Stonehedge Stormwater Improvements South Burlington, VT June 18, 2013
Stonehedge Outline •Project Objectives •Background •Financing •Existing Stormwater System •Proposed Improvements •Next Steps and Schedule Page 1
Stonehedge Project Objectives •Add stormwater treatment and control prior to discharging to Potash Brook � Will address State stormwater permit issues to facilitate transfer of system to the City •Improve the overall stormwater collection and conveyance system as part of effort to provide treatment and control � Will address some of the existing drainage/flooding problems Page 2
Stonehedge Background •Stormwater system installed in phases beginning in 1970s •No stormwater treatment or control •Flooding and nuisance drainage problems now common •Condo Associations (and not City Stormwater Utility) currently responsible for stormwater system •State stormwater permit issues � Original stormwater permit expired in 1985 � Renewal not possible because discharge to “Stormwater Impaired” streams (Potash to the north, Bartlett to the South) � Renewal process: State’s Engineering Feasibility Analysis to develop a “best-fit” solution •Previous conceptual study •Grant from the Corps of Engineers for current project Page 3
Stonehedge Financing (1/3) •Engineering Costs: ~$120,000 •Construction: ~$530,000 (working estimate) •City has a project agreement with Army Corps of Engineers (ACOE). ACOE will be responsible for 65% of project costs ($422,500). •South Burlington Stormwater Utility and Stonehedge residents responsible for remaining 35% of project costs ($227,500). Page 4
Stonehedge Financing (2/3) •The City of South Burlington owns 25% of the impervious area that is covered by the State permit and will pay 25% of the remaining project costs ($56,875). •The Stonehedge homeowner associations own 75% of the impervious area that is covered by the State permits and will pay 75% of the remaining project costs ($170,625). •Public vote in March 2011 authorized a Stormwater Special Assessment District. Page 5
Stonehedge Financing (3/3) With ACOE Funding Without ACOE Funding ACOE Share of Project Cost $422,500 $- Stonehedge Share of $170,625 $487,500 Project Cost City Share of Project Cost $56,875 $162,500 Total Project Cost $650,000 $650,000 Estimated Cost/Unit $845 $2,413 (202 units) Construction costs are working estimates that will be refined as the design is advanced. Page 6
Stonehedge Existing Stormwater System: Overall •Catch basins/pipes •Open swales •Off-site runoff •No treatment or control Page 7
Stonehedge Existing Stormwater System: Photos Existing Swale Swale and Culvert Roadside Ditch Cedar Glen Road Catch Basin Potash Brook Page 8
Stonehedge Proposed Improvements: Overview •Refinement of L&D Conceptual Plan •Primary Components: � Improved capture of stormwater on Cedar Glen Drive � Improved interception of off-site water � Expanded closed-pipe system � Three new bioretention areas � New stormwater pond Page 9
Stonehedge Proposed Improvements: Previous Concept Page 10
Stonehedge Proposed Improvements: Current Site Plan Page 11
Stonehedge Proposed Improvements: Bioretention Page 12
Stonehedge Proposed Improvements: Pond Site Plan Page 13
Stonehedge Proposed Improvements: Pond Profile Page 14
Stonehedge Next Steps and Schedule •Complete design (late 2013) •Complete permitting (early 2014) •Select Contractor (Spring 2014) •Construction (Summer 2014) •Schedule dependent on Army Corps of Engineers Page 15
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