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BoRit Questions & Answers - Stream Bank Stabilization

BoRit Questions & Answers Main Page

  1. Is the ramp across Rose Valley Creek complete?  (8-26-2009)

  2. How long will the ramp be in place?  (8-26-2009)

  3. What type of riprap (stones) is being used to stabilize Rose Valley Creek? (8-26-2009)

  4. While the ramp is in place, will there be any cabled concrete mats (CCM) and/or riprap placed around the ramp to prevent erosion? (8-26-2009)

  5. Are there any methods that EPA can use to dissipate floodwater energy in the Rose Valley Creek?  (8-26-2009)

  6. What is EPA’s schedule for completing the work at Rose Valley Creek? (8-26-2009)

  7. What is EPA doing to ensure that the stream bank stabilization is successful? (8-26-2009)

  8. How will EPA prevent failure during overflow situations (e.g., rip rap cover over the cabled concrete mats)?  (8-26-2009)

  9. Given the relatively smooth sidewalls formed by the cabled concrete mats (CCM), has the Rose Valley Creek post removal action been modeled to generate the design criteria - ­maximum flow rate, velocity, depth? If so, what did the model show? What are the impacts to the Wissahickon Creek if an isolated and severe storm event falls in the Rose Valley watershed, but the water level in the Wissahickon Creek is not impacted (e.g., impact of water velocity through the pipes on the far bank of the Wissahickon Creek)? (8-26-2009)

  10. What is the current clay content of the soil used for backfill on the bank and ramp? What range of percentage clay (passing through a #200 sieve) is the desired for the backfill material? Will you need to amend the fill that has been trucked in already? Will the backfill readily drain water? If water is retained, will it impact the stability of the fill, surrounding slopes (especially on the reservoir side where some seep is desirable), and/or of the ramp? (8-26-2009)

  11. What will the seed mix be for planting along the Rose Valley banks? (8-26-2009)

  12. Are there plans to save rocks, etc. removed from Rose Valley Creek bed that may contain natural macroinvertebrate populations that can be used to reestablish the population after the removal action has been completed?  (8-26-2009)

  13. Will EPA be provided Record Drawings at the completion of the removal action showing how the cabled concrete mats (CCM) and slopes were installed?  (8-26-2009)

  14. What are the anticipated costs for the removal action on Rose Valley Creek? (8-26-2009)

  15. What asbestos experts at EPA or outside EPA are being consulted concerning the removal action for Rose Valley? (8-26-2009)

  16. What is the permeability (or barrier) to the passage of asbestos fibers of these various products (cabled concrete mats, geocells, etc.), in addition to the efficacy in preventing erosion? (8-26-2009)

  17. Is there scientific research and documentation that explains how the geocell and concrete blocking system are adequate systems to contain asbestos contamination? (8-25-2009)

  18. What would the flow in the creek need to be to worry about overtopping, flowing to the southeast, and/or around the ramp?  (8-21-2009)

  19. Are there any back up computations that support the design for Phase 2 of EPA’s removal actions? (8-21-2009)

  20. What is the maximum flow rate (full pipe) discharging from the culvert and what the maximum flow would be that could flow through the new Corrugated Metal Pipe (CMP) culverts? (8-21-2009)

  21. The southern end of the new Rose Valley Creek discharge pipes show them outside the bottom of the bank of the creek. Are there any issues associated with this situation?  (8-21-2009)

  22. The Tannery Run creek appears to have a steep (75 degree) sloped bank (20 feet high) located approximately 150 feet upstream from the Wissahickon Creek in an unrestricted area.  Could this present a hazard? (8-21-2009)

  23. Will EPA continue to photo document the conditions of Tannery Run and Rose Valley Creeks prior to and after the removal action? (8-10-2009)

  24. What will be done with the soil excavated from Rose Valley? (8-10-2009)

  25. What did EPA do with the wood chips from the trees that were taken down?  (8-10-2009)

  26. Why is EPA removing the asbestos-containing material (ACM) pipe debris? (8-10-2009)

  27. How does the amount of disturbance to the asbestos that EPA has performed differ from a full removal of the asbestos-containing material (ACM)? (8-7-2009)

  28. If EPA were to have started removing the waste back in June of 2008, how much asbestos-containing material  would have been removed by now? (8-7-2009)

  29. Does the lack of asbestos fibers on the air monitors during intrusive activity prove that a full removal can be obtained safely albeit with careful systematic approaches? (8-7-2009)

  30. Is EPA considering removing the asbestos piles as a permanent solution and will EPA’s work alleviate flooding issues in West Ambler? (8-7-2009)

  31. Are the actions being taken by EPA’s Removal Program considered a permanent remedy for the site? (8-7-2009)

  32. Is it possible for asbestos to float on the water and therefore, travel off site with the flowing water?  (8-3-2009)

  33. What has EPA done to prevent asbestos materials from migrating off site? (8-3-2009)

  34. Is the integrity of the reservoir being considered for the type of work being done nearby? (8-3-2009)

  35. Asbestos materials have been observed downstream from BoRit. Where is it coming from and is it harmful? (8-3-2009)

  36. How much asbestos-containing material (ACM) has been removed from the site? Has anything been removed from the easement portion of the site? (5-18-2009)

  37. Will EPA cover exposed areas where asbestos materials are visible with hydroseed or temporarily grass the area? (9-5-2008)

  38. Will EPA use a crane when removing the 70 big trees from along the Wissahickon and how will EPA keep the dust levels down? What will be done with the trees after they are felled? (9-5-2008)

  39. Is EPA at the site when work is being done? (9-5-2008)

  40. Why has the EPA chosen to construct a temporary road on the BoRit pile when there are other areas close to the Tannery run and Wissahickon creek that could provide just as easy an access? (9-5-2008)

  41. Why is EPA clearing the pile? (9-5-2008)

  42. Why did EPA start/begin grubbing at the Whitpain Park? (9-5-2008)

  43. Did EPA grub 16 acres in the park and leave it uncovered? (9-5-2008)

  44. What percentage of asbestos is present in the Whitpain surface soil? (9-5-2008)

  45. Why are the earth mover contractors so high up on the "BoRit" pile with the equipment? (9-5-2008)

  46. Is the Whitpain Park going to be a staging area for depositing materials needed to stabilize the stream bank and/or for a decontamination area? (9-5-2008)

  47. Will there be any activity before the next Community Advisory Group (CAG) meeting? If so, what will be taking place? (9-5-2008)

  48. Are EPA contractors going to lay down a fabric and clean soils on all working areas at the park to prevent getting to the asbestos soil? (9-5-2008)

  49. Will there be full time supervision and inspection by the Occupational Safety and Health Administration and/or other agencies? (9-5-2008)

  50. What are the Army Corps (US ACE) recommendations on the creek and reservoir bank restoration; is funding available for this work? (1-2008)

  51. Is EPA proceeding with respect for the natural environment of the Wissahickon Watershed? (12-27-2007)

  52. Is EPA considering some type of dense, thorny vegetation to plant along the stream banks. Such vegetation would make it difficult for trespassers to get to the embankments, or to disturb the cover that is to be installed. This vegetation would also help stabilize the embankments and would prevent erosion. (12-27-2007)

  53. Will EPA coordinate with the Pennsylvania Department of Transportation (PennDOT) on the removal of the dam in the Wissahickon Creek? (12-27-2007)

  54. Does EPA plan to monitor the effectiveness of the stream bank stabilization work? (12-27-2007)

  55. Does EPA intend to comply with state laws regarding erosion and sediment control? (12-27-2007)

  56. Will EPA coordinate and work with resource agencies including the
    U.S. Army Corps of Engineers, the Pennsylvania Department of Environmental Protection, the Pennsylvania Department of Conservation and Natural Resources, PA Fish & Boat Commission, and the PA Historical and Museum Commission? (12-27-2007)

  57. Does EPA require authorization all federal, state, county, or local agencies before work begins on the proposed actions? (12-27-2007)

  58. Has EPA decided how they plan to stabilize the stream bank and stop migration of asbestos? (1-24-2007)

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  1. Is the ramp across Rose Valley Creek complete?  (8-26-2009)
    Yes, the ramp across Rose Valley Creek is complete.

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  2. How long will the ramp be in place?  (8-26-2009)

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    The temporary ramp across Rose Valley Creek will stay in place throughout the duration of the removal action (all phases). The ramp was designed based on the two-year peak flow of Rose Valley. The ramp may stay in place if it is needed for the Remedial Investigation, and it may also be needed for any future Remedial Action. It is still too early to know when the ramp will be removed.

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  3. What type of riprap (stones) is being used to stabilize Rose Valley Creek? (8-26-2009)

    The type of stone being used for riprap, which was based on flow calculations, is R4 (mainly 6” to 12”) stone.

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  4. While the ramp is in place, will there be any cabled concrete mats (CCM) and/or riprap placed around the ramp to prevent erosion? (8-26-2009)

    Riprap stone has been placed on each end of the ramp, and CCM will be placed close to the ramp while leaving space to allow for the ramp to be removed. CCM will be placed in the remaining portion of the creek once the ramp is removed.

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  5. Are there any methods that EPA can use to dissipate floodwater energy in the Rose Valley Creek?  (8-26-2009)

    Stone will be placed by the headwall (where Rose Valley enters the site) to help reduce the water's energy. In addition, the cabled concrete mat are shaped in a way to help reduce the water’s energy.

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  6. What is EPA’s schedule for completing the work at Rose Valley Creek? (8-26-2009)

    Phase II of the Removal Action is projected to be completed by the end of 2009. For Phase II, EPA will be pumping the water out in sections of Rose Valley starting mid­ September. At the latest, the pumping will continue until the end of the year. In addition to the water pumping, EPA will be reshaping the stream banks in preparation for cabled concrete mats installation.

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  7. What is EPA doing to ensure that the stream bank stabilization is successful? (8-26-2009)

    During the design of Phase II, the Army Corps of Engineers has considered the many aspects of the stabilization to ensure it is not undermined by common factors seen in the stream. While there are no absolute guarantees, we are confident that the design is appropriate for this setting.

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  8. How will EPA prevent failure during overflow situations (e.g., rip rap cover over the cabled concrete mats)?  (8-26-2009)

    The general design is the same for the length of the stream. However, the company who wins the bid will provide details on how to lay the mats on the stream. As far as the section just before the ramp, that will be a field adjustment. Most likely, the area will be protected with R4 (mainly 6” to 12” rock) riprap.

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  9. Given the relatively smooth sidewalls formed by the cabled concrete mats (CCM), has the Rose Valley Creek post removal action been modeled to generate the design criteria - ­maximum flow rate, velocity, depth? If so, what did the model show? What are the impacts to the Wissahickon Creek if an isolated and severe storm event falls in the Rose Valley watershed, but the water level in the Wissahickon Creek is not impacted (e.g., impact of water velocity through the pipes on the far bank of the Wissahickon Creek)? (8-26-2009)

    Once vegetated, the sidewalls formed by the CCM will not be smooth. The CCM, by the nature it is constructed, is not smooth due to concrete blocks spaced throughout the mat. Modeling has not been conducted regarding post-Removal Action scenarios.

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  10. What is the current clay content of the soil used for backfill on the bank and ramp? What range of percentage clay (passing through a #200 sieve) is the desired for the backfill material? Will you need to amend the fill that has been trucked in already? Will the backfill readily drain water? If water is retained, will it impact the stability of the fill, surrounding slopes (especially on the reservoir side where some seep is desirable), and/or of the ramp? (8-26-2009)

    EPA staff are still reviewing this question.

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  11. What will the seed mix be for planting along the Rose Valley banks? (8-26-2009)

    The seed mix for the flood plain will consist of ERNST 178 mix and the slopes will receive ERNST 181 mix.

    ERNST 178 consists of the following plant species:
    • Carex vulpinoidea (Fox Sedge)
    • Panicum clandestinum, 'Tioga' ('Tioga' Deer Tongue)
    • Schizachyrium scoparium, PA ecotype (Little Bluestem, PA Ecotype)
    • Chamaecrista faseieulate (Partridge Pea)
    • Elymus riparius (Riverbank Wild Rye)
    • Elymus virginicus (Virginia Wild Rye)
    • Verbena hastate (Blue Vervain)
    • Andropogn gerardii, 'Niagara' ('Niagara' Big Bluestem)
    • Heliopsis helianthoides (Ox Eye Sunflower)
    • Viburnum dentatum (Arrow Wood)
    • Cornus amomum (Silky Dogwood)
    • Panicum virgatum, 'Shelter' (‘Shelter' Switchgrass)
    • Sorghastrum nutans, PA Ecotype (Indiangrass, PA Ecotype)
    • Asclepias syriaca (Common Milkweed)
    • Desmodium canadense (Showy Tick Trefoil)
    • Eupatorium fistulosum (Joe Pye Weed)
    • Eupatorium maculatum (Spotted Joe Pye Weed)
    • Eupatorium perfoliatum (Boneset)
    • Juneus effuses (Soft Rush)
    • Monarda flstulosa (Wild Bergamot)
    • Penstemon digitalis (Tall White Beard Tongue)
    • Rhus Typhina (Staghorn Sumac)
    • Rudbeckia hirta (Black Eyed Susan)
    • Baptisia australis (Blue False Indigo)
    • Euthamia graminifolia (Grass Leaved Goldenrod)
    • Vernonia gigantean (Giant Ironweed)
    • ERNST 181 consists of the following plant species:
    • Lolium multiflorum (Annual Ryegrass)
    • Schizaehyrium scoparium, Eastern ecotype (Little Bluestem, Eastern Ecotype)
    • Elymus Canadensis (Canada Wild Rye)
    • Panicum virgatum, 'Shelter' ('Shelter' Switchgrass)
    • Agrostis perennans (Autumn Bentgrass)
    • Tridens flavus (Purple Top)
    • Coreopsis lanceolata (Lance Leaved Coreopsis)
    • Agrostis scabra (Tickle grass [Rough Bentgrass])
    • Elymus virginicus (Virginia Wild Rye)
    • Penstemon digitalis (Tall White Beard Tongue)
    • Monarda fistulosa (Wild Bergamot)

  12. Are there plans to save rocks, etc. removed from Rose Valley Creek bed that may contain natural macroinvertebrate populations that can be used to reestablish the population after the removal action has been completed?  (8-26-2009)

    EPA will attempt to save as many rocks as possible to be reintroduced to the creek bed following the stabilization actions.

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  13. Will EPA be provided Record Drawings at the completion of the removal action showing how the cabled concrete mats (CCM) and slopes were installed?  (8-26-2009)

    Yes, EPA will be provided Record Drawings at the completion of the Removal Action showing how the CCM was installed.

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  14. What are the anticipated costs for the removal action on Rose Valley Creek? (8-26-2009)

    The anticipated costs for the Removal Action on Rose Valley Creek will approximately be $800,000 to $1,000,000.

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  15. What asbestos experts at EPA or outside EPA are being consulted concerning the removal action for Rose Valley? (8-26-2009)

    EPA has been referring to the federal National Emissions Standards for Hazardous Air Pollutants (NESHAP) regulations regarding asbestos cleanups throughout the process. Thus far, EPA has met and/or exceeded many of the requirements listed in NESHAP when it comes to asbestos cleanups. An "asbestos expert" is not necessary as long as NESHAP regulations are met. EPA does keep in contact with EPA's and the Pennsylvania Department of Environmental Protection’s  NESHAP experts throughout the cleanup.

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  16. What is the permeability (or barrier) to the passage of asbestos fibers of these various products (cabled concrete mats, geocells, etc.), in addition to the efficacy in preventing erosion? (8-26-2009)

    The physical properties of asbestos are the reason that asbestos is not expected to move through soil. It is a mineral (i.e. rock) and dense, having a specific gravity typically reported as ranging between 2.0 and 3.5 (two to three times heavier than water) depending on the mineral variety. Asbestos is made up of fibers and although the fibers and fiber fragments can be microscopic, these particles are still large, complex molecules in the microscopic environment. The fibers are not soluble and therefore can not be transported in a water solution like other, smaller contaminant molecules and ionic species. The particles are also too large to be transported preferentially by other physical-chemical processes like diffusion. Therefore, asbestos fibers tend to remain stationary within the soil matrix. In other words, in a natural soil setting asbestos fibers do not move through the soil.
     
    An analysis published by EPA in April 1977, Movement of Selected Metals, Asbestos, and cyanide in soil: Applications to waste disposal Problems, EPA Publication Number EPA-600/2-77-020, describes the potential for asbestos movement through soil. Although the author, Dr. Wallace H. Fuller, recognizes the paucity of data specific to asbestos, he argues that asbestos is reasonable expected to behave like similarly sized clay particles, which have been extensively studied.

    "Although there are no data on mobility of asbestos in soil, predictions about its behavior can be made with reasonable confidence. Since the weathering products of asbestos are the common nonhazardous salts of Ca, Mg, and Si, physical transport is the only mode of movement in soil which is of significance. The extensive data on movement of clay-sized (<2u diameter) particles by strictly physical processes provide a convenient yardstick for gauging the probable behavior of asbestos in soil. Clay particles 0.1 to 2.0 uin diameter are estimated to move at a rate of 1 to 10 cm per 3,000 to 40,000 years, depending on the soil texture (Berkland, 1974). There is no reason to expect that asbestos particles of similar size would move differently from this. Consequently asbestos migration through soil will not be a problem of any significance."

    It can be added that larger particles (i.e. the longer fibers of the asbestos minerals) are expected to be even more resistant to movement due to physical impedance.

    Specifically, as was stated in EPA's memo to the RRM Group in July 2009, there are approximately two feet of material between the asbestos and the surface on the Wissahickon Creek stream bank.  Because asbestos is a fiber, it does not move freely in soil. In addition to keeping the asbestos in place, the bank was designed to withstand the forces on the Wissahickon Creek stream bank. So far, we have had two big storms and the Phase I work is still intact. The concrete cable mats serve the same purpose.

    As part of the Removal Program, EPA is charged with reducing the immediate risk (and in this case, the potential risk), that may be posed by a site. Although EPA is not aware of any scientific research specifically citing these technologies being used on an asbestos site, the manner in which these phases have been planned ensures that the asbestos will not pose a risk to human health and the environment by essentially capping the asbestos waste. Capping is a practice commonly used to address asbestos waste sites. National Emissions Standards for Hazardous Air Pollutants spells out the minimum capping requirements to ensure there will be not emissions. What we are doing will likely exceed those requirements. In addition, the stream bank stabilizations were designed to specifically hold up to the types of forces that these banks will face during storm conditions. Thus, the stabilization's purpose is two­fold: capping the asbestos waste in place on the stream banks, and stabilizing the stream banks in order to withstand conditions found in the Wissahickon and Rose Valley Creeks and Tannery Run.

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  17. Is there scientific research and documentation that explains how the geocell and concrete blocking system are adequate systems to contain asbestos contamination? (8-25-2009)

    The physical properties of asbestos are the reason that asbestos is not expected to move through soil. It is a mineral (i.e. rock) and dense, having a specific gravity typically reported as ranging between 2.0 and 3.5 (two to three times heavier than water) depending on the mineral variety. Asbestos is made up of fibers and although the fibers and fiber fragments can be microscopic, these particles are still large, complex molecules in the microscopic environment. The fibers are not soluble and therefore can not be transported in a water solution like other, smaller contaminant molecules and ionic species. The particles are also too large to be transported preferentially by other physical-chemical processes like diffusion. Therefore, asbestos fibers tend to remain stationary within the soil matrix. In other words, in a natural soil setting asbestos fibers do not move through the soil.
     
    An analysis published by EPA in April 1977, Movement of Selected Metals, Asbestos, and cyanide in soil: Applications to waste disposal Problems, EPA Publication Number EPA-600/2-77-020, describes the potential for asbestos movement through soil. Although the author, Dr. Wallace H. Fuller, recognizes the paucity of data specific to asbestos, he argues that asbestos is reasonable expected to behave like similarly sized clay particles, which have been extensively studied.

    "Although there are no data on mobility of asbestos in soil, predictions about its behavior can be made with reasonable confidence. Since the weathering products of asbestos are the common nonhazardous salts of Ca, Mg, and Si, physical transport is the only mode of movement in soil which is of significance. The extensive data on movement of clay-sized (<2u diameter) particles by strictly physical processes provide a convenient yardstick for gauging the probable behavior of asbestos in soil. Clay particles 0.1 to 2.0 uin diameter are estimated to move at a rate of 1 to 10 cm per 3,000 to 40,000 years, depending on the soil texture (Berkland, 1974). There is no reason to expect that asbestos particles of similar size would move differently from this. Consequently asbestos migration through soil will not be a problem of any significance."

    It can be added that larger particles (i.e. the longer fibers of the asbestos minerals) are expected to be even more resistant to movement due to physical impedance.

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  18. What would the flow in the creek need to be to worry about overtopping, flowing to the southeast, and/or around the ramp?  (8-21-2009)

    The flow of Rose Valley would need to exceed 220 cubic feet per second for the water to flow around the ramp. Please keep in mind that water would likely go around the pipe, onto the flood plain.

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  19. Are there any back up computations that support the design for Phase 2 of EPA’s removal actions? (8-21-2009)

    The Army Corps of Engineers (US ACE) designed the plans for Phase 2 of the removal action. Any computations related to the design for Phase 2 would have been conducted by the US ACE. Most of the backup documentation is for slope stability analysis. If there are specific computations that the public would like to see, please contact EPA and we will work with the US ACE to provide them.

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  20. What is the maximum flow rate (full pipe) discharging from the culvert and what the maximum flow would be that could flow through the new Corrugated Metal Pipe (CMP) culverts? (8-21-2009)

    The maximum flow rate discharging from the culvert (including the two five feet circular pipes) is 440 cubic feet per second, which equates to a velocity of about 5.64 feet per second. The maximum flow rate that could flow through the new CMP culverts is half of the maximum flow rate, which would be 220 cubic feet per second.

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  21. The southern end of the new Rose Valley Creek discharge pipes show them outside the bottom of the bank of the creek. Are there any issues associated with this situation?  (8-21-2009)

    EPA staff is still reviewing this question.

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  22. The Tannery Run creek appears to have a steep (75 degree) sloped bank (20 feet high) located approximately 150 feet upstream from the Wissahickon Creek in an unrestricted area.  Could this present a hazard? (8-21-2009)

    EPA will be addressing the stabilization of Tannery Run following the stabilization of Rose Valley Creek. Access to Tannery Run is restricted near the site due to asbestos contamination.

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  23. Will EPA continue to photo document the conditions of Tannery Run and Rose Valley Creeks prior to and after the removal action? (8-10-2009)

    EPA will continue to document our efforts during the stream bank stabilizations with photos. Community members are encouraged to visit the EPA Field Office at 324 West Maple Avenue, Ambler, Pennsylvania to see the photos, and any other documents associated with the site.

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  24. What will be done with the soil excavated from Rose Valley? (8-10-2009)

    The asbestos-containing material (ACM) and organic material near the ACM will be bagged and placed on a roll-off-container, which is then covered. The roll-offs are then sent to landfills in York, PA or Shippensburg, PA, both of which accept hazardous waste.

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  25. What did EPA do with the wood chips from the trees that were taken down?  (8-10-2009)

    The wood chips from the clearing and grubbing were ground to a fine material, spread on-site, and covered with soil.

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  26. Why is EPA removing the asbestos-containing material (ACM) pipe debris? (8-10-2009)
    The ACM pipes on the stream banks need to be removed in order to prep the slopes for the stream bank stabilization. Once the pipes are removed, soil can be placed on the slopes to ensure a flat surface for the cabled-concrete mats to be installed.

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  27. How does the amount of disturbance to the asbestos that EPA has performed differ from a full removal of the asbestos-containing material (ACM)? (8-7-2009)

    EPA cannot be certain of the level of disturbance that has occurred in the past and how that would compare to a full removal of ACM at the site. It is likely that the level of asbestos in the air was highly elevated when the manufacturing facility was in operation. EPA's efforts at the site have been minimally invasive, as there has not been a large amount of excavation done at the site in comparison to a complete removal. It is likely that excavation would further increase the risk posed by the site, as well as the complexity of the clean up.

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  28. If EPA were to have started removing the waste back in June of 2008, how much asbestos-containing material  would have been removed by now? (8-7-2009)

    EPA is not certain how much waste could have been excavated. Excavation of waste is a potential remedy that may be evaluated during the Feasibility Study for the site.

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  29. Does the lack of asbestos fibers on the air monitors during intrusive activity prove that a full removal can be obtained safely albeit with careful systematic approaches? (8-7-2009)

    The feasibility of such an effort may be evaluated during the Remedial Program's Feasibility Study, which would be able to evaluate the safety of such a remedy.

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  30. Is EPA considering removing the asbestos piles as a permanent solution and will EPA’s work alleviate flooding issues in West Ambler? (8-7-2009)

    EPA's current plan to stabilize the stream bank will address the short-term, potential risk. A remedy such as complete removal would need to be evaluated during the Remedial Investigation/Feasibility Study, as the Remedial Program will address the long-term, potential risks at the site.

    The flooding problem associated with Rose Valley stem from issues upstream of the site. Although EPA currently has plans to slightly widen Rose Valley, it is not believed to significantly alleviate the flooding issues in West Ambler.

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  31. Are the actions being taken by EPA’s Removal Program considered a permanent remedy for the site? (8-7-2009)

    EPA's current plan to stabilize the stream bank will address the short-term, potential risk. A remedy such as complete removal would need to be evaluated during the Remedial Investigation/Feasibility Study as the Remedial Program will address the long-term, potential risks at the site.

    The Remedial Program does have the option to remove the current stabilization work if it is necessary to make the site more protective of human health and the environment. It is important to note that stream bank stabilization on the Wissahickon Creek has proven to be very effective during storm events.

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  32. Is it possible for asbestos to float on the water and therefore, travel off site with the flowing water?  (8-3-2009)

    The specific gravity of asbestos in its natural mineral form is typically listed at approximately 2.0 and 3.0, depending on the type of asbestos. This is two to three times heavier than water, and, therefore, asbestos fibers are not expected to float. "Shredded" asbestos is often listed as having a specific gravity of 0.3, which being less than 1.0, would imply that shredded asbestos would be lighter than water and be expected to float. This is a misnomer. Shredding asbestos would make the mineral appear light and fluffy like raw cotton, but the asbestos fibers themselves would not change in density. The individual dense fibers would be surrounded by significant volumes of air making the whole mass less dense. However, when shredded asbestos is wet, water replaces the air in the shredded mass, and the fibers, being still heavier than water, sink.

    Note that in certain conditions small particles of dense substances can float because of the strong surface tension characteristic of water (see the high school science experiments on surface tension where a paperclip can "float" in a container of water). However, the conditions for this include the particles being dry and the water being still and clean. Movement, disturbances, or the presence of other substances in the water will interrupt the water's surface tension, causing the particles to sink. It is unlikely that rain water or water from the creek would be still, undisturbed, and free from other substances enough to float asbestos.

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  33. What has EPA done to prevent asbestos materials from migrating off site? (8-3-2009)

    Following the stabilizations of the stream banks, EPA's Removal Program will assess portions of the Wissahickon Creek downstream from the site, and pick up asbestos-containing material that may be associated with the site. EPA will wait until the stabilizations are complete, to ensure a more complete cleanup.

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  34. Is the integrity of the reservoir being considered for the type of work being done nearby? (8-3-2009)

    EPA and the owners of the reservoir, the Wissahickon Waterfowl Preserve, are in constant communication regarding work that is conducted near the reservoir. EPA's contractors are aware of any hazards that may be associated with the work being conducted at the site. EPA, in consultation with the Army Corps of Engineers, has considered the integrity of the reservoir when planning for Phase II of the Removal Action. Any questions regarding the maintenance of the reservoir should be directed to the Wissahickon Waterfowl Preserve.

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  35. Asbestos materials have been observed downstream from BoRit. Where is it coming from and is it harmful? (8-3-2009)

    The majority of the asbestos-containing material (ACM) found downstream from the site has been historically washed down from the slopes of the Wissahickon Creek, Rose Valley Creek, and Tannery Run. EPA's current efforts to stabilize the slopes will prevent further ACM from leaving the site. The Remedial Project Manager is aware of the ACM downstream from the site, and will plan accordingly during the Remedial Investigation.

    Although there has not been significant surface water testing downstream of the site, EPA has not had a surface water sample from the Wissahickon Creek, Rose Valley, and Tannery Run above the Maximum Contaminant Level for asbestos.

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  36. How much asbestos-containing material (ACM) has been removed from the site? Has anything been removed from the easement portion of the site? (5-18-2009)

    Large pieces of ACM were removed, when possible, during the stream bank stabilization. Approximately 460 tons of material was sent to a landfill. It is important to note that the 460 tons includes organic material (soil, vegetation, etc.), contaminated soil, and ACM. Any soil or organic material that was suspected of being contaminated was treated as suspected waste, and disposed of properly. In addition to materials other than ACM being included in the waste amount, dust suppression was used while picking up and consolidating the pile, which made the materials wet and added to the weight.

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  37. Will EPA cover exposed areas where asbestos materials are visible with hydroseed or temporarily grass the area? (9-5-2008)

    Where asbestos is exposed on the surface either due to erosion or as a result of our activities (e.g., vegetation removal), EPA has been covering exposed areas with imported soil and wood chips (from tree cutting). Having said that, although this is an active construction site, we do not plan to hydro seed or temporarily grass the areas we have covered with clean fill material (soil/wood chips). We are getting ready to start the actual construction and even if we were to hydro-seeded or temporarily grassed those areas the vegetation would probably not take before we start. However, once we are done with the stabilization part, most of the stream bank will be seeded.

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  38. Will EPA use a crane when removing the 70 big trees from along the Wissahickon and how will EPA keep the dust levels down? What will be done with the trees after they are felled? (9-5-2008)

    Most of the large trees will be cut by hand using chainsaws. Prior to final cuts the tree will be secured by a claw attachment on the excavator which lowers the tree to the ground and transports it to a staging area where the trees are prepared to be fed into the chipper. The tree chippings will be spread on the site surface. We have and will continue to use dust suppression while cutting trees.

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  39. Is EPA at the site when work is being done? (9-5-2008)

    Yes. The EPA On-Scene Coordinator has been on-site since the first day of field activities, Monday, July 7, 2008. He has talked to some residents as they drive by the Site. Direct supervision of workers is conducted by the WRS Compass Response Manager. Additional EPA and Army Corps of Engineers personnel have also been requested.

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  40. Why has the EPA chosen to construct a temporary road on the BoRit pile when there are other areas close to the Tannery run and Wissahickon creek that could provide just as easy an access? (9-5-2008)
     
    EPA cleared the vegetation on the flat and stable surface of the Pile Property. EPA does not intend to cut into the pile to make an access road. The alternative of working from the parking lots on the east side of Tannery Run was considered but it is not feasible due to the nature of the adjoining businesses (food service and auto repairs) and the steep slope along the creek. We are evaluating different alternatives to get access to these locations.

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  41. Why is EPA clearing the pile? (9-5-2008)

    The clearing and grubbing activities are in preparation for the stream bank stabilization work.

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  42. Why did EPA start/begin grubbing at the Whitpain Park? (9-5-2008)

    The park property is going to be our main staging area. Therefore, we needed to clear the brush to start mobilizing our equipment and build the access roads for when we start bringing the materials which will be used for the stream bank work.

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  43. Did EPA grub 16 acres in the park and leave it uncovered? (9-5-2008)

    EPA did not grub or clear the entire 16 acre park property. Brush/vegetation was cut and the dead vegetation was left on the ground surface. The subsurface soils have not been disturbed, and a soil cover over the cleared vegetation is viewed as unnecessary at this time.

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  44. What percentage of asbestos is present in the Whitpain surface soil? (9-5-2008)

    Results from the October 2007 soil sampling event at the Park revealed asbestos content of 0.003 percent in the first three inches. Historical sampling shows that at deeper depth the asbestos content increases.

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  45. Why are the earth mover contractors so high up on the "BoRit" pile with the equipment? (9-5-2008)

    Those areas are being covered with dirt.

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  46. Is the Whitpain Park going to be a staging area for depositing materials needed to stabilize the stream bank and/or for a decontamination area? (9-5-2008)

    The Park will be used for both staging and decontamination purposes.

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  47. Will there be any activity before the next Community Advisory Group (CAG) meeting? If so, what will be taking place? (9-5-2008)

    Yes, there will be activity before the next CAG meeting. Clearing and grubbing activities will continue along the eastern bank of the Wissahickon Creek. In addition, we might start getting the materials needed for building the access roads.

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  48. Are EPA contractors going to lay down a fabric and clean soils on all working areas at the park to prevent getting to the asbestos soil? (9-5-2008)

    Access roads will be built to sustain heavy traffic and to protect the soil and vegetative cover at the Park. A fabric layer will be placed on certain areas of the Park, to provide a barrier between the ground surface and the materials that will be stockpiled there.

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  49. Will there be full time supervision and inspection by the Occupational Safety and Health Administration and/or other agencies?
    (9-5-2008)

    No, there will be no full time supervision by any other agency. However, a representative from the U.S. Army Corps of Engineers will be on­site as the construction manager. In addition, EPA is working closely with the Agency for Toxic Substances and Disease Registry, the Pennsylvania Department of Health, the Pennsylvania Department of Environmental Protection and the Montgomery County Health Department at this Site and welcomes their observations and comments on the operations.

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  50. What are the Army Corps (US ACE) recommendations on the creek and reservoir bank restoration; is funding available for this work? (1-2008)

    The US ACE’s final report has been available for almost a year at the BoRit Website. Please follow the following link to the document.
     
    http://www.epaosc.org/sites/2475/files/usace%20proposal.pdf

    Part of the question is about funding: If EPA decides that implementation of the US ACE recommendations is necessary, funding will be requested.

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  51. Is EPA proceeding with respect for the natural environment of the Wissahickon Watershed? (12-27-2007)

    EPA plans to conduct work in a responsible and respectful manner. EPA is evaluating ecologically friendly technology for use in this project and plans to construct it to withstand potentially severe weather conditions.

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  52. Is EPA considering some type of dense, thorny vegetation to plant along the stream banks. Such vegetation would make it difficult for trespassers to get to the embankments, or to disturb the cover that is to be installed. This vegetation would also help stabilize the embankments and would prevent erosion. (12-27-2007)

    Assuming compatibility with the chosen and necessary stabilization method, EPA plans to plant vegetation on the stream banks as it will serve a dual purpose to stabilize the banks and to deter trespassing. EPA will consider the plants listed in Appendix A.

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  53. Will EPA coordinate with the Pennsylvania Department of Transportation (PennDOT) on the removal of the dam in the Wissahickon Creek? (12-27-2007)

    Yes.  EPA will coordinate with PennDOT.

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  54. Does EPA plan to monitor the effectiveness of the stream bank stabilization work? (12-27-2007)

    EPA intends to monitor the work done until establishment of the vegetative cover (i.e., one growing season or at least one year).

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  55. Does EPA intend to comply with state laws regarding erosion and sediment control? (12-27-2007)

    Generally, EPA is required by law to comply with the substantive requirements of applicable federal and state regulations. As a practical matter, EPA intends to seek the input of the County and local government on these issues.

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  56. Will EPA coordinate and work with resource agencies including the
    U.S. Army Corps of Engineers, the Pennsylvania Department of Environmental Protection, the Pennsylvania Department of Conservation and Natural Resources, PA Fish & Boat Commission, and the PA Historical and Museum Commission? (12-27-2007)

    EPA has been and will continue working closely with other government entities in this project, several of whom already have inter-agency agreements with EPA in place.

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  57. Does EPA require authorization all federal, state, county, or local agencies before work begins on the proposed actions? (12-27-2007)

    Generally, EPA is required by law to comply with the substantive requirements of applicable federal and state regulations. As a practical matter, EPA intends to seek the input of the County and local government on these issues.

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  58. Has EPA decided how they plan to stabilize the stream bank and stop migration of asbestos? (1-24-2007)

    EPA planned to conduct a site reconnaissance to identify the area(s) in need of stabilization to stop erosion and migration of asbestos into adjacent watershed. To date, based on validated sampling results (i.e., surface water and sediment) EPA has not identified any area in which migration is occurring.

    In the October 2006 public meeting, EPA explained that the U.S. Army Corps of
    Engineering was brought to the Site to provide EPA with some potential short and long term options for bank stabilization (the report is posted on the website).
     
    EPA will not make a final decision about a remedy, if any, for the Site until the sampling program has been completed. At that time, EPA will decide which stabilization option, if any will be selected for the Site.

    It is important to remember that EPA makes decisions based on risk calculated using validated data.

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