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Harold L Nelson PE F ASCE Civil Engineer
Pittsfield MA 01201
January 25 2011
Ms Susan Svirsky EPA Rest of River Project Manager
clo Weston Solutions 10 Lyman Street Pittsfield MA 01201
RE Housatonic River - Rest of River (ROR) Revised Corrective Measures Study (CMS) Report October 2010 New Technology for New Options
Dear Ms Svirsky
Thank you for inviting public comment on the above report As a stakeholder I note the CMS process has consumed over ten years of effort by EPA and GE for the risk analysis development of protection goals modeling and finally investigation and evaluation of a range of corrective measures or cleanup procedures This effort has resulted in thousands of pages of text tables maps diagrams and
photos in accordance with provisions of the Consent Decree (CD) signed in October 1999
GE notes in the revised CMS that significant harm would occur to the river ecosystem from removal of sediment and floodplain soil as a result of any of the remedial alternatives The more work done the more damage would occur Alternatives SED 10FP 9 the new GE preference for least damage
would still require significant removal of sediment and soil This removal work would be designed to minimize harm and meet most of the EPA requirements But even if SED 10FP 9 were designed with these goals and concerns there would be severe risks
There have been significant developments in remediation technology since work started on the CMS
Some of the new technology includes computer mapping for control of preCision contour dredging and volume reduction processing of contaminated sediment None of this new technology has been considered in the revised CMS We suggest their use would offer a higher level of cleanup reduced impact on the ecosystem and a reduced volume of material to be processed and stored Details of this technology are described in this letter
Core tests of sediment and soil used in the CMS are now over 10 years old Spatial averaging was used to interpret the location and degree of contamination used in the CMS Given the nature of sedimentation movement (scour) during flooding events the accuracy of this data should be verified with new testing And if preCision contour dredging were adopted as we propose the frequency of
cores (smaller spacing) would need to be increased for generating engineered contour maps
Finally Woods Pond presents a unique opportunity for additional dredging beyond PCB remediation The purpose would be to raise trap efficiency and reduce transport of sediments further down the river I suggest this additional dredging should be considered and made part of a f ~ lJI~LIJ C lr~ J~-=_---=-I
~~copy~DYJ~~ WJAN 26 201 1 ~
eMS New Technology for New Options 14 12511
By
Engineered Contour Mapping
Every river or stream is a moving body of water and sediment When a river such as the Housatonic flows into Woods Pond the reduced flow (velocity) of the water causes sedimentation or settling of
particles to the bottom Sedimentation also occurs around obstacles in the river such as structures piling or tree stumps where there are eddies and reduced flow When velocity of the water is raised during an extreme event like spring runoff sediment particles may again become water borne and move until their velocity is reduced and the sedimentation process begins again There has never been dredging (would appear) in the 100 year history of Woods Pond The configuration and shallow
depth are ideal for sedimentation
When dredging plans are engineered for the pond there should be two objectives The first is to remove as much of the contaminated sediment as possible so as to minimize transport down the river in a future flooding event The second is to restore trap efficiency to as high a level as possible so as to retain new sediment flowing into the pond from upstream sources during normal or extreme events Trap efficiency varies with characteristics of the sediment and retention time or rate of flow in the pond The latter is controlled by the geometry and runoff characteristics Trap efficiency is the ratio or percentage of sediment retained to sediment entering the pond
Computer maps for operating a preCision contour dredge are generated from surveys and software using GPS multi-beam sonar laser scanners and aerial orthophotography In a state of art contour dredge they are used to define location of PCB contaminated sediment control dredging and verify results after dredging During a preliminary survey core samples from the waterbed taken at close intervals are used to identify location size and depth of PCB pockets Depending on hydrology the
depth of PCB contamination can very from 6 inches to 10 feet PCB contamination is seldom spread uniformly over a waterbed Software mapping programs produce three-dimensional grid maps that are accurate within inches Color codings on a monitor in the dredge show the operator where to dredge and provide real time (three dimensional control) of the auger at all times
Costs for generating these sophisticated surveys are offset by savings in the volume of material that is dredged and processed and the cost of engineered capping Contour dredging minimizes the amount of clean material removed and minimizes the contaminated material that is missed from dredging Thorough dredging is achieved and over dredging minimized Printouts from the RCS system provide as-built records of the finished bottom and are mandatory with some agencies including the NYS Department of Environmental Protection
PCB concentrations existing in sediments of Reaches 5 and 6 are shown in the Maps and Figures folder available at ltwww epa govheg ion1 2gethesitehestofrivermap~gt The data is presented in the CMS report in support of the risk analyses and modeling but would not be adequate for the
contour computer maps proposed In addition changes in location and concentration of PCBs need to be confirmed from original surveys which are now over 10 years old
Precision Contour Dredging
Precision contour dredges are small hydraulic dredges that can operate effectively in water depths of 3 to 20 feet Most of Woods Pond and downstream portions of Reach 5 would be suitable for operation of a precision contour dredge Many upstream portions of Reach 5 could also be made suitable by controlling the water level with temporary sheet piling dams or weirs
eMS New Technology for New Options 24 12511
Conventional hydraulic dredges normally remove accumulated sediment to a uniform elevation for a channel such as in navigational dredging Precision contour dredges remove sediment to variable elevations and locations according to an engineered contour dredging plan based on field cores and surveys Precision hydraulic dredging is the least invasive and most efficient way of removing
sediment where there are environmental considerations Dredge guidance technologies and software enable dredging accuracy within close tolerances in contaminated areas
A finished grade contour dredging plan in electronic format created from a field survey is used to guide the dredge operator Digging or dredging depths are varied according to the dredging plan
Precision dredges are typically outfitted with GPS and digital compass positioning systems electronic depth gages and flow devices for monitoring discharge A guidance computer is used to log data track dredging coverage and record a final hydrographic survey of the finished bottom This is a mandatory requirement with the New York State Department of Environmental Protection
An 8 inch Mud Cat precision hydraulic dredge equipped with an 8 foot wide cutter head typically digs by moving itself forward in a series of parallel lines each successive pass slightly overlapping the previous one The operation proceeds in grids using cables draped along the desired course to move the dredge Unlike mechanical dredging currently approved for the Hudson River cleanup resuspension of sediment in the waterway is minimal Silk curtains or other barriers can be used to
keep turbidity contained however Resuspension of sediment on a recent project in Lake Champlain was so minimal that dredging proceeded during public bathing on an adjacent beach
A precision hydraulic dredge can be outfitted leased andor purchased from several companies in the dredging industry At lease two companies offer real time control software for precision dredging one
of which is headquartered in Middletown CT Three precision hydraulic dredges are currently working the Fox River cleanup in Wisconsin Precision hydraulic dredges have been used recently on projects located on Lake Champlain and Long Island The Long Island project which removed contaminated sediment from above the original waterbed as a tidal pond used real time controls that made constant adjustments for changing ocean tides
Slurry from the dredge would be pumped directly to a processing plant for treatment
Volume Reduction Processing
Separation of contaminated silt from sediment volume reduction and reuse of treated material were major goals of a processing scheme developed in the Netherlands and now being used on the Fox River cleanup in Wisconsin The Dutch had simply run out of space for transporting and landfilling contaminated sediment and a new approach was necessary
At the Fox River project where two Dutch firms are part of a cleanup joint venture dredged slurry is pumped directly to a processing plant where water sand and debris are removed from the slurry leaving a contaminated silt to be treated and filter pressed to make a dry filter cake Volume reduction from sediment to filter cake is significant Sand removed during processing is washed tested and reused as fill or sold for other beneficial uses Water from the slurry is filtered and used in processing or returned to the river
According to a cover story in the August 3 2009 issue of Engineering New Record Just-in-Time Dredging Pulls Out Toxins the incoming slurry first runs through a scalping screen that takes out rocks wood ships bottles and other debris larger than 6 mm in diameter The debris is sent to a land
eMS New Technology for New Oplions 34 12511
fill and the remaining sand water and silt move to separator cyclones that remove sand from the slurry The first set of separators remove grains from 6 mm to 150 microns in diameter the preferred size for making concrete The second set removes grains down to 63 microns
From there the remaining silty water goes to a conditioning tank where it is dosed with a polymer and stirred to uniform consistency before being pumped into a settling tank There the silt and polymer settle to the bottom as a sludge while the water rises to the top and is pumped to a water filtration system for cleaning testing reusing or returning to the river The water-treatment system has three identical filter trains that consist of sand filters bag filters carbon filters and canister filters
The sludge or silt is pump[ed to eight of the worlds largest filter presses Each press can squuze 600 cf of wet sludge into 18 tons of dry filter cake in 75 minutes
Dredged slurry from a Woods PondRiver dredge could be pumped directly to a similar scaled down processing plant to remove debris dewater desand and filter press contaminated sludge to make
filter cake The processing plant could be located at the former Devos parcel off New Lenox Road or further downstream closer to Woods Pond Booster pumps could be used to maintain slurry flow to the processing plant Clean sand could be belted to deposit in the Lane quarry for storage and resale Concentrated filter cake could be transported and landfilled GE notes in the revised CMS that a local upland disposal facility beyond the flood plain would be best suited to meet criteria for
the study Presumably such a facility would be for dewatered untreated sediment (not filter cake) similar to material stored in controversial Hill 78
Conclusions and New Options for the CMS
The primary purpose of this letter was to focus on three new procedures for the ROR cleanup Though mentioned none had been considered by GE in their previous CMS studies They are procedures which improve mapping dredging and processing of PCB contaminated sediment They have been developed since the Housatonic CMS process started which may account for their omission by GE In summary the three procedures would diminish over dredging and processing and
diminish the volume of contaminated material to be transported and stored They are recognized procedures currently being used on projects around the world because of their effectiveness
The secondary purpose was to encourage dredging in Woods Pond to restore the original trapping efficiency of sediment in the pond and provide a unique barrier for sediment transport in future years This is a natural step that needs consideration and incorporation in the final work plan Raising the trap efficiency along with improved mapping and dredging would also obviate the need for river bed capping and stabilizing of river banks in Reach 5
The new GE web site Options for the Housatonic at WWWll ousatonicoptions com recommends
Monitored Natural Recovery (MNR) versus other alternatives in the Revised CMS I would suggest a new alternative with modified cleanup procedures as outlined in this letler would be preferable to MNR Again thank you for this opportunity to comment
Sincerely
~~La bull Harold Nelson Civil Engineer PE F ASCE
eMS New Tecllnology for New Options 44 12511
Engineered Contour Mapping
Every river or stream is a moving body of water and sediment When a river such as the Housatonic flows into Woods Pond the reduced flow (velocity) of the water causes sedimentation or settling of
particles to the bottom Sedimentation also occurs around obstacles in the river such as structures piling or tree stumps where there are eddies and reduced flow When velocity of the water is raised during an extreme event like spring runoff sediment particles may again become water borne and move until their velocity is reduced and the sedimentation process begins again There has never been dredging (would appear) in the 100 year history of Woods Pond The configuration and shallow
depth are ideal for sedimentation
When dredging plans are engineered for the pond there should be two objectives The first is to remove as much of the contaminated sediment as possible so as to minimize transport down the river in a future flooding event The second is to restore trap efficiency to as high a level as possible so as to retain new sediment flowing into the pond from upstream sources during normal or extreme events Trap efficiency varies with characteristics of the sediment and retention time or rate of flow in the pond The latter is controlled by the geometry and runoff characteristics Trap efficiency is the ratio or percentage of sediment retained to sediment entering the pond
Computer maps for operating a preCision contour dredge are generated from surveys and software using GPS multi-beam sonar laser scanners and aerial orthophotography In a state of art contour dredge they are used to define location of PCB contaminated sediment control dredging and verify results after dredging During a preliminary survey core samples from the waterbed taken at close intervals are used to identify location size and depth of PCB pockets Depending on hydrology the
depth of PCB contamination can very from 6 inches to 10 feet PCB contamination is seldom spread uniformly over a waterbed Software mapping programs produce three-dimensional grid maps that are accurate within inches Color codings on a monitor in the dredge show the operator where to dredge and provide real time (three dimensional control) of the auger at all times
Costs for generating these sophisticated surveys are offset by savings in the volume of material that is dredged and processed and the cost of engineered capping Contour dredging minimizes the amount of clean material removed and minimizes the contaminated material that is missed from dredging Thorough dredging is achieved and over dredging minimized Printouts from the RCS system provide as-built records of the finished bottom and are mandatory with some agencies including the NYS Department of Environmental Protection
PCB concentrations existing in sediments of Reaches 5 and 6 are shown in the Maps and Figures folder available at ltwww epa govheg ion1 2gethesitehestofrivermap~gt The data is presented in the CMS report in support of the risk analyses and modeling but would not be adequate for the
contour computer maps proposed In addition changes in location and concentration of PCBs need to be confirmed from original surveys which are now over 10 years old
Precision Contour Dredging
Precision contour dredges are small hydraulic dredges that can operate effectively in water depths of 3 to 20 feet Most of Woods Pond and downstream portions of Reach 5 would be suitable for operation of a precision contour dredge Many upstream portions of Reach 5 could also be made suitable by controlling the water level with temporary sheet piling dams or weirs
eMS New Technology for New Options 24 12511
Conventional hydraulic dredges normally remove accumulated sediment to a uniform elevation for a channel such as in navigational dredging Precision contour dredges remove sediment to variable elevations and locations according to an engineered contour dredging plan based on field cores and surveys Precision hydraulic dredging is the least invasive and most efficient way of removing
sediment where there are environmental considerations Dredge guidance technologies and software enable dredging accuracy within close tolerances in contaminated areas
A finished grade contour dredging plan in electronic format created from a field survey is used to guide the dredge operator Digging or dredging depths are varied according to the dredging plan
Precision dredges are typically outfitted with GPS and digital compass positioning systems electronic depth gages and flow devices for monitoring discharge A guidance computer is used to log data track dredging coverage and record a final hydrographic survey of the finished bottom This is a mandatory requirement with the New York State Department of Environmental Protection
An 8 inch Mud Cat precision hydraulic dredge equipped with an 8 foot wide cutter head typically digs by moving itself forward in a series of parallel lines each successive pass slightly overlapping the previous one The operation proceeds in grids using cables draped along the desired course to move the dredge Unlike mechanical dredging currently approved for the Hudson River cleanup resuspension of sediment in the waterway is minimal Silk curtains or other barriers can be used to
keep turbidity contained however Resuspension of sediment on a recent project in Lake Champlain was so minimal that dredging proceeded during public bathing on an adjacent beach
A precision hydraulic dredge can be outfitted leased andor purchased from several companies in the dredging industry At lease two companies offer real time control software for precision dredging one
of which is headquartered in Middletown CT Three precision hydraulic dredges are currently working the Fox River cleanup in Wisconsin Precision hydraulic dredges have been used recently on projects located on Lake Champlain and Long Island The Long Island project which removed contaminated sediment from above the original waterbed as a tidal pond used real time controls that made constant adjustments for changing ocean tides
Slurry from the dredge would be pumped directly to a processing plant for treatment
Volume Reduction Processing
Separation of contaminated silt from sediment volume reduction and reuse of treated material were major goals of a processing scheme developed in the Netherlands and now being used on the Fox River cleanup in Wisconsin The Dutch had simply run out of space for transporting and landfilling contaminated sediment and a new approach was necessary
At the Fox River project where two Dutch firms are part of a cleanup joint venture dredged slurry is pumped directly to a processing plant where water sand and debris are removed from the slurry leaving a contaminated silt to be treated and filter pressed to make a dry filter cake Volume reduction from sediment to filter cake is significant Sand removed during processing is washed tested and reused as fill or sold for other beneficial uses Water from the slurry is filtered and used in processing or returned to the river
According to a cover story in the August 3 2009 issue of Engineering New Record Just-in-Time Dredging Pulls Out Toxins the incoming slurry first runs through a scalping screen that takes out rocks wood ships bottles and other debris larger than 6 mm in diameter The debris is sent to a land
eMS New Technology for New Oplions 34 12511
fill and the remaining sand water and silt move to separator cyclones that remove sand from the slurry The first set of separators remove grains from 6 mm to 150 microns in diameter the preferred size for making concrete The second set removes grains down to 63 microns
From there the remaining silty water goes to a conditioning tank where it is dosed with a polymer and stirred to uniform consistency before being pumped into a settling tank There the silt and polymer settle to the bottom as a sludge while the water rises to the top and is pumped to a water filtration system for cleaning testing reusing or returning to the river The water-treatment system has three identical filter trains that consist of sand filters bag filters carbon filters and canister filters
The sludge or silt is pump[ed to eight of the worlds largest filter presses Each press can squuze 600 cf of wet sludge into 18 tons of dry filter cake in 75 minutes
Dredged slurry from a Woods PondRiver dredge could be pumped directly to a similar scaled down processing plant to remove debris dewater desand and filter press contaminated sludge to make
filter cake The processing plant could be located at the former Devos parcel off New Lenox Road or further downstream closer to Woods Pond Booster pumps could be used to maintain slurry flow to the processing plant Clean sand could be belted to deposit in the Lane quarry for storage and resale Concentrated filter cake could be transported and landfilled GE notes in the revised CMS that a local upland disposal facility beyond the flood plain would be best suited to meet criteria for
the study Presumably such a facility would be for dewatered untreated sediment (not filter cake) similar to material stored in controversial Hill 78
Conclusions and New Options for the CMS
The primary purpose of this letter was to focus on three new procedures for the ROR cleanup Though mentioned none had been considered by GE in their previous CMS studies They are procedures which improve mapping dredging and processing of PCB contaminated sediment They have been developed since the Housatonic CMS process started which may account for their omission by GE In summary the three procedures would diminish over dredging and processing and
diminish the volume of contaminated material to be transported and stored They are recognized procedures currently being used on projects around the world because of their effectiveness
The secondary purpose was to encourage dredging in Woods Pond to restore the original trapping efficiency of sediment in the pond and provide a unique barrier for sediment transport in future years This is a natural step that needs consideration and incorporation in the final work plan Raising the trap efficiency along with improved mapping and dredging would also obviate the need for river bed capping and stabilizing of river banks in Reach 5
The new GE web site Options for the Housatonic at WWWll ousatonicoptions com recommends
Monitored Natural Recovery (MNR) versus other alternatives in the Revised CMS I would suggest a new alternative with modified cleanup procedures as outlined in this letler would be preferable to MNR Again thank you for this opportunity to comment
Sincerely
~~La bull Harold Nelson Civil Engineer PE F ASCE
eMS New Tecllnology for New Options 44 12511
Conventional hydraulic dredges normally remove accumulated sediment to a uniform elevation for a channel such as in navigational dredging Precision contour dredges remove sediment to variable elevations and locations according to an engineered contour dredging plan based on field cores and surveys Precision hydraulic dredging is the least invasive and most efficient way of removing
sediment where there are environmental considerations Dredge guidance technologies and software enable dredging accuracy within close tolerances in contaminated areas
A finished grade contour dredging plan in electronic format created from a field survey is used to guide the dredge operator Digging or dredging depths are varied according to the dredging plan
Precision dredges are typically outfitted with GPS and digital compass positioning systems electronic depth gages and flow devices for monitoring discharge A guidance computer is used to log data track dredging coverage and record a final hydrographic survey of the finished bottom This is a mandatory requirement with the New York State Department of Environmental Protection
An 8 inch Mud Cat precision hydraulic dredge equipped with an 8 foot wide cutter head typically digs by moving itself forward in a series of parallel lines each successive pass slightly overlapping the previous one The operation proceeds in grids using cables draped along the desired course to move the dredge Unlike mechanical dredging currently approved for the Hudson River cleanup resuspension of sediment in the waterway is minimal Silk curtains or other barriers can be used to
keep turbidity contained however Resuspension of sediment on a recent project in Lake Champlain was so minimal that dredging proceeded during public bathing on an adjacent beach
A precision hydraulic dredge can be outfitted leased andor purchased from several companies in the dredging industry At lease two companies offer real time control software for precision dredging one
of which is headquartered in Middletown CT Three precision hydraulic dredges are currently working the Fox River cleanup in Wisconsin Precision hydraulic dredges have been used recently on projects located on Lake Champlain and Long Island The Long Island project which removed contaminated sediment from above the original waterbed as a tidal pond used real time controls that made constant adjustments for changing ocean tides
Slurry from the dredge would be pumped directly to a processing plant for treatment
Volume Reduction Processing
Separation of contaminated silt from sediment volume reduction and reuse of treated material were major goals of a processing scheme developed in the Netherlands and now being used on the Fox River cleanup in Wisconsin The Dutch had simply run out of space for transporting and landfilling contaminated sediment and a new approach was necessary
At the Fox River project where two Dutch firms are part of a cleanup joint venture dredged slurry is pumped directly to a processing plant where water sand and debris are removed from the slurry leaving a contaminated silt to be treated and filter pressed to make a dry filter cake Volume reduction from sediment to filter cake is significant Sand removed during processing is washed tested and reused as fill or sold for other beneficial uses Water from the slurry is filtered and used in processing or returned to the river
According to a cover story in the August 3 2009 issue of Engineering New Record Just-in-Time Dredging Pulls Out Toxins the incoming slurry first runs through a scalping screen that takes out rocks wood ships bottles and other debris larger than 6 mm in diameter The debris is sent to a land
eMS New Technology for New Oplions 34 12511
fill and the remaining sand water and silt move to separator cyclones that remove sand from the slurry The first set of separators remove grains from 6 mm to 150 microns in diameter the preferred size for making concrete The second set removes grains down to 63 microns
From there the remaining silty water goes to a conditioning tank where it is dosed with a polymer and stirred to uniform consistency before being pumped into a settling tank There the silt and polymer settle to the bottom as a sludge while the water rises to the top and is pumped to a water filtration system for cleaning testing reusing or returning to the river The water-treatment system has three identical filter trains that consist of sand filters bag filters carbon filters and canister filters
The sludge or silt is pump[ed to eight of the worlds largest filter presses Each press can squuze 600 cf of wet sludge into 18 tons of dry filter cake in 75 minutes
Dredged slurry from a Woods PondRiver dredge could be pumped directly to a similar scaled down processing plant to remove debris dewater desand and filter press contaminated sludge to make
filter cake The processing plant could be located at the former Devos parcel off New Lenox Road or further downstream closer to Woods Pond Booster pumps could be used to maintain slurry flow to the processing plant Clean sand could be belted to deposit in the Lane quarry for storage and resale Concentrated filter cake could be transported and landfilled GE notes in the revised CMS that a local upland disposal facility beyond the flood plain would be best suited to meet criteria for
the study Presumably such a facility would be for dewatered untreated sediment (not filter cake) similar to material stored in controversial Hill 78
Conclusions and New Options for the CMS
The primary purpose of this letter was to focus on three new procedures for the ROR cleanup Though mentioned none had been considered by GE in their previous CMS studies They are procedures which improve mapping dredging and processing of PCB contaminated sediment They have been developed since the Housatonic CMS process started which may account for their omission by GE In summary the three procedures would diminish over dredging and processing and
diminish the volume of contaminated material to be transported and stored They are recognized procedures currently being used on projects around the world because of their effectiveness
The secondary purpose was to encourage dredging in Woods Pond to restore the original trapping efficiency of sediment in the pond and provide a unique barrier for sediment transport in future years This is a natural step that needs consideration and incorporation in the final work plan Raising the trap efficiency along with improved mapping and dredging would also obviate the need for river bed capping and stabilizing of river banks in Reach 5
The new GE web site Options for the Housatonic at WWWll ousatonicoptions com recommends
Monitored Natural Recovery (MNR) versus other alternatives in the Revised CMS I would suggest a new alternative with modified cleanup procedures as outlined in this letler would be preferable to MNR Again thank you for this opportunity to comment
Sincerely
~~La bull Harold Nelson Civil Engineer PE F ASCE
eMS New Tecllnology for New Options 44 12511
fill and the remaining sand water and silt move to separator cyclones that remove sand from the slurry The first set of separators remove grains from 6 mm to 150 microns in diameter the preferred size for making concrete The second set removes grains down to 63 microns
From there the remaining silty water goes to a conditioning tank where it is dosed with a polymer and stirred to uniform consistency before being pumped into a settling tank There the silt and polymer settle to the bottom as a sludge while the water rises to the top and is pumped to a water filtration system for cleaning testing reusing or returning to the river The water-treatment system has three identical filter trains that consist of sand filters bag filters carbon filters and canister filters
The sludge or silt is pump[ed to eight of the worlds largest filter presses Each press can squuze 600 cf of wet sludge into 18 tons of dry filter cake in 75 minutes
Dredged slurry from a Woods PondRiver dredge could be pumped directly to a similar scaled down processing plant to remove debris dewater desand and filter press contaminated sludge to make
filter cake The processing plant could be located at the former Devos parcel off New Lenox Road or further downstream closer to Woods Pond Booster pumps could be used to maintain slurry flow to the processing plant Clean sand could be belted to deposit in the Lane quarry for storage and resale Concentrated filter cake could be transported and landfilled GE notes in the revised CMS that a local upland disposal facility beyond the flood plain would be best suited to meet criteria for
the study Presumably such a facility would be for dewatered untreated sediment (not filter cake) similar to material stored in controversial Hill 78
Conclusions and New Options for the CMS
The primary purpose of this letter was to focus on three new procedures for the ROR cleanup Though mentioned none had been considered by GE in their previous CMS studies They are procedures which improve mapping dredging and processing of PCB contaminated sediment They have been developed since the Housatonic CMS process started which may account for their omission by GE In summary the three procedures would diminish over dredging and processing and
diminish the volume of contaminated material to be transported and stored They are recognized procedures currently being used on projects around the world because of their effectiveness
The secondary purpose was to encourage dredging in Woods Pond to restore the original trapping efficiency of sediment in the pond and provide a unique barrier for sediment transport in future years This is a natural step that needs consideration and incorporation in the final work plan Raising the trap efficiency along with improved mapping and dredging would also obviate the need for river bed capping and stabilizing of river banks in Reach 5
The new GE web site Options for the Housatonic at WWWll ousatonicoptions com recommends
Monitored Natural Recovery (MNR) versus other alternatives in the Revised CMS I would suggest a new alternative with modified cleanup procedures as outlined in this letler would be preferable to MNR Again thank you for this opportunity to comment
Sincerely
~~La bull Harold Nelson Civil Engineer PE F ASCE
eMS New Tecllnology for New Options 44 12511
