----------1+----~~~--0~~ rr~J(5UU mew =shy_ __0_l4poundDODD M1f qdo ~~middot--------

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----~~--------------------------

I I

------~~ Jlt ~ J10ftL~~2lpound~-~) ~ - j~ 1 ~ ~------~L~)~c___~H--- - -----t tfl-2

-----------------------------------------------------------shy

----shy----shy---shy-----i

------+1--shy

~~~_Ls_~l11 _ v _amp110 j)40 j ~~ = l-n1- fi--J l) _______ _ _____-400 jd ltSc1lij101 _ -2-5 Pl rn 11 W4rjshy

-

L CCyen1~~ whv t LQtLtj1d1-n

j(wr ~~rmiddot--shy

Lur1hu gTL-~ L1 1-1 )JS ~--~--~---F~~~~-----------------shy

~~1 +---~shy---=shy- tf l~tf (Y J

---shy

-- --- --middot-H----- --------------------------shy

++----~ 4ltmiddot~1_f i1tVamp~C~~ _lht~ ~vt~il r1~---shy----- -----~-LuLltY- u t~tLUC Std lrt1afO cfue___ Ait~lu ~__llff ~--shy

--------------------------------------------------shy

---------~---------------------------------------------shy

City of New Bedford Massachusetts

Main Interceptor Grit and Sediment Removal

January 2009

Technical Document

Appendix 0 Current Work and Investigations

sampler was used for grit depths deeper than 4-6 inches while a clam-style dredge was most effective for the shallower depths (1-4 inches) Figure D-1 shows a typical set-up during the sampling program

Grit and sediment depths were calculated as the difference between the manhole rim to invert (based on record drawings) and rim to grit measurements The distance to the top of the grit was measured by tape measure andor graduated markings on the core sampler Material investigation activities were recorded in a field book included in Appendix A of COMs New Bedford Main Interceptor Grit Investigation Report dated February 2008

D232 Grit Characterization

The grit sampling results indicate that the grit and sediment material generally includes fine gravel and coarse to medium sand sized particles This is consistent with the 1990 COM grit study Additionally the results indicate these physical properties were generally consistent throughout the interceptor The specific gravity (SG) (ratio of materials weight to the weight of an equal volume of water) of the samples averaged 265 One sample MH-20080 was reported to have a SG of 245 The laboratory indicated that this sample contained an oily product that skewed the test results and the actual SG is probably closer to 265 The laboratory results for the physical characteristic analyses are provided in Appendix C of COMs New Bedford Main Interceptor Grit Investigation Report dated February 2008

Deeper grit samples tended to have a fluidized layer on top (-0-6 inches) with the bottom material having a varying makeup of compacted material that ranged from mostly fine sand and silt to a poorly graded material having the same coarse sand and fine gravel as found in the top -6 inches

COM submitted the 31 grit samples to Alpha Analytical Laboratories for PCB analyses by MCP method 8082 The samples were extracted by the Accelerated Solvent Exchange (AES) extraction method 3546 Table 2-1 of COMs report New Bedford Main Interceptor Grit Investigation Report dated February 2008 summarizes the PCB results for each of the grit samples collected The laboratory data packages are provided in Appendix D

PCBs were detected in all but one sample above the method detection limits and PCB concentrations ranged from of 0180 to 2770 mgkg The data indicate that two samples had PCB detections above the TSCA disposal criteria of 50 ppm These results are summarized below

bull MH-23783-2 2770 mgkg bull 12-15 inch depth interval at manhole 237+83

bull MH-22680 145 mgkg bull 0-11 inch depth interval at manhole 226+80

CDM D-4

o

Appendix A Project Background and History

This Appendix provides a brief history of the project and background information on previous studies that have been conducted between 1980 and 2006

Al Introduction COM and the City have been working together to identify and quantify the extent of grit deposition and PCB contamination within the Citys Main Interceptor extending approximately 19000-ft from the intersection of Pearl Street and Acushnet Avenue southerly to the intersection of West Rodney French Boulevard and South Rodney French Boulevard Several investigations have taken place since the 1980s including extensive sampling by COM in 1987 1990 and 2007 and the City in 2006 The sampling programs identified approximately 2700 cubic yards to 5500 cubic yards of material along the invert of the interceptor The grit and sediment buildup is associated with sand and debris carried by storm water drainage from City streets into the combined sewer system from catch basins and other structures Deposition of grit along the invert of the Main Interceptor is a result of low velocities from a number of factors including shallow pipe slope obstructions pipe directional changes and reduced wastewater flows

PCB contamination of the grit is the result of industrial activities discharging PCB contaminated waste to the Citys collection system between 1930 and the 1970s Grit samples taken by COM as part of the 2007 program indicates that a 3256-ft section of Interceptor between Pearl Street and Acushnet Avenue and Water Street and William Street exceed PCB concentrations of 50 ppm requiring disposal at a Toxic Substance Control Act (TSCA) approved landfill for PCB remediation waste The remainder of the samples south of William Street indicate PCB concentrations between 10 ppm and non-detect

A2 Project Background The New Bedford Main Intercepting Sewer extending from the intersection of Pearl Street and Acushnet A venue to the former screen house on Rodney French Boulevard has accumulated grit deposits which have significantly reduced its flow capacity The extent of grit accumulation covers approximately 17300 linear feet The Interceptor sewer size and configuration varies through this area from a minimum height of 69 inches to a maximum height of 92 inches at the downstream end

The grit deposits were the subject of an investigation completed by COM and documented in a report titled Report on Part I of Grit Investigation in Main Interceptor dated May 1990 The report documented the presence of grit accumulated within the interceptor from station 328+81 in Belleville Avenue to station 100+00 in Rodney French Blvd Grit thickness was measured at 69 out of a total of 77 manholes on the interceptor Composite grit samples were obtained from 30 manhole locations and analyzed for various contaminants including polychlorinated biphenyls

CDM A-1

~pendixA

Appendix A Project Background and History

(PCBs) The interceptor was divided into eleven segments delineated based on estimated equal volumesof grit The investigation indicated PCB concentrations in excess of 50 mgkg in six of the eleven sample groups The investigation indicated decreasing concentrations of PCBs with distance downstream with concentrations anticipated to average below 50 mgkg downstream of station 247+90 The report included a profile of the interceptor showing grit thickness and provides a baseline for the recent grit investigation indicating the continued accumulation of grit

The June 2006 grit investigation by the City of New Bedford (City) included the collection of eight composite samples with analyses for the following parameters

Total Organic Carbon (TOC) Total Petroleum Hydrocarbons (TPH) PCBs Volatile Organic Hydrocarbons (VOC) Semivolatile Organic Hydrocarbons (SVOC)

The results indicated total PCB concentrations ranging from 022 mgkg to 4530 mgkg with the highest concentration reported at one of the upstream locations in the vicinity of Willis Street The lowest PCB concentration was reported furthest downstream at station 157+03 at the intersection of Delano Street and Second Street The analytical data also indicated eleva ted concentrations of other contaminants however it is likely that the PCB concentrations will be the primary factor regarding disposal requirements The volume of grit in the interceptor was estimated at 5500 CY

A3 Project Location The grit is present in the New Bedford Main Interceptor from Station 253+70 near the intersection of Pearl Street and Acushnet Avenue to Station 79+57 at the location of the former screen house on West Rodney French Boulevard The project location is shown on Figures 1-1 and 1-2 appended to this Appendix from the New Bedford Main

Interceptor Grit Investigation Report by COM dated February 2008

CDM A-2

AopendixA

I I

------~~ Jlt ~ J10ftL~~2lpound~-~) ~ - j~ 1 ~ ~------~L~)~c___~H--- - -----t tfl-2

-----------------------------------------------------------shy

----shy----shy---shy-----i

------+1--shy

~~~_Ls_~l11 _ v _amp110 j)40 j ~~ = l-n1- fi--J l) _______ _ _____-400 jd ltSc1lij101 _ -2-5 Pl rn 11 W4rjshy

-

L CCyen1~~ whv t LQtLtj1d1-n

j(wr ~~rmiddot--shy

Lur1hu gTL-~ L1 1-1 )JS ~--~--~---F~~~~-----------------shy

~~1 +---~shy---=shy- tf l~tf (Y J

---shy

-- --- --middot-H----- --------------------------shy

++----~ 4ltmiddot~1_f i1tVamp~C~~ _lht~ ~vt~il r1~---shy----- -----~-LuLltY- u t~tLUC Std lrt1afO cfue___ Ait~lu ~__llff ~--shy

--------------------------------------------------shy

---------~---------------------------------------------shy

City of New Bedford Massachusetts

Main Interceptor Grit and Sediment Removal

January 2009

Technical Document

Appendix 0 Current Work and Investigations

sampler was used for grit depths deeper than 4-6 inches while a clam-style dredge was most effective for the shallower depths (1-4 inches) Figure D-1 shows a typical set-up during the sampling program

Grit and sediment depths were calculated as the difference between the manhole rim to invert (based on record drawings) and rim to grit measurements The distance to the top of the grit was measured by tape measure andor graduated markings on the core sampler Material investigation activities were recorded in a field book included in Appendix A of COMs New Bedford Main Interceptor Grit Investigation Report dated February 2008

D232 Grit Characterization

The grit sampling results indicate that the grit and sediment material generally includes fine gravel and coarse to medium sand sized particles This is consistent with the 1990 COM grit study Additionally the results indicate these physical properties were generally consistent throughout the interceptor The specific gravity (SG) (ratio of materials weight to the weight of an equal volume of water) of the samples averaged 265 One sample MH-20080 was reported to have a SG of 245 The laboratory indicated that this sample contained an oily product that skewed the test results and the actual SG is probably closer to 265 The laboratory results for the physical characteristic analyses are provided in Appendix C of COMs New Bedford Main Interceptor Grit Investigation Report dated February 2008

Deeper grit samples tended to have a fluidized layer on top (-0-6 inches) with the bottom material having a varying makeup of compacted material that ranged from mostly fine sand and silt to a poorly graded material having the same coarse sand and fine gravel as found in the top -6 inches

COM submitted the 31 grit samples to Alpha Analytical Laboratories for PCB analyses by MCP method 8082 The samples were extracted by the Accelerated Solvent Exchange (AES) extraction method 3546 Table 2-1 of COMs report New Bedford Main Interceptor Grit Investigation Report dated February 2008 summarizes the PCB results for each of the grit samples collected The laboratory data packages are provided in Appendix D

PCBs were detected in all but one sample above the method detection limits and PCB concentrations ranged from of 0180 to 2770 mgkg The data indicate that two samples had PCB detections above the TSCA disposal criteria of 50 ppm These results are summarized below

bull MH-23783-2 2770 mgkg bull 12-15 inch depth interval at manhole 237+83

bull MH-22680 145 mgkg bull 0-11 inch depth interval at manhole 226+80

CDM D-4

o

Appendix A Project Background and History

This Appendix provides a brief history of the project and background information on previous studies that have been conducted between 1980 and 2006

Al Introduction COM and the City have been working together to identify and quantify the extent of grit deposition and PCB contamination within the Citys Main Interceptor extending approximately 19000-ft from the intersection of Pearl Street and Acushnet Avenue southerly to the intersection of West Rodney French Boulevard and South Rodney French Boulevard Several investigations have taken place since the 1980s including extensive sampling by COM in 1987 1990 and 2007 and the City in 2006 The sampling programs identified approximately 2700 cubic yards to 5500 cubic yards of material along the invert of the interceptor The grit and sediment buildup is associated with sand and debris carried by storm water drainage from City streets into the combined sewer system from catch basins and other structures Deposition of grit along the invert of the Main Interceptor is a result of low velocities from a number of factors including shallow pipe slope obstructions pipe directional changes and reduced wastewater flows

PCB contamination of the grit is the result of industrial activities discharging PCB contaminated waste to the Citys collection system between 1930 and the 1970s Grit samples taken by COM as part of the 2007 program indicates that a 3256-ft section of Interceptor between Pearl Street and Acushnet Avenue and Water Street and William Street exceed PCB concentrations of 50 ppm requiring disposal at a Toxic Substance Control Act (TSCA) approved landfill for PCB remediation waste The remainder of the samples south of William Street indicate PCB concentrations between 10 ppm and non-detect

A2 Project Background The New Bedford Main Intercepting Sewer extending from the intersection of Pearl Street and Acushnet A venue to the former screen house on Rodney French Boulevard has accumulated grit deposits which have significantly reduced its flow capacity The extent of grit accumulation covers approximately 17300 linear feet The Interceptor sewer size and configuration varies through this area from a minimum height of 69 inches to a maximum height of 92 inches at the downstream end

The grit deposits were the subject of an investigation completed by COM and documented in a report titled Report on Part I of Grit Investigation in Main Interceptor dated May 1990 The report documented the presence of grit accumulated within the interceptor from station 328+81 in Belleville Avenue to station 100+00 in Rodney French Blvd Grit thickness was measured at 69 out of a total of 77 manholes on the interceptor Composite grit samples were obtained from 30 manhole locations and analyzed for various contaminants including polychlorinated biphenyls

CDM A-1

~pendixA

Appendix A Project Background and History

(PCBs) The interceptor was divided into eleven segments delineated based on estimated equal volumesof grit The investigation indicated PCB concentrations in excess of 50 mgkg in six of the eleven sample groups The investigation indicated decreasing concentrations of PCBs with distance downstream with concentrations anticipated to average below 50 mgkg downstream of station 247+90 The report included a profile of the interceptor showing grit thickness and provides a baseline for the recent grit investigation indicating the continued accumulation of grit

The June 2006 grit investigation by the City of New Bedford (City) included the collection of eight composite samples with analyses for the following parameters

Total Organic Carbon (TOC) Total Petroleum Hydrocarbons (TPH) PCBs Volatile Organic Hydrocarbons (VOC) Semivolatile Organic Hydrocarbons (SVOC)

The results indicated total PCB concentrations ranging from 022 mgkg to 4530 mgkg with the highest concentration reported at one of the upstream locations in the vicinity of Willis Street The lowest PCB concentration was reported furthest downstream at station 157+03 at the intersection of Delano Street and Second Street The analytical data also indicated eleva ted concentrations of other contaminants however it is likely that the PCB concentrations will be the primary factor regarding disposal requirements The volume of grit in the interceptor was estimated at 5500 CY

A3 Project Location The grit is present in the New Bedford Main Interceptor from Station 253+70 near the intersection of Pearl Street and Acushnet Avenue to Station 79+57 at the location of the former screen house on West Rodney French Boulevard The project location is shown on Figures 1-1 and 1-2 appended to this Appendix from the New Bedford Main

Interceptor Grit Investigation Report by COM dated February 2008

CDM A-2

AopendixA

-----------------------------------------------------------shy

----shy----shy---shy-----i

------+1--shy

~~~_Ls_~l11 _ v _amp110 j)40 j ~~ = l-n1- fi--J l) _______ _ _____-400 jd ltSc1lij101 _ -2-5 Pl rn 11 W4rjshy

-

L CCyen1~~ whv t LQtLtj1d1-n

j(wr ~~rmiddot--shy

Lur1hu gTL-~ L1 1-1 )JS ~--~--~---F~~~~-----------------shy

~~1 +---~shy---=shy- tf l~tf (Y J

---shy

-- --- --middot-H----- --------------------------shy

++----~ 4ltmiddot~1_f i1tVamp~C~~ _lht~ ~vt~il r1~---shy----- -----~-LuLltY- u t~tLUC Std lrt1afO cfue___ Ait~lu ~__llff ~--shy

--------------------------------------------------shy

---------~---------------------------------------------shy

City of New Bedford Massachusetts

Main Interceptor Grit and Sediment Removal

January 2009

Technical Document

Appendix 0 Current Work and Investigations

sampler was used for grit depths deeper than 4-6 inches while a clam-style dredge was most effective for the shallower depths (1-4 inches) Figure D-1 shows a typical set-up during the sampling program

Grit and sediment depths were calculated as the difference between the manhole rim to invert (based on record drawings) and rim to grit measurements The distance to the top of the grit was measured by tape measure andor graduated markings on the core sampler Material investigation activities were recorded in a field book included in Appendix A of COMs New Bedford Main Interceptor Grit Investigation Report dated February 2008

D232 Grit Characterization

The grit sampling results indicate that the grit and sediment material generally includes fine gravel and coarse to medium sand sized particles This is consistent with the 1990 COM grit study Additionally the results indicate these physical properties were generally consistent throughout the interceptor The specific gravity (SG) (ratio of materials weight to the weight of an equal volume of water) of the samples averaged 265 One sample MH-20080 was reported to have a SG of 245 The laboratory indicated that this sample contained an oily product that skewed the test results and the actual SG is probably closer to 265 The laboratory results for the physical characteristic analyses are provided in Appendix C of COMs New Bedford Main Interceptor Grit Investigation Report dated February 2008

Deeper grit samples tended to have a fluidized layer on top (-0-6 inches) with the bottom material having a varying makeup of compacted material that ranged from mostly fine sand and silt to a poorly graded material having the same coarse sand and fine gravel as found in the top -6 inches

COM submitted the 31 grit samples to Alpha Analytical Laboratories for PCB analyses by MCP method 8082 The samples were extracted by the Accelerated Solvent Exchange (AES) extraction method 3546 Table 2-1 of COMs report New Bedford Main Interceptor Grit Investigation Report dated February 2008 summarizes the PCB results for each of the grit samples collected The laboratory data packages are provided in Appendix D

PCBs were detected in all but one sample above the method detection limits and PCB concentrations ranged from of 0180 to 2770 mgkg The data indicate that two samples had PCB detections above the TSCA disposal criteria of 50 ppm These results are summarized below

bull MH-23783-2 2770 mgkg bull 12-15 inch depth interval at manhole 237+83

bull MH-22680 145 mgkg bull 0-11 inch depth interval at manhole 226+80

CDM D-4

o

Appendix A Project Background and History

This Appendix provides a brief history of the project and background information on previous studies that have been conducted between 1980 and 2006

Al Introduction COM and the City have been working together to identify and quantify the extent of grit deposition and PCB contamination within the Citys Main Interceptor extending approximately 19000-ft from the intersection of Pearl Street and Acushnet Avenue southerly to the intersection of West Rodney French Boulevard and South Rodney French Boulevard Several investigations have taken place since the 1980s including extensive sampling by COM in 1987 1990 and 2007 and the City in 2006 The sampling programs identified approximately 2700 cubic yards to 5500 cubic yards of material along the invert of the interceptor The grit and sediment buildup is associated with sand and debris carried by storm water drainage from City streets into the combined sewer system from catch basins and other structures Deposition of grit along the invert of the Main Interceptor is a result of low velocities from a number of factors including shallow pipe slope obstructions pipe directional changes and reduced wastewater flows

PCB contamination of the grit is the result of industrial activities discharging PCB contaminated waste to the Citys collection system between 1930 and the 1970s Grit samples taken by COM as part of the 2007 program indicates that a 3256-ft section of Interceptor between Pearl Street and Acushnet Avenue and Water Street and William Street exceed PCB concentrations of 50 ppm requiring disposal at a Toxic Substance Control Act (TSCA) approved landfill for PCB remediation waste The remainder of the samples south of William Street indicate PCB concentrations between 10 ppm and non-detect

A2 Project Background The New Bedford Main Intercepting Sewer extending from the intersection of Pearl Street and Acushnet A venue to the former screen house on Rodney French Boulevard has accumulated grit deposits which have significantly reduced its flow capacity The extent of grit accumulation covers approximately 17300 linear feet The Interceptor sewer size and configuration varies through this area from a minimum height of 69 inches to a maximum height of 92 inches at the downstream end

The grit deposits were the subject of an investigation completed by COM and documented in a report titled Report on Part I of Grit Investigation in Main Interceptor dated May 1990 The report documented the presence of grit accumulated within the interceptor from station 328+81 in Belleville Avenue to station 100+00 in Rodney French Blvd Grit thickness was measured at 69 out of a total of 77 manholes on the interceptor Composite grit samples were obtained from 30 manhole locations and analyzed for various contaminants including polychlorinated biphenyls

CDM A-1

~pendixA

Appendix A Project Background and History

(PCBs) The interceptor was divided into eleven segments delineated based on estimated equal volumesof grit The investigation indicated PCB concentrations in excess of 50 mgkg in six of the eleven sample groups The investigation indicated decreasing concentrations of PCBs with distance downstream with concentrations anticipated to average below 50 mgkg downstream of station 247+90 The report included a profile of the interceptor showing grit thickness and provides a baseline for the recent grit investigation indicating the continued accumulation of grit

The June 2006 grit investigation by the City of New Bedford (City) included the collection of eight composite samples with analyses for the following parameters

Total Organic Carbon (TOC) Total Petroleum Hydrocarbons (TPH) PCBs Volatile Organic Hydrocarbons (VOC) Semivolatile Organic Hydrocarbons (SVOC)

The results indicated total PCB concentrations ranging from 022 mgkg to 4530 mgkg with the highest concentration reported at one of the upstream locations in the vicinity of Willis Street The lowest PCB concentration was reported furthest downstream at station 157+03 at the intersection of Delano Street and Second Street The analytical data also indicated eleva ted concentrations of other contaminants however it is likely that the PCB concentrations will be the primary factor regarding disposal requirements The volume of grit in the interceptor was estimated at 5500 CY

A3 Project Location The grit is present in the New Bedford Main Interceptor from Station 253+70 near the intersection of Pearl Street and Acushnet Avenue to Station 79+57 at the location of the former screen house on West Rodney French Boulevard The project location is shown on Figures 1-1 and 1-2 appended to this Appendix from the New Bedford Main

Interceptor Grit Investigation Report by COM dated February 2008

CDM A-2

AopendixA

j(wr ~~rmiddot--shy

Lur1hu gTL-~ L1 1-1 )JS ~--~--~---F~~~~-----------------shy

~~1 +---~shy---=shy- tf l~tf (Y J

---shy

-- --- --middot-H----- --------------------------shy

++----~ 4ltmiddot~1_f i1tVamp~C~~ _lht~ ~vt~il r1~---shy----- -----~-LuLltY- u t~tLUC Std lrt1afO cfue___ Ait~lu ~__llff ~--shy

--------------------------------------------------shy

---------~---------------------------------------------shy

City of New Bedford Massachusetts

Main Interceptor Grit and Sediment Removal

January 2009

Technical Document

Appendix 0 Current Work and Investigations

sampler was used for grit depths deeper than 4-6 inches while a clam-style dredge was most effective for the shallower depths (1-4 inches) Figure D-1 shows a typical set-up during the sampling program

Grit and sediment depths were calculated as the difference between the manhole rim to invert (based on record drawings) and rim to grit measurements The distance to the top of the grit was measured by tape measure andor graduated markings on the core sampler Material investigation activities were recorded in a field book included in Appendix A of COMs New Bedford Main Interceptor Grit Investigation Report dated February 2008

D232 Grit Characterization

The grit sampling results indicate that the grit and sediment material generally includes fine gravel and coarse to medium sand sized particles This is consistent with the 1990 COM grit study Additionally the results indicate these physical properties were generally consistent throughout the interceptor The specific gravity (SG) (ratio of materials weight to the weight of an equal volume of water) of the samples averaged 265 One sample MH-20080 was reported to have a SG of 245 The laboratory indicated that this sample contained an oily product that skewed the test results and the actual SG is probably closer to 265 The laboratory results for the physical characteristic analyses are provided in Appendix C of COMs New Bedford Main Interceptor Grit Investigation Report dated February 2008

Deeper grit samples tended to have a fluidized layer on top (-0-6 inches) with the bottom material having a varying makeup of compacted material that ranged from mostly fine sand and silt to a poorly graded material having the same coarse sand and fine gravel as found in the top -6 inches

COM submitted the 31 grit samples to Alpha Analytical Laboratories for PCB analyses by MCP method 8082 The samples were extracted by the Accelerated Solvent Exchange (AES) extraction method 3546 Table 2-1 of COMs report New Bedford Main Interceptor Grit Investigation Report dated February 2008 summarizes the PCB results for each of the grit samples collected The laboratory data packages are provided in Appendix D

PCBs were detected in all but one sample above the method detection limits and PCB concentrations ranged from of 0180 to 2770 mgkg The data indicate that two samples had PCB detections above the TSCA disposal criteria of 50 ppm These results are summarized below

bull MH-23783-2 2770 mgkg bull 12-15 inch depth interval at manhole 237+83

bull MH-22680 145 mgkg bull 0-11 inch depth interval at manhole 226+80

CDM D-4

o

Appendix A Project Background and History

This Appendix provides a brief history of the project and background information on previous studies that have been conducted between 1980 and 2006

Al Introduction COM and the City have been working together to identify and quantify the extent of grit deposition and PCB contamination within the Citys Main Interceptor extending approximately 19000-ft from the intersection of Pearl Street and Acushnet Avenue southerly to the intersection of West Rodney French Boulevard and South Rodney French Boulevard Several investigations have taken place since the 1980s including extensive sampling by COM in 1987 1990 and 2007 and the City in 2006 The sampling programs identified approximately 2700 cubic yards to 5500 cubic yards of material along the invert of the interceptor The grit and sediment buildup is associated with sand and debris carried by storm water drainage from City streets into the combined sewer system from catch basins and other structures Deposition of grit along the invert of the Main Interceptor is a result of low velocities from a number of factors including shallow pipe slope obstructions pipe directional changes and reduced wastewater flows

PCB contamination of the grit is the result of industrial activities discharging PCB contaminated waste to the Citys collection system between 1930 and the 1970s Grit samples taken by COM as part of the 2007 program indicates that a 3256-ft section of Interceptor between Pearl Street and Acushnet Avenue and Water Street and William Street exceed PCB concentrations of 50 ppm requiring disposal at a Toxic Substance Control Act (TSCA) approved landfill for PCB remediation waste The remainder of the samples south of William Street indicate PCB concentrations between 10 ppm and non-detect

A2 Project Background The New Bedford Main Intercepting Sewer extending from the intersection of Pearl Street and Acushnet A venue to the former screen house on Rodney French Boulevard has accumulated grit deposits which have significantly reduced its flow capacity The extent of grit accumulation covers approximately 17300 linear feet The Interceptor sewer size and configuration varies through this area from a minimum height of 69 inches to a maximum height of 92 inches at the downstream end

The grit deposits were the subject of an investigation completed by COM and documented in a report titled Report on Part I of Grit Investigation in Main Interceptor dated May 1990 The report documented the presence of grit accumulated within the interceptor from station 328+81 in Belleville Avenue to station 100+00 in Rodney French Blvd Grit thickness was measured at 69 out of a total of 77 manholes on the interceptor Composite grit samples were obtained from 30 manhole locations and analyzed for various contaminants including polychlorinated biphenyls

CDM A-1

~pendixA

Appendix A Project Background and History

(PCBs) The interceptor was divided into eleven segments delineated based on estimated equal volumesof grit The investigation indicated PCB concentrations in excess of 50 mgkg in six of the eleven sample groups The investigation indicated decreasing concentrations of PCBs with distance downstream with concentrations anticipated to average below 50 mgkg downstream of station 247+90 The report included a profile of the interceptor showing grit thickness and provides a baseline for the recent grit investigation indicating the continued accumulation of grit

The June 2006 grit investigation by the City of New Bedford (City) included the collection of eight composite samples with analyses for the following parameters

Total Organic Carbon (TOC) Total Petroleum Hydrocarbons (TPH) PCBs Volatile Organic Hydrocarbons (VOC) Semivolatile Organic Hydrocarbons (SVOC)

The results indicated total PCB concentrations ranging from 022 mgkg to 4530 mgkg with the highest concentration reported at one of the upstream locations in the vicinity of Willis Street The lowest PCB concentration was reported furthest downstream at station 157+03 at the intersection of Delano Street and Second Street The analytical data also indicated eleva ted concentrations of other contaminants however it is likely that the PCB concentrations will be the primary factor regarding disposal requirements The volume of grit in the interceptor was estimated at 5500 CY

A3 Project Location The grit is present in the New Bedford Main Interceptor from Station 253+70 near the intersection of Pearl Street and Acushnet Avenue to Station 79+57 at the location of the former screen house on West Rodney French Boulevard The project location is shown on Figures 1-1 and 1-2 appended to this Appendix from the New Bedford Main

Interceptor Grit Investigation Report by COM dated February 2008

CDM A-2

AopendixA

City of New Bedford Massachusetts

Main Interceptor Grit and Sediment Removal

January 2009

Technical Document

Appendix 0 Current Work and Investigations

sampler was used for grit depths deeper than 4-6 inches while a clam-style dredge was most effective for the shallower depths (1-4 inches) Figure D-1 shows a typical set-up during the sampling program

Grit and sediment depths were calculated as the difference between the manhole rim to invert (based on record drawings) and rim to grit measurements The distance to the top of the grit was measured by tape measure andor graduated markings on the core sampler Material investigation activities were recorded in a field book included in Appendix A of COMs New Bedford Main Interceptor Grit Investigation Report dated February 2008

D232 Grit Characterization

The grit sampling results indicate that the grit and sediment material generally includes fine gravel and coarse to medium sand sized particles This is consistent with the 1990 COM grit study Additionally the results indicate these physical properties were generally consistent throughout the interceptor The specific gravity (SG) (ratio of materials weight to the weight of an equal volume of water) of the samples averaged 265 One sample MH-20080 was reported to have a SG of 245 The laboratory indicated that this sample contained an oily product that skewed the test results and the actual SG is probably closer to 265 The laboratory results for the physical characteristic analyses are provided in Appendix C of COMs New Bedford Main Interceptor Grit Investigation Report dated February 2008

Deeper grit samples tended to have a fluidized layer on top (-0-6 inches) with the bottom material having a varying makeup of compacted material that ranged from mostly fine sand and silt to a poorly graded material having the same coarse sand and fine gravel as found in the top -6 inches

COM submitted the 31 grit samples to Alpha Analytical Laboratories for PCB analyses by MCP method 8082 The samples were extracted by the Accelerated Solvent Exchange (AES) extraction method 3546 Table 2-1 of COMs report New Bedford Main Interceptor Grit Investigation Report dated February 2008 summarizes the PCB results for each of the grit samples collected The laboratory data packages are provided in Appendix D

PCBs were detected in all but one sample above the method detection limits and PCB concentrations ranged from of 0180 to 2770 mgkg The data indicate that two samples had PCB detections above the TSCA disposal criteria of 50 ppm These results are summarized below

bull MH-23783-2 2770 mgkg bull 12-15 inch depth interval at manhole 237+83

bull MH-22680 145 mgkg bull 0-11 inch depth interval at manhole 226+80

CDM D-4

o

Appendix A Project Background and History

This Appendix provides a brief history of the project and background information on previous studies that have been conducted between 1980 and 2006

Al Introduction COM and the City have been working together to identify and quantify the extent of grit deposition and PCB contamination within the Citys Main Interceptor extending approximately 19000-ft from the intersection of Pearl Street and Acushnet Avenue southerly to the intersection of West Rodney French Boulevard and South Rodney French Boulevard Several investigations have taken place since the 1980s including extensive sampling by COM in 1987 1990 and 2007 and the City in 2006 The sampling programs identified approximately 2700 cubic yards to 5500 cubic yards of material along the invert of the interceptor The grit and sediment buildup is associated with sand and debris carried by storm water drainage from City streets into the combined sewer system from catch basins and other structures Deposition of grit along the invert of the Main Interceptor is a result of low velocities from a number of factors including shallow pipe slope obstructions pipe directional changes and reduced wastewater flows

PCB contamination of the grit is the result of industrial activities discharging PCB contaminated waste to the Citys collection system between 1930 and the 1970s Grit samples taken by COM as part of the 2007 program indicates that a 3256-ft section of Interceptor between Pearl Street and Acushnet Avenue and Water Street and William Street exceed PCB concentrations of 50 ppm requiring disposal at a Toxic Substance Control Act (TSCA) approved landfill for PCB remediation waste The remainder of the samples south of William Street indicate PCB concentrations between 10 ppm and non-detect

A2 Project Background The New Bedford Main Intercepting Sewer extending from the intersection of Pearl Street and Acushnet A venue to the former screen house on Rodney French Boulevard has accumulated grit deposits which have significantly reduced its flow capacity The extent of grit accumulation covers approximately 17300 linear feet The Interceptor sewer size and configuration varies through this area from a minimum height of 69 inches to a maximum height of 92 inches at the downstream end

The grit deposits were the subject of an investigation completed by COM and documented in a report titled Report on Part I of Grit Investigation in Main Interceptor dated May 1990 The report documented the presence of grit accumulated within the interceptor from station 328+81 in Belleville Avenue to station 100+00 in Rodney French Blvd Grit thickness was measured at 69 out of a total of 77 manholes on the interceptor Composite grit samples were obtained from 30 manhole locations and analyzed for various contaminants including polychlorinated biphenyls

CDM A-1

~pendixA

Appendix A Project Background and History

(PCBs) The interceptor was divided into eleven segments delineated based on estimated equal volumesof grit The investigation indicated PCB concentrations in excess of 50 mgkg in six of the eleven sample groups The investigation indicated decreasing concentrations of PCBs with distance downstream with concentrations anticipated to average below 50 mgkg downstream of station 247+90 The report included a profile of the interceptor showing grit thickness and provides a baseline for the recent grit investigation indicating the continued accumulation of grit

The June 2006 grit investigation by the City of New Bedford (City) included the collection of eight composite samples with analyses for the following parameters

Total Organic Carbon (TOC) Total Petroleum Hydrocarbons (TPH) PCBs Volatile Organic Hydrocarbons (VOC) Semivolatile Organic Hydrocarbons (SVOC)

The results indicated total PCB concentrations ranging from 022 mgkg to 4530 mgkg with the highest concentration reported at one of the upstream locations in the vicinity of Willis Street The lowest PCB concentration was reported furthest downstream at station 157+03 at the intersection of Delano Street and Second Street The analytical data also indicated eleva ted concentrations of other contaminants however it is likely that the PCB concentrations will be the primary factor regarding disposal requirements The volume of grit in the interceptor was estimated at 5500 CY

A3 Project Location The grit is present in the New Bedford Main Interceptor from Station 253+70 near the intersection of Pearl Street and Acushnet Avenue to Station 79+57 at the location of the former screen house on West Rodney French Boulevard The project location is shown on Figures 1-1 and 1-2 appended to this Appendix from the New Bedford Main

Interceptor Grit Investigation Report by COM dated February 2008

CDM A-2

AopendixA

Appendix 0 Current Work and Investigations

sampler was used for grit depths deeper than 4-6 inches while a clam-style dredge was most effective for the shallower depths (1-4 inches) Figure D-1 shows a typical set-up during the sampling program

Grit and sediment depths were calculated as the difference between the manhole rim to invert (based on record drawings) and rim to grit measurements The distance to the top of the grit was measured by tape measure andor graduated markings on the core sampler Material investigation activities were recorded in a field book included in Appendix A of COMs New Bedford Main Interceptor Grit Investigation Report dated February 2008

D232 Grit Characterization

The grit sampling results indicate that the grit and sediment material generally includes fine gravel and coarse to medium sand sized particles This is consistent with the 1990 COM grit study Additionally the results indicate these physical properties were generally consistent throughout the interceptor The specific gravity (SG) (ratio of materials weight to the weight of an equal volume of water) of the samples averaged 265 One sample MH-20080 was reported to have a SG of 245 The laboratory indicated that this sample contained an oily product that skewed the test results and the actual SG is probably closer to 265 The laboratory results for the physical characteristic analyses are provided in Appendix C of COMs New Bedford Main Interceptor Grit Investigation Report dated February 2008

Deeper grit samples tended to have a fluidized layer on top (-0-6 inches) with the bottom material having a varying makeup of compacted material that ranged from mostly fine sand and silt to a poorly graded material having the same coarse sand and fine gravel as found in the top -6 inches

COM submitted the 31 grit samples to Alpha Analytical Laboratories for PCB analyses by MCP method 8082 The samples were extracted by the Accelerated Solvent Exchange (AES) extraction method 3546 Table 2-1 of COMs report New Bedford Main Interceptor Grit Investigation Report dated February 2008 summarizes the PCB results for each of the grit samples collected The laboratory data packages are provided in Appendix D

PCBs were detected in all but one sample above the method detection limits and PCB concentrations ranged from of 0180 to 2770 mgkg The data indicate that two samples had PCB detections above the TSCA disposal criteria of 50 ppm These results are summarized below

bull MH-23783-2 2770 mgkg bull 12-15 inch depth interval at manhole 237+83

bull MH-22680 145 mgkg bull 0-11 inch depth interval at manhole 226+80

CDM D-4

o

Appendix A Project Background and History

This Appendix provides a brief history of the project and background information on previous studies that have been conducted between 1980 and 2006

Al Introduction COM and the City have been working together to identify and quantify the extent of grit deposition and PCB contamination within the Citys Main Interceptor extending approximately 19000-ft from the intersection of Pearl Street and Acushnet Avenue southerly to the intersection of West Rodney French Boulevard and South Rodney French Boulevard Several investigations have taken place since the 1980s including extensive sampling by COM in 1987 1990 and 2007 and the City in 2006 The sampling programs identified approximately 2700 cubic yards to 5500 cubic yards of material along the invert of the interceptor The grit and sediment buildup is associated with sand and debris carried by storm water drainage from City streets into the combined sewer system from catch basins and other structures Deposition of grit along the invert of the Main Interceptor is a result of low velocities from a number of factors including shallow pipe slope obstructions pipe directional changes and reduced wastewater flows

PCB contamination of the grit is the result of industrial activities discharging PCB contaminated waste to the Citys collection system between 1930 and the 1970s Grit samples taken by COM as part of the 2007 program indicates that a 3256-ft section of Interceptor between Pearl Street and Acushnet Avenue and Water Street and William Street exceed PCB concentrations of 50 ppm requiring disposal at a Toxic Substance Control Act (TSCA) approved landfill for PCB remediation waste The remainder of the samples south of William Street indicate PCB concentrations between 10 ppm and non-detect

A2 Project Background The New Bedford Main Intercepting Sewer extending from the intersection of Pearl Street and Acushnet A venue to the former screen house on Rodney French Boulevard has accumulated grit deposits which have significantly reduced its flow capacity The extent of grit accumulation covers approximately 17300 linear feet The Interceptor sewer size and configuration varies through this area from a minimum height of 69 inches to a maximum height of 92 inches at the downstream end

The grit deposits were the subject of an investigation completed by COM and documented in a report titled Report on Part I of Grit Investigation in Main Interceptor dated May 1990 The report documented the presence of grit accumulated within the interceptor from station 328+81 in Belleville Avenue to station 100+00 in Rodney French Blvd Grit thickness was measured at 69 out of a total of 77 manholes on the interceptor Composite grit samples were obtained from 30 manhole locations and analyzed for various contaminants including polychlorinated biphenyls

CDM A-1

~pendixA

Appendix A Project Background and History

(PCBs) The interceptor was divided into eleven segments delineated based on estimated equal volumesof grit The investigation indicated PCB concentrations in excess of 50 mgkg in six of the eleven sample groups The investigation indicated decreasing concentrations of PCBs with distance downstream with concentrations anticipated to average below 50 mgkg downstream of station 247+90 The report included a profile of the interceptor showing grit thickness and provides a baseline for the recent grit investigation indicating the continued accumulation of grit

The June 2006 grit investigation by the City of New Bedford (City) included the collection of eight composite samples with analyses for the following parameters

Total Organic Carbon (TOC) Total Petroleum Hydrocarbons (TPH) PCBs Volatile Organic Hydrocarbons (VOC) Semivolatile Organic Hydrocarbons (SVOC)

The results indicated total PCB concentrations ranging from 022 mgkg to 4530 mgkg with the highest concentration reported at one of the upstream locations in the vicinity of Willis Street The lowest PCB concentration was reported furthest downstream at station 157+03 at the intersection of Delano Street and Second Street The analytical data also indicated eleva ted concentrations of other contaminants however it is likely that the PCB concentrations will be the primary factor regarding disposal requirements The volume of grit in the interceptor was estimated at 5500 CY

A3 Project Location The grit is present in the New Bedford Main Interceptor from Station 253+70 near the intersection of Pearl Street and Acushnet Avenue to Station 79+57 at the location of the former screen house on West Rodney French Boulevard The project location is shown on Figures 1-1 and 1-2 appended to this Appendix from the New Bedford Main

Interceptor Grit Investigation Report by COM dated February 2008

CDM A-2

AopendixA

Appendix A Project Background and History

This Appendix provides a brief history of the project and background information on previous studies that have been conducted between 1980 and 2006

Al Introduction COM and the City have been working together to identify and quantify the extent of grit deposition and PCB contamination within the Citys Main Interceptor extending approximately 19000-ft from the intersection of Pearl Street and Acushnet Avenue southerly to the intersection of West Rodney French Boulevard and South Rodney French Boulevard Several investigations have taken place since the 1980s including extensive sampling by COM in 1987 1990 and 2007 and the City in 2006 The sampling programs identified approximately 2700 cubic yards to 5500 cubic yards of material along the invert of the interceptor The grit and sediment buildup is associated with sand and debris carried by storm water drainage from City streets into the combined sewer system from catch basins and other structures Deposition of grit along the invert of the Main Interceptor is a result of low velocities from a number of factors including shallow pipe slope obstructions pipe directional changes and reduced wastewater flows

PCB contamination of the grit is the result of industrial activities discharging PCB contaminated waste to the Citys collection system between 1930 and the 1970s Grit samples taken by COM as part of the 2007 program indicates that a 3256-ft section of Interceptor between Pearl Street and Acushnet Avenue and Water Street and William Street exceed PCB concentrations of 50 ppm requiring disposal at a Toxic Substance Control Act (TSCA) approved landfill for PCB remediation waste The remainder of the samples south of William Street indicate PCB concentrations between 10 ppm and non-detect

A2 Project Background The New Bedford Main Intercepting Sewer extending from the intersection of Pearl Street and Acushnet A venue to the former screen house on Rodney French Boulevard has accumulated grit deposits which have significantly reduced its flow capacity The extent of grit accumulation covers approximately 17300 linear feet The Interceptor sewer size and configuration varies through this area from a minimum height of 69 inches to a maximum height of 92 inches at the downstream end

The grit deposits were the subject of an investigation completed by COM and documented in a report titled Report on Part I of Grit Investigation in Main Interceptor dated May 1990 The report documented the presence of grit accumulated within the interceptor from station 328+81 in Belleville Avenue to station 100+00 in Rodney French Blvd Grit thickness was measured at 69 out of a total of 77 manholes on the interceptor Composite grit samples were obtained from 30 manhole locations and analyzed for various contaminants including polychlorinated biphenyls

CDM A-1

~pendixA

Appendix A Project Background and History

(PCBs) The interceptor was divided into eleven segments delineated based on estimated equal volumesof grit The investigation indicated PCB concentrations in excess of 50 mgkg in six of the eleven sample groups The investigation indicated decreasing concentrations of PCBs with distance downstream with concentrations anticipated to average below 50 mgkg downstream of station 247+90 The report included a profile of the interceptor showing grit thickness and provides a baseline for the recent grit investigation indicating the continued accumulation of grit

The June 2006 grit investigation by the City of New Bedford (City) included the collection of eight composite samples with analyses for the following parameters

Total Organic Carbon (TOC) Total Petroleum Hydrocarbons (TPH) PCBs Volatile Organic Hydrocarbons (VOC) Semivolatile Organic Hydrocarbons (SVOC)

The results indicated total PCB concentrations ranging from 022 mgkg to 4530 mgkg with the highest concentration reported at one of the upstream locations in the vicinity of Willis Street The lowest PCB concentration was reported furthest downstream at station 157+03 at the intersection of Delano Street and Second Street The analytical data also indicated eleva ted concentrations of other contaminants however it is likely that the PCB concentrations will be the primary factor regarding disposal requirements The volume of grit in the interceptor was estimated at 5500 CY

A3 Project Location The grit is present in the New Bedford Main Interceptor from Station 253+70 near the intersection of Pearl Street and Acushnet Avenue to Station 79+57 at the location of the former screen house on West Rodney French Boulevard The project location is shown on Figures 1-1 and 1-2 appended to this Appendix from the New Bedford Main

Interceptor Grit Investigation Report by COM dated February 2008

CDM A-2

AopendixA

Appendix A Project Background and History

(PCBs) The interceptor was divided into eleven segments delineated based on estimated equal volumesof grit The investigation indicated PCB concentrations in excess of 50 mgkg in six of the eleven sample groups The investigation indicated decreasing concentrations of PCBs with distance downstream with concentrations anticipated to average below 50 mgkg downstream of station 247+90 The report included a profile of the interceptor showing grit thickness and provides a baseline for the recent grit investigation indicating the continued accumulation of grit

The June 2006 grit investigation by the City of New Bedford (City) included the collection of eight composite samples with analyses for the following parameters

Total Organic Carbon (TOC) Total Petroleum Hydrocarbons (TPH) PCBs Volatile Organic Hydrocarbons (VOC) Semivolatile Organic Hydrocarbons (SVOC)

The results indicated total PCB concentrations ranging from 022 mgkg to 4530 mgkg with the highest concentration reported at one of the upstream locations in the vicinity of Willis Street The lowest PCB concentration was reported furthest downstream at station 157+03 at the intersection of Delano Street and Second Street The analytical data also indicated eleva ted concentrations of other contaminants however it is likely that the PCB concentrations will be the primary factor regarding disposal requirements The volume of grit in the interceptor was estimated at 5500 CY

A3 Project Location The grit is present in the New Bedford Main Interceptor from Station 253+70 near the intersection of Pearl Street and Acushnet Avenue to Station 79+57 at the location of the former screen house on West Rodney French Boulevard The project location is shown on Figures 1-1 and 1-2 appended to this Appendix from the New Bedford Main

Interceptor Grit Investigation Report by COM dated February 2008

CDM A-2

AopendixA

Appendix 0 Current Work and Investigations

The data indicate that PCB contaminated grit above 50 ppm is generally limited to the upper 3200 feet of the Main Interceptor between Pearl Street and Williams Street PCBs are generally found in greater concentrations in the upper reaches of the interceptor above MH-220+64 The data show that the deeper grit material has greater concentrations of PCBs than the shallower samples PCB congeniers were mostly reported to be Aroclors 1260 and 1242 with less frequent occurrences of Aroclors 1016 and 1254

Sixteen samples were reported with PCB concentrations above the Massachusetts Landfill Reuse Criteria of 2mgkg

COM submitted six grit samples in addition to one duplicate sample for additional analyses Samples were submitted to Alpha Analytical Laboratories for analyses of metals VOCs SVOCs and TPH to provide additiona l disposal characterization Additionally Toxicity Characteristic Leaching Procedure (TCLP) analyses were performed on five of those samples including the duplicate Table 3-1 provides the results of these additional analyses for chemicals detected Table 3-2 provides the results of the TCLP analyses These tables are included in the Appendix of this Appendix The laboratory reports are provided in Appendix D of COMs New Bedford Main Interceptor Grit Investigation Report dated February 2008

The data generally show benzene toluene ethylbenzene and xylenes (BTEX) constituents in the VOC analyses and most metals reported above method detection limits Diesel range total petroleum hydrocarbons are found in significant concentrations ranging from 660- 3520 mg kg

The TCLP analyses indicated only the lead result above the detection limit in sample MH-15703 with a concentration of 17 mgL below the TCLP standard of 50 mgL

D3 Grit Removal Pilot Study Plan COM and the City of New Bedford initially intended to complete a pilot study which included the removal disposal transporting dewatering and handling of 100 cubic yards of material dredged from the Main Interceptor The intent of the program was to develop an understanding of the cleaning process potential issues during full scale removal and to understand the mechanisms by which PCBs could transport downstream

COM completed the preparation of the Grit Removal Pilot Study Plan however due to the extensive flooding that continues to occur along the Interceptor and the potential for futu re contamination of the receiving waters and public health concerns related to the flooding the pilot program was terminated with the intent to fast track the full scale removal of the material

A copy of COMs New Bedford Main Interceptor Grit Removal Pilot Study Plan dated June 2008 is appended to this Appendix

D-5

Appendix D Current Work and Investigations

hole with subsidence of the surrounding ground surface around the pipe is a major concern

The program also identified a possible hydraulic restriction at the location of the old screen house on West Rodney French Boulevard Within this location the main interceptor changes diameter from 96-in to about 24-in for a 10-ft length PipeEye International was unable to proceed through this restriction

05 Volume of Material The amount of grit present in the Main Interceptor has been estimated at approximately 2700 to 5500 cubic yards (CY) based on measurement of the thickness of grit deposits at manhole locations in 2005 and 2007 A profile showing the location and extent of grit deposition is included within Appendix B

The recent underwater sonar and CCIV inspection of 16900-ft of the Main Interceptor identified 3100 cubic yards of material for the area inspected PipeEye International was unable to sonar and ccrv inspection several sewer reaches which are believed to contain the worst deposits of grit due to excessive water depths within the pipeline It is believed that the volume of material is somewhere between the previously estimated 2700 cubic yards and 5500 cubic yards

06 Summary of Findings The 2007 and 2008 field programs were conducted to further classify and characterize the volume and nature of material within the Main Interceptor since the last series of testing was conducted in the 1990s All aspects of the field program were approved by EPA Region 1 The following summarizes the findings

bull Grit Oassification - The results of the program indicated that two grit and sediment samples reported PCB concentrations above 50 ppm These two samples indicate that grit and sediment from a 3256 feet section of the Main Interceptor between Sta 220+64 and Sta 253+20 would require disposal at a TSCA landfill approved for PCJ remediation waste greater than 50 ppm Approximately one half of the 31 samples collected indicate PCB concentrations above the Massachusetts Landfill Reuse Criteria of 2 ppm In addition several other exceedences of the MassDEP Policy Comm-97-001 standards for reuse and disposal as contaminated soil at Massachusetts Landfills were reported indicating restrictions on disposal alternatives

bull Volume of Material- The estimated volume of material within the interceptor is as follows

Grit with PCB concentrations greater than 50 ppm- 800 cubic yards -1200 cubic yards

0middot8

Appendix 0 Current Work and Investigations

Grit with PCB concentrations between 50 ppm and 1 ppm- 1800 cubic yards and 4400 cubic yards

Grit with PCB concentrations greater than 50 ppm within structurally suspect pipeline under Route 18 - 60 cubic yards - 130 cubic yards

bull Underwater Sonar and CCTV Inspection- The findings of the sonar and CCTV inspection indicate that

More grit exists within the Main Interceptor than originally anticipated particularly within the downstream reaches and north ofmiddot the Whale Building (Sta 234+50)

The interceptor is undergoing hydrogen sulfide corrosion

The structural integrity of the interceptor is suspect at certain locations

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Appendix D Current Work and Investigations

hole with subsidence of the surrounding ground surface around the pipe is a major concern

The program also identified a possible hydraulic restriction at the location of the old screen house on West Rodney French Boulevard Within this location the main interceptor changes diameter from 96-in to about 24-in for a 10-ft length PipeEye International was unable to proceed through this restriction

05 Volume of Material The amount of grit present in the Main Interceptor has been estimated at approximately 2700 to 5500 cubic yards (CY) based on measurement of the thickness of grit deposits at manhole locations in 2005 and 2007 A profile showing the location and extent of grit deposition is included within Appendix B

The recent underwater sonar and CCIV inspection of 16900-ft of the Main Interceptor identified 3100 cubic yards of material for the area inspected PipeEye International was unable to sonar and ccrv inspection several sewer reaches which are believed to contain the worst deposits of grit due to excessive water depths within the pipeline It is believed that the volume of material is somewhere between the previously estimated 2700 cubic yards and 5500 cubic yards

06 Summary of Findings The 2007 and 2008 field programs were conducted to further classify and characterize the volume and nature of material within the Main Interceptor since the last series of testing was conducted in the 1990s All aspects of the field program were approved by EPA Region 1 The following summarizes the findings

bull Grit Oassification - The results of the program indicated that two grit and sediment samples reported PCB concentrations above 50 ppm These two samples indicate that grit and sediment from a 3256 feet section of the Main Interceptor between Sta 220+64 and Sta 253+20 would require disposal at a TSCA landfill approved for PCJ remediation waste greater than 50 ppm Approximately one half of the 31 samples collected indicate PCB concentrations above the Massachusetts Landfill Reuse Criteria of 2 ppm In addition several other exceedences of the MassDEP Policy Comm-97-001 standards for reuse and disposal as contaminated soil at Massachusetts Landfills were reported indicating restrictions on disposal alternatives

bull Volume of Material- The estimated volume of material within the interceptor is as follows

Grit with PCB concentrations greater than 50 ppm- 800 cubic yards -1200 cubic yards

0middot8

Appendix 0 Current Work and Investigations

Grit with PCB concentrations between 50 ppm and 1 ppm- 1800 cubic yards and 4400 cubic yards

Grit with PCB concentrations greater than 50 ppm within structurally suspect pipeline under Route 18 - 60 cubic yards - 130 cubic yards

bull Underwater Sonar and CCTV Inspection- The findings of the sonar and CCTV inspection indicate that

More grit exists within the Main Interceptor than originally anticipated particularly within the downstream reaches and north ofmiddot the Whale Building (Sta 234+50)

The interceptor is undergoing hydrogen sulfide corrosion

The structural integrity of the interceptor is suspect at certain locations

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Grit with PCB concentrations between 50 ppm and 1 ppm- 1800 cubic yards and 4400 cubic yards

Grit with PCB concentrations greater than 50 ppm within structurally suspect pipeline under Route 18 - 60 cubic yards - 130 cubic yards

bull Underwater Sonar and CCTV Inspection- The findings of the sonar and CCTV inspection indicate that

More grit exists within the Main Interceptor than originally anticipated particularly within the downstream reaches and north ofmiddot the Whale Building (Sta 234+50)

The interceptor is undergoing hydrogen sulfide corrosion

The structural integrity of the interceptor is suspect at certain locations

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