2011 Road Management Plan for Brackett and Pond Roads, Wakefield, NH
The purpose of the Road Management Plan is to address the declining water quality of Lovell Lake caused by runoff from Brackett and Pond Roads carrying sediment and phosphorus. Unimproved roads are commonplace in the Lakes Region of New Hampshire in an area with a substantial seasonal population. Unimproved roads and associated maintenance are well documented as major sources of sediment and phosphorus to surface water and may account for as much as 80% of the sediment load and 40% of the phosphorus load within a watershed. Studies have shown that during highly erosive storm events, sediment concentrations may be observed to exceed 100,000 mg/L with averages for gravel roads >3,000 mg/l (Clinton and Vose 2003) whereas a typical low use paved road would be ~100 mg/L (Hagen and Walker 2006). The impacts from these sediment laden waters can be substantial and directly impact the value, aesthetics, and usability of our lakes. As seasonal populations grow and become permanent, the number of road miles and driveways will increase, and maintenance demands for these unimproved surfaces will increase.
Another issue of concern is that road maintenance practices, while improving road drainage, often contribute significantly to erosion and sedimentation. The process of improving roadside conveyance through ditching is routine and a necessary element of road maintenance. However, the addition of erosion and sedimentation control practices to this routine maintenance will reduce the threat to surface waters.
A range of strategies exist to reduce impacts ranging from practical road maintenance techniques, to road and drainage improvements, and non-structural approaches (i.e. catch basin cleaning, vegetative stabilization) targeted to minimize erosion and sedimentation. This Road Management Plan (RMP) presents recommendations for Brackett and Pond Roads, and a review of locations identified to be primary problem areas. The locations are prioritized for cost and sediment load. This review finds that by addressing the top 7 of the 14 identified locations, over 44,000 lbs of sediment per year can be eliminated from reaching Lovell Lake. That represents 79% of the total estimated sediment load from the 14 sites. These 7 improvements are estimated to cost $28,300. Costs include only materials. Labor and equipment are not included as these are anticipated to be a component of existing operations and maintenance by municipal staff. Costs do not represent detailed design costs which are still required and are for planning purposes only. These estimates are useful for planning, pursuing additional funding and illustrating the relative ranking of each location.
The approaches and techniques recommended in the RMP can all be implemented by existing Town staff. Recommendations include additional equipment and labor demands, both available for purchase or hire. The equipment expenses range from minimal to that equivalent to a large service vehicle.
A generalized management approach for Brackett and Pond Roads is described below. At most sites, treatment strategies were very similar and consisted of: 1) establishing stable, adequately sized drainage, 2) with upstream sedimentation structures (i.e. hooded deep sump catch basins, gravel check dams), 3) installation of road crossings for surface runoff, 4) use of water quality controls post culvert that could filter, infiltrate and dissipate high velocity flows, and 5) stabilized conveyance to the lake.
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