A: Downtown Diversion Pipe

Transcription

1 A: Downtown Diversion Pipe b c with modifications Map highlighting conservation easement. The diversion pipe would run along the railroad. Will divert 40-44% of total flow.; and 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 West watershed junction box. Location the diversion pipe would leave the railroad at Dibble road.

2 B1: Extend Existing Pipe Section of the alterations made to the canyon in order to extend the existing pipe. Map showing the suggested extension of the pipe. Minimizes amount of new sediment from entering Barton s Pond; Easiest method to stabilize the canyon; and Could be constructed without any additional permits. Existing canyon walls that would be filled in and stabilized to extend the pipe. The existing pipe that would be extended through the canyon of Sand River Drawbacks Does not dissipate the force of the flow of water or energy; and The problem is shifted downstream. Considerations Flow still needs to be returned to the surface.

3 B2: Gabion Baskets as an Erosion Solution Flow a Pipe Permeable Geotextile Fabric b with modifications d Sections of the gabions along Sand River a - Section the length of the section of proposed gabions b - Section of a gabion dam c - Section of the gabion walls with permeable geotextile fabric d - Section of gabion walls without permeable layer against the earth e Generated images of proposed gabion walls e - The gabion walls directly after installation f - The gabion walls 15 years after installation f Ease of handling and transportation; 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 vertical conditions; Potential safety issues; and Must include a geotextile feature to prevent erosion behind the gabions.

4 B3: Open Concrete Vaults with some modifications 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 Provides for stabilized vertical slopes; Dissipates energy; and Alternate flow. with some modifications Open concrete vault walls and floor to prevent erosion Disadvantages More costly than the B-2 option of gabions; and Less aesthetically pleasing than vegetated gabions.

5 B4: Closed Storage Vaults with some modifications Section of a closed concrete vault Precast concrete vault system Source: contech-cpi.com Corrugated plastic pipe for stormwater storage. Source: hydrologicsolutions.com Corrugated metal pipe for stormwater storage. Source: contech-cpi.com Concrete pipe with open bottom. Source: terrestorm.com 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 Modest ground water recharge. Drawbacks Costs Maintenance Longer construction time Limited storage volume Considerations Flow still needs to be returned to surface; and Canyon walls still require stabilization.

6 C1: Restore Barton s Pond Dam Barton s Pond Bridge with new dam options. 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. Earthen dam installed at Barton s Pond Bridge. C2: Hydro-Modification of Existing Barton s Pond Wingwalls at Barton s Pond Bridge Wingwalls with flashboards being used Retains existing ecological functions and values of forested wetlands; Provides temporary flood storage; and Provides staging for downstream restoration. Disadvantages Would provide modest flood control for larger events.

7 C3: Maintain Existing Barton s Pond Forested Wetlands Conditions Barton s Pond looking down stream from the bridge. Forested wetlands of Barton s Pond 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 upstream from the bridge. Barton s Bridge looking downstream from water level.

8 Priority 2: Upstream Infiltration and Storage Examples of Green Infrastructure Potential Areas in Aiken for Infiltration and Storage 1. Stormwater first runs into the curb cut. 2. Then stormwater exits the curb cut pipe Possible option for a rain garden or planted bioswale in the existing green space of Aiken A suitable area for two bioswales that would blend in with the surroundings 3. Next the stormwater enters the detention area. 4. Finally, the stormwater runs through the bioswale. Another area that is appropriate for an unobtrusive bioswale Illustration of a corporate setting bioswale. Illustrations of stormwater management options. Source: