Sand River Ecological Restoration Master Plan

Transcription

1 Sand River Ecological Restoration Master Plan Preferred Alternative Analysis Clemson University Research Team October 30, 2008 Sand River Ecological Restoration Master Plan

2 Brief Overview of Meetings Project Kick Off Meeting: Date: Week of January 24, 2008 Key Agenda Items: Introduction of Partners Introduction to Master Plan Process and Scope of Work Extent of Problem and Alternatives Breakout Groups Reconvene and Summary of Draft Goals Next Steps Visioning Workshop 1 Date: Week of February 18, 2008 Key Agenda Items: Introduction and Ecological Restoration Overview Break into Vision Groups Discussion and Q&A of different approaches Closing Remarks, next steps Close Meeting and Wrap-Up Visioning Workshop 2 Date: Week of May 5, 2008 Key Agenda Item: Ecological Restoration Decision Tree Visioning Workshop 3 Date: Week of October 27, 2008 Key Agenda Items: Brief Overview of Past Meetings and Principles Clemson Preferred Alternative for Sand River Sand River Ecological Restoration Master Plan

3 Sand River Ecological Restoration Master Plan Why do an ecological restoration master plan? outline the vision and goals and establish the priorities for the restoration program facilitate restoration efforts that are multiparty, multi-jurisdictional, and multi-year provide continuity for a long-term project serve as a funding tool provide excellent communication tool ensure cumulative effects of individual projects within the Sand River watershed will result in a self-sustaining ecosystem

4 Sand River Ecological Restoration Master Plan Project Area A holistic approach to the restoration of Sand River is desired by all parties and will require the development of a master plan that balances stormwater management with habitat preservation and restoration. Watersheds: Downtown (CSX and Red Cross) South Boundary Dibble Road Highland Park Coker Spring Palmetto Clark Road Houndslake Fox Chase

5 Sand River Ecological Restoration Master Plan Watersheds Dibble Road (Tea Cottage) Highland Park Sand River Headwaters Hitchcock Woods Coker Springs Palmetto Clark Road Fox Chase Houndslake (Nursery Field

6 Sand River Ecological Restoration Master Plan Dibble Road (Tea Cottage) Highland Park Land Use Hitchcock Woods Fox Chase Clark Road Coker Springs Palmetto Sand River Headwaters Houndslake (Nursery Field

7 Master Plan Process: a collaborative blueprint 1.0 Project Background, Site History, Story of Place 2.0 Plan Development Process Project Vision Guiding Principles 3.0 Existing Conditions The Regional Setting Climate Geology and Soils Regional Landscape Storm Water Hydrology Land Use, Zoning, and Recreational Uses Ecological Conditions: available data and pre-construction sampling Hydrology Soils and Sediment Conditions Channel and Riparian Conditions Upland, Wetland and Riparian Vegetation Communities Bird and Wildlife Communities Fish and Aquatic Communities Threatened and Endangered Species Potential Ecological Threats Water and Sediment Contamination Urban Development Invasive Species Sand River Ecological Restoration Master Plan

8 Master Plan Contents 4.0 Remediation/Stabilization of Canyon 5.0 Ecological Reference Sites 6.0 Ecological Restoration Plan THE VISION: Restoration Goals / Objectives / Actions Reducing Threats to Ecological Integrity Phasing of Restoration Activities Approval Process for Individual Projects Institutional Strategy to Insure Long Term Protection and Management Funding Individual Projects Benchmarks Adaptive Management Commitment Monitoring, Photo-documentation, Adopt-A-Stream Program, Archives 7.0 References 8.0 Appendices Sand River Ecological Restoration Master Plan

9 Ecological Restoration Guiding Principles 1. The restored ecosystem contains characteristic assemblage of species 2. Consists of indigenous species to greatest extent possible 3. Physical environment is capable of sustaining reproducing populations of species along the trajectory 4. Restored ecosystem functions normally for its stage of development 5. Restored ecosystem is integrated into the larger landscape 6. Potential threats to the ecosystem are eliminated or reduced 7. Restored ecosystem is resilient to normal periodic stress 8. Ecosystem is self-sustaining Sand River Ecological Restoration Master Plan

10 Intact: Retain control over resources Degraded: Lost control over resources Hydrology, nutrient cycling, erosion, energy capture, temperatures Seriously damaged ecosystems: lose control over resources and the capacity for self-repair (termed biophysical degradation) are less resilient to stress provide few ecosystem services often cross the threshold for self recovery Sand River Ecological Restoration Master Plan

11 Ecosystem Development Three outcomes of reclamation: Restoration Rehabilitation Replacement Crucial changes occur in structure and function of ecosystems: the structure becomes more complex by an increase in number and diversity of species the functions increase in terms of biomass and cycling of nutrients. Sand River Ecological Restoration adapted Master from PlanBradshaw, 1987

12 Ecological Restoration Sand River Ecological Restoration Master Plan A natural landscape or ecosystem is one that developed by natural processes and that is selforganizing and self-maintaining A cultural landscape or ecosystem is one that has developed under the influence of both natural and human-imposed organization

13 Historic and Present: Restoration to point in time Sand River Ecological Restoration Master Plan Values Problems Solutions What is the trajectory or endpoint?

14 What is Good Ecological Restoration? Ecological Fidelity: Structural and functional replication Economic And Durable Prescription Historical Cultural Social Political Moral Aesthetic Adapted from Eric Higgs, Nature by Design Sand River Ecological Restoration Master Plan

15 What elements of the Sand River restoration are most important? Ecology History Culture Question 1 What ecological preferences do you have for the Sand River solution? Be able to once again jump across creek Reduce sediment flow Maintain what s there Restore buffer Restore forest itself Remove sand from original forest floor Stabilize current ecology Allow nature to take its course Restore indigenous plant and animal species Address stormwater upstream Avoid unintended consequences Restore or recognize Robinson s Pond Get unnecessary water out of the woods Remove private party introduced plant species Group strongly preferred not to introduce any additional artificial hardening Group expressed dislike of Gabion Basket design Return natural hydrology Prefer to disconnect the current stormwater infrastructure Restoration/establishment of new stabilized profile of Sand River Remove silt and sediment if possible or at least curb its flow near Cathedral Isle Stop/reduce undercutting of banks leading to more and more sediment flow Sand River Ecological Restoration Master Plan

16 Sand River Ecological Restoration Master Plan Ecology History Culture What elements of the Sand River restoration are most important? Question 2 What historical considerations need to be taken into account for the restoration of Sand River? Need to assess/survey/record long history There has never been a complete cultural assessment of the use of the woods onative American Archeological Sites onote Civil War encampment in center of woods Prefer not to disclose specific cultural history locations to general public In general, group would prefer to return woods as they were 100 years ago (where possible) Maintain Memorial Gate Access Whitney Drive Preserve Tea Cottage (pavilion area) Restore Barton s Pond Bring back to the way it looked in the 1920 s and 50 s. Attract native water fowl Bring woods plant species back to its state prior to modern settlement

17 Sand River Ecological Restoration Master Plan Ecology History Culture What elements of the Sand River restoration are most important? Question 3 What cultural aspects should be factored into the Sand River solution? Keep recreational activities Keep current trails Keep areas safe from erosion, flash floods, and gullies No additional bridges Minimize manmade obstructions (no power lines, pipes, etc.) Any new items introduced need to be literally temporary in that the device is not disguised but actually removed when possible Focus on equestrian compatibility Don t restore Dam Preserve recreational activities Equestrian trails Fox hunt Group would like definition of health/safety consequences of doing nothing Preserve equestrian trails/usability

18 Draft Major Goals The Sand River Ecological Restoration Master Plan is divided into six major goals: 1. In conjunction with restoration activities, maintain recreational, educational, and environmental stewardship activities for Hitchcock Woods Foundation and City of Aiken residents; 2. Stabilize and remediate Sand River canyon; 3. Evaluate opportunities to reduce stormwater flows; 4. Conserve and protect ecologically sensitive habitats; 5. Improve water and sediment quality conditions in Sand River and reduce the threat of future contamination; and 6. Restore selected ecosystem components in a manner that is consistent with the ecological restoration guiding principles. Sand River Ecological Restoration Master Plan

19 Sand River Ecological Restoration Master Plan

20 A: Downtown Diversion Pipe b c Source: Woolpert, Inc with modifications Map highlighting conservation easement. The diversion pipe would run along the railroad. Advantages 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.

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22 B1: Extend Existing Pipe Source: Woolpert, Inc Source: Woolpert, Inc Section of the alterations made to the canyon in order to extend the existing pipe. Map showing the suggested extension of the 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. 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.

23 B2: Gabion Baskets as an Erosion Solution a Source: Woolpert, Inc Pip e Flo w Permeabl e Geotextile Fabric b Source: Woolpert, Inc Source: Woolpert, Inc with modifications d Sections of the gabions along Sand River a Section of the proposed gabions running down the river 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 Source: Woolpert, Inc Source: Woolpert, Inc Source: Woolpert, Inc Advantages 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.

24 B3: Open Concrete Vaults Source: Woolpert, Inc with some modifications Source: Woolpert, Inc with some modifications Section of an open concrete vault with a gabion dam Generated view of proposed open concrete vault P i p e F l o w Advantages Aerial view of Sand River with concrete vault walls and gabion dams installed Provides for stabilized vertical slopes; Dissipates energy; and Alternate flow. Source: Woolpert, Inc 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.

25 B4: Closed Storage Vaults Source: Woolpert, Inc 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 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 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.

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27 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. Barton s Pond Bridge with new dam options. 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 Advantages 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.

28 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 upstream from the bridge. Barton s Bridge looking downstream from water level.

29 Sand River Ecological Restoration Master Plan Priority 1 Decisions Priority Required two decision to: are 1) Dissipate stormwater energy being covered 2) Stabilize the canyon 3) Provide for storage Decision Point 1: Divert Downtown Flows or Consolidate Flows Decision Point 2: Type of Storage and Capacity Engineered Pond Decision Point 3: Barton s Pond Storage

30 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.

31 Sand River Ecological Restoration Master Plan Priority 1 Decisions Priority Required two decision to: are 1) Dissipate stormwater energy being covered 2) Stabilize the canyon 3) Provide for storage Decision Point 1: Divert Downtown Flows or Consolidate Flows Decision Point 2: Type of Storage and Capacity Engineered Pond Decision Point 3: Barton s Pond Storage

32 Sand River Ecological Restoration Master Plan Request from Mayor Cavanaugh and City Council Member Jane Vaughters: Provide an objective preferred alternative for Sand River rehabilitation and/or restoration based on Clemson s review of Sand River studies.

33 Preferred Alternative: Upstream Options [Infiltration and Detention] 105 acres of green medians in the downtown, CSX, and South Boundary watersheds Green Infrastructure Strategy: Maximize the greenspaces as bioswales and rainfilters. Median Bioswale Concept 1 Available median green spaces in downtown Aiken for potential green infrastructure program. The potential for limited infiltration and velocity reduction of stormwater from these watersheds should be evaluated. Median Bioswale Concept 2

34 Preferred Alternative of Sand River: Components Delivery Junction Box Energy Dissipation and Sedimentation Junction Box Surface Water Entrance Cement Mattress Wing Walls Plunge Pool Discharge Energy Dissipation Sediment Forebay Barton s Pond Wetlands Barton s Pond Wetland Multiple Flow Control Structures Earthen Dam Remediated Cathedral Aisle Wetlands Peggy s Pond

35 Underground Storage with Dual Pipe Sand River Ecological Restoration Master Plan Forebay with Shallow Pool Pool Earthen Dam with Concrete Emergency Spillway

36 Preferred Alternative of Sand River: Components Earthen Dam Service Roads Wide Peggy s Pond Barton s Pond Wetlands Cathedral Aisle Wetland Remediation Energy Dissipation Area Sand River Dual Pipe System PriorityTributary Stabilization

37 Preferred Alternative for Sand River: Phasing Phase Objective Time Required Pre Construction Dual Pipe In Line Storage & Detention (1.5 year storm event) Detention Area 1: Peggy s Pond Acquisition & Permitting Detention Area 2: Red Cross Detention Basin Acquisition & Permitting 1 2 Months 1 2 Months 1 2 Months Conceptual Cross Sectional View of Sand River at Different Phases Phase I Construction of Access Roads and Lay Down Areas c 1 2 Months Phase II Clearing and Rough Grading in and Near the 1 2 Months Main Channel Excavation of Peggy s Pond (Beginning) Phase III Construction of Pipe Beginning at Upper End 8 10 Months and Moving Downstream Excavation of Peggy s Pond (Finish) Construction of Barton s Pond Wetlands Earthen Dam Tributary Stabilization Phase IV Final Grading and Stabilization 1 2 Months Phase: Pre Construction Phase III: Proposed In line Storage During Construction Total Pre Construction Time Total Construction Time TOTAL PRE CONSTRUCTION & CONSTRUCTION TIME Cathedral Aisle Remediation (Post Bank Stabilization) Evaluate & Finalize Green Infrastructure Storage 1 2 Months Months MONTHS 6 8 Months Months Phase: Post Construction

38 Preferred Alternative: Budget For Sand River Channel Improvements PRELIMINARY ESTIMATE DESCRIPTION QUANTITY UNIT UNIT PRICE AMOUNT CONSTRUCTION COSTS UPSTREAM DETENTION 2 L.S. $ 150, $300,000 MOBILIZATION (5%) 1 L.S. $ 350, $350,000 CONSTRUCTION STAKES, LINES & GRADES 1 L.S. $ 20, $20,000 CONSTRUCTION ENGINEERING INSPECTION (testing) 1 L.S. $ 25, $25,000 CONSTRUCTION ENGINEERING INSPECTION (Const Admin) 1 L.S. $ 70, $70,000 CLEARING AND GRUBBING 40 ACRE $ 6, $240,000 REMOVAL OF STRUCTURES AND OBSTRUCTIONS 1 L.S. $ 15, $15,000 BORROW EXCAVATION C.Y. $ $440,000 WASTE EMBANKMENT 500 C.Y. $ $5,000 UNCLASSIFIED EXCAVATION C.Y. $ 5.00 $700,000 FINE GRADING S.Y. $ 4.00 $776,000 ENERGY DISSIPATION (Plunge pool) 1 EA. $ 20, $20,000 GEOTEXTILE FABRIC 2850 S.Y. $ 5.00 $14,250 TRENCHING C.Y. $ 3.00 $131,976 10' DIAMETER RCP PIPE 7200 L.F. $ $5,148,000 10' DIAMETER ELBOW 15 EA. $ 7, $112,500 4' MANHOLES 20 EA. $ 2, $40,000 ENDWALL 1 EA. $ 8, $8,000 GABIONS 3800 CY $ $551,000 RENO MATTRESSES 444 CY $ $64,380 SLOPE DRAINS 10 EA. $ 2, $20,000 #57 STONE 9576 CY $ $478,800 EROSION CONTROL MAT S.Y. $ 3.00 $321,000 SEEDING (MULCHED) 15.0 ACRE $ 2, $31,500 TEMPORARY SEEDING (40% OF SEEDING) 6.0 ACRE $ 1, $8,322 LANDSCAPING 1.0 L.S. $ 6, $6,000 SILT FENCE L.F. $ 3.00 $48,000 BARTON'S POND EXCAVATION AND DAM 1.0 EA. $ 1,304, $1,304,000 PEGGY'S POND EXCAVATION AND DAM 1.0 EA. $ 1,043, $1,043,000 TRIBUTARY STABILIZATION 1 4 EA. $ 164, $658,000 SUBTOTAL CONSTRUCTION COST $12,949,728 ENGINEERING 1 L.S. $ 647, $647,486 ENVIRONMENTAL PERMITTING 1 L.S. $ 95, $95,000 CONSTRUCTION ADMINISTRATION 1 L.S. $ 517, $517,989 SUBTOTAL DESIGN AND PERMITTING COST $1,260,476 CONTINGENCY (30%) $3,884,918 TOTAL ESTIMATED PROJECT COST With Reinforced Concrete Piping: $18,095,122 TOTAL ESTIMATED PROJECT COST With Aluminum Piping Alternative: $16,003,265 *Construction cost does not include utility relocation, landscaping or r/w acquisition. 1. "spot repairs" within the Coker Springs, Palmetto, Clark Road, Dibble Road, and Fox Chase sub-watersheds.

39 Preferred Alternative: Budget For Sand River Channel Improvements PRELIMINARY ESTIMATE DESCRIPTION QUANTITY UNIT UNIT PRICE AMOUNT CONSTRUCTION COSTS UPSTREAM DETENTION 2 L.S. $ 150, $300,000 MOBILIZATION (5%) 1 L.S. $ 350, $350,000 CONSTRUCTION STAKES, LINES & GRADES 1 L.S. $ 20, $20,000 CONSTRUCTION ENGINEERING INSPECTION (testing) 1 L.S. $ 25, $25,000 CONSTRUCTION ENGINEERING INSPECTION (Const Admin) 1 L.S. $ 70, $70,000 CLEARING AND GRUBBING 40 ACRE $ 6, $240,000 REMOVAL OF STRUCTURES AND OBSTRUCTIONS 1 L.S. $ 15, $15,000 BORROW EXCAVATION C.Y. $ $440,000 WASTE EMBANKMENT 500 C.Y. $ $5,000 UNCLASSIFIED EXCAVATION C.Y. $ 5.00 $700,000 FINE GRADING S.Y. $ 4.00 $776,000 ENERGY DISSIPATION (Plunge pool) 1 EA. $ 20, $20,000 GEOTEXTILE FABRIC 2850 S.Y. $ 5.00 $14,250 TRENCHING C.Y. $ 3.00 $131,976 10' DIAMETER RCP PIPE 7200 L.F. $ $5,148,000 10' DIAMETER ELBOW 15 EA. $ 7, $112,500 4' MANHOLES 20 EA. $ 2, $40,000 ENDWALL 1 EA. $ 8, $8,000 GABIONS 3800 CY $ $551,000 RENO MATTRESSES 444 CY $ $64,380 SLOPE DRAINS 10 EA. $ 2, $20,000 #57 STONE 9576 CY $ $478,800 EROSION CONTROL MAT S.Y. $ 3.00 $321,000 SEEDING (MULCHED) 15.0 ACRE $ 2, $31,500 TEMPORARY SEEDING (40% OF SEEDING) 6.0 ACRE $ 1, $8,322 LANDSCAPING 1.0 L.S. $ 6, $6,000 SILT FENCE L.F. $ 3.00 $48,000 BARTON'S POND EXCAVATION AND DAM 1.0 EA. $ 1,304, $1,304,000 PEGGY'S POND EXCAVATION AND DAM 1.0 EA. $ 1,043, $1,043,000 TRIBUTARY STABILIZATION 1 4 EA. $ 164, $658,000 SUBTOTAL CONSTRUCTION COST $12,949,728 ENGINEERING 1 L.S. $ 647, $647,486 ENVIRONMENTAL PERMITTING 1 L.S. $ 95, $95,000 CONSTRUCTION ADMINISTRATION 1 L.S. $ 517, $517,989 SUBTOTAL DESIGN AND PERMITTING COST $1,260,476 CONTINGENCY (30%) $3,884,918 TOTAL ESTIMATED PROJECT COST With Reinforced Concrete Piping: $18,095,122 TOTAL ESTIMATED PROJECT COST With Aluminum Piping Alternative $16,003,265 *Construction cost does not include utility relocation, landscaping or r/w acquisition. 1. "spot repairs" within the Coker Springs, Palmetto, Clark Road, Dibble Road, and Fox Chase sub-watersheds.

40 Sand River Ecological Restoration Master Plan

41 Extension of pipe through canyon Sand River Ecological Restoration Master Plan

42 Dual Pipe for Storage and Detention Sand River Ecological Restoration Master Plan Re-Create Sand River on Top of Pipe to Receive Overland Flow

43 Headwaters of Barton s Pond Sand River Ecological Restoration Master Plan

44 Utilize Barton s Pond Forested Wetland for Temporary Storage Sand River Ecological Restoration Master Plan

45 Water control structures and earthen dam with emergency spillway Sand River Ecological Restoration Master Plan

46 After remediation, begin ecological restoration of Cathedral Aisle wetlands Flushing with sediment starved water from Barton s Pond Wetland Sand River Ecological Restoration Master Plan

47 Sand River Ecological Restoration Master Plan

48 Sand River Ecological Restoration Master Plan Provide a blueprint for the remediation of the storm water canyon and restoration of natural communities and ecosystem processes within the Sand River watershed; Describe how the proposed restoration activities will integrate with landscape processes of energy flows, nutrient cycling, wildlife movement, hydrologic flows, and community succession; Implement a long-term strategy to protect and maintain the restored sites

49 Next Step Proposed Develop and sign a Memorandum of Agreement/Understanding between the City of Aiken and the Hitchcock Woods Foundation to proceed with consideration of the proposed alternative. Sand River Ecological Restoration Master Plan