Barrier Removal Sediment Barrier Removal Sediment Management Management Presentation to the Rivers Management Advisory Committee Presentation to the Rivers Management Advisory Committee May 9, 2011 May 9, 2011
General Dam Information General Dam Information New Hampshire has more than 5,100 active and inactive New Hampshire has more than 5,100 active and inactive dams that have been inventoried by the DES Dam dams that have been inventoried by the DES Dam Bureau. Bureau. Over 75% are privately owned. Over 75% are privately owned. The impoundments created by dams may enable and/or The impoundments created by dams may enable and/or enhance recreational uses such as boating, fishing and enhance recreational uses such as boating, fishing and swimming. They may also provide fire protection, swimming. They may also provide fire protection, hydropower production, water supply, and flood control. hydropower production, water supply, and flood control.
The Benefits of Dam Removal The Benefits of Dam Removal Eliminates a public safety hazard. Eliminates a public safety hazard. Provides cost savings to dam owners and tax payers. Provides cost savings to dam owners and tax payers. Improves water quality. Improves water quality. Eliminates barriers to fish and other aquatic species. Eliminates barriers to fish and other aquatic species. Restores river habitats. Restores river habitats. Reestablishes normal sediment dynamics. Reestablishes normal sediment dynamics.
Dam Removal in New Hampshire Dam Removal in New Hampshire The NH River Restoration Task Force was formed in The NH River Restoration Task Force was formed in 2000 with the goal of exploring opportunities to remove 2000 with the goal of exploring opportunities to remove dams primarily to restore rivers and eliminate public dams primarily to restore rivers and eliminate public safety hazards. safety hazards. In 2001 DES created the Dam Removal and River In 2001 DES created the Dam Removal and River Restoration Program within the Dam Bureau to assist Restoration Program within the Dam Bureau to assist dam owners with technical, regulatory and financial dam owners with technical, regulatory and financial aspects of dam removal. aspects of dam removal.
Dam Removal in NH continued… Dam Removal in NH continued… Since 2001, 14 dam removal projects have been Since 2001, 14 dam removal projects have been completed. completed. The most recent was the Homestead Woolen Dam in The most recent was the Homestead Woolen Dam in West Swanzey in 2010. West Swanzey in 2010. Currently there are nearly a dozen other dams under Currently there are nearly a dozen other dams under consideration for removal. consideration for removal.
Primary Issues Facing Dam Removal Primary Issues Facing Dam Removal Projects Projects Fisheries and wildlife Fisheries and wildlife Funding Funding Historic resources Historic resources Hydrology and hydraulics Hydrology and hydraulics Sediment Sediment
Why Develop a Sediment Assessment & Why Develop a Sediment Assessment & Management Protocol? Management Protocol? Sediment management methods have been inconsistent Sediment management methods have been inconsistent and handled on a project- -by by- -project basis. project basis. and handled on a project Uncertainty for dam owners and consultants, often Uncertainty for dam owners and consultants, often leading to significant additional effort and expense. leading to significant additional effort and expense. Need a standardized, science Need a standardized, science- -based methodology that based methodology that can be applied to any dam removal project in the state. can be applied to any dam removal project in the state. Provide consistency for dam owners, consultants and Provide consistency for dam owners, consultants and regulatory agencies, and reduce project costs. regulatory agencies, and reduce project costs.
Contributors to the Protocol Contributors to the Protocol DES (Dam Bureau, 401 Water Quality Program, Rivers DES (Dam Bureau, 401 Water Quality Program, Rivers Management Program, Wetlands Bureau, Waste Management Program, Wetlands Bureau, Waste Management Division and Coastal Program) Management Division and Coastal Program) New Hampshire Fish & Game Department New Hampshire Fish & Game Department Massachusetts Department of Fish & Game Massachusetts Department of Fish & Game National Marine Fisheries Service National Marine Fisheries Service American Rivers American Rivers
Assumptions 1. Barrier removal is beneficial to river health. 2. The total volume of potentially mobile impounded sediment is critical to the sediment management process. As such, the level of sediment contaminant testing should be commensurate with the volume of potentially mobile impounded sediment. 3. Projects with small amounts of potentially mobile impounded sediment and no or limited due diligence issues should be able to proceed with no contaminant testing. 4. Sediment assessment and management protocols should not always be determined on a case-by-case basis. A standardized sediment assessment and management protocol should be utilized until specific sediment volume or contamination thresholds are exceeded. 5. Natural erosion of the potentially mobile impounded sediment should be the preferred sediment management alternative unless conditions/ factors dictate otherwise.
DRAFT Barrier Removal Sediment Assessment & Management Protocol Flow Chart #1 Yes Conduct due diligence review #2 Determine quantity and potential mobility of impounded sediment, and assess whether mobile portion of sediment is likely to “cause problems” downstream #3 Yes Does due diligence review suggest contaminant or other issues? No #5 #4 No contaminant Is mobile portion of impounded No Yes testing or sediment sediment likely to “cause problems” management required downstream?
Due Diligence Information Due Diligence Information Dam specific (i.e., current and historical purposes of Dam specific (i.e., current and historical purposes of dam and impoundment, assessment of dam’s structural dam and impoundment, assessment of dam’s structural integrity, has dam been breached?, has impoundment integrity, has dam been breached?, has impoundment been dredged?) been dredged?) Hydrological (i.e., stream gage data, FEMA flood maps) Hydrological (i.e., stream gage data, FEMA flood maps) Natural Resource (i.e., aquatic resources, Natural Resource (i.e., aquatic resources, rare/threatened/endangered species, exemplary natural rare/threatened/endangered species, exemplary natural communities) communities)
Due Diligence Information cont… Due Diligence Information cont… Waterbody and watershed (i.e., current and historical Waterbody and watershed (i.e., current and historical land use activities at site and upstream, presence of land use activities at site and upstream, presence of downstream infrastructure, recreational, commercial and downstream infrastructure, recreational, commercial and other uses of impoundment and downstream channel). other uses of impoundment and downstream channel). Contamination (i.e., hazardous waste sites, landfills Contamination (i.e., hazardous waste sites, landfills and/or solid waste disposal sites, oil/toxic spill sites, and/or solid waste disposal sites, oil/toxic spill sites, NPDES outfalls, and Superfund sites). NPDES outfalls, and Superfund sites).
DRAFT Barrier Removal Sediment Assessment & Management Protocol Flow Chart #1 Yes Conduct due diligence review #2 Determine quantity and potential mobility of impounded sediment, and assess whether mobile portion of sediment is likely to “cause problems” downstream #3 Yes Does due diligence review suggest contaminant or other issues? No #5 #4 No contaminant Is mobile portion of impounded No Yes testing or sediment sediment likely to “cause problems” management required downstream?
Fundamental Questions Fundamental Questions 1. How best to determine potential mobility of impounded 1. How best to determine potential mobility of impounded sediment? sediment? - Wisconsin method? - Wisconsin method? 2. How to assess whether the mobile portion of impounded 2. How to assess whether the mobile portion of impounded sediment is likely to “cause problems” downstream? sediment is likely to “cause problems” downstream? - OK if quantity of mobile sediment is ≤ 0.5 times the ≤ 0.5 times the - OK if quantity of mobile sediment is annual sediment load of the waterbody. annual sediment load of the waterbody.
DRAFT Barrier Removal Sediment Assessment & Management Protocol Flow Chart #1 Yes Conduct due diligence review #2 Determine quantity and potential mobility of impounded sediment, and assess whether mobile portion of sediment is likely to “cause problems” downstream #3 Yes Does due diligence review suggest contaminant or other issues? No #5 #4 No contaminant Is mobile portion of impounded No Yes testing or sediment sediment likely to “cause problems” management required downstream?
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