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NH Dams LLC Dam Maintenance and Construction Services

• Maintain dam and appurtenant structures per NH DES Dam Bureau Dam Safety regulations
• Exercise, maintain and repair dam outlet works, gates, flashboards, etc.
• Maintain and update dam safety records (OMR, EAP, DSSMP, DSSMR)
• Monitor and regulate water levels in accordance with the approved OMR
• Monitor seepage, leakage, and dam stability in accordance with approved OMR, and report to client and Dam Bureau,
• Provide Owner’s representation at Dam Safety Inspections
• Provide repairs to dam and appurtenant structures in accordance with Dam Bureau approved plans.

Details about our Services

Buffer Maintenance

• Buffer Maintenance
  • Review NH DES Dam Bureau files to determine extent of dam structure requiring maintenance and monitoring. Often times additional outlet structures are identified through this process.
  • Buffer maintenance is scheduled routinely as required, specific to the site, as frequent as weekly but can be annual or less frequent, and can be done on an as needed/on call basis.
  • Low impact buffer maintenance can be used in environmentally sensitive areas or at the owner’s request

Outlet Works Maintenance

• Outlet Works Maintenance
  • Includes leaf and limb/log removal.
  • Debris can be disposed of onsite or taken away to be properly disposed of.
  • Work is accomplished through manual removal, or mechanical if so equipped
  • In cases where the dam is equipped with sluice gates, low level outlets, etc., depending on historical frequency of use/exercise of gate/outlet structure, dive inspection services can be provided
  • If maintenance records are not available, dive inspection and engineering design can be provided to establish existing conditions, and for use in subsequent dam safety records.
• Operate outlet devices in accordance with Dam Bureau approved Operations, Maintenance and Response Plan (OMR)
  • Each dam is required to have an Operations, Maintenance and Response Plan. This plan establishes the minimum maintenance required by the dam owner, and is the basis for maintenance operations
  • Dam and spillways equipped with such operable devices require exercising of those devices on a routine basis, typically annually.
  • In many cases, the operation of those devices coincides with the annual lowering and raising of water levels within the impoundment. However, sometimes the dams maintain normal pool year-round, with no reason to operate water control devices, i.e. dams are run-of-river.
  • In all cases, exercising of outlet devices is stipulated in the OMR, and is part of normal maintenance.

Dam Safety Documentation Services

• Provide observation report for every site visit, to note observations and activities
  • Given the Dam Safety inspection interval, Dam Safety Engineers rely on owner communication to remain informed as to what routine maintenance has been done, and what efforts have been made to comply with any outstanding letter of deficiency (LOD) items. Providing the dam owner with routine observation reports intended for routing to the Dam Bureau, is a proactive approach to maintaining a collaborative relationship with the Dam Bureau.
• Review contact list and verify individuals and respective contact information are valid.
• Review plan and confirm stated response resources are valid, maintained, and/or available
  • e. sand bags and sand maintained onsite, or local contractor with materials still in business and aware they are identified as a resource in the EAP
• Confirm precipitation data used in dam failure is still valid (this is a simple online query at Northeast Regional Climate Center, precipitation values for storm events change periodically, ie the rainfall that constitutes the 100-year rainfall changes as data is revised)
• Confirm EAP has been tested IAW required frequency

Maintain embankments

• Mow/maintain earth embankment dam area as needed
  • This will include a pre-assessment to determine locations of animal burrows, slides, worn paths, etc, requiring filling and leveling. Earth embankment will be mowed, weed wacked, or otherwise groomed to maintain vegetative growth, prevent woody growth, and monitor areas of animal or human influenced damage to the earth embankment integrity.
  • Animal burrows, human and animal paths, etc., that jeopardize the integrity of the earth embankment will be filled, leveled, and seeded.