQ — DWR 1636 Mail Service Center Raleigh, North Carolina 27699 Subject: 2nd Semi -Annual Groundwater Monitoring Report — 2020 Former BP Facility #24163 381 Knollwood Street Winston-Salem, North Carolina 27103 Incident Number: 6400 (Closed) Risk Classification: Low (No Further Action) Dear Mr. Rogers: On behalf of Atlantic Richfield Company (ARCO), a BP Products North America, Inc. (BP) affiliated company, Arcadis G&M of North Carolina is submitting the attached 2nd Semi -Annual Groundwater Monitoring Report — 2020 for the above referenced site. An electronic copy of this report including the associated laboratory analytical report is included with the attached CD. Please contact me at (919) 328-5605 with any questions or concerns related to the Report or this incident number. Sincerely, Arcadis G&M of North Carolina, Inc. Hardik Patel AFS Project Manager Copies: File — BP #24163 RECEIVED OCT 2 8 2020 NC DEQIDWR Central Office Arcadis U.S., Inc. 111-D Sanders Lane Bluefield, VA 24605 Tel 276 322 3679 Fax 276 322 3946 www.arcadis.com ENVIRONMENT Date: October 23, 2020 Contact: Hardik Patel Phone: 919.328.5605 Email: Hardik.Patel@arcadis.com Our ref: 30013560 (GP16BPNA.NC10) $4 ARCA DIV `b�ul�t�n'-`,and s t�Y Atlantic Richfield Company c/o BP Products North America, Inc. z"" bt:MI-ANNUAL MUNITORING REPORT - 2020 Former BP Facility #24163 381 Knollwood Street Winston-Salem, Forsyth Count NCDEQ Incident #6400 (Close Injection Permit #W10400198 October 2020 2nd Semi -Annual Monitoring Report - 2020 ARM Hardik Patel AFS Project Manager i :C. Scott P it 19 l 2o`La V"CAWEANo.25659 . t el l, 2ND SEMI-ANNUAL MONITORING REPORT -2020 Prepared for: Atlantic Richfield Company c/o BP Products North America, Inc. Mr. Kyle Christie — Project Manager 1919 Mariposa Lane Fullerton, CA 92833 Tel 714.815.8971 Prepared by: Arcadis G&M of North Carolina, Inc. 5420 Wade Park Blvd. Suite 350 Raleigh, North Carolina 27607 Tel 919.854.1282 Fax 919.854.5448 www.arcadis-us.com Environmental Our Ref.: 30013560 Date: October 14, 2020 This document is intended only for the use of the individual or entity for which it was prepared and may contain information that is privileged, confidential and exempt from disclosure under applicable law. Any dissemination, distribution or copying of this document is strictly prohibited. arcadis.com ES-1 2"d Semi -Annual Monitoring Report - 2020 2"d Semi -Annual Monitoring Report - 2020 Former BP Facility #24163 381 Knollwood St Winston-Salem, Forsyth County, North Carolina Latitude 360 5' 25.94"N Longitude 80017' 11.79"W (Reference Figure 1) Groundwater Incident #: Risk Classification: Reason for Risk Classification: Land Use Category: Source of Release: Date of Release Discovery: Estimated Quantity of Release: Cause of Release: Responsible Party: Property Owner: 6400 (Closed) Low (No Further Action) Dissolved -phase Sulfate concentrations above groundwater quality standards (2L) Industrial/Commercial Former gasoline UST system(s) 1983 Unknown Former UST System Atlantic Richfield Company c/o BP Products North America, Inc. Attn: Kyle Christie 1919 Mariposa Lane Fullerton, CA 92833 (714) 815-8971 Mr. Charles Sherren Thruway Shopping Center, LLC. 7501 Wisconsin Ave., Suite 1500 Bethesda, Maryland, 20814 (301) 986-2925 ext. 215 a Professional Engineer for Arcadis G&M of North Carolha, I , do certi 3 ie information contained in this report is correct and accurate to the best of & my k8owlidge.SE&Iis M of North Carolina, Inc. is licensed to practice geology and engineering in North ina erti ication numbers of the company are C-155 (geology) and C-1869 (engineering). n�f7 �. arcadis.com ES-2 2°d Semi -Annual Monitoring Report - 2020 CONTENTS 1.0 Site History and Characterization ................. 2.0 Groundwater Monitoring ................................ 2.1 Groundwater Gauging ............................ 2.2 Groundwater Sampling ........................... 2.3 Groundwater Analytical Results ............. 3.0 Site Remediation........................................... 3.1 Remediation Activities to Date ................ 4.0 Conclusions and Recommendations ............ TABLFr- Table 1. Monitoring Well Construction Data Table 2. Groundwater Elevation Data Table 3. Summary of Groundwater Analytical Data FIGURES Figure 1. Site Location Map Figure 2. Site Map Figure 3. Potentiometric Surface Map — September 1, 2020 Figure 4. Groundwater Analytical Data — August 2018 - September 2020 Figure 5. Sulfate Isoconcentration Map — September 1, 2020 APPENDICES A — Historical Groundwater Elevation Data B — Laboratory Analytical Report and Chain -of -Custody Record — April 2, 2020 C — Historical Groundwater Analytical Data ............................. 5 ............................. 6 ............................. 6 ............................. 6 ............................. 7 ............................. 7 ............................. 7 ............................. 8 arcadis.com ES-3 2°d Semi -Annual Monitoring Report - 2020 EXECUTIVE SUMMARY On behalf of Atlantic Richfield Company (ARCO), a BP Products North America, Inc. (BP) affiliated company, Arcadis G&M of North Carolina, Inc. (Arcadis) personnel performed the semi-annual groundwater sampling of groundwater monitoring wells associated with Former BP Facility #24163 located at 381 Knollwood Street, in Winston-Salem, Forsyth County, North Carolina (the Site) on September 1, 2020. All groundwater monitoring activities were conducted in response to the final project evaluation requirement specified in Part VII, Item 5 of the Renewal Issuance of Injection Permit W10400198 from the North Carolina Department of Environmental Quality (NCDEQ) Division of Water Quality — Aquifer Protection Section in April 2013. On September 1, 2020, Arcadis completed a semi-annual groundwater monitoring and sampling event at the Site. Two (2) groundwater monitoring wells (MW-8R and MW-6) were gauged to determine the depth to water (DTW). DTW ranged from 12.72 feet below top of casing (btoc) in groundwater monitoring well MW-8R to 11.80 feet btoc in groundwater monitoring well MW-6. The historical groundwater flow direction for the Site is towards the southeast. On September 1, 2020, groundwater samples were collected from groundwater monitoring wells MW-8R and MW-6. The maximum concentrations of selected dissolved -phase COCs found during the September 2020 sampling events are summarized in the table below: Maximum Groundwater Concentrations (September 1, 2020) Chemical of Monitoring Well Concentration North Carolina Concern ID (tng/L) Groundwater (COC) Quality (2L) Standards Sulfate MW-8R 442 250 Note: Concentration in Bold exceeds the applicable North Carolina GCL Standard mg/L: milligrams per liter Dissolved phase sulfate concentrations decreased compared to historical groundwater analytical data. Dissolved phase sulfate was detected above the applicable North Carolina Groundwater Quality (21L) Standard at groundwater monitoring well MW-8R only. Arcadis recommends continuing the semi-annual groundwater monitoring and sampling program at the Site to document the natural attenuation of sulfate. The next semi-annual groundwater monitoring and sampling event is scheduled for March 2021. Groundwater monitoring wells MW-8R and MW-6 will be gauged to evaluate the potentiometric surface at the Site. Groundwater samples will be collected from MW-8R and MW-6 for analysis of sulfate by Standard Method 9056A. A Semi -Annual Groundwater Monitoring Report documenting the proposed activities for 2020 will be submitted to the NCDEQ for review and approval within 45-days of receipt of the laboratory analytical report. arcadis com ES-4 2na Semi -Annual Monitoring Report - 2020 1.0 SITE HISTORY AND CHARACTERIZATION Former BP Facility #24163 is located at 381 Knollwood Street, Winston-Salem, Forsyth County, North Carolina (the Site). The Site is currently owned by Thruway Shopping Center, LLC. and serves as a parking lot adjacent to surrounding retail stores. The site property is approximately 0.5 acres, covered by asphalt and concrete, and was formerly developed as a retail fueling station which housed gasoline, diesel, waste oil, and kerosene Underground Storage Tanks (USTs). A site location map is presented as Figure 1 and a site map is shown as Figure 2. The North Carolina Department of Environmental Quality (NCDEQ) issued groundwater incident number 6400 due to a subsurface release of gasoline that occurred on or before September 14, 1983 from a ruptured product line associated with the UST system. The quantity of the release remains unknown. One (1) 10,000-gallon steel gasoline UST, three (3) 6,000-gallon steel gasoline USTs, and one (1) 10,000-gallon steel diesel UST were removed from the site in 1990. Three (3) 10,000-gallon gasoline USTs, one (1) 10,000-gallon diesel UST, and one (1) 550-gallon waste oil UST were subsequently installed at the site and the site was purchased by M. M. Fowler, Inc. in January 1994 and continued operation until 2004. The remaining five USTs were removed before 2005 and the site was razed. Site geology and hydrogeology include surficial deposits immediately underlying the site are described generally as sandy silts that grade upward to clayey silts and silty clays. Bedrock beneath the site is mapped as a strongly foliated biotite gneiss and schist. The maximum depth of investigation at the site has been approximately 55 feet below ground surface (bgs); bedrock has not been encountered during site investigation work. Historically, the range for shallow groundwater beneath the site is approximately 11 to 14 feet bgs, and groundwater flow direction is toward the southeast with an apparent horizontal gradient of approximately 0.012 feet per foot (ft/ft). The calculated groundwater seepage velocity for shallow groundwater beneath the site is approximately 2.8 feet per year. Two activated sodium persulfate injections were performed at the Site on June 4 — 9, 2012 and June 3 — 6, 2013 under Underground Injection Control (UIC) Permit #W10400198 which was issued by the NCDEQ Division of Water Quality on August 9, 2011. Approximately 11,237-gallons of sodium persulfate and 6,826-gallons of sodium persulfate were injected at the Site on June 4 — 9, 2012 and June 3 — 6, 2013, respectively. The NCDEQ Risk Classification for this site was reduced to "Low' on January 23, 2015 after issuing a request for Notice of Residual Petroleum (NORP). The NORP was recorded with the Forsyth County Register of Deeds on March 18, 2015 and imposed the following perpetual restriction on the Site property: • Groundwater: Groundwater from the site is prohibited from use as a water supply. Water supply wells of any kind shall not be installed or operated on the site. No Further Action (NFA) status was granted for the subject incident number by the NCDEQ on April 28, 2015. In accordance with UIC Permit #WI0400198, dissolved -phase concentrations of sulfate are being monitored on a semi-annual basis at the Site. Closure of UIC Permit #W10400198 will be requested once arcadis.com 2"d Semi -Annual Monitoring Report - 2020 dissolved -phase sulfate concentrations are no longer detected above the North Carolina Groundwater Quality (2L) Standards. 2.0 GROUNDWATER MONITORING 2.1 Groundwater Gauging On September 1, 2020, Arcadis G&M of North Carolina, Inc. (Arcadis) personnel gauged groundwater monitoring wells MW-8R and MW-6. Groundwater monitoring well MWA 9 was paved over and presumed destroyed when Arcadis arrived on site. Arcadis contacted NCDEQ and got approval to sample MW-6 in lieu of MW-19. Gauging was conducted with a water interface probe (IP) prior to purging and sampling to determine DTB and DTW. The IP and attached tape, marked in 0.01-foot increments, were properly decontaminated before each use with Alconox soap and rinsed with distilled water. The DTW was measured from the marked survey point on the top of well casing (TOC). All measurements were recorded to the nearest 0.01-foot increment. The DTW ranged from 12.72 btoc in groundwater monitoring well MW-8R to 11.80 feet btoc in groundwater monitoring well MW-6. Groundwater monitoring well construction details are included in Table 1. Current groundwater elevations are summarized in Table 2. Historical groundwater gauging data is provided in Appendix A. A potentiometric surface map depicting historical groundwater flow direction is provided as Figure 3. 2.2 Groundwater Sampling On September 1, 2020, groundwater monitoring wells MW-8R and MW-6 were purged of stagnant water to prepare for groundwater sampling. Prior to purging, the amount of water to be removed was calculated using the following formula: 3.1415 x r2 x (TD-DTW) x 7.481 = gallons of water (1 well volume) Where: r = radius of well (in feet) TD = total depth of well (in feet) DTW = depth to water (in feet) In order to ensure that the water in the wells after purging is representative of the water in the aquifer, a minimum of three well volumes were removed. Groundwater samples obtained from the groundwater monitoring well were collected from disposable polyethylene bailers using new nylon rope. Groundwater samples were placed in laboratory supplied containers and shipped on wet ice to TestAmerica Inc. in Pensacola, Florida, for analysis of Sulfate (SO4) by Standard Method 9056A. Groundwater samples submitted for sulfate analysis were collected in 250-milliliter plastic bottles. arcadis com 6 2"d Semi -Annual Monitoring Report - 2020 The laboratory analytical report and chain -of -custody record for the September 1, 2020 groundwater sampling event is included as Appendix B. 2.3 Groundwater Analytical Kesults Groundwater analytical data from the September 1, 2020 groundwater sampling event indicated the following: • Dissolved -phase concentrations of sulfate were detected in concentrations exceeding the applicable North Carolina 2L Standard of 250 milligrams per liter (mg/L) in groundwater monitoring well MW-8R (442 mg/L). Current groundwater analytical results are presented in Table 3. Historical groundwater analytical data can be found in Appendix C. A dissolved phase concentration map is presented as Figure 4. A sulfate isoconcentration map depicting the dissolved -phase extent of sulfate exceeding the applicable 2L groundwater quality standard is presented in Figure 5. 3.0 SITE REMEDIATION 3.1 Remediation Activities to Date Summarized in the table below is a chronology of remediation activities performed at the site to date: Date September 14, 1983 Activity Subsurface release of gasoline from a ruptured product line associated with the UST system December 1990 UST systems associated with release removed; 500 tons of contaminated soil removed during UST closure 1992 Vacuum Extraction System Installed 1992 - 1994 Vacuum Extraction System Operation 1994 - 2011 Monitoring of site June 4 — 9, 2012 Activated Sodium Persulfate (ASP) injection event. Approximately 11,237-gallons of sodium persulfate injected. June 3 — 6, 2013 ASP injection event. Approximately 6,826-gallons of sodium persulfate injected. 2013 - Present Monitored Natural Attenuation arcadis com 2nd Semi -Annual Monitoring Report - 2020 4.0 CONCLUSIONS & RECOMMENDATIONS Dissolved -phase sulfate was detected above the applicable 2L groundwater quality standard for sulfate of 250 mg/L in only groundwater monitoring well MW-8R on September 1, 2020. Arcadis recommends continuing the semi-annual groundwater monitoring and sampling program at the Site to document the natural attenuation of sulfate. The next semi-annual groundwater monitoring and sampling event is scheduled for March 2021. Groundwater monitoring wells MW- 8R and MW-6 will be gauged to evaluate the potentiometric surface at the Site. Groundwater samples will be collected from MW-8R and MW-6 for analysis of sulfate by Standard Method 9056A. A Semi -Annual Groundwater Monitoring Report documenting the proposed activities for 2021 will be submitted to the NCDEQ for review and approval within 45-days of receipt of the laboratory analytical report. arcadis com Tables ff /Jr f F l Table 1 Monitoring Well Construction Data Former BP Service Station No. 24163 381 Knollwood Street Winston-Salem, Forsyth County, North Carolina �RCJ-�DIS ' fornatun3lend uuiltazsets MW-3 In Use Type II 99.03 20 2 NA - NA NA MW-5 Abandoned Type II 99.39 25.5 4 10.5 - 25.5 81.4 MW-5R In Use Type II NS 20 2 10 - 20 NA MW-6 In Use Type II 98.68 25.5 4 10.5 - 25.5 80.7 MW-6i In Use Type III 99.26 55 2 50 - 55 46.8 MW-8 Abandoned Type II 97.84 24 6 NA - NA NA MW-8R In Use Type II NS 20 2 10 - 20 NA MW-14 In Use Type II 100.44 22 4 7 - 22 85.9 MW-15 In Use Type II 99.91 22 4 7 - 22 85.4 MW-16 In Use Type II 97.42 25 2 10 - 25 79.9 MW-17 In Use Type II 100.00 22 4 7 - 22 85.5 MW-18 In Use Type II NS 20 2 10 - 20 NA MW-19 Destroyed (6) Type II NS 20 2 10 - 20 NA Notes: 1. Reported in feet below grade 2. Measured in feet relative to site datum 3. Conestoga Rover and Associates, a former consultant for this Site, previously reported that no reference was found to the following wells: MW-1, MW-9, MWA0, MWA 1, MWA2 or MW-13. These wells are presumed to be abandoned. 4. Monitoring wells MW-5 and MW-8 were abandoned on 5/19/2010 and replaced with monitoring wells MW-5R and MW-8R the same day. 5. Monitoring wells MW-18 and MW-19 were installated on October 25, 2011. 6. Monitoring well MWA 9 was paved over and presumed destroyed on 312512020. NA = Not Applicable / Available NS = Not Surveyed TOC = Top of Casing Page 1 of 1 Table 2 Groundwater Elevation Data Former BP Service Station No. 24163 381 Knollwood Street Winston-Salem, Forsyth County, North Carolina P ARCADIS f MW-8R 9/1/2020 # NS ND 12.72 0.00 NM MW-6 9/1/2020 98.68 ND 11.80 0.00 86.88 MW-19 9/1/2020 Paved Over - Destroyed Notes: 1. Measured in feet relative to site datum 2. Corr. GW Elev. _ (ref. point elevation) - (depth to groundwater) + (LNAPL thickness)(LNAPL specific gravity) 3. LNAPL specific gravity assumed to be 0.73 LNAPL = Light non -aqueous phase liquid ND = Not Detected NM = Not Measured NS = Not Surveyed TOC = Top of casing btoc = below top of casing Page 1 of 1 Table 3 Summary of Groundwater Analytical Data Former BP Service Station No. 24163 381 Knollwood Street Winston-Salem, Forsyth County, NC 04ARCADIS � t�t�� Date Sampled 9/1/2020 9/1/2020 Units mg/L mg/L Sulfate 442 38.6 Notes: mg/L - milligrams per liter BOLD text indicates exceendance of NC groundwater standard 2L for sulfate (250 mg/L). Page 1 of 1 FIGURES rk r q A-1 L6.D1NGTqP 17 3k z ri fhow 3; d -Y 8 Q Z! (C GT E REST DR `1 FOREST I F CAROLINA CI DS DR N rEORGIAAVE,' f -CO -1V?*y USX, r W .6 JR1 g; NG;HA C 1:7 X QA D r SITE LOCATION, AVE # WESTOVERAN M. - o >o-, 1�;JAG 1�kWOODAVES :_7MAPLEW�&�AVE M., DHUR AVE s HAWTHORNE-RD' t S r WALKER AVE Lu WES 'SON A y -REALLY DR t J RD EROKLC M, 29 REFERENCE: BASE MAP USGS 7.5. MIN. TOPO. QUAD., VANSTOWSALEM WEST, NC, 2016. 1 0 2000' 4000' ATLANTIC RICHFIELD COMPANY C/O BP PRODUCTS NORTH AMERICA, INC. z Approximate Scale: 1 in. 2000 ft. FORMER BP STATION 24163 bA 381 KNOLLWOOD ST., WINSTON-SALEM, NORTH CAROLINA 0 =� j a: 2nd SEMI-ANNUAL MONITORING REPORT-2020 Q. E A A S AREA 05. w LOCATION SITE LOCATION MAP + FIGURE ARCADIS bdtasmb fornsuffd1 ow NORTH CAROLINA 1 W W OC 0 0 J z LEGEND: ig — - — PROPERTY LINE U.P. U.P.• I ABANDONED GROUNDWATER MONITORING WELL U.P. ONCRE -- DESTROYED -PAVED OVER GRASS E CTRIC M TER FORMER PRODUCT LINE PARKING i I OC.B. CATCH BASIN Mi -17 O M.H. MANHOLE ` 18K AREA LIGHT a U.P. UTILITY POLE ' ' _& F.H. FIRE HYDRANT ASPHALT TRASH �' ❑ TELEPHONE PARKING ENCLOSURE , F ii LARGE MANHOLE COVER METAL N GROUNDWATER MONITORING WELL SHED F — — — — — — I METAL SHED FORMERFORMER LINE UST AREA I ----- BP SERVICE STATION MW-18 CONCRETE TT PAD 40, G0. 0 MW-5R FMWT-�+, � OQ F.H. I W_8 FORMER POF- ISLAND (N 1 FORMER MW-61 I CANOPY MW 8R PARKING _ IMW-19— J FORMER [� I, I jC{'��j gESEL UST — I , AREA MW-6 I 1. - - FORMER PUMP ISLAND (TYP) 1 FOF IER TAN 4OLD 0 0 0 0 0 0 0 0 FORMER C= VENT RISERS NOTE: 1. MONITORING WELL LOCATIONS ARE APPROXIMATE. 2. THE SITE IS A VACANT PARKING LOT. ALL SITE FEATURES EXCEPT PARKING LOT CURBS AND ROADWAYS REPRESENT FORMER SITE CHARACTERISTICS. 1 I) I ( CONCRETE' r FORMER T �f 0 30' 60' CANOPY — r GRAPHIC SCALE f ATI AMTI(` RI(`u GIFI I'1 f'r%hAPANIV OG� �� MER W-1 FVEENTIRISERS W W O O J O Z O m U.P. U.P. U.P. GRASS - t I KlL t ARKING M R MW-17 ASPHALT TRASH PARKING ENCLOSURE METAL , SHED r — — — — — — I METAL SHED FORMERFORMER UST AREA LINE I BP SERVICE STATION MW- CONCRETE YYY PAD MW-5 MW-8R I MW-6 (86.88) 1 i O O m O M.H. MW-5R FORMER PUMP ISLAND (TYP) I 11 _ J FORMER MW-19 DIESEL UST p _ _ AREA I_ J� FOF AER TAN AOLD O O O O O O o 0 FORMER VENT RISERS gop -- FORMER CANOPY 0 4+ 0 PARKING FORMERPLIMP ISLAND (TYP) CONCRETE FORMER CANOPY _ I I FORMER VENT RISERS LEGEND: — - — PROPERTY LINE ABANDONED GROUNDWATER MONITORING WELL DESTROYED -PAVED OVER FORMER PRODUCT LINE CATCH BASIN O M.H. MAN HOLE &-o AREA LIGHT ■ U.P. UTILITY POLE �} F'H' FIRE HYDRANT ❑T TELEPHONE LARGE MANHOLE COVER GROUNDWATER MONITORING WELL (86.88) GROUNDWATER ELEVATION (NSVD) NOT SURVEYED TO VERTICAL DATUM AMSORICAL DEPICTED GROUNDWATER FLOW (FT IN DIREFT AMSL FEET ABOVE MEAN SEA LEVEL NOTE: 1. MONITORING WELL LOCATIONS ARE APPROXIMATE. 2. THE SITE IS A VACANT PARKING LOT. ALL SITE FEATURES EXCEPT PARKING LOT CURBS AND ROADWAYS REPRESENT FORMER SITE CHARACTERISTICS. 3. MW -19 WAS UNABLE TO LOCATE, HENCE NOT GAUGED. 0 30' 60' GRAPHIC SCALE C/O BP PRODUCTS NORTH AMERICA, INC. FORMER BP STATION 24163 381 KNOLLWOOD ST., WINSTON-SALEM, NORTH CAROLINA 2nd SEMI-ANNUAL MONITORING REPORT - 2020 POTENTIOMETRIC SURFACE MAP SEPTEMBER 01, 2020 FIGURE ARCADIS I 1.1-ei-m 3 fia O_m m a m m ogi`dp aFo oho SOU O y 0 co �mm�i_ LU pQIV �g$ $c �aa m mo �Sga Y'0 O c�fmq (ZU� w W r U) 0 0 J 0 Z MW-8R Date 1 8/20/2018 3/15/2019 1 10/8/2019 1 3/25/2020 1 9/1/2020 Sulfate 436 60 1 475 1 450 1442 MW-6 Date 1 3/25/2020 9/1/2020 Sulfate 1 25.2 38.6 U.P. U.P. GRASS F.H!j 1-6i U.P. PARKING Mi-17I ASPHALT TRASH PARKING ENCLOSURE , METAL SHED O r — — — — — — ! METAL SHED FORMERFORMER UST AREA LINE BP SERVICE ' STATION '----- MW-18 CONCRETE TTT PAD 40, O`0 MW-5R MW-14 MW-5 f �3MW-8FORMERISLAND 1 , O MW-8R FORMER I PARKING JW� W-19MW-6 _ FORMER DIESEL UST I , FORMER PUMP =J l I ISLAND (TYP) CONCRETE —7 FO ER �S/ TAN iOLD 0 0 0 0 o FORMER 0 0 0 - CANOPY I FORMER VENT RISERS O M.H. FORMER VENT RISERS LEGEND: — — — PROPERTY LINE } ABANDONED GROUNDWATER MONITORING WELL DESTROYED -PAVED OVER FORMER PRODUCT LINE Q C.B. CATCH BASIN O M"H' MAN HOLE 0-0 AREA LIGHT 0 U.P. UTILITY POLE -b F.H. FIRE HYDRANT ❑ TELEPHONE El LARGE MANHOLE COVER GROUNDWATER MONITORING WELL mg/L MILLIGRAMS PER LITER NS NOT SAMPLED LEGEND Abbreviation I Constituent 2 L SO4 I Sulfate I 250 NOTE: 1. THE NORTH CAROLINA 2L STANDARD FOR SULFATE IS 250 mg/L 2. VALUES IN BOLD EXCEED NORTH CAROLINA 2L STANDARDS. MW-19 Date 1 8/20/2018 3/15/2019 10/8/2019 3/25/2020 9/1/2020 Sulfate 1 806 1,150 783 NS I NS 0 30' 60' GRAPHIC SCALE C/O BP PRODUCTS NORTH AMERICA, INC. FORMER BP STATION 24163 381 KNOLLWOOD ST., WINSTON-SALEM, NORTH CAROLINA 2nd SEMI-ANNUAL MONITORING REPORT - 2020 GROUNDWATER ANALYTICAL DATA AUGUST 2018 - SEPTEMBER 2020 FIGURE + ARCADIS I � `" � 4 CI m U.P. GRASS e- U.P. PARKING MW-17 ASPHALT TRASH PARKING ENCLOSURE METAL , SHED r — — — — — — METAL SHED FORMER GASOLINE I FORMER UST AREA I BP SERVICE STATION MW-1 S T CONCRETE PAD �I F� MW-5R BMW-5 ` FORMER PUMP ISLAND (TYP) MWB {44Zi ( FoRp MW-19 NESELoar MW-6 AREA (38.6) 1 • FORMER CANOPY II FOF AER TAN 4OLD 0 0 0 0 O O O O J'a FORMER C= VENT RISERS RN t-- FORMER PUMP ISLAND (TYP) CONCRETE FORMER CANOPY I I_ FORMER VENT RISERS LEGEND: — PROPERTY LINE ABANDONED GROUNDWATER MONITORING WELL DESTROYED - PAVED OVER FORMER PRODUCT LINE C.B. CATCH BASIN O M.H. MAN HOLE 0-0 AREA LIGHT ■ U.P. UTILITY POLE F.H. FIRE HYDRANT ❑ TELEPHONE Fl LARGE MANHOLE COVER GROUNDWATER MONITORING WELL (442) SULFATE CONCENTRATION (mg/L) -2er ESTIMATED SULFATE CONCENTRATION CONTOUR 2L STANDARD (mg/L) (mg/L) MILLIGRAMS PER LITER NOTE: 1. THE NORTH CAROLINA 2L STANDARD FOR SULFATE IS 250 mg/L 2. SHADED VALUES EXCEED NORTH CAROLINA 2L STANDARDS. 0 30, 60' GRAPHIC SCALE APPENDIX ►4 Historical Groundwater Elevation Data Appendix A Historical Groundwater Elevation Data /aRGaDIS� Former EIP Service Station No. 24163 381 Knollwood Street Winston-Salem, Forsyth County, North Carolina ` 06/24/93 NO 1389 0 00 85.14 " 08/23/94 NO 14.36 0.00 84.67 • 03/21/95 ND 13.58 0.00 85.45 • 08/06/96 ND 13.54 0.00 85.49 ` 11/17/98 ND 14.09 0.00 84.94 ` =19/01 ND 14.11 0.00 84.92 " 09/12/01 ND 14.41 0.00 84.62 • 12/27/01 ND 14.51 0.00 84.52 • 03/05/02 ND 14.29 0.00 84.74 05/13/03 ND 14.35 0.00 84.68 12/09/03 ND 13.63 0.00 85.40 03/23/06 ND 13.64 0.00 85.39 05/08/07 ND 13.40 0.00 85.63 05/14/08 ND 13.42 0.00 85.61 05/28/09 ND 13.31 0.00 85.72 06/27/10 ND 13.07 0.00 85.96 10/31/11 ND 13.87 0.00 85.16 MW-3 05/22/12 99.03 ND 13.55 0.00 85.48 06/14/12 ND 13.53 0.00 85.50 07/09/12 ND 13.98 0.00 85.05 08/14/12 ND 14.24 0.00 84.79 09/19/12 ND 14.08 0.00 84.95 12/05/12 ND 14.42 0.00 84.61 02/26/13 NO 13.55 0.00 85.48 06/31/13 NU 13.58 0.00 85.45 08/28/13 NO 13.57 0.00 85.46 11/07/13 NO 14.30 0.00 84.73 02/27/14 NO 13.28 0.00 85.75 06/02/14 NO 13.34 0.00 85.69 10/16/14 NO 14.18 0.00 84.86 04/23/15 NO 13.54 0.00 85.49 04/28/16 NO 13.51 0.00 85.52 09/19/16 NO 13.92 0.00 85.11 03/03/17 NO NM 0.00 NM 06/24/93 NO 13.51 0.00 85.88 08/23/94 ND 13.82 0.00 85.57 03/21/95 ND 13.71 0.00 86.68 08/05/96 ND 13.54 0.00 85.85 11/17/98 ND 14.08 0.00 85.31 06/19/01 NM NM NM NM 09/12/01 ND 14.46 0.00 84.93 MW-5 12/27/01 99.39 14.51 15.07 0.56 84.73 03/05/02 14.45 14.88 0.43 84.82 05/12/03 NM NM NM NM 12/09/03 13.18 13.60 0.42 86.10 03/23/06 NO 13.67 0.00 85.72 05/08/07 NO 13.45 0.00 85.94 05/14/08 NO 13.51 0.00 85.88 05/28/09 NO 13.39 0.00 86.00 Page 1 of 5 Appendix A �^ _ Historical Groundwater Elevation Data �" ARCADIS SEE. Former BP Service Station No. 24163 381 Knollwood Street Winston-Salem, Forsyth County, North Carolina 10131111 ND 13.97 0.00 NM 05/22/12 ND 13.66 0.00 NM 06/14/12 ND 13.73 0.00 NM 07/09/12 ND 14.18 0.00 NM 08/14/12 ND 14.45 0.00 NM 09/19/12 ND 14.35 0.00 NM 12/05/12 ND 14.68 0.00 NM 02/26/13 ND 13.89 0.00 NM 05/31/13 ND 13.77 0.00 NM 08/28/13 ND 13.83 0.00 NM MW-5R 11/07/13 NS ND 14.53 0.00 NM 02/27/14 ND 13.39 0.00 NM 06/02/14 ND 13.47 0.00 NM 10/16/14 ND 14.32 0.00 NM 04/23/15 ND 13.69 0.00 NM 10/13/15 ND 14.19 0.00 NM 04/28/16 ND 13.61 0.00 NM 09/19/16 ND 13.99 0.00 NM 03/03/17 ND 14.01 0.00 NM 09/20/17 ND 13.67 1.00 NM 03/01/18 ND 13.62 0.00 NM 08/20/18 ND 13.61 0.00 NM ' 06/24/93 ND 12.31 0.00 86.37 ` 08/23/94 ND 12.61 0.00 86.07 " 03/21/95 ND 13.15 0.00 85.53 " 08/05/96 ND 12.39 0.00 86.29 ' 11/17/98 ND 13.16 0.00 85.52 ' 06/19/01 NM NM NM NM ` 09/12/01 ND 13.51 0.00 85.17 " 12/27/01 ND 13.61 0.00 85.07 " 03/05/02 ND 11.02 0.00 87.66 05/12/03 ND 11.10 0.00 87.58 MW_6 12/09/03 98.68 ND 13.49 0.00 85.19 03/23/06 ND 11.79 0.00 86.89 05/08/07 ND 12.50 0.00 86.18 05/14/08 ND 12.16 0.00 86.52 05/28/09 ND 10.64 0.00 88.04 05/27/10 ND 11.84 0.00 85.84 10/31/11 ND 12.95 0.00 85.73 06/02/14 ND 12.38 0.00 86.30 03/25/20 ND 11.50 0.00 87.18 09/01/20 ND 11.80 0.00 86.88 06/24/93 ND NM 0.00 NM 08/23/94 ND NM 0.00 NM 03/21/95 ND 14.75 0.00 84.51 08/05/96 ND 14.13 0.00 85.13 11/17/98 ND 14.09 0.00 85.17 06/19/01 ND 18.07 0.00 81.19 09/12/01 ND 16.60 0.00 82.66 12/27/01 ND 14.61 0.00 84.65 03/05/02 ND 14.96 0.00 84.30 MW-6i 05/12/03 99.26 ND 15.17 0.00 84.09 12/09/03 ND 13.55 0.00 85.71 03/23/06 ND 13.55 0.00 85.71 05/08/07 ND 12.93 0.00 86.33 05/14/08 ND 13.22 0.00 86.04 05/28/09 ND 13.39 0.00 85.87 05/27/10 ND 13.23 0.00 86.03 10/31/11 ND 13.90 0.00 85.36 06/02/14 ND 13.35 0.00 85.91 04/28/16 ND 13.55 0.00 85.71 Page 2 of 5 Appendix A Historical Groundwater Elevation Data ARC4DIS Former BP Service Station No. 24163 381 Knoliwood Street Winston-Salem, Forsyth County, North Carolina ' DB23*4 ND 12.14 000 6570 • 03/21/95 ND 12.02 0.00 85.82 • 08/05/96 ND 11.99 0.00 85.85 ' 11/17/98 ND 12.53 0.00 85.31 06/19/01 NM NM NM NM ' 09/12/01 ND 12.67 0.00 85.17 12/27/01 14.47 15.03 0.56 83.26 MW-8 • 03/05/02 9784 12.42 12.60 0.18 85.38 05/12/03 NM NM NM NM 12/09/03 13.32 13.56 0.24 84.47 03/23/06 ND 12,15 0.00 85.69 05/08/07 ND 11.90 0.00 85.94 05/14/08 ND 11.95 0.00 85.89 05r28/09 ND 11.70 0.00 86.14 05/27/10 ND 12.97 0.00 NM 10/31/11 ND 13.34 0.00 NM 05/22/12 ND f 13.69 0.00 NM 06/14/12 ND 14.94 0.00 NM 07/09/12 ND 14.08 0.00 NM 08/14/12 ND 14.29 0.00 NM 09/19/12 ND 14.08 0.00 NM 12/05/12 ND 14.53 0.00 NM 02P26/13 ND 13.80 0.00 NM 05/31/13 ND 13.61 0.00 NM OB/28/13 ND 13.74 0.00 NM 11/07/13 ND 14.42 0.00 NM 02/27/14 ND 13.33 0.00 NM MW-8R 06/02/14 NS ND 13.34 0.00 NM 10/16/14 ND 14.18 0.00 NM 04/23/15 ND 13.57 0.00 NM 10/13/15 ND 14.08 0.00 NM 04/28/16 ND 13.53 0.00 NM 09/19/16 ND 13.91 0.00 NM 03/03/17 ND 13.92 0.00 NM 09/20/17 ND 13.61 0.00 NM 03/01/18 ND 13.63 0.00 NM 08/20/18 ND 13.52 0.00 NM 03/15/19 ND 13.35 0.00 NM 10/08/19 ND 13.54 0.00 NM 03/25/20 ND 12.59 0.00 NM 09/01/20 ND 12.72 0.00 NM 06/24/93 NM NM NM NM 08/23/94 NM NM NM NM 03/21/95 ND 13.55 0.00 86.89 08/05/95 ND 13.64 0.00 86.80 11 /17/98 N D 14.26 0.00 86.18 06/19/01 ND 14.55 0.00 85.89 09/12/01 ND 14.81 0.00 85.63 12/27/01 ND 14.85 0.00 85.59 03/05/02 ND 14.64 0.00 85.80 MW-14 05/12/03 100.44 ND 13.41 0.00 87.03 12/09/03 ND 13.51 0.00 86.93 03/23/06 ND 13.82 0.00 86.62 05/08/07 ND 13.54 0.00 86.90 05/14/08 ND 13.64 0.00 86.80 06/28/09 ND 13.47 0.00 86.97 05/27/10 ND 13.00 0.00 87.44 10/13/11 ND 14.14 0.00 86.30 06/02/14 ND 13.42 0.00 87.02 04/28/16 ND 13.65 0.00 86.79 Page 3 of 5 Appendix A �n Historical Groundwater Elevation Data /aRCI�DIS Former BP Service Station No 24163 381 Knollwood Street Winston-Salem, Forsyth County, North Carolina 06/24/93 NM NM NM NM 08/23/94 NM NM NM NM 03/21/95 NO 12.83 0.00 87.08 08/05/96 ND 12.77 0.00 87.14 11/17/98 ND 13.58 0.00 86.33 06/19/01 ND 13.80 0.00 86.11 09/12/01 NO 14.18 0.00 85.73 12/27/01 ND 14.29 0.00 85.62 03/05/02 ND 13.98 0.00 85.93 05/12/03 NM 12.75 NM 87.16 MW-15 12/09/03 99.91 ND 12.89 0.00 87.02 03/23/06 NO 13.14 0.00 86.77 06/08/07 NO 12.90 0.00 87.U1 05/14/08 NO 13.12 0.00 86.79 05/28/09 NO 12.90 0.00 87.01 05/27/10 NO 12.25 0.00 87.66 10/31/11 NO 13.61 0.00 86.30 06/02/14 NO 12.82 0.00 87.09 10/16/14 NO 13.91 0.00 86.00 04/28/16 NO 13.15 0.00 86.76 06/24/93 NM NM NM NM 08/23/94 NM NM NM NM 03/21/95 NO 12.06 0.00 85.36 08/05/96 NO 12.09 0.00 85.33 11/17/98 NO 12.60 0.00 84.82 06/19/01 NO 12.74 0.00 84.58 09/12/01 ND 12.98 0.00 84.44 12/27/01 NM NM NM NM 03/05/02 ND 12.83 0.00 84.59 MW-16 05/12/03 97.42 NM NM NM NM 12/09/03 NO 12.13 0.00 85.29 03/23/06 NO 12.18 0.00 85.24 05/08/07 NM NM NM NM 05/14/08 NO 12A3 0.00 85.39 05/28/09 NO 11.96 0.00 85.46 05/27/10 ND 11.69 0.00 85.73 10/31/11 ND 12.45 0.00 84.97 11 /07113 N D 12.68 0.00 84.54 06/02114 ND 11.97 0.00 85.45 06/24/93 NM NM NM NM 08/23194 NM NM NM NM 03/21/95 ND 14.42 0.00 85.58 08/05/96 NO 14.46 0.00 85.54 11/17/98 ND 14.91 0.00 85.09 06/19/01 ND 15.03 0.00 84.97 09/12/01 ND 15.28 0.00 84.72 12/27/01 NO 15.37 0.00 84.63 03/05/02 ND 15.15 0.00 84.85 05/12/03 NM 14.15 NM 85.85 MW-17 10000 12/09/03 NO 14.50 0.00 85.50 03/23/06 ND 14.45 0.00 86.55 05/08/07 ND 14.22 0.00 85.78 05/14/08 ND 14.22 0.00 85.78 05/28/00 NO 14.12 0.00 85.88 05/27/10 ND 13.90 0.00 86.10 10/31/11 ND 14.72 0.00 85.28 06/02/14 ND 14.14 0.00 85.86 04/28/16 ND 14.36 1 0.00 85.64 Page 4 of 5 Appendix A III+►► Historical Groundwater Elevation Data /aRCI�DIS Former BP Service Station No. 24163 381 Knollwood Street Winston-Salem, Forsyth County, North Carolina 10/31/11 NO 1396 0.00 NM 0522/12 NO 14.10 0.00 NM 06/14/12 NO 13.61 0.00 NM 07/09/12 NO 14.05 0.00 NM 08/14/12 NO 14.43 0.00 NM 09/19/12 NO 14.34 0.00 NM 12/05/12 NO 14.62 0.00 NM 0226/13 NO 14.67 0.00 NM 05/31/13 NO 14.57 0.00 NM 0828/13 NO 14.33 0.00 NM 11/07/13 NO 14.51 0.00 NM MW-18 NS 0227114 NO 13.76 0-00 NM 06/02/14 NO 13.55 0.00 NM 10/16/14 NO 14.37 0.00 NM 0423115 NO 13.84 0.00 NM 10/13/15 NO 14.81 0.00 NM 0428/16 NO 13.62 0.00 NM 09/19/16 NO 14.04 0.00 NM 03/03/17 NO 14.08 0.00 NM 0920/17 NO 13.21 0.00 NM 03/01/18 NO 13.60 0.00 NM 0820/18 NO 13,42 0.00 NM 10/31/11 NO 13.75 0.00 NM 0522/12 NO 13.37 0.00 NM 06/14/12 NO 13.39 0.00 NM 07/09/12 NO 13.89 0.00 NM 08/14/12 NO 14.13 0.00 NM 09/19/12 NO 14.02 0.00 NM 12/05/12 NO 14.39 0.00 NM 0226/13 NO 13.62 0.00 NM 05/31/13 NO 13.47 0.00 NM 0828/13 NO 13.56 0.00 NM 11/07/13 NO 14.25 0.00 NM 0227/14 NO 13.17 0.00 NM MW-19 06/02/14 NS NO 13.14 0.00 NM 10/16/14 NO 14.03 0.00 NM 0423/15 NO 13.46 0.00 NM 10/13/15 NO 14.01 0.00 NM 0428/16 NO 13.38 0.00 NM 09/19/16 NO 13.75 0.00 NM 03/03/17 NO 13.79 0.00 NM 0920117 NO 13.48 0.00 NM 03/01/18 NO 13.42 0.00 NM 08/20/18 NO 13.38 0.00 NM 03/15/19 NO 12.22 0.00 NM 10/08/19 NO 13.27 0.00 NM 032520 Paved Over - Destroyed (4) Notes: 1. Measured in feet relative to site datum 2. Corr. GW Elev. = (ref. paint elevation) - (depth to groundwater) + (LNAPL thickness)(LNAPL specific gravity) 3. LNAPL specific gravity assumed to be 0.73 4. MW-19 was paved over and presumed destroyed on 3125/2020. - Prior to URS' work at this Site, monitoring well MW-3 has previously been reported as MW-2, monitoring well MW- 6 has previously been reported as MW-B, and monitoring well MW-8 has previously been reported as MW-6. LNAPL = Light non -aqueous phase liquid NO = Not detected NM = Not measured NS = Not Surveyed TOO = Top of casing btoc = below tap of casing - During the May 2003 sampling event LNAPL was observed in MW-5. Depth to groundwater and thickness of LNAPL were not measured. Page 5 of 5 ►APPENDIX B Laboratory Analytical Report and Chain -of -Custody Record -- September 1, 2020 r i if r APPENDIX D Historical Groundwater Analytical Data Appendix C Historical Groundwater Analytical Summary Former BP Service Station No. 24163 381 Knollwood Street Winston-Salem, Forsyth County, North Carolina 00 ARMDIS NC GCL: NC 2L Units:. 5,000 1 p9A 84,500 600 pgA 260,000 600 po 85,500 500 H n 20,000 20 1 1 NE 260 m /l NE NE MgA 5/13/2003 8.5 0.98 J f 0.61 J 1.7 J 8 -- - 12/9/2003 47.4 14.3 1.9 8.1 37.3 - - 3/23/2006 4.5 J < 0.5 < 0.5 UJ < 1 UJ 5.5 - 5/8/2007 40.4 3.7 1.4 2 J 13.1 - 5/14/2008 4.3 J < 0.8 < 0.7 < 0.8 14 -- - 5/28/2009 5.4 0.44 J 0.14 J 0.49 J 5.6 - 5/27/2010 0.44 J < 0.11 0.3 J < 0.32 4.8 - - 10/31/2011 5.5 0.76 < 0.17 U 0.38 J 19.1 8.4 405 5/22/2012 < 0.43 U < 0.2 < 0.2 < 0.52 4.6 15.3 378 6/14/2012 12.1 6.7 0.72 4.7 15.4 6.6 J 344 7/9/2012 2.2 1.6 2.6 3 14.7 9.9 393 MW-3 8/14/2012 2 2.1 <0.13 0.4J 17.9 3.6 303 9/19/2012 2.7 0.66 < 0.13 0.33 J 19.8 2.8 459 12/5/2012 11.3 1.2 0.43 J 1.1 J 19.3 0.78 J 377 2/26/2013 0.23 J < 0.1 < 0.1 < 0.22 5.4 32.6 338 5/31/2013 0.32 J < 0.1 < 0.1 < 0.22 10.5 17.9 334 8/28/2013 3.6 0.53 0.12 J 0.31 J 10.3 21.9 457 11/1/2013 4.3 0.27 J 0.13 J < 0.22 10 21.7 536 2/27/2014 < 0.1 < 0.1 < 0.1 < 0.2 1.3 42.2 198 6/3/2014 0.48 J 0.15 J < 0.1 < 0.2 3.1 - - 10116/2014 - - - - 18.0 372 4/23/2015 - - - - 22.8 296 9/19/2016 - - - 21.3 - 3/23/2006 2,440 32,000 13,500 16,100 - - 3/23/2006 11 7 2,370 30,700 13,200 16,400 - - 5/8/2007 i a t) 1,590 21,100 6,920 6,830 -- - 518/20071') 7 4^a 1,680 20,100 9,290 9,360 -- - MW-5 5/14/2008 2,100 29,000 12,000 18,000 -- - 5/14/2008 (1) i'.• ^_L'J 2,100 30,000 12.000 18,000 - - 528/2009 _ y j[ 2,330 25,700 13,400 6,920 -- - 512812009(1) 14 ! 2,240 22,100 12,900 6,510 - - 5/27/2010 6 10 j( 2.810 24,300 J 15,700 4,330 - 5/2712010(1) L u'�9 2,380 30,100 J 13,300 4,250 - - 10/31/2011 T. V,:J,,,,g 2,660 28,000 13.800 3,830 <1 <5 10131/2011 (1)M 2,870 24,600 14.800 4,070 - - 5/22/2012 3,470 32,200 19.200 3,820 < 5 179 6/15/2012 (2) 244 227 1.190 1,120 36.9 6,070 1,820 7/9/2012 I 336 J 481 J 2,010 J 2,400 J 48.4 J 6,470 2,620 MW-SR 8/14/2012 201 283 1,050 1,300 48.5 14,700 4,190 9/19/2012 158 181 650 883 114 19,000 3,280 12/5/2012 754 505 2,220 2,380 1,160 13,600 1,840 2/26/2013 1,360 878 3,520 3,940 1,660 8,520 1,530 5/31/2013 1,410 1,380 5,930 6,220 1,150J 4,680 1,560 8/28/2013 165 178 489 1,380 417 13,900 1,590 11/7/2013 214 131 331 969 651 14,400 1,570 2127/2014 142 177 328 1,060 240 2,990 807 61VA14 266 436 1040 2520 519J - - 10/16/2014 - - - - - 9,950 1,390 4/23/2015 - - - - 6,980 1,510 10/13/2015 - - - - - 6,790 - 4/28/2016 - - - - -- 2,980 - MW-5R 9/19/2016 - - - - 2,880 - 3/3/2017 - - - - -- 3,570 - MD/2017 -- - - - - 1,060 - 3/1/2018 - - - 163 - WO/2018 -- - - - -- 147 - Page 1 of 4 Appendix C Historical Groundwater Analytical Summary Former BP Service Station No. 24163 381 Knollwood Street Winston-Salem, Forsyth County, North Carolina 04ARCADIS; `r NC GCL:' NC 2L' Units:; 5,000 1 pSA 64,500 600 W 260.000 600 V911 85,500 500 jj9A f 20,000 '; 20 p9A NE 250 M911 NE NE I 5i12(2rX3 < 0.5 0.6; 1 < U.5 < 1 s - - 12/9/2003 j 2.3 0.64 J 1.1 3.6 17.6 - - 12/92003 ; 2.4 0.68 J 1.1 3.8 18 - - 3/23/2006 t 0.76 J 0.59 J 3.6 2.8 J 1.1 - - 5/8/2007 < 0.5 < 0.5 < 0.5 < 1 < 0.5 - - 5/14/2008 < 0.5 < 0.8 < 0.7 < 0.8 < 0.5 - - M W� 5/28/2009 < 0.05 < 0.05 < 0.06 < 0.14 0.17 J - - 5/27/2010 < 0.11 0.13 J 0.38 J 0.46 J < 0.12 - 10/31/2011 8.7 J 11.7 J 27.5 J 132 J <0.26 UJ 131 2,130 6WO14 17.6 J 50.4 J 31.6 J 99.4 J 783 J 3/25/2020 - - - - - 25.2 -- 9/1/2020 - - - - 38.6 - 5/12/2003 < 0.5 < 0.5 < 0.5 1.1 J < 0.5 - - 12/9/2003 < 2.5 < 2.5 < 2.5 < 5 < 2.5 - - 3/23/2006 49.7 18.9 4B.7 443 3,560 - - 5/8/2007 < 25 < 25 < 25 < 50 6,910 - - MW-61 5/14/2008 5.2J <2 <1.8 <2 3,400 - - 5/28/2009 2.5 < 0.05 < 0.06 < 0.14 1,150 - -- 527/2010 1.6 J < 1.1 < 1.1 < 3.2 492 - -- 10/31/2011 0.41 J < 0.36 < 0.32 < 0.75 122 < 1 76.1 612J2014 <0.1 <0.1 <0.1 <0.2 3.3 - - 3/23/2006 671 1,340 1,230 8,100 124 - - 5/8/2007 1,160 799 196 2,990 1,440 - - MW-8 5/14/2008 600 1,800 700 3,000 190 - - 5/28/2009 1,390 2,050 357 3,310 1,560 - 5/27/2010 FA IICI 2,870 31,700 15,700 6,260 - - 10/31/2011 8�Ok 3,180 32,100 17,200 3,170 < 1 < 5 5/22/2012 a VO 3,360 36,400 J 17,800 3,920 < 5 119 6/15/2012 (2) 726 47 J 760 242 J 96.3 J 4,760 22,200 7/9/2012 4,540 J 1,870 J 17,100 J 10,800 J 1,530 J 6,570 4,500 8/14/2612 4,370 1,610 19,300 8,780 2,000 7,010 1,560 9/19/2012 i 4,780 1,800 20.900 10,400 2,600 6,700 1,100 12/5/2012 W'7 1rp 2,440 31,900 13,800 4,560 2,410 635 2/26/2013 - 7.:7:, 2,480 30,500 13,400 4,530 959 590 5/31/2013 a °40 3,040 30.500 12,500 4,200 439 437 8/28/2013 1,600 628 5,390 3,990 1,380 4,770 703 11/7/2013 1,130 329 2,440 1,830 1,770 7,460 766 2/27/2014 1,020 603 3,200 3,430 1,190 7,670 940 6/2/2014 1 1,360 J 680 J 3,510 J 3,330 J 2.110 J - - MW-8R 6/2/2014 f11 1,540 556 J 3,660 2,630 J 2,640 J - 10/16/2014 3,310 883 9,070 4,990 3,910 3,560 842 4/23/2015 - - - - - 2,060 812 10/13/2015 - - -- - - 1,600 - 4/29/2016 - - - - - 1,64o - 9/19/2016 - - - - - 1,330 - 3/3/2017 - - - - - 1,720 - 9/20/2017 - - - - - 797 - 3/1/2018 - - - - 677 - 820/2018 - - - - 436 - 3/15/2019 - -- - - - 60 - 10/8/2019 - - - - - 476 - 325/2020 - -- -- - - 450 - 9/1/2020 -- - -- - - 442 - 5/12/2003 < 0.5 < 0.5 < 0.5 < 1 0.52 J - - 12/9/2003 < 0.5 < 0.5 < 0.5 < 1 5.9 - 323/2006 < 0.5 < 0.5 < 0.5 < 1 < 0.5 - 5/8/2007 < 0.5 < 0.5 < 0.5 < 1 < 0.5 - - MW-14 5/142008 <0.6 <0.8 <0.7 <0.8 <0.5 - - 528/2009 < 0.06 < 0.05 0.077 J < 0.14 < 0.06 - - 5272010 < 0.11 < 0.11 < 0.11 < 0.32 < 0.12 - - 10/31/2011 < 0.13 < 0.15 < 0.42 U < 0.3 < 0.13 43.2 < 5 6/3/2014 < 0.1 < 0.1 -0.1 < 0.2 -0.1 - -- Page 2 of 4 Appendix C �'^ ! Historical Groundwater Analytical Summary P* ARCADIS ! �_ Former BP Service Station No. 24163 381 Knollwood Street Winston-Salem, Forsyth County, North Carolina NC GCL:' NC 2L` Units: 5,000 1 84,500 600 260,000 600 85,500 500 A 20,000 20 n NE 250 m /I NE NE mail 5123 20 0 015 1.6 - - 5/8/2007 < 0.5 < 0.5 < 0.5 2.2 J < 0.5 - 5/14/2008 < 0.5 < 0.8 < 0.7 3.7 J I < 0.5 - -- MW-15 527/2010 <0.11 <0.11 <0.11 <0.32 i <0.12 - - 10/312011 <0.13 <0.16 <0.13 <0.3 <0.13 <1 <5 6/3/2014 < 0.1 < 0.1 < 0.1 < 0.2 < 0.1 - 10/16/2014 <0.1 <0.1 <0.1 <0.2 <0.1 - - 3232005 < 2.5 90.8 15.8 836 2.8 J - -- 5/142008 <0.5 160 15 1,600 4.1 J - -- 5272010 3.6 54.7 J 5.1 525 J 1.3 - - MW-16 10/31 /2011 < 0.65 17.2 < 1.4 U 321 < 0.65 194 < 5 11/72013 - - - - 55.4 < 5 6/3/2014 < 0.1 25 0.92 417 J < 0.1 - 5/132003 57.7 < 0.5 < 0.5 < 1 69 - - 5/13/2003 40.8 < 0.5 < 0.5 < 1 63.3 - - 12/92003 6.6 0.65 J < 0.5 < 1 80.6 - - 3/23/2006 1 < 0.5 < 0.5 < 1 58.9 - - 5/82007 < 0.5 < 0.5 < 0.5 < 1 17.4 - - MW 17 5/142008 3.7 J < 0.8 < 0.7 < 0.8 19 - - 5282009 7 < 0.05 0.076 J < 0.14 14.5 - - 5272010 5.7 < 0.11 < 0.11 < 0.32 12.4 - - 10/31 /2011 0.51 0.16 J < 0.81 U 0.57 J 8.9 < 1 422 6/32014 < 0.1 < 0.1 < 0.1 < 0.2 4.1 - - 10/31/2011 3,140 996 11,100 6,950 1,140 8.2 446 522/2012 2,280 2,790 18,200 12,000 789 < 5 307 6/15/2012121 373 910 4,800 3,910 114 10,600 3,410 7/92012 1,730 J 2,170 J 15,000 J 9,750 J 676 J 2,300 835 8/14/2012 3,020 2,990 24,400 12,800 1,090 768 580 9/19/2012 3,190 3,090 22,600 14,000 1,240 322 542 12/5/2012 3,370 2,970 20,100 12,800 1,380 32 436 2/26/2013 2,510 2,970 10,100 8,690 1,140 13.8 500 5/31/2013 2,780 3,070 8,210 5,740 1,000 83.3 475 8/28/2013 182 368 730 1,660 139 7,860 2,230 11/7/2013 1,140 727 4,910 3,250 694 2,640 1,370 MW-18 2/27/2014 16.6 109 20.2 45.8 18.5 4,310 1,270 6/22014 26.2 J 125 J 37.5 J 31.6 J 37.4 J - 10/16/2014 359 388 244 138 364 1,540 513 423/2015 - - - - 780 1,100 10/13/2015 - - - - 516 - 4292016 -- - - - -- 79.4 - 9/19/2016 - - - - - 377 - 3/3/2017 -- - - - -- 295 - 920/2017 - - - - - 257 - 3/12018 -- - - - - 253 - 820/2018 - - - - - 173 - Page 3 of 4 Appendix C Historical Groundwater Analytical Summary Former BP Service Station No. 24163 381 Knollwood Street Winston-Salem, Forsyth County, North Carolina A ARCADIS �.R NC GCL:5,000 84,500 26D,000 95,500 B 20.000 NE NE NC 2L 1 , 600 600 500 20 250 NE Units:- ligA Pgfi V9A 1 RgA uQA m /I m I I 1(ra1/2+011 2,3td3 I 1,3i?0 1 8jX 7,040 1 5,160 3.7 425 5/22/2012 ' 2,700 1,560 14,200 7,940 4,880 < 5 310 6/1512012 "1 4,020 1,440 18,200 7,940 3,290 1,090 6,520 7/9/2012 2,910 30.400 J 16,300 5,330 232 991 8/14/2012 2,420 1,650 14,200 8,370 4,090 469 1.080 9/19/2012 2,090 1,630 12,900 8,640 3,960 260 690 12/5/2012 2,320 1,B10 15,200 10,400 4,010 58.8 588 2/26/2013 2,210 1,110 10,600 6,990 3.890 169 503 5/31/2013 1,830 894 8,820 5,250 3,120 1,630 606 8/28/2013 2,710 J 1,190 J 13,100 7,420 J 3,240 J 2,660 525 11f7/2013 2,020 984 9,850 5,620 2,260 2,890 255 2/27/2014 2,550 1,400 10,900 7,880 3,320 2,790 322 MW-19 6/2/2014 2,370 1,260 11,900 7,260 2,830 - - 10/16/2014 - - - - - 2,340 632 4/23/2015 - - - - 2,640 514 10/13/2015 - - - - - 1,960 4/28/2016 - - - - - 1,780 - 9/19/2016 - - - - -- 1,270 - 3/3/2017 - - - - -- 941 - 9/20/2017 - - - - -- 1,020 -- 3/1/2018 - - - - - 746 8/20/2018 - - - - - 806 - 3/15/2019 - - - - - 1,160 10/8/2019 - - - - - 783 3/25/2020 Paved Over - Destroyed Notes: n1 Field duplicate iz) Alkalinity, sulfate, and carbon dioxide samples were collected 6/1412012 and volatile organic analysis samples were collected 6115112. -" - Not sampled or analyzed < - Not detected at the specked detection limit pg/l - Micrograms per Liter GCL - Gross Contamination Level 2L - North Carolina Groundwater Quality (2L) Standard J - Estimated value mg/I - Milligrams per Liter MTBE - Methyl tert-Butyl Ether NE - Not established U - Not present above the associated level; blank contamination exists UJ - Not detected and the detection limit is estimated BOLD text indicates 2L exceedance ®Bold cell with green highlight indicates GCL exceedence Activated sodium persulfate injections were performed at the site from June 4, 2012, to June 9, 2012, and from June 3, 2013. to June 6. 2013. Page 4 of 4 04ARCADISI b i nd Arcadis U.S., Inc. 111-D Sanders Lane Bluefield, Virginia 24605 Tel 276 322 3879 Fax 276 322 3946 www.arcadis.com