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HomeMy WebLinkAbout3402_Forsyth_HanesMillRoad_MSWLF_Closed_Unlined_MNA_FID1681558_20220608hdrinc.com January 11, 2022 Ms. Jaclynne Drummond, Compliance Hydrogeologist NC Department of Environmental Quality Division of Waste Management, Solid Waste Section 1646 Mail Service Center Raleigh, NC 27699-1646 Re: Monitored Natural Attenuation Effectiveness Report Hanes Mill Road Sanitary Landfill Permit No. 34-02 Winston-Salem, North Carolina Dear Ms. Drummond: On behalf of City of Winston-Salem, HDR Engineering, Inc. of the Carolinas (HDR) is submitting this Monitored Natural Attenuation Effectiveness Report for the Spring 2021 event, as requested in correspondence from the North Carolina Department of Environment and Natural Resources (NCDENR), dated September 22, 2008. The modeling results indicate that the input parameters for the BIOCHLOR natural attenuation screening model are applicable and that biodegradation of chlorinated organic compounds via monitored natural attenuation (MNA) remains active at the site. In 2021, the BIOCHLOR scores have generally increased from the 2020 scores, indicating slightly limited to adequate evidence of biodegradation. BIOCHLOR output for monitoring wells OW-3, OW- 4, OW-1 OD and OW-17D for the March 2021 sampling event are included as Attachment 1. Based on these data, HDR reviewed the V Semi -Annual 2021 Water Quality Monitoring Event report prepared by Golder to substantiate the BIOCHLOR results. Specifically, HDR reviewed groundwater quality data from the March 2021 sampling event for empirical evidence of biodegradation through detection of tetrachloroethene (PCE) daughter products. If biodegradation is occurring, concentrations of PCE should decrease over time, while concentrations of trichloroethene (TCE), 1,2-dichloroethene, and vinyl chloride should increase as PCE breaks down to its daughter products. HDR prepared concentration versus time graphs for wells OW-3, OW-4, OW-1 OD, and OW-17D to evaluate trends in chlorinated volatile organic compounds (Attachment 2). 440 S Church Street, Suite 1000, Charlotte, NC 28202-2075 704.338.6700 City of Winston-Salem I Hanes Mill Road Sanitary Landfill ��� Monitored Natural Attenuation Effectiveness Report Down -gradient from the waste mass, concentrations of TCE, 1,2-dichloroethene, and vinyl chloride appear to have increased slightly since 2009 in wells OW-1 OD and OW-17D, indicating that generation of PCE daughter products is occurring. The trends observed in laboratory data do not directly support the BIOCHLOR results for the Spring 2021 modeling period. One potential explanation for variability in concentrations could be minor changes in flow direction between seasons or between years. A second potential explanation for the conflicting interpretations is that BIOCHLOR was designed as a linear two-dimensional attenuation model assuming a single point source of groundwater impacts. The Hanes Mill Road Landfill does not represent a single point source for impacts, as the site -specific contaminants of concern could be distributed throughout some or all of the 71-acre closed unlined facility. Additionally, given the areal extent of the landfill, components of groundwater likely flow southeast toward South Branch Creek in the vicinity of wells OW-3 and OW-4 and southwest toward Grassy Creek in the vicinity of wells OW-10D and OW-17D. Thus, a modeled flow path from OW-3 to OW-4 to OW-1 OD to OW-17D is non -linear and unlikely to be represented adequately by the BIOCHLOR model. While HDR understands that modeling via BIOCHLOR is required by the NCDEQ, we recommend that trending of chlorinated VOCs and daughter products be used to support evidence that biodegradation is continuing at the closed unlined facility. Please contact us with any questions or concerns regarding this report. Sincerely, HDR Engineering, Inc. of the Carolinas Mark P. Filardi, PG Michael D. Plummer Associate, Senior Geologist SAA Waste Section Manager cc: Jan McHargue, PE, City of Winston-Salem file Enclosures Attachment 1 BIOCHLOR Modeling Results for March 2021 Monitoring Period Hanes Landfill Closed Unlined Cell Assumption The maximum chlorinated compound concentrations (PCE, TCE, DCE, and VC) from the groundwater monitoring available from 2002 to 2021 were used because the actual source concentrations are unknown. Model Input Data 1. Advection: Seepage Velocity, hydraulic gradient, and effective porosity (presented in figure below) are all based on site conditions at the landfill. 2. Dispersion Input Parameter: ax, ay/ax, and az/ax inputs are all based on the instruction for the BIOCHLOR program 3. Adsorption: Default values from the BIOCHLOR program were applied. A soil bulk density of 1.6 kg/L, foc of 1.8 x 10-1, and Koc values of 426 L/kg (PCE), 130 L/kg (TCE), 125 L/kg (DCE), 30 L/kg (VC), and 302 L/kg (ETH) were used within the model to calculate a retardation factor of 2.87. This value was used throughout the rest of the model. 4. Biotransformation: The biotransformation first orders Decay coefficients lamda (1/yr) for PCE-TCE (0.45), TCE-DCE (0.55), DCE-VC (0.8), and VC-ETH (12) from Zone 1 were obtained based on Table 2.2 of the BIOCHLOR Addendum Manual (March 2002); and were adjusted by fitting 2021 field VOC data to the sequential 1st order decay modeling VOC concentration curve. 5. General: Only the VOC data from 2002 to current period for the OW wells were available and the source VOC concentrations unknown. The maximum groundwater VOC concentrations from 2002 to 2021 were used as the source input and the modeling time is therefore set for 20 years (from 2002 to 2021). The model width is 1000 ft (limited zone of VOC detection based on historic data) and modeling length is 600 ft (maximum distance from landfill to the down gradient stream). 6. Source Data: The source data entered into the model determine how the concentrations in the source area change over time. The source thickness in the saturated zone is 50 ft. For the source concentrations the maximum groundwater VOC concentrations from 2002 to 2021 were used. These are: PCE = 0.026 mg/L; TCE 0.19 mg/L; DCE = 0.39 mg/L; VC = 0.13 mg/L; and ETH = 0.028 mg/L. The maximum Decay Rate Constants ks (1/yr) allowed by the model were used. 7. Field Data: The groundwater data collected in the field efforts from 2021 were used for the PCE, TCE, DCE and VC concentrations for OW-3 (20 ft from the source), OW-4 (30 ft from the source), OW-1 OD (215 ft from the source), and OW-17D (450 ft from the source). The field data values can be found in the BIOCHLOR Natural Attenuation Decision Support System figure below in the seventh section (Field Data for Comparison). Results 1. MNA Screening Score: The MNA screening scores were 14, 13, 17, and 17 for OW-3, OW-4, OW-1 OD, and OW-17D, respectively for the March 2021 event. A score from 6 to 14 means there is limited evidence for anaerobic biodegradation of chlorinated organics, which was seen in wells OW-17D, OW-4, and OW-10D. Well OW-3 was in the range of 15 to 20 which means adequate evidence for anaerobic biodegradation of chlorinated organics. 2. Biochlor Modeling Results: The Biochlor modeling results of PCE, TCE, DCE and VC for both No -Degradation and Biotransformation for 0 to 600 ft from the source (landfill waste border) are tabulated for each compound (see figures below). These results are compared to the field data collected in March 2021 from OW-3, OW-4, OW-1 OD and OW-17D. The results showed that none of the compound concentrations decreased with distance from the landfill and the model estimated PCE, TCE and DCE appears to increase in concentration with distance to the landfill. The dissolved chlorinated solvent concentrations along plume centerline (mg/L) at Z=0 figures below show the modeled No Degradation (red line), Biotransformation (blue line) and field data from site (black box with yellow plus sign). The model estimated concentrations with biotransformation for all constituents match more closely the value and magnitude of the value in the biotransformation line, however only VC field data from the site show the same general trend as the Biotransformation line. The model estimated TCE concentration at 420 ft (9 ug/L) and 480 ft (6 ug/L) down gradient from the landfill were still slightly above the 2L standard (3 ug/L). The TCE concentration decreased to the 2L level at 540 ft downgradient from the landfill. These model estimated results indicate that the MNA biodegradation of the chlorinated organic compounds have limited evidence for anaerobic biodegradation of chlorinated organics. Natural Attenuation Screening Protocol Interpretation Score OW-3 Score: 14 Scroll to End of Table Inadequate evidence for anaerobic biodegradation* of chlorinated organics 0 to 5 Limited evidence for anaerobic biodegradation* of chlorinated organics 6 to 14 The following is taken from the usEPA protocol (USEPA, 199 ).. The results of this scoring process have no regulatory significance. Adequate evidence for anaerobic biodegradation* of chlorinated organics 15 to 20 Strong evidence for anaerobic biodegradation* of chlorinated organics >20 Concentration in " reductive dechlorination F Points Analysis Most Contam. Zone Interpretation Yes No Awarded Oxygen* <0.5 mg/L Tolerated, suppresses the reductive pathway at higher concentrations O 0 0 > 5mg/L Not tolerated; however, VC may be oxidized aerobically 0 0 Nitrate' <1 mg/L At higher concentrations may compete with reductive pathway 0 0 2 Iron II* >1 mg/L Reductive pathway possible; VC may be oxidized under Fe III-reducin conditions 0 3 Sulfate* <20 mg/L At higher concentrations may compete with reductive pathway 0 2 Sulfide* >1 mg/L Reductive pathway possible 0 0 Methane* >0.5 mg/L Ultimate reductive daughter product, VC Accumulates 0 0 Oxidation Reduction Potential* (ORP) <50 millivolts (mV) Reductive pathway possible 0 1 <-100mV Reductive pathway likely 0 0 0 PH' 5 < pH < 9 Optimal range for reductive pathway 0 0 0 TOC >20 mg/L Carbon and energy source; drives dechlorination; can be natural or anthropogenic 0 0 Temperature* >20°C At T >20°C biochemical process is accelerated 0 0 Carbon Dioxide >2x background Ultimate oxidative daughter product 0 0 Alkalinity >2x background Results from interaction of carbon dioxide with aquifer minerals 0 0 0 Chloride* >2x background Daughter product of organic chlorine 0 2 Hydrogen >1 nM Reductive pathway possible, VC may accumulate 0 0 Volatile Fatty Acids >0.1 mg/L Intermediates resulting from biodegradation of aromatic compounds; carbon and energy source 0 O 0 BTEX* >0.1 mg/L Carbon and energy source; drives dechlorination 0 0 PCE* Material released 0 0 TCE* Daughter product of PCE si O O 2 DCE* Daughter product of TCE. If cis is greater than 80% of total DCE it is likely a daughter product of TCE'/; 1,1-DCE can be a them. reaction product of TCA O 0 VC* Daughter product of DCE'/ O O 2 1,1,1- Trichloroethane* Material released 0 0 DCA Daughter product of TCA under reducing conditions 0 0 Carbon Tetrachloride Material released 0 O 0 Chloroethane* Daughter product of DCA or VC under reducing conditions 0 0 Ethene/Ethane >0.01 mg/L Daughter product of VC/ethene 0 O 0 >0.1 mg/L Daughter product of VC/ethene 0 U 0 Chloroform Daughter product of Carbon Tetrachloride 0 0 Dichloromethane Daughter product of Chloroform 0 0 * required analysis. a/ Points awarded only if it can be shown that the compound is a daughter product SCORE Reset (i.e., not a constituent of the source NAPL). Natural Attenuation Screening Protocol Interpretation Score OW-4 Score: 13 Scroll to End of Table Inadequate evidence for anaerobic biodegradation* of chlorinated organics 0 to 5 Limited evidence for anaerobic biodegradation* of chlorinated organics 6 to 14 The following is taken from the usEPA protocol (USEPA, 199 ).. The results of this scoring process have no regulatory significance. Adequate evidence for anaerobic biodegradation* of chlorinated organics 15 to 20 Strong evidence for anaerobic biodegradation* of chlorinated organics >20 Concentration in " reductive dechlorination F Points Analysis Most Contam. Zone Interpretation Yes No Awarded Oxygen* <0.5 mg/L Tolerated, suppresses the reductive pathway at higher concentrations 0 O 3 > 5mg/L Not tolerated; however, VC may be oxidized aerobically O 0 Nitrate' <1 mg/L At higher concentrations may compete with reductive pathway 0 O 2 Iron II* >1 mg/L Reductive pathway possible; VC may be oxidized under Fe III-reducin conditions O 0 Sulfate* <20 mg/L At higher concentrations may compete with reductive pathway OO O 2 Sulfide* >1 mg/L Reductive pathway possible O 0 Methane* >0.5 mg/L Ultimate reductive daughter product, VC Accumulates O 0 Oxidation Reduction Potential* (ORP) <50 millivolts (mV) Reductive pathway possible O 0 0 <-100mV Reductive pathway likely O 0 0 PH- 5 < pH < 9 Optimal range for reductive pathway 0 O 0 TOC >20 mg/L Carbon and energy source; drives dechlorination; can be natural or anthropogenic O 0 Temperature* >20°C At T >20°C biochemical process is accelerated O 0 Carbon Dioxide >2x background Ultimate oxidative daughter product O 0 Alkalinity >2x background Results from interaction of carbon dioxide with aquifer minerals O 0 0 Chloride* >2x background Daughter product of organic chlorine 0 2 Hydrogen >1 nM Reductive pathway possible, VC may accumulate O 0 Volatile Fatty Acids >0.1 mg/L Intermediates resulting from biodegradation of aromatic compounds; carbon and energy source O 0 0 BTEX* >0.1 mg/L Carbon and energy source; drives dechlorination O 0 PCE* Material released 0 O 0 TCE* Daughter product of PCE si O O 2 DCE* Daughter product of TCE. If cis is greater than 80% of total DCE it is likely a daughter product of TCE'/; 1,1-DCE can be a them. reaction product of TCA O 0 VC* Daughter product of DCE'/ O O 2 1,1,1- Trichloroethane* Material released O 0 DCA Daughter product of TCA under reducing conditions O 0 Carbon Tetrachloride Material released O O 0 Chloroethane* Daughter product of DCA or VC under reducing conditions O 0 Ethene/Ethane >0.01 mg/L Daughter product of VC/ethene O O 0 >0.1 mg/L Daughter product of VC/ethene O U 0 Chloroform Daughter product of Carbon Tetrachloride O 0 Dichloromethane Daughter product of Chloroform O 0 * required analysis. a/ Points awarded only if it can be shown that the compound is a daughter product SCORE Reset (i.e., not a constituent of the source NAPL). Natural Attenuation Screening Protocol Interpretation Score OW-10D Score: 17 Scroll to End of Table Inadequate evidence for anaerobic biodegradation* of chlorinated organics 0 to 5 Limited evidence for anaerobic biodegradation* of chlorinated organics 6 to 14 The following is taken from the usEPA protocol (USEPA, 199 ).. The results of this scoring process have no regulatory significance. Adequate evidence for anaerobic biodegradation* of chlorinated organics 15 to 20 Strong evidence for anaerobic biodegradation* of chlorinated organics >20 Concentration in " reductive dechlorination F Points Analysis Most Contam. Zone Interpretation Yes No Awarded Oxygen* <0.5 mg/L Tolerated, suppresses the reductive pathway at higher concentrations 0 O 3 > 5mg/L Not tolerated; however, VC may be oxidized aerobically 0 0 Nitrate' <1 mg/L At higher concentrations may compete with reductive pathway 0 0 2 Iron II* >1 mg/L Reductive pathway possible; VC may be oxidized under Fe III-reducin conditions 0 0 Sulfate* <20 mg/L At higher concentrations may compete with reductive pathway OO 0 2 Sulfide* >1 mg/L Reductive pathway possible 0 0 Methane* >0.5 mg/L Ultimate reductive daughter product, VC Accumulates 0 3 Oxidation Reduction Potential* (ORP) <50 millivolts (mV) Reductive pathway possible 0 1 <-100mV Reductive pathway likely 0 0 0 PH- 5 < pH < 9 Optimal range for reductive pathway 0 0 0 TOC >20 mg/L Carbon and energy source; drives dechlorination; can be natural or anthropogenic 0 0 Temperature* >20°C At T >20°C biochemical process is accelerated 0 0 Carbon Dioxide >2x background Ultimate oxidative daughter product 0 0 Alkalinity >2x background Results from interaction of carbon dioxide with aquifer minerals 0 0 0 Chloride* >2x background Daughter product of organic chlorine 0 2 Hydrogen >1 nM Reductive pathway possible, VC may accumulate 0 0 Volatile Fatty Acids >0.1 mg/L Intermediates resulting from biodegradation of aromatic compounds; carbon and energy source 0 0 0 BTEX* >0.1 mg/L Carbon and energy source; drives dechlorination 0 0 PCE* Material released 0 0 0 TCE* Daughter product of PCE si O O 2 DCE* Daughter product of TCE. If cis is greater than 80% of total DCE it is likely a daughter product of TCE'/; 1,1-DCE can be a them. reaction product of TCA O 0 VC* Daughter product of DCE'/ O O 2 1,1,1- Trichloroethane* Material released 0 0 DCA Daughter product of TCA under reducing conditions 0 0 Carbon Tetrachloride Material released 0 O 0 Chloroethane* Daughter product of DCA or VC under reducing conditions 0 0 Ethene/Ethane >0.01 mg/L Daughter product of VC/ethene 0 O 0 >0.1 mg/L Daughter product of VC/ethene 0 U 0 Chloroform Daughter product of Carbon Tetrachloride 0 0 Dichloromethane Daughter product of Chloroform 0 0 * required analysis. a/ Points awarded only if it can be shown that the compound is a daughter product SCORE Reset (i.e., not a constituent of the source NAPL). Natural Attenuation Screening Protocol Interpretation Score OW-17D Score: 17 Scroll to End of Table Inadequate evidence for anaerobic biodegradation* of chlorinated organics 0 to 5 Limited evidence for anaerobic biodegradation* of chlorinated organics 6 to 14 The following is taken from the usEPA protocol (USEPA, 199 ).. The results of this scoring process have no regulatory significance. Adequate evidence for anaerobic biodegradation* of chlorinated organics 15 to 20 Strong evidence for anaerobic biodegradation* of chlorinated organics >20 Concentration in " reductive dechlorination F Points Analysis Most Contam. Zone Interpretation Yes No Awarded Oxygen* <0.5 mg/L Tolerated, suppresses the reductive pathway at higher concentrations 0 O 3 > 5mg/L Not tolerated; however, VC may be oxidized aerobically 0 0 Nitrate' <1 mg/L At higher concentrations may compete with reductive pathway 0 0 2 Iron II* >1 mg/L Reductive pathway possible; VC may be oxidized under Fe III-reducin conditions 0 0 Sulfate* <20 mg/L At higher concentrations may compete with reductive pathway OO 0 2 Sulfide* >1 mg/L Reductive pathway possible 0 0 Methane* >0.5 mg/L Ultimate reductive daughter product, VC Accumulates 0 3 Oxidation Reduction Potential* (ORP) <50 millivolts (mV) Reductive pathway possible 0 1 <-100mV Reductive pathway likely 0 0 0 PH- 5 < pH < 9 Optimal range for reductive pathway 0 0 0 TOC >20 mg/L Carbon and energy source; drives dechlorination; can be natural or anthropogenic 0 0 Temperature* >20°C At T >20°C biochemical process is accelerated 0 0 Carbon Dioxide >2x background Ultimate oxidative daughter product 0 0 Alkalinity >2x background Results from interaction of carbon dioxide with aquifer minerals 0 0 0 Chloride* >2x background Daughter product of organic chlorine 0 2 Hydrogen >1 nM Reductive pathway possible, VC may accumulate 0 0 Volatile Fatty Acids >0.1 mg/L Intermediates resulting from biodegradation of aromatic compounds; carbon and energy source 0 0 0 BTEX* >0.1 mg/L Carbon and energy source; drives dechlorination 0 0 PCE* Material released 0 0 TCE* Daughter product of PCE si O O 2 DCE* Daughter product of TCE. If cis is greater than 80% of total DCE it is likely a daughter product of TCE'/; 1,1-DCE can be a them. reaction product of TCA O 0 VC* Daughter product of DCE'/ O O 2 1,1,1- Trichloroethane* Material released 0 0 DCA Daughter product of TCA under reducing conditions 0 0 Carbon Tetrachloride Material released 0 O 0 Chloroethane* Daughter product of DCA or VC under reducing conditions 0 0 Ethene/Ethane >0.01 mg/L Daughter product of VC/ethene 0 O 0 >0.1 mg/L Daughter product of VC/ethene 0 U 0 Chloroform Daughter product of Carbon Tetrachloride 0 0 Dichloromethane Daughter product of Chloroform 0 0 * required analysis. a/ Points awarded only if it can be shown that the compound is a daughter product SCORE Reset (i.e., not a constituent of the source NAPL). DISSOLVED CHLORINATED SOLVENT CONCENTRATIONS ALONG PLUME CENTERLINE (mg/L) at Z=0 Distance from Source (ft) PCE No Degradation Biotransformation 0 60 120 180 240 300 360 420 480 540 600 0.026 0.026 0.025 0.023 0.021 0.018 0.015 0.012 0.009 0.006 0.004 0.0260 0.018 0.013 0.008 0.006 0.004 0.002 0.002 0.001 0.001 0.000 Field Data from Sitel 1 0.004 —No Degradation/Production 0.03 J 0.03 E 0.02 V r_ 0.02 c� 0.01 c 0.01 0 V 0.00 0 100 Prepare Animation Monitorinq Well Locations 0.007 1 1 1 1 1 -Sequential 1 st Order Decay 0 Field Data from Site See PCE Jvv I V L See DCE 0 See VC 600 See ETH 200 300 400 500 600 700 Distance From Source (ft.) i irne: 20.0 Years Return to Input To All To Array Log Linear DISSOLVED CHLORINATED SOLVENT CONCENTRATIONS ALONG PLUME CENTERLINE (mg/L) at Z=0 TCE No Degradation Biotransformation Distance from Source (ft) 0 60 120 180 240 300 360 420 480 540 600 0.190 0.187 0.181 0.168 0.151 0.130 0.108 0.085 0.063 0.045 0.030 0.1900 0.128 0.086 0.057 0.037 0.024 0.015 0.010 0.006 0.004 0.002 Field Data from Site 1 0.007 —No Degradation/Production IIyII; J 0.18 0.16 E 0.14 = 0.12 0.10 a 0.08 L = 0.06 v 0.04 c 0.02 V 0.00 Prepare Animation Monitorino Well Locations (ft) 215 450 0.009 0.015 —Sequential 1st Order Decay C Field Data from Site i irne: 20.0 Years Log `�Linear Return to To All To Array Input DISSOLVED CHLORINATED SOLVENT CONCENTRATIONS ALONG PLUME CENTERLINE (mg/L) at Z=0 Distance from Source (ft) DCE No Degradation Biotransformation 0 60 120 180 240 300 360 420 480 540 600 0.390 0.385 0.371 0.346 0.310 0.267 0.221 0.174 0.130 0.092 0.061 0.3900 0.250 0.159 0.101 0.063 0.039 0.025 0.015 0.009 0.005 0.003 Field Data from Sitel —No Degradation/Production 0.45 J 0.40 0.35 0.30 C 0.25 0.20 0.15 0.10 = 0.05 V 0.00 0 100 Prepare Animation Monitorinq Well Locations 0.001 1 0.018 1 —Sequential 1st Order Decay C Field Data from Site 600 200 300 400 500 Distance From Source (ft.) 700 See PCE See TCE See DCE See VC See ETH i irne: 20.0 Years Return to Input To All To Array Log Linear DISSOLVED CHLORINATED SOLVENT CONCENTRATIONS ALONG PLUME CENTERLINE (mg/L) at Z=0 Distance from Source (ft) VC No Degradation Biotransformation 0 60 120 180 240 300 360 420 480 540 600 0.130 0.128 0.124 0.115 0.103 0.089 0.074 0.058 0.043 0.031 0.020 0.1300 0.016 0.007 0.005 0.003 0.002 0.001 0.001 0.000 0.000 0.000 Field Data from Sitel 0.058 1 —No Degradation/Production 0.14 0.12 E 0.10 = 0.08 O 0.06 0 = 0.04 d = 0.02 V 0.00 0 100 Prepare Animation Monitorinq Well Locations 1 0.001 1 1 1 1 —Sequential 1st Order Decay C Field Data from Site See PCE 0 See DCE 0 0 See VC 600 See ETH 200 300 400 500 600 700 Distance From Source (ft.) i irne: 20.0 Years Return to Input To All To Array Log Linear