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B1: Extend Existing Pipe

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B1: Extend Existing Pipe A: Downtown Diversion Pipe b c Source: Woolpert, Inc. 2006 with modifications Map highlighting conservation easement. Advantages • Will divert 40-44% of total flow.; and The diversion pipe would run along the railroad. • Reduce the impact on Sand River because it would reduce the outflow from the 10’ pipe. Disadvantages • Conservation easement will be needed along the railroad; • Will require additional storage capacity; and • Will be costly. CSX Railroad and Red Cross Location the diversion pipe would West watershed junction box. leave the railroad at Dibble road. B1: Extend Existing Pipe Source: Woolpert, Inc. 2006 Source: Woolpert, Inc. 2006 Map showing the suggested extension of the pipe. Section of the alterations made to the canyon in order to extend the existing pipe. Advantages • Minimizes amount of new sediment from entering Barton’s Pond; • Easiest method to stabilize the canyon; and • Could be constructed without any additional permits. Drawbacks • Does not dissipate the force of the flow of water or energy; and • The problem is shifted downstream. Considerations Existing canyon walls that The existing pipe that would be • Flow still needs to be returned to the surface. would be filled in and stabilized extended through the canyon of to extend the pipe. Sand River B2: Gabion Baskets as an Erosion Solution Flow a Source: Woolpert, Inc. 2006 Pipe Permeable Geotextile Fabric d b Source: Woolpert, Inc. 2006 Source: Woolpert, Inc. 2006 with modifications Source: Woolpert, Inc. 2006 Sections of the gabions along Sand River a - Section the length of the section of proposed gabions b - Section of a gabion dam Advantages c - Section of the gabion walls with permeable geotextile fabric • Ease of handling and transportation; d - Section of gabion walls without permeable layer against the earth • Speed of construction; • Aesthetically more pleasing than some options; • Provides more natural stream pattern and profile; • Dissipates the energy of the stream; and • If properly constructed, vegetated gabions strengthen with time. Disadvantages • Potentially will continue to allow for soil expansion and contraction leading to destabilized e Source: Woolpert, Inc. 2006 f Source: Woolpert, Inc. 2006 vertical conditions; Generated images of proposed gabion walls • Potential safety issues; and e - The gabion walls directly after installation • Must include a geotextile feature to prevent f - The gabion walls 15 years after installation erosion behind the gabions. B3: Open Concrete Vaults Source: Woolpert, Inc. 2006 with some modifications Source: Woolpert, Inc. 2006 with some modifications Section of an open concrete vault with a gabion dam Generated view of proposed open concrete vault Flow Pipe Aerial view of Sand River with concrete vault walls and gabion dams installed Advantages • Provides for stabilized vertical slopes; • Dissipates energy; and • Alternate flow. Disadvantages • More costly than the B-2 option of gabions; and Source: Woolpert, Inc. 2006 with some modifications • Less aesthetically pleasing than vegetated Open concrete vault walls and floor to prevent erosion gabions. B4: Closed Storage Vaults Concrete pipe with open bottom. Source: Woolpert, Inc. 2006 with some modifications Source: terrestorm.com Section of a closed concrete vault Advantages • Provides short term storage for stormwater from rain events less significant than a 2 year storm; • Reduction in the speed of the water flow; • Canyon is stabilized long term; • Modest improvement to water quality; and Corrugated plastic pipe for • Modest ground water recharge. stormwater storage. Source: hydrologicsolutions.com Drawbacks • Costs • Maintenance • Longer construction time • Limited storage volume Precast concrete vault system Considerations Source: contech-cpi.com Corrugated metal pipe for • Flow still needs to be returned to surface; and stormwater storage. Source: contech-cpi.com • Canyon walls still require stabilization. C1: Restore Barton’s Pond Dam Advantages • Restoration of previous surface water feature; • Possible increased storage capacity depends on dam configuration; and • Provides staging for downstream restoration. Drawbacks • Significant cost for excavation; and • Loss of functions and values of existing forested wetland. Barton’s Pond Bridge with new dam options. Earthen dam installed at Barton’s Pond Bridge. C2: Hydro-Modification of Existing Barton’s Pond Advantages • Retains existing ecological functions and values of forested wetlands; • Provides temporary flood storage; and • Provides staging for downstream restoration. Disadvantages Wingwalls at Barton’s Pond Wingwalls with flashboards being • Would provide modest flood control for larger Bridge used events. C3: Maintain Existing Barton’s Pond Forested Wetlands Conditions Barton’s Pond looking down stream from the bridge. Forested wetlands of Barton’s Pond Advantages • No additional cost; and • Preserves existing conditions. Drawbacks • No flood storage; and • Adds additional risk to future restoration projects downstream. Barton’s Pond area looking Barton’s Bridge looking upstream from the bridge. downstream from water level. Priority 2: Upstream Infiltration and Storage Examples of Green Infrastructure Potential Areas in Aiken for Infiltration and Storage Possible option for a rain garden or planted bioswale in the existing green space of Aiken 1. Stormwater first runs 2. Then stormwater exits into the curb cut. the curb cut pipe A suitable area for two bioswales that would blend in with the surroundings 3. Next the stormwater 4. Finally, the stormwater enters the detention area. runs through the bioswale. Another area that is appropriate for an unobtrusive bioswale www.ia.nrcs.usda.gov/news/images/Pics/BioswaleSmall.jpg Source: www.asla.org/awards/2006/06winners/images/thumbnails/t079_08.gif Illustration of a corporate Illustrations of stormwater setting bioswale. management options..
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