State Of North Carolina Department Of Environmental .

Risk Management PlanATC Associates of North Carolina, P.C.Brothers CleanersDSCA ID DC920007Protection of Groundwater UseATC evaluated the protection of groundwater use pathway assuming a point-of-exposure (POE)at the nearest property boundary downgradient of the current plume extent on the source property,which is located approximately 230 feet downgradient of the source area. For groundwater, theshallow monitoring well containing the highest contaminant concentration (MW-2) was utilizedas the representative concentrations. For soil, the soil sample collected post-SVE operationcontaining the highest contaminant concentration (SB-1 2016) was utilized as the representativeconcentration. Modeling was performed using the DSCA risk calculator. The modeling results forthe protection of groundwater use evaluation indicated no exceedances of site-specific target levels(SSTLs) for source groundwater or source soil that would result in exceedances of 2L Standardsat the POE. These results are corroborated by groundwater monitoring data which demonstratethat the plume is stable and confined to the source property. Since groundwater contaminantconcentrations on the source property are above 2L Standards, the risk assessment recommendedthat land-use controls be implemented on this property to prevent the installation of water supplywells.Protection of Surface WaterThe protection of surface water pathway was modeled assuming a POE at the nearest surface waterbody downgradient of the plume, which is approximately 180 feet downgradient of the sourcearea. This surface water body is Marsh Creek, which is a Class C surface water body. Forgroundwater, the shallow monitoring well containing the highest contaminant concentration (MW2) was utilized as the representative concentrations. For soil, the soil sample collected post-SVEoperation containing the highest contaminant concentration (SB-1 2016) was utilized as therepresentative concentration. Modeling was performed using the DSCA risk calculator. Themodeling results indicated no exceedances of SSTLs for source groundwater or source soil thatwould result in exceedances of Title 15A NCAC 2B .0200 Standards (2B Standards) at the POE.The results are corroborated by surface water sampling data. Surface water samples have beencollected from the downgradient surface water body during 15 sampling events. PCE was detectedduring one sampling event at a concentration above the 2B Standard. However, four subsequentsampling events at this location indicated no exceedances of 2B Standards. Based on these data,4

Risk Management PlanATC Associates of North Carolina, P.C.Brothers CleanersDSCA ID DC920007the risk assessment concluded that the protection of surface water pathway does not pose anunacceptable risk.The risk assessment concluded that the risks associated with the contamination could be managedthrough implementation of land-use controls, as detailed in this RMP. Therefore, the riskassessment recommended risk-based closure for the site. Land-use controls proposed for the sitebased on the results of the risk assessment are depicted on Figure 9. Land-use controls are furtherdiscussed in Section 6.0.4.0 REMEDIAL ACTION PLAN COMPONENTS4.1 Summary of Prior Assessment and Interim ActionsThe source property is approximately 17 acres in size and associated with a primary address of6116 Falls of Neuse Road in Raleigh, North Carolina. The source property currently contains acommercial shopping center, North Ridge Shopping Center. Surrounding properties are primarilycommercial and residential. The contamination associated with the site is confined to the sourceproperty.The former Brothers Cleaners operated utilizing PCE from approximately 1980 to 1998 in a tenantspace located in the northern portion of the shopping center at 6144 Falls of Neuse Road. BrothersCleaners operated as a pick-up/drop-off location from 1998 to approximately June 2015, when thefacility became Tide Cleaners. The former Brothers Cleaners and adjacent shoe repair shop spaceswere renovated and combined to become Tide Cleaners, which is currently operating in the spaceas a pick-up/drop-off location with no active dry-cleaning activities.In August 2001, an initial assessment was conducted at the facility by EMG as part of a propertytransaction. Soil and groundwater samples collected as part of the investigation indicateddetectable concentrations of PCE in soil and groundwater samples collected beneath the formerwaste drum storage area. The Brothers Cleaners site was subsequently accepted into the DSCAProgram in January 2002.5

Risk Management PlanATC Associates of North Carolina, P.C.Brothers CleanersDSCA ID DC920007Mid-Atlantic Associates, Inc. performed a prioritization assessment at the site in March 2004. Aspart of assessment activities, three permanent monitoring wells (MW-1 through MW-3) wereinstalled, a receptor survey was completed, and soil and groundwater samples were collected.During the receptor survey, a private water supply well was identified approximately 1,250 feetnortheast of the facility and an unnamed tributary to Marsh Creek was identified approximately150 feet downgradient of the facility.ENSR performed assessment of the extent of impacted soil and groundwater between 2006 and2007. As part of the assessment activities, 18 soil borings were advanced and soil samples werecollected to delineate the extent of impacted soil. A total of 12 temporary wells were initiallyinstalled and sampled to evaluate the extent of impacted groundwater. Four shallow monitoringwells (MW-5 through MW-8) and one deep monitoring well (DMW-1) were then installed andsampled to complete the monitoring well network. Surface water samples were collected from thedowngradient stream that indicated no exceedances of 2B Standards. The assessment activitieswere documented in four assessment reports completed by ENSR in 2006 and 2007. ENSR thenperformed four quarterly groundwater and surface water sampling events. The results of thesampling indicated that the groundwater plume was adequately defined and no exceedances of 2BStandards were detected in surface water.A Tier 1 and 2 risk assessment was completed by ENSR in July 2008. The results of the riskassessment identified exceedances of acceptable risk levels for the protection of groundwater andsurface water pathways using POEs located at the downgradient property boundary anddowngradient surface water body, respectively.In March 2009, ATC recommended installation of an SVE system to remediate impacted soil andinjection of 3DMe (a proprietary remediation solution) to remediate impacted groundwater. A SVEsystem was subsequently installed that included extraction from four SVE points. The SVE systembegan operation in September 2009. Injection of 3DMe was completed in October 2009. Duringthe injection event, approximately 594 gallons of 3DMe solution were injected into the direct-pushlocations (IDP-1 through IDP-10). Post-injection monitoring events were subsequently performedthat indicated evidence of enhanced reductive dechlorination of chlorinated solvent constituents ingroundwater.6

Risk Management PlanATC Associates of North Carolina, P.C.Brothers CleanersDSCA ID DC920007In 2009, ATC initiated vapor intrusion sampling in the source property building. The results of theinitial indoor air and sub-slab gas sampling events indicated exceedances of acceptable risk levelsin the Brothers Cleaners space and the adjacent North Hills Shoe & Luggage Repair space.Emissions from dry-cleaned clothing in the Brothers Cleaners space appeared to be contributingto indoor air impacts.Vapor intrusion also appeared to be contributing to impacts so mitigation wasdeemed warranted. The SVE system was subsequently expanded to include seven additionalinterior extraction points. Indoor air and sub-slab gas samples were also collected in the tenantspaces adjacent to the shoe repair space, which were occupied by Kerr Drugs and Rapid Fitness atthe time of the sampling. Sampling in these spaces indicated no exceedances of acceptable risklevels.The SVE system remained operational until 2012. The system was then shut down and vaporintrusion sampling was performed to evaluate whether the vapor intrusion risk had been fullymitigated. The results of indoor air sampling indicated concentrations were reduced in comparisonto sampling events prior to remediation, but indoor air concentrations remained above acceptablerisk levels. Additional evaluation was performed that indicated the remaining exceedances inindoor air were attributed to vapor emissions from dry-cleaned clothing in the Brothers Cleanersspace as well as chemicals used in the shoe repair space. As such, no further mitigation wasrecommended for the site.Periodic groundwater and surface water monitoring events were completed at the site through2014. PCE was detected in one surface water sample at a concentration slightly above the 2BStandard (4.1 micrograms per liter [μg/L] versus 2B Standard of 3.3 μg/L) in April 2010. However,no exceedances of 2B Standards were detected during four subsequent quarterly sampling events.As such, the exceedance was not considered a significant concern. The results of the groundwatersampling events indicated that the plume was adequately defined and stable.In January 2016, ATC performed soil sampling in order to evaluate post-remediation contaminantconcentrations in soil. Two soil samples were collected at the approximate locations indicating thehighest historical concentrations. The results of the sampling indicated significantly reducedconcentrations, which were attributed to the SVE remedial activities.7

Risk Management PlanATC Associates of North Carolina, P.C.Brothers CleanersDSCA ID DC920007On September 20, 2016, ATC completed a risk assessment for the site. As discussed in detail inSection 3.0, the risk assessment concluded that risks associated with the contamination could bemanaged through implementation of land-use controls for the source property, as detailed in thisRMP. Based on the results of the risk assessment, ATC recommended risk-based closure for thesite.4.2 Remedial ActionAccording to the DSCA Program’s RAG, no remedial action is necessary if four site conditionsare met. Each of these conditions and their applicability to the subject site are addressed below.Condition 1: The dissolved plume is stable or decreasing.Periodic groundwater monitoring has been conducted at the site since 2004. Constituents ofconcern (COCs) detected at the site historically above 2L Standards include PCE, TCE, mochloromethane are typically associated with chlorinated drinking water and are likelyassociated with a city water line release rather than the dry-cleaning solvent release. Trans-1,2DCE and vinyl chloride were not detected above 2L Standards during the two most recent samplingevent. Therefore, ATC focused on the constituents PCE, TCE, and cis-1,2-DCE for the plumestability evaluation.ATC used the GSI Mann-Kendall Toolkit for Constituent Trend Analysis (Mann-Kendall) toevaluate trends for monitoring wells showing exceedances of 2L Standards for key COCs. Thetrend analyses reported stable, decreasing, or no trends for all COCs and monitoring wells withthe exception of cis-1,2-DCE in well MW-2 and TCE in well MW-4. For these exceptions, ATCfurther reviewed concentrations versus time graphs and data collected over time to evaluatestability. For well MW-2, cis-1,2-DCE concentrations showed increases following injection,which is to be expected since cis-1,2-DCE is a breakdown product of reductive dechlorination ofPCE. However, if only the most recent four sampling events are used, the Mann-Kendall analysis8

Risk Management PlanATC Associates of North Carolina, P.C.Brothers CleanersDSCA ID DC920007reports a decreasing trend. For well MW-4, the concentration of TCE shows little variability overtime and concentrations exceed the 2L Standard by a small margin (maximum concentration of3.8 μg/L versus 2L Standard of 3 μg/L). Based on these data, ATC concludes that the plumeassociated with the site is stable or decreasing. Documentation of the plume stability evaluationincluding a table showing historical groundwater analytical data and the Mann-Kendall analysesare included in Appendix A. A figure showing monitoring well locations is included as Figure 4.Condition 2: The maximum concentration within the exposure unit for every complete exposurepathway of any COC is less than ten times the representative concentration of that COC.ATC evaluated the representative concentrations calculated during the risk assessment and foundthat this condition has been met for all COCs and exposure pathways.Condition 3: Adequate assurance is provided that the land-use assumptions used in the DSCAProgram’s risk assessment process are not violated for current or future conditions.Land-use controls will be implemented for the source property to ensure the assumptions made inthe risk assessment remain valid in the future. Refer to Section 6.0 for additional details regardingthe proposed land-use controls for the site.Condition 4: There are no ecological concerns at the site.ATC completed a Level 1 Ecological Risk Assessment for the site in accordance with the DSCAProgram’s RAG. The results of the evaluation indicate that the release does not pose anunacceptable ecological risk. The completed Level 1 Ecological Risk Assessment Checklists Aand B and associated attachments are included in Appendix B.The site’s compliance with the four above referenced conditions confirms that the contaminantconcentrations are not likely to pose an unacceptable risk either at present or in the future. Theplume is expected to naturally attenuate over time and the appropriate remedial action is toimplement appropriate land-use controls for the source property where soil and groundwatercontamination is present.9

Risk Management PlanATC Associates of North Carolina, P.C.Brothers CleanersDSCA ID DC9200075.0 DATA COLLECTED DURING RMP IMPLEMENTATIONNo further sampling or other data collection activities are proposed for the site, as long as theassumptions detailed in the Notice of Dry-Cleaning Solvent Remediation (NDCSR) remain valid.As such, this section is not applicable.6.0 LAND-USE CONTROLSThe land-use controls proposed for the site are based on the results of the risk assessment as wellas the DSCA Program’s standard protocol. Based on these criteria, the following land-use controlsare proposed for the source property:1. Without prior written approval from NCDEQ, Areas “A” and Area “B” of the propertyshall not be used for:a.child care centers or schools; orb.mining or extraction of coal, oil, gas or any mineral or non-mineral substances.2. No activities that encounter, expose, remove or use groundwater (for example, installationof water supply wells, fountains, ponds, lakes or swimming pools that use groundwater, orconstruction or excavation activities that encounter or expose groundwater) may occur inArea “A” and Area “B” on the property without prior approval of NCDEQ.3. Soil in Area “C” may not be removed or disturbed unless approved in writing in advanceby NCDEQ or its successor in function, except for routine landscape maintenance andemergency utility repair. In the event of emergency utility repair, NCDEQ shall be givenwritten notice of any such emergency repair no later than the next business day, and furtherrelated assessment and remedial measures may be required.4. Except for routine maintenance, no construction activities or change in property use thatcause or create an unacceptable human health risk from vapor intrusion may occur in Area10

Risk Management PlanATC Associates of North Carolina, P.C.Brothers CleanersDSCA ID DC920007“A” on the property without prior approval of NCDEQ. These activities include but are notlimited to: construction of new buildings, removal and construction of part of a building,construction of sub-grade structures that encounter contaminated soil or places buildingusers in close proximity to contaminated groundwater, change from non-residential toresidential property, change in tenant space usage, and addition of residential property useon higher floors.5. Structural modifications that may cause or create an increased risk from vapor intrusion inArea “A” of the property require the property owner to demonstrate to the satisfaction ofNCDEQ that the indoor air in the structure does not pose an unacceptable risk to theoccupants following modifications. These modifications include but are not limited to:modification or replacement of heating, ventilation or air conditioning (HVAC) systems,removal or replacement of the building slab, installation of multiple conduits or pipingthrough the building slab, modifications to building walls or ceilings that may change airflow.6.Prior to using the former Brothers Cleaners (now Tide Cleaners) building space for anypurpose other than an active dry-cleaner or pick-up/drop-off dry-cleaning business, theproperty owner shall notify NCDEQ and demonstrate that the indoor air in this buildingspace does not pose an unacceptable risk to future occupants.Institutional controls will be implemented to ensure that land-use conditions are maintained andmonitored until the land-use controls are no longer required for the site. A NDCSR was preparedfor the source property to comply with the land-use control requirements. The NDCSR is includedin Appendix C. Refer to the NDCSR for the specific language to be incorporated to address eachof the risk assessment assumptions detailed above. A plat showing the locations and types of drycleaning solvent contamination is included as an exhibit to the NDCSR. The locations of drycleaning solvent contamination are where contaminants have been detected above unrestricted usestandards.11

Risk Management PlanATC Associates of North Carolina, P.C.Brothers CleanersDSCA ID DC9200077.0 LONG-TERM STEWARDSHIP PLANThe NDCSR contains a clause which requires that the owner of the property submit notarized“Annual Certification of Land-Use Restrictions” to NCDEQ on an annual basis certifying that theNDCSR remains recorded with the Register of Deeds and that the LURs are being complied with.An example of such a certification is included in Appendix D.8.0 RMP IMPLEMENTATION SCHEDULEBecause the contamination is stable, confined to the source

Dec 20, 2018 · that there are risks that exceed applicable target levels on the source property. These risks will be . adjacent shoe repair shop (North Hills Shoe & Luggage Repair), and release source areas are located. . to the former dry-cleaner and shoe repair shop. Modeling was performed using the DSCA risk calculator. The results of the modeling for .