1.2 Performance Objective 2 Decreasing Concentration Trends in Downgradient Wells

Transcription

1 . DEMONSTRATION OF COMPLIANCE The % Design Report for the Temporary System included a Demonstration of Compliance Plan that listed three Performance Objectives for the Temporary System. These Performance Objectives include: ) Hydraulic Capture demonstrate hydraulic capture of groundwater over the width of the,-dioxane and volatile organic compound (VOC) plumes using groundwater potentiometric elevation data collected in accordance with the Hydraulic Monitoring Plan. ) Decreasing Concentrations Trends - demonstrate decreasing concentrations of,-dioxane and VOCs over time at monitoring wells between extraction well EW- and the municipal well Assabet IA. This objective is evaluated using water quality data collected from groundwater monitoring wells in accordance with the Water Quality Monitoring Plan. 3) Treatment System Effectiveness demonstrate that effluent from the treatment system, does not exceed discharge standards listed in the Remediation General Permit (RGP) prior to discharge to the Assabet River. This objective is evaluated by comparing analytical data collected in accordance with the Treatment System Monitoring Plan to discharge standards listed in the RGP. Based on data collected in August and September 8, the temporary system is meeting these Performance Objectives. The sub-sections below summarize achievement of the Performance Objectives.. Performance Objective Hydraulic Capture Groundwater potentiometric elevation contours in overburden and bedrock interpreted using data collected on September 7, 8 are presented on Figures and. The potentiometric contours reflect the Temporary System operating at gallons per minute (gpm). The estimated extent of the groundwater capture zone in overburden is shown on Figure and was drawn based on potentiometric contours. Groundwater elevation data are presented on Figure and in Table. As shown on Figure, the estimated extent of hydraulic capture in the overburden from pumping at EW- extends beyond the width of the,-dioxane plume. Because the estimated groundwater capture zone extends beyond the width of the plume, the Temporary System is meeting the Hydraulic Capture Performance Objective. Further, as presented below, the width of the,- dioxane plume transverse to EW- has decreased since pumping began on June, 7.. Performance Objective Decreasing Concentration Trends in Downgradient Wells Groundwater analytical data that were collected as part of the operation of the temporary treatment system are provided in Tables. (Overburden) and. (Bedrock). Concentrations and Performance Objectives include evaluating VOCs (TCE specifically) in addition to,-dioxane. Since the TCE plume above the Cleanup Goal is generally contained within the extent of the,-dioxane plume, capture of VOCs is evaluated based on,-dioxane results.

2 isoconcentration contours for,-dioxane in overburden samples collected between September 9 and, 8 are presented on Figure. The bedrock,-dioxane distribution plan (Figure ) has been expanded compared to those submitted in previous demonstration of compliance reports to include most recent,-dioxane concentrations in bedrock wells located on the former Nuclear Metals property. Most recent,-dioxane concentrations and isoconcentration contours for bedrock are labeled with the month and year of detections. Consequently, the bedrock,-dioxane isoconcentration contours on this plan have been drafted to honor the historical detections and infer the shape and extent of the bedrock plume based on most recent available data.,-dioxane and trichloroethene concentration trend plots by monitoring location are provided in Attachment. The following analysis of,-dioxane concentration trends in overburden is presented for upgradient, cross-gradient and downgradient locations relative to EW-... Upgradient of EW- At location MW-SD, immediately upgradient of EW-, the concentration has dropped from.9 µg/l in May 7 (pre-pumping), to below µg/l in July 7 to less than µg/l in June 8, and down to.33 µg/l in September 8. The September 8 detection represents the first time that the concentration at MW-SD had dropped below the. µg/l Record of Decision ROD Cleanup Level. At location MW-SD3 (further upgradient of EW-) the concentration has dropped from 7. µg/l during baseline sampling to. in September 7. In the following sampling rounds, the concentrations at this well have been fluctuating from approximately 9 to 9 µg/l with a most recent detection of.3 µg/l in September 8. Overall, the,-dioxane concentrations at this well exhibit a decreasing trend since groundwater extraction began. The baseline concentration at MW-BS3, located in bedrock upgradient of the MW-3 cluster, was. µg/l. The concentration reached a high of. µg/l in June 8 but dropped to.8 µg/l in September 8. The June 8 increase in concentration at this well may have been due to,-dioxane becoming mobilized from the core of the bedrock plume located near MW-BS. The presumably mobilized concentrations of,-dioxane have not migrated to MW-BS3 where the September 8 concentration of.33 µg/l, was within the. to.989 µg/l range of detections reported since sampling began in May 7. It should be noted that although these concentrations in bedrock are elevated relative to overburden, the total mass of,-dioxane in bedrock is small due to significantly lower groundwater discharge rates in bedrock compared to overburden. The shallow bedrock and deep overburden concentrations in this area will be closely monitored in the future sampling events... Cross-Gradient of EW-,-dioxane data from monitoring wells cross-gradient of EW- show low or decreasing trends since pumping began in May 7. At MW-SD (cross-gradient to the north), the U.S. Environmental Protection Agency (USEPA),, Record of Decision (ROD), Nuclear Metals, Inc. Superfund Site, Concord, MA, September

3 concentration in September 8 was.3 µg/l and has always been below the. µg/l detected in baseline sampling in May 7. Cross-gradient well PT-9 (to the south) has dropped from.8 µg/l during baseline sampling to non-detect levels between September 7 and June 8, and an estimated 3 concentration of.9 in September 8. The estimated width of the,-dioxane plume above. µg/l located transverse to EW- has decreased from approximately 37 feet during baseline sampling in May 7 to approximately 9 feet in December 7, 8 feet in March 8 and approximately feet in September Downgradient of EW- Concentrations of,-dioxane in samples from wells between EW- and Assabet-A have decreased or fluctuated over time.,-dioxane concentrations detected in EW- samples collected on August 9, 8 were below µg/l (7. µg/l detected in an influent duplicate sample) for the second time since the system went into operation. Wells at approximate increasing distances downgradient of EW- include MW-SDA, MW-SD, MW-SD, MW-SD37 and MW-S (Figure ). These wells are downgradient of the EW- capture zone. Concentration trends for these wells include: MW-SDA - initially decreased from a baseline concentration of. µg/l to non-detect levels in July 7. Following an increasing trend observed at this well between August and December 7, the concentration dropped to.9 µg/l in March 8 and.77 µg/l in June 8. In September 8, the concentration increased to 8. µg/l which is the third highest concentration detected at this well. This detection may be attributable to temporary lack of capture during the following EW- shutdowns in August 8; o August 8 to 3 EW- shut down for hours due to failure of pressure transducer; o August EW- shut down for hours due to an issue with the programmable logic controller; and, o August EW- shut down for 7. hours for carbon vessel change out. As a result of these shutdown periods, the total system operation for the month of August 8 was estimated at 8%. MW-SD - decreased from a baseline concentration of. µg/l to. µg/l in September 7 and has remained relatively steady through December 7 (. µg/l in December 7). In September 8,-dioxane was detected at a concentration of 3.3 µg/l, slightly higher than the lowest detection of.99 µg/l reported in April 8; 3 Estimated concentrations are flagged with a J qualifier by the analytical laboratory. Groundwater analytical figures for baseline sampling in May 7 are included in Status Report # dated July, 7.

4 MW-SD has fluctuated but overall has decreased from a baseline concentration of. µg/l to.89 µg/l in March 8. The June and September 8 concentrations detected in this well were slightly higher at., and 3.33 µg/l, respectively. The concentrations at this well continue to maintain an overall decreasing trend; MW-SD37 has fluctuated but remained relatively stable ranging from. to 7.77 µg/l since pumping began. The September 8 detection of. µg/l represents the first time,-dioxane has dropped below µg/l at this well since the May 7 baseline sampling; and, MW-S - has fluctuated but remained relatively stable ranging from. to 8.8 µg/l between May and December 7 and decreased to. µg/l in September 8. The September 8 concentration represents the lowest,-dioxane detection at this well since its installation in January 7. Wells on the perimeter of the plume downgradient of EW- include MW-SD38, MW-SD39 and MW-SD3. MW-SD38 continued its slightly decreasing trend with the September 8 detection of.7 µg/l.,-dioxane was not detected at MW-SD39 in September 8 for the third time since pumping began and decreased at MW-SD3 from.3 µg/l in December 7 to.9 µg/l in September 8. Overall, the,-dioxane concentration trends in wells located between EW- and Assabet-A are stable or decreasing since extraction began. Concentrations in wells located immediately downgradient and along the centerline of the plume have generally been decreasing. This performance objective will take the longest amount of time to meet as a certain number of pore volumes need to be pumped and residual,-dioxane in groundwater downgradient of the EW- capture zone will need time to migrate further downgradient to achieve concentration reductions at Assabet A. However, groundwater performance monitoring data collected through March 8 indicate this Performance Objective is in the process of being met. TCE concentrations at MW-SD3 have increased slightly relative to pre-pumping conditions between July and December 7 and the TCE plume does not appear to be wholly contained within the,-dioxane plume at this location. However, the TCE concentrations in March, June, and September 8, were between. and 3.7 µg/l, below the Cleanup Goal of µg/l. These concentrations remain below those historically detected in the downgradient areas. The MW-3 well cluster and downgradient wells will be carefully monitored in future monitoring events..3 Performance Objective 3 Water Treatment Effectiveness Results from performance sampling of the treatment system are provided in Table 3. Included are performance data from the system collected through October 9, 8. and,- dioxane have been detected in the effluent samples at concentrations below their respective RGP limits. The treatment system results show that the temporary system is effectively removing VOCs from the influent groundwater and that VOCs and semi-volatile organic compounds (SVOCs) in

5 the treated effluent are below RGP limits. Results also show that concentrations of other RGP parameters, including metals with exception of iron, total petroleum hydrocarbons and general chemistry parameters, are below RGP limits. Iron was detected in the samples collected on September and October 9, 8 at, µg/l and 9,7 µg/l, respectively which exceeded the Water Quality-Based Effluent Limitation (WQBEL) of, µg/l for fresh water. This exceedance is attributable to a sampling method error; the sampler port is a low point of the effluent side of the system. This low point allows for sediment to settle, resulting in high iron concentrations. Because the influent of the system was measured at, µg/l, an effluent sample of 9,7 µg/l does appear to be a sampling error. Additional samples were taken on October, 8 however were not yet available at the time of this report.

6 Figures

7 A8-78 (NM) CLF- UNA- A7-78 (8.99) R- R-3 (7.7) A-78 (7.98) 8 UNA- R- (8.) 8 AR- R-A (8.7) 8 7 A-78 (7.33) 7 CLF- 7 B- (.8) 8 MW-SD (3.) (3.33) MW-BS 7 3 MW-BS37 MW-SD3 (.97) (.9) PT-. MW-S (.7) (.) MW-SD (.) (.33) MW-SDA (3.8) (8.) MW-S37 (.79) (.37) 3 EW- (3.8) (7.) MW-SD37 (.) (.) MW-SD (.) (.3) MW-SD (.83) (3.3) LF-SBR LF-DBR CLF- MW-BS PT- (.7) PT-9 (.3) (.9 J) AR-PHS (.7) MW-SD3 (.98) (.78) MW-BS3 PT-P (.) (.8 J) MW-SD3 (.9) (.3) MW-BS3 MW-S39 (.99) (<.39) MW-SD39 (.) (<.7) MW-BM MW-BS3 3 MW-S3 (.7) (<.) 8 9 MW-S8 Bedrock Monitoring Well New Staff Gauge and Drive Point Piezometer Locations (November 7) Assabet River Stage Location Active Public Water Supply Well Site Boundary DRAFT Groundwater Contour in Overburden (ft NGVD) - September 8 Estimated Groundwater Contour in Overburden (ft NGVD) - September 8 ASBRV-U Q:\GISProjects\BR9-NMISite\Projects\Updates_8\GWE_D_OB_September8.mxd /8/8 :7: AM (.7) Groundwater September 7, 8 (ft NGVD) Concentration September 9-, 8 (µg/l) 8 ASBRV-U (.) Isoconcentration Contour in Overburden (µg/l) September 8 Estimated Isoconcentration Contour in Overburden (µg/l) September 8 (3.83) MW-BS8 MW-S (8.) 7 Monitoring Well Wetlands Surface Water GZW-- MW-BS P-3A MW- (.) MW-BS GZW-- MW-BS3 P-A OW-3 MW-SD3 (.38) (. J) SW- (.83 J) P- 7 MW-S (.39) MW-S3 (.) MW-SD3 (.97) P- GZW-8- GZW-8- MW-BS 7 OW- (9.8) SW-3 (.8) P-A MW-SD (.8) MW-BS. ASBRV-D MW-S (.8) MW-BS3 Extraction Well CLF- MW-S3 (.97) (.833) MW-BS39 Legend CLF- SW- (.99 J) 8 3 MW-BS38 PZ-MPond (.83) CLF-3A CLF-3B CLF-3C LF-D (.9) Estimated Capture Zone for EW- at. GPM MW-SD38 (.3) (.7) MW-SM (.) (.) MW-SD (.3) (.9) 9 7 SG-MPond (.8) MW-S38 (.) (.83). CLF-3 LF-8DBR CLF (.) ASSABET IA (.3) PZ-A (7.3) LF-8SBR CLF- PZ-TPond (.) ASSABET IIA(.83) PZ-A (.8) CLF-A CLF-B CLF-C LF-8D (.8) SG-TPond (.) 3 CLF- AR- (.3) AR- (7.) CLF-9 GZW-- GZW-- MW-S9 MW-SD9 GZW-- P-3 SW- P- MW-S MW-SD MW-S MW-SD MW-SM3 MW- MW-BS3 MW-BM3 MW-BS3 MW-S MW- ML-- ML-- ML--3 MW-S7 MW-SD7 MW-BS MW-SD3 MW-BS MW-S3 MW-SD3 MW-T MW-S MW-SD MW-BS MW-8A GZW-9- GZW-9- ML-3- ML-3-3 MW-S7 MW-SD7 MW-BS7 MW-S7 TW- PW- MW-S MW-S Notes: MW-S3 : Water levels were collected on September 7, 8. MW-T MW-S HB- GZW-7- : The average pumping rate at municipal well Assabet A, for the 7-hour period prior to the water level round was 87 gpm, and for Assabet IIA was 3 gpm. GZW-7- HBPZ-R 3: Where multi-level overburden wells exist at a single location, data from the most appropriate well was prioritized in GZW-7S HB- MW-S8 Nuclear Metals, Inc. Superfund Site drafting contours. In general, contours represent deeper overburden. HB-7 HB- : Equipotentials were estimated by kriging the water elevations using Surfer 9. Kriging is a weighted moving average HB- Concord, Massachusetts HB-S interpolation (extrapolation) method that minimizes the estimated variance of a predicted point (node) with the MW-S9 weighted average of its neighbors. The contours were further adjusted using professional judgement. MW-BS MW-S3 MW-S8 MW- : Groundwater elevation contours are interpreted and may not represent actual flow directions or gradients. MW-S : EW- has been pumping at a rate of gpm since June data from groundwater monitoring wells were collected on September 9-, data for EW- was collected on August 9, 8. PW- 9. NM = Not Measured. SW-A Acton, Massachusetts November 8 Feet Groundwater s and Concentration in Overburden September 8 de maximis, inc. MW-S PW- TW- Figure MW-B

8 73-8 A-78 CLF- CLF- B- AR- CLF- CLF- ASSABET IIA LF-8SBR (.)(NS) LF-8DBR (.)(NS) PZ-A LF CLF-3 CLF-7 MW-S38 MW-SD38 MW-BS38 (3.39)(<.) (9/8) 3 MW-SD MW-BS (.)(<.7) (9/8) ASSABET A MW-SD3 3 7 MW-BS3 (.)(3.) (9/8) MW- P-3A MW-BS (NM)(8.) (7/3) MW-SD3 MW-BS3 (7.8)(<.78) (/) ML--3 ML-- ML-- MW-S MW-SD GZW-- MW-BS (7.9)(.) (/) GZW-- GZW--3 GZW-- GZW-- (NM)(8) (/) PW-8 MW-S MW-SD MW-BS7 MW-S7 MW-S3 MW-SD3 MW-S7 MW-S GZW-7-(NM)(39) (/) MW-S8 TW- MW-S MW-S9 HB- HB-9 HB-7 HBPZ-R GZW-7- HB- MW- MW-S3 PW- PW- MW-S MW-T GZW-7S Holding Basin MW-BS MW-S7 MW-8A MW-8 MW-BS3 (NM)(.) (8/3) MW-BM3 (NM)(3.8) (8/3) ML-3-3 MW-T MW-S MW-SD MW-BS MW- MW-SM3 MW-SD3 MW-BS3 MW-S3 GZW-9- ML-3- MW-SD7 MW-SD7 MW-BS GZW-9- ML-3- ML--3 (NM)(.9) (7/3) SW- MW-S MW-SD MW-S3 MW- P- GZW-- MW-S9 MW-SD9 MW-BS8 (NM)(7.) (7/3) MW-S P-3 ML-- ML-- MW-S8 7 MW-BS OW-3 7 MW-S OW- P-A OW- 3. MW-S PW- GZW-8- (NM)(.99) (/) GZW-8- MW-BS3 (.)(<.3) (9/8) MW-S3 MW-SD3 P- P- MW-BM (.89)(3.3) (/) 7 PT- P-A MW-BS (.)(83.) (9/8) MW-BS39 (3.)(<.3) (9/8) MW-BS (.88)(.9) (/). MW-BS (3.8)(<.3) (9/8) PT-9 MW-SD PT-P MW-SD3 MW-S39 MW-SD MW-BS37 (.)(<.) (9/8) MW-S37 MW-SD37 3 MW-S MW-SD EW- CLF- MW-S MW-BS3 (.7)(.8) (9/8) MW-BS3 (.97)(.33) (9/8) MW-SDA MW-S3 MW-SD3 MW-SD MW-SD PZ-A CLF- MW-SD 3 AR- LF-8SBR (.3899)(NS) LF-8DBR (.)(NS) LF-8 LF-8D CLF-3A CLF-3B CLF-3C CLF-3 LF-D CLF- MW-SM CLF-A CLF-B CLF-C GZW- HB- HB- MW-S8 HB-S MW-S TW- 3 PW- 33< 3@ =9!=<7B=@ 7< +3:: 'C@ / 3 +/ B3@ #D3@ C@ 3<!=<7B=@ 7< +3:: '7B3 G B7D3 $C:7 +/ B3@ 'C>>:G +3::.7 (/) 7=F/ <3 =<3<B@ / B7=<A I!=<B, =::3B3 +3B:/ <A 7=F/ <3 '# =<3<B@ / B7=< =<B=C@ 7< #D3@ C@ 3< I AB7; / B3 7=F/ <3 '# =<3<B@ / B7=< =<B=C@ 7< #D3@ C@ 3< I % - '$@ =83BA- & "! '7B3-$@ =83BA-) >/ B3A. -!=AB&33<B. MW-S MW-T "=B3A MW-SD $=AB3 7=F/ <3 =<3<B@ / 3>@ 3A3<B B3 ; 33<B / B/ =@ 3/ 3@ =9 E3:: E3@ 3 7=F/ <3 / A 33< A/ ; >:3 7AB=@ 7/ ::G J K 7<7/ B3A :3AA B/ < :/ =@ / B=@ 3>=@ B7< :7; 7B =C<E/ B3@ :3D/ B7=< =<B=C@ 7< 3@ =9 B +/ B3@ :3D3:A E3@ 3 =::3B3 =< '3>B3; =; / ACA3B = E3::A 7<:C3 / A B = B3 "=< ( 7; 7B7/ : &3; =D/ : B7=< PW-7A " * '3>B3; 3@ "( & ( 3; >=@ /@ G (@ 3/ B; 3<B 'GAB3; ; =<7B=@ 7< >@ =@ /; MW-S ( 3 / D3@ / 3 >C; / B3 / B ; C<77>/ : E3:: AA/ 3B =@ B3 =C@ >3@ 7= >@ 7=@ B= B3 E/ B3@ =C< E/ A / ::=<A >3@ ; 7<CB3 AB7; / =C<E/ B3@ :3D/ B7=< =<B=C@ 7< >; / < =@ AA/ 3B E/ A >; HA-9 3@ =9 B " * '3>B3; =C<E/ B3@ 3?C7>=B3<B7/ : / < 7=F/ <3 7A==<3<B@ / B7=< =<B=C@ A E3@ 3 3 CA7< >@ =3AA7=</ : 8C3; 3<B / < ; / G 3>@ 3A3<B / BC/ : :=E =<7B7=<A / 73<BA +3@ 3 ; C:B7 :3D3: 3@ =9 E3::A 3F7AB / B / A7<:3 :=/ B7=< 7=F/ <3 / =C<E/ B3@ 3:3D/ =; B3 A/ ::=E3@ E3:: E3@ 3 BG>7/ ::G >@ 7=@ 7B7H 3 / B7< =<B=C@ A + / A 33< >C; >7< / B / B3 = >; A7<3 C<3 "! "=B ; 3/ AC@ 3 "' "=B A/ ; >:3 Groundwater s and MW-S Distribution in MW-S9 Bedrock Groundwater, Most Recent Data Through September 8 HA- HA-A :A < 'C>3@ C< '7B3 =<=@!/ AA/ CA3BBA DRAFT 7=F-7=F. &. #B. E7B. + ; F! 33B de maximis, inc. B=<!/ AA/ CA3BBA "=D3; 3@ Figure

9 Tables

10 Table - Groundwater and Surface Water Data Demonstration of Compliance Plan Non Time Critical Removal Action (NTCRA) Nuclear Metals Superfund Site Concord, MA Geosyntec Consultants Location Name Measuring Point (TOR; ft NGVD) Geologic Unit Depth to Water (ft) Baseline: //7 Groundwater (ft NGVD) Week : /3/7 Flowrate = 7-8 GPM Depth to Water (ft) Groundwater (ft NGVD) Week : //7 Flowrate = GPM Depth to Water (ft) Groundwater (ft NGVD) Week 3: /3/7 Flowrate = GPM Depth to Water (ft) Groundwater (ft NGVD) Week : //7 Flowrate = GPM Depth to Water (ft) Groundwater (ft NGVD) Week : /8/7 Flowrate = GPM Depth to Water (ft) Groundwater (ft NGVD) Week : 7//7 Flowrate = GPM Depth to Water (ft) Groundwater (ft NGVD) EW- 3. Overburden Overburden AR Overburden AR Overburden AR-PHS 8. Surface Water ASBRV-U 38.8 Surface Water.7.7*..3*..*..79*..8* 3..9*.3.*.8.77* *.79.* B Overburden LF-D. Overburden LF-DBR. Bedrock LF-SBR. Bedrock MW-S 9.9 Overburden MW-BS 93.8 Bedrock MW-S 3. Overburden MW-BM 3. Bedrock MW-BS 3.8 Bedrock MW-S 3. Overburden MW-SD 3. Overburden MW-BS 3.8 Bedrock MW-BS3 39. Bedrock MW-S3 3.3 Overburden MW-SD Overburden MW-BS3 3.3 Bedrock MW-SD3 33. Overburden MW-BS3 33. Bedrock MW-S Overburden MW-SD Overburden MW-BS Bedrock MW-S3 3.9 Overburden MW-SD Overburden MW-BS3 3.7 Bedrock MW-S37.9 Overburden MW-SD37. Overburden MW-BS37.9 Bedrock MW-S38 3. Overburden MW-SD Overburden MW-BS Bedrock MW-S Overburden MW-SD Overburden MW-BS39 3. Bedrock MW-S 38.7 Overburden MW-SD 38.7 Overburden MW-BS 38.7 Bedrock MW-SD 3. Overburden MW-SDA 37.7 Overburden MW-SD Overburden MW-SD 37. Overburden MW-SD. Overburden MW-SM. Overburden MW-SD.37 Overburden MW-BS.3 Bedrock OW- 3.3 Overburden Abandoned Abandoned Abandoned Abandoned Abandoned Abandoned OW-.9 Overburden PT-9 3. Overburden PT Overburden PZ-A 39.8 Overburden PZ-A 37.7 Overburden PT- 3.3 Overburden A Overburden A Overburden A Overburden LF8D 33.8 Overburden LF8DBR 33.7 Bedrock LF8SBR 33.8 Bedrock R Overburden R-A 38.8 Overburden R-3P.97 Overburden A8-78 Not Measured PZ-Mpond 9. Overburden SG-Mpond 8.8 Surface Water PZ-Tpond 8. Overburden SG-Tpond 8. Surface Water Notes. NGVD = National Geodetic Vertical Datum of 99.. TOR = top of riser 3. ft = feet. "-" = not measured. Flowrate is the groundwater extraction rate from well EW-.. * denotes a corrected elevation. Measurment location was changed due to accessibility to bridge during construction. The elevation difference was surveyed and determined to be 8.3 feet. Month 3: 8//7 Flowrate = GPM Depth to Water (ft) Groundwater (ft NGVD) Month : 9//7 Flowrate = GPM Depth to Water (ft) Groundwater (ft NGVD) Month : //7 Flowrate = GPM Depth to Water (ft) Groundwater (ft NGVD) Month : /9/7 Flowrate = GPM Depth to Water (ft) Groundwater (ft NGVD) Quarter : /8/7 Flowrate = GPM Depth to Water (ft) Groundwater (ft NGVD) Quarter : 3//8 Flowrate = GPM Depth to Water (ft) Groundwater (ft NGVD) Quarter 3: //8 Flowrate = GPM Depth to Water (ft) Groundwater (ft NGVD) Quarter : 9/7/8 Flowrate = GPM Depth to Water (ft) Groundwater (ft NGVD) Page of November 8

11 Table.- Groundwater Quality Results- Overburden Demonstration of Compliance Plan Non-Time Critical Removal Action (NTCRA) Nuclear Metals Superfund Site Concord, MA Overburden ASSABET-A ASSABET-A MW- MW-S3 MW-SD3 PT-P MW-S3 MW-SD3 MW-SD37 MW-S37 MW-S38 MW-SD38 Parameter Unit PRG 7//8 8//8 9//8 7//8 8//8 9//8 /8/8 9//8 /8/8 9/9/8 /8/8 9/9/8 /7/8 9//8 //8 9/9/8 //8 9/9/8 //8 9//8 //8 9/9/8 //8 9//8 //8 9//8 General Chemistry Sulfate as SO µg/l Volatile Organic Compounds,,,-Tetrachloroethane µg/l < <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <.,,-Trichloroethane µg/l < < J.3 J <. <. <. <. <. <. <. <. <. <. <. <. <. <.,,,-Tetrachloroethane µg/l < <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <.,,-Trichloroethane µg/l < <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <.,-Dichloroethane µg/l < <..89 J.. J. J <. <. <. <. <. <. <. <.. J. J <. <. <. <. <. <.,-Dichloroethene µg/l < <..88 J...87 J.8 J.3 J <. <. <. <. <. <...9 J <. <. <. <...,-Dichloropropene µg/l < <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <.,,3-Trichlorobenzene µg/l < <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <.,,3-Trichloropropane µg/l < <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <.,,-Trichlorobenzene µg/l < <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <.,,-Trimethylbenzene µg/l < <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <.,-Dibromo-3-chloropropane µg/l < <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <.,-Dibromoethane µg/l < <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <.,-Dichlorobenzene µg/l < <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <.,-Dichloroethane µg/l < <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <.,-Dichloroethylene (total) µg/l < <..9 J. J. J <. <. <. <. <. <. <..9 J...9 <. <. <. <. <. <.,-Dichloropropane µg/l < <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <.,3,-Trimethylbenzene µg/l < <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <.,3-Dichlorobenzene µg/l < <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <.,3-Dichloropropane µg/l < <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <.,3-Dichloropropene, Total µg/l < <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <.,-Dichlorobenzene µg/l < <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <.,-Dichloropropane µg/l < <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. -Chlorotoluene µg/l < <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. -Hexanone µg/l < <. <. J <. <. J <. <. J <. <. J <. <. <. <. <. <. <. <. <. <. <. <. <. -Chlorotoluene µg/l < <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. -Methyl--Pentanone µg/l < <. <. <. <. J <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. Acetone µg/l < <. <. <. <. J <. <. <. <. <. <. J <. <. J <. <. <. <. <. <. J <. <. <. Benzene µg/l < <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. Bromobenzene µg/l < <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. Bromochloromethane µg/l < <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. Bromodichloromethane µg/l < <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. Bromoform µg/l < <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. Bromomethane µg/l < <. <. <. <. J <. <. <. <. <. <. J <. <. J <. <. <. <. <. <. J <. <. <. Carbon disulfide µg/l < <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. Carbon tetrachloride µg/l < <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. Chlorobenzene µg/l < <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. Chloroethane µg/l < <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. Chloroform µg/l < <.. J. J <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. Chloromethane µg/l < <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. cis-,-dichloroethene µg/l < <..9 J. J. J <. <. <. <. <. <. <..9 J...9 <. <. <. <. <. <. cis-,3-dichloropropene µg/l < <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. Dibromochloromethane µg/l < <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. Dibromomethane µg/l < <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. Dichlorodifluoromethane µg/l < <. <. J <. <. J <. <. J <. <. J <. <. <. <. <. <. <. <. <. <. <. <. <. Ethyl ether µg/l < <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. Ethyl tert-butyl ether µg/l < <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. Ethylbenzene µg/l < <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. Hexachlorobutadiene µg/l < <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. Volatile Organic Compounds cont. Isopropyl Ether µg/l < <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. Isopropylbenzene µg/l < <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. m-&p-xylenes µg/l < <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. Methyl Ethyl Ketone (-Butanone) µg/l < <. <. J <. <. <. <. J <. <. J <. <. <. <. <. <. <. <. <. <. <. <. <. Methyl tert-butyl ether µg/l < <. <. <. <. <. <. <. <. <. <. <..77 J. J..3 <. <. <. <. <. <. Methylene Chloride µg/l < <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. Naphthalene µg/l < <. <. J <. <. <..3 J <. <. J <. <. <. <. <. <. <. <. <. <. <..33 J <. N-Butylbenzene µg/l < <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. N-Propylbenzene µg/l < <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. o-xylene µg/l < <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. P-Isopropyltoluene µg/l < <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. Sec-Butylbenzene µg/l < <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. Styrene µg/l < <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. tert-amyl methyl ether µg/l < <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. Tert-Butylbenzene µg/l < <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. Tetrachloroethylene µg/l < <..3 J.33 J <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. Tetrahydrofuran µg/l < <. <. <. <. J <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. Toluene µg/l < <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. trans-,-dichloroethene µg/l < <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. trans-,3-dichloropropene µg/l < <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. µg/l < < J.7 J.9 J.3 J <. <. <. <. <. <. Trichlorofluoromethane µg/l < <. <. <. <. <. <. <..37 J. J <. <. <. <. <. <. <. <. <. <. <. <. Vinyl Chloride µg/l < <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <.. J. J Xylenes (total) µg/l < <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. <. Semi Volatile Organic Compounds µg/l. c < J.8 J <.3 <. <.. J J,N Detected concentrations are bold Exceedances of the PRG are shaded gray

12 Table.- Groundwater Quality Results- Overburden Demonstration of Compliance Plan Non-Time Critical Removal Action (NTCRA) Nuclear Metals Superfund Site Concord, MA Overburden MW-S39 MW-SD39 MW-S MW-SD MW-SD MW-SDA MW-SD3 MW-SD MW-SD MW-S MW-SD PT-9 Parameter Unit PRG //8 9//8 //8 9//8 /7/8 9//8 /7/8 9//8 //8 9//8 8//8 9//8 //8 9//8 8//8 9//8 //8 9//8 //8 9//8 //8 9//8 /7/8 9//8 General Chemistry Sulfate as SO µg/l J Volatile Organic Compounds,,,-Tetrachloroethane µg/l -- <. <. <. <. <. <. <. J <. <. <. -- <. <. <. -- <. <. <. <. <. <. <. <. J <.,,-Trichloroethane µg/l -- <. <. <. <. <. <. <. J <. <. <. -- <. <. <. -- <. <. <. <. <. <. <. <. J <.,,,-Tetrachloroethane µg/l -- <. <. <. <. <. <. <. J <. <. <. -- <. <. <. -- <. <. <. <. <. <. <. <. J <.,,-Trichloroethane µg/l -- <. <. <. <. <. <. <. J <. <. <. -- <. <. <. -- <. <. <. <. <. <. <. <. J <.,-Dichloroethane µg/l -- <. <. <. <. <. <. <. J <. <. <. --. J <. <. -- <. <. <..8 J.3 J <. <. <. J <.,-Dichloroethene µg/l -- <. <. <. <. <. <. <. J < <. <. --. <. <....7 J.7 J <. J <.,-Dichloropropene µg/l -- <. <. <. <. <. <. <. J <. <. <. -- <. <. <. -- <. <. <. <. <. <. <. <. J <.,,3-Trichlorobenzene µg/l -- <. <. <. <. <. <. <. J <. <. <. -- <. <. <. -- <. <. <. <. <. <. <. <. J <.,,3-Trichloropropane µg/l -- <. <. <. <. <. <. <. J <. <. <. -- <. <. <. -- <. <. <. <. <. <. <. <. J <.,,-Trichlorobenzene µg/l -- <. <. <. <. <. <. <. J <. <. <. -- <. <. <. -- <. <. <. <. <. <. <. <. J <.,,-Trimethylbenzene µg/l -- <. <. <. <. <. <. <. J <. <. <. -- <. <. <. -- <. <. <. <. <. <. <. <. J <.,-Dibromo-3-chloropropane µg/l -- <. <. <. <. <. <. <. J <. <. <. -- <. <. <. -- <. <. <. <. <. <. <. <. J <.,-Dibromoethane µg/l -- <. <. <. <. <. <. <. J <. <. <. -- <. <. <. -- <. <. <. <. <. <. <. <. J <.,-Dichlorobenzene µg/l -- <. <. <. <. <. <. <. J <. <. <. -- <. <. <. -- <. <. <. <. <. <. <. <. J <.,-Dichloroethane µg/l -- <. <. <. <. <. <. <. J <. <. <. -- <. <. <. -- <. <. <. <. <. <. <. <. J <.,-Dichloroethylene (total) µg/l -- <. <..7 J.8 J <. <. <. J <. <. < J.. -- <. <. <.. J. J <. <. <. J <.,-Dichloropropane µg/l -- <. <. <. <. <. <. <. J <. <. <. -- <. <. <. -- <. <. <. <. <. <. <. <. J <.,3,-Trimethylbenzene µg/l -- <. <. <. <. <. <. <. J <. <. <. -- <. <. <. -- <. <. <. <. <. <. <. <. J <.,3-Dichlorobenzene µg/l -- <. <. <. <. <. <. <. J <. <. <. -- <. <. <. -- <. <. <. <. <. <. <. <. J <.,3-Dichloropropane µg/l -- <. <. <. <. <. <. <. J <. <. <. -- <. <. <. -- <. <. <. <. <. <. <. <. J <.,3-Dichloropropene, Total µg/l -- <. <. <. <. <. <. <. J <. <. <. -- <. <. <. -- <. <. <. <. <. <. <. <. J <.,-Dichlorobenzene µg/l -- <. <. <. <. <. <. <. J <. <. <. -- <. <. <. -- <. <. <. <. <. <. <. <. J <.,-Dichloropropane µg/l -- <. <. <. <. <. <. <. J <. <. <. -- <. <. <. -- <. <. <. <. <. <. <. <. J <. -Chlorotoluene µg/l -- <. <. <. <. <. <. <. J <. <. <. -- <. <. <. -- <. <. <. <. <. <. <. <. J <. -Hexanone µg/l -- <. <. <. <. <. J <. <. J <. <. <. -- <. <. <. -- <. <. <. <. <. <. <. <. J <. -Chlorotoluene µg/l -- <. <. <. <. <. <. <. J <. <. <. -- <. <. <. -- <. <. <. <. <. <. <. <. J <. -Methyl--Pentanone µg/l -- <. <. <. <. <. <. <. J <. <. <. -- <. <. <. -- <. <. <. <. <. <. <. <. J <. Acetone µg/l -- <. <.. J <. <. <. <. J <. <. <. -- <. <. <. -- <. <. <. <. J <. <. <. <. J <. Benzene µg/l -- <. <. <. <. <. <. <. J <. <. <. -- <. <. <. -- <. <. <. <. <. <. <. <. J <. Bromobenzene µg/l -- <. <. <. <. <. <. <. J <. <. <. -- <. <. <. -- <. <. <. <. <. <. <. <. J <. Bromochloromethane µg/l -- <. <. <. <. <. <. <. J <. <. <. -- <. <. <. -- <. <. <. <. <. <. <. <. J <. Bromodichloromethane µg/l -- <. <. <. <. <. <. <. J <. <. <. -- <. <. <. -- <. <. <. <. <. <. <. <. J <. Bromoform µg/l -- <. <. <. <. <. <. <. J <. <. <. -- <. <. <. -- <. <. <. <. <. <. <. <. J <. Bromomethane µg/l -- <. <. <. <. <. <. <. J <. <. <. -- <. <. <. -- <. <. <. <. J <. <. <. <. J <. Carbon disulfide µg/l -- <. <. <. <. <. <. <. J <. <. <. -- <. <. <. -- <. <. <. <. <. <. <. <. J <. Carbon tetrachloride µg/l -- <. <. <. <. <. <. <. J <. <. <. -- <. <. <. -- <. <. <. <. <. <. <. <. J <. Chlorobenzene µg/l -- <. <. <. <. <. <. <. J <. <. <. -- <. <. <. -- <. <. <. <. <. <. <. <. J <. Chloroethane µg/l -- <. <. <. <. <. <. <. J <. <. <. -- <. <. <. -- <. <. <. <. <. <. <. <. J <. Chloroform µg/l -- <. <. <. <. <. <. <. J <. <. <. -- <. <. <. -- <. <. <. <. <. <. <. <. J <. Chloromethane µg/l -- <. <. <. <. <. <. <. J <. <. <. -- <. <. <. -- <. <. <. <. <. <. <. <. J <. cis-,-dichloroethene µg/l -- <. <..7 J.8 J <. <. <. J <. <. < J.. -- <. <. <.. J. J <. <. <. J <. cis-,3-dichloropropene µg/l -- <. <. <. <. <. <. <. J <. <. <. -- <. <. <. -- <. <. <. <. <. <. <. <. J <. Dibromochloromethane µg/l -- <. <. <. <. <. <. <. J <. <. <. -- <. <. <. -- <. <. <. <. <. <. <. <. J <. Dibromomethane µg/l -- <. <. <. <. <. <. <. J <. <. <. -- <. <. <. -- <. <. <. <. <. <. <. <. J <. Dichlorodifluoromethane µg/l -- <. <. <. <. <. J <. <. J <. <. <. -- <. <. <. -- <. <. <. <. <. <. <. <. J <. Ethyl ether µg/l -- <. <. <. <. <. <. <. J <. <. <. -- <. <. <. -- <. <. <. <. <. <. <. <. J <. Ethyl tert-butyl ether µg/l -- <. <. <. <. <. <. <. J <. <. <. -- <. <. <. -- <. <. <. <. <. <. <. <. J <. Ethylbenzene µg/l -- <. <. <. <. <. <. <. J <. <. <. -- <. <. <. -- <. <. <. <. <. <. <. <. J <. Hexachlorobutadiene µg/l -- <. <. <. <. <. <. <. J <. <. <. -- <. <. <. -- <. <. <. <. <. <. <. <. J <. Volatile Organic Compounds cont. Isopropyl Ether µg/l -- <. <. <. <. <. <. <. J <. <. <. -- <. <. <. -- <. <. <. <. <. <. <. <. J <. Isopropylbenzene µg/l -- <. <. <. <. <. <. <. J <. <. <. -- <. <. <. -- <. <. <. <. <. <. <. <. J <. m-&p-xylenes µg/l -- <. <. <. <. <. <. <. J <. <. <. -- <. <. <. -- <. <. <. <. <. <. <. <. J <. Methyl Ethyl Ketone (-Butanone) µg/l -- <. <. <. <. <. J <. <. J <. <. <. -- <. <. <. -- <. <. <. <. <. <. <. <. J <. Methyl tert-butyl ether µg/l -- <. <.. J. J <. <. <. J <. <. < J. J.3 -- <. <. <..8 J. J.8 J.7 J <. J <. Methylene Chloride µg/l -- <. <. <. <. <. <. <. J <. <. <. -- <. <. <. -- <. <. <. <. <. <. <. <. J <. Naphthalene µg/l -- <. <. <. <. <. J <..33 J <..3 J <. -- <. <. <. -- <..33 J <. <. <. <. <..3 J <. N-Butylbenzene µg/l -- <. <. <. <. <. <. <. J <. <. <. -- <. <. <. -- <. <. <. <. <. <. <. <. J <. N-Propylbenzene µg/l -- <. <. <. <. <. <. <. J <. <. <. -- <. <. <. -- <. <. <. <. <. <. <. <. J <. o-xylene µg/l -- <. <. <. <. <. <. <. J <. <. <. -- <. <. <. -- <. <. <. <. <. <. <. <. J <. P-Isopropyltoluene µg/l -- <. <. <. <. <. <. <. J <. <. <. -- <. <. <. -- <. <. <. <. <. <. <. <. J <. Sec-Butylbenzene µg/l -- <. <. <. <. <. <. <. J <. <. <. -- <. <. <. -- <. <. <. <. <. <. <. <. J <. Styrene µg/l -- <. <. <. <. <. <. <. J <. <. <. -- <. <. <. -- <. <. <. <. <. <. <. <. J <. tert-amyl methyl ether µg/l -- <. <. <. <. <. <. <. J <. <. <. -- <. <. <. -- <. <. <. <. <. <. <. <. J <. Tert-Butylbenzene µg/l -- <. <. <. <. <. <. <. J <. <. <. -- <. <. <. -- <. <. <. <. <. <. <. <. J <. Tetrachloroethylene µg/l -- <. <. <. <. <. <..3 J <. <. <. -- <. <. <. -- <. <. <. <. <. <. <. <. J <. Tetrahydrofuran µg/l -- <. <. <. <. <. <. <. J <. <. <. -- <. <. <. -- <. <. <. <. <. <. <. <. J <. Toluene µg/l -- <. <. <. <. <. <. <. J <. <. <. -- <. <. <. -- <. <. <. <. <. <. <. <. J <. trans-,-dichloroethene µg/l -- <. <. <. <. <. <. <. J <. <. <. -- <. <. <. -- <. <. <. <. <. <. <. <. J <. trans-,3-dichloropropene µg/l -- <. <. <. <. <. <. <. J <. <. <. -- <. <. <. -- <. <. <. <. <. <. <. <. J <. µg/l <. <..3 J. J <. <..7 J.. J.3 J J <. <...88 J. J. J.7 J.3 J Trichlorofluoromethane µg/l -- <. <. <. <. <. <. <. J <. <. <. -- <. <. <. -- <. <. <. <. <. <. <. <. J <. Vinyl Chloride µg/l <. <. <. <. <. <. <. J <. <.. J --. J <. <. --. J <. <..8 J. J <. <. <. J <. Xylenes (total) µg/l -- <. <. <. <. <. <. <. J <. <. <. -- <. <. <. -- <. <. <. <. <. <. <. <. J <. Semi Volatile Organic Compounds µg/l. c <.7 <.39 <. < <..9 J Detected concentrations are bold Exceedances of the PRG are shaded gray

13 Table.- Groundwater Quality Results- Bedrock Demonstration of Compliance Plan Non-Time Critical Removal Action (NTCRA) Nuclear Metals Superfund Site Concord, MA Bedrock ASSABET-A ASSABET-A MW-BS MW-BS3 MW-BS3 MW-BS3 MW-SD3 Parameter Unit PRG 7//8 8//8 9//8 7//8 8//8 9//8 7//8 9//8 /8/8 9/9/8 /8/8 9/9/8 /7/8 9//8 /7/8 9//8 General Chemistry Sulfate as SO µg/l Metals Iron, dissolved µg/l Iron, total µg/l Volatile Organic Compounds,,,-Tetrachloroethane µg/l < <. <. <. <. J <. <. <. <. <. <. J <.,,-Trichloroethane µg/l < <. <. <. <. J <. <. <. <. <..9 J.8 J,,,-Tetrachloroethane µg/l < <. <. <. <. J <. <. <. <. <. <. J <.,,-Trichloroethane µg/l < <. <. <. <. J <. <. <. <. <. <. J <.,-Dichloroethane µg/l < <.... J <..7 J. J <. <.. J.7 J,-Dichloroethene µg/l < <. <..3 J. J <...9 J <. <..9 J.8 J,-Dichloropropene µg/l < <. <. <. <. J <. <. <. <. <. <. J <.,,3-Trichlorobenzene µg/l < <. <. <. <. J <. <. <. <. <. <. J <.,,3-Trichloropropane µg/l < <. <. <. <. J <. <. <. <. <. <. J <.,,-Trichlorobenzene µg/l < <. <. <. <. J <. <. <. <. <. <. J <.,,-Trimethylbenzene µg/l < <. <. <. <. J <. <. <. <. <. <. J <.,-Dibromo-3-chloropropane µg/l < <. <. <. <. J <. <. <. <. <. <. J <.,-Dibromoethane µg/l < <. <. <. <. J <. <. <. <. <. <. J <.,-Dichlorobenzene µg/l < <. <. <. <. J <. <. <. <. <. <. J <.,-Dichloroethane µg/l < <. <. <. <. J <. <. <. <. <. <. J <.,-Dichloroethylene (total) µg/l < <..3 J. J.8 J. J.7 J.8 J <. <..3 J. J,-Dichloropropane µg/l < <. <. <. <. J <. <. <. <. <. <. J <.,3,-Trimethylbenzene µg/l < <. <. <. <. J <. <. <. <. <. <. J <.,3-Dichlorobenzene µg/l < <. <. <. <. J <. <. <. <. <. <. J <.,3-Dichloropropane µg/l < <. <. <. <. J <. <. <. <. <. <. J <.,3-Dichloropropene, Total µg/l < <. <. <. <. J <. <. <. <. <. <. J <.,-Dichlorobenzene µg/l < <. <. <. <. J <. <. <. <. <. <. J <.,-Dichloropropane µg/l < <. <. <. <. J <. <. <. <. <. <. J <. -Chlorotoluene µg/l < <. <. <. <. J <. <. <. <. <. <. J <. -Hexanone µg/l < <. <. <. <. J <. <. J <. <. J <. <. J <. -Chlorotoluene µg/l < <. <. <. <. J <. <. <. <. <. <. J <. -Methyl--Pentanone µg/l < <. <. <. <. J <. <. <. <. <. <. J <. Acetone µg/l < <. <. <. <. J <. <. <. <. <. <. J <. Benzene µg/l < <. <. <. <. J <. <. <. <. <. <. J <. Bromobenzene µg/l < <. <. <. <. J <. <. <. <. <. <. J <. Bromochloromethane µg/l < <. <. <. <. J <. <. <. <. <. <. J <. Bromodichloromethane µg/l < <. <. <. <. J <. <. <. <. <. <. J <. Bromoform µg/l < <. <. <. <. J <. <. <. <. <. <. J <. Bromomethane µg/l < <. <. <. <. J <. <. <. <. <. <. J <. Carbon disulfide µg/l < <. <. <. <. J <. <. <. <. <. <. J <. Carbon tetrachloride µg/l < <. <. <. <. J <. <. <. <. <. <. J <. Chlorobenzene µg/l < <. <. <. <. J <. <. <. <. <. <. J <. Chloroethane µg/l < <. <. <. <. J <. <. <. <. <. <. J <. Chloroform µg/l < <. <. <. <. J <. <. <. <. <. <. J <. Chloromethane µg/l < <. <. <. <. J <. <. <. <. <. <. J <. cis-,-dichloroethene µg/l < <..3 J. J.8 J. J.7 J.8 J <. <..3 J. J cis-,3-dichloropropene µg/l < <. <. <. <. J <. <. <. <. <. <. J <. Dibromochloromethane µg/l < <. <. <. <. J <. <. <. <. <. <. J <. Dibromomethane µg/l < <. <. <. <. J <. <. <. <. <. <. J <. Dichlorodifluoromethane µg/l < <. <. <. <. J <. <. J <. <. J <. <. J <. Ethyl ether µg/l < <. <. <. <. J <. <. <. <. <. <. J <. Ethyl tert-butyl ether µg/l < <. <. <. <. J <. <. <. <. <. <. J <. Ethylbenzene µg/l < <. <. <. <. J <. <. <. <. <. <. J <. Hexachlorobutadiene µg/l < <. <. <. <. J <. <. <. <. <. <. J <. Volatile Organic Compounds cont. Isopropyl Ether µg/l < <. <. <. <. J <. <. <. <. <. <. J <.

14 Table.- Groundwater Quality Results- Bedrock Demonstration of Compliance Plan Non-Time Critical Removal Action (NTCRA) Nuclear Metals Superfund Site Concord, MA Bedrock ASSABET-A ASSABET-A MW-BS MW-BS3 MW-BS3 MW-BS3 MW-SD3 Parameter Unit PRG 7//8 8//8 9//8 7//8 8//8 9//8 7//8 9//8 /8/8 9/9/8 /8/8 9/9/8 /7/8 9//8 /7/8 9//8 Isopropylbenzene µg/l < <. <. <. <. J <. <. <. <. <. <. J <. m-&p-xylenes µg/l < <. <. <. <. J <. <. <. <. <. <. J <. Methyl Ethyl Ketone (-Butanone) µg/l < <. <. <. <. J <. <. J <. <. J <. <. J <. Methyl tert-butyl ether µg/l < <. <. <. <. J <. <. <. <. <. <. J <. Methylene Chloride µg/l < <. <. <. <. J <. <. <. <. <. <. J <. Naphthalene µg/l < <. <. <..3 J <..3 J <. <. J <. <. J <. N-Butylbenzene µg/l < <. <. <. <. J <. <. <. <. <. <. J <. N-Propylbenzene µg/l < <. <. <. <. J <. <. <. <. <. <. J <. o-xylene µg/l < <. <. <. <. J <. <. <. <. <. <. J <. P-Isopropyltoluene µg/l < <. <. <. <. J <. <. <. <. <. <. J <. Sec-Butylbenzene µg/l < <. <. <. <. J <. <. <. <. <. <. J <. Styrene µg/l < <. <. <. <. J <. <. <. <. <. <. J <. tert-amyl methyl ether µg/l < <. <. <. <. J <. <. <. <. <. <. J <. Tert-Butylbenzene µg/l < <. <. <. <. J <. <. <. <. <. <. J <. Tetrachloroethylene µg/l < <. <..38 J <. J <..3 J.3 J <. <..78 J. J Tetrahydrofuran µg/l < <. <. <. <. J <. <. <. <. <. <. J <. Toluene µg/l < <. <. <. <. J <. <. <. <. <. <. J <. trans-,-dichloroethene µg/l < <. <. <. <. J <. <. <. <. <. <. J <. trans-,3-dichloropropene µg/l < <. <. <. <. J <. <. <. <. <. <. J <. µg/l < < J.73 J.3. <. <.. J. Trichlorofluoromethane µg/l < <. <. <. <. J <. <. <. <. <. <. J <. Vinyl Chloride µg/l < <. <. <. <. J <. <. <. <. <. <. J <. Xylenes (total) µg/l < <. <. <. <. J <. <. <. <. <. <. J <. Semi Volatile Organic Compounds µg/l. c < Detected concentrations are bold Exceedances of the PRG are shaded gray