nashville zoo at grassmere stream and water quality improvements quality improvements littlejohn...

Nashville Zoo at Nashville Zoo at GrassmereGrassmere

Stream and WaterStream and Water Quality ImprovementsQuality Improvements

Littlejohn Engineering Associates, Inc.Littlejohn Engineering Associates, Inc.

Civil & Environmental Consultants, Inc.Civil & Environmental Consultants, Inc.

Stream ImprovementStream ImprovementObjectivesObjectives

Bank Stabilization Opportunities Limited

Re-establish Stream at Location of Lower End Pond

Exotic Plant Control (privet, honeysuckle, et. al.)

Re-establish Native Vegetation Habitat Amendments (slab rock, log

drop structures for crayfish)

Project SiteProject Site

Phase V –Construct middle wetland

Phase I –Construct and line pond, construct water quality forebays

Phase II –Construct upper wetland

Phase III -Construct/install water recirculation system

Project SiteProject Site

Phase IV -Options:• Convert existing pond into wetland• Re-establish stream, remove pond

Phase II -Options:• Construct lower off-line wetland

Line Existing Water Quality Pond to Retain Water

Water Quality Improvements - Water Quality Improvements - Upper EndUpper End

Raise Height of Existing Weir to Increase Pond Capacity

Construct Water Quality Forebay for Storm Water from Adjacent Business Park

Upper Wetland Adjacent to Storm Water Retention Pond, 1.5± Ac.

Construct/Install Recirculation System to Supply Water from Retention Pond to Upper Wetland and to the Stream

Construct/Install Catch Basins and Piping to Direct Storm Water from Upper Parking Lot to Forebay on East Side of Water Quality Retention Pond

Construct/Install Pump and Force Main to Remove Water from Lower End of Stream and Pump to Retention Pond and Upper Wetland

Middle Wetland Adjacent to Pond, 0.25± Acre

Water Quality Improvements – Water Quality Improvements – Middle Middle

Improve Flow Through Pond to Reduce Algal Growth

Lower Wetland adjacent to stream, 1.0± Acre

Water Quality Improvements – Water Quality Improvements – Lower End Lower End

Possible Stream Restoration (300 feet) and Elimination of Existing Pond

Possible Wetland Creation/Restoration of Existing Pond

Mitigation Credits EarnedMitigation Credits Earned

Consider Project as a Whole to Earn Maximum Credits

Overall Ratio Expected to be 4:1 2,580± Feet of Stream Generates 645

Credits at $200/foot or $129,000 Wetlands Creation Credited at 4:1 Ratio;

4 Acres of Wetlands Generates 1 Acre of Credit or $25,000

Total Credit Dollars Earned $154,000

Conceptual Plan Conceptual Plan Opinion of Probable Opinion of Probable Construction CostConstruction Cost

Construct Retention Pond and Forebays $225,000

Water Quality Upgrade of Parking Area $80,000

Water Recirculation (force main with pump) $110,000

Construct/Create Upper Wetland $45,000

Conceptual PlanConceptual Plan Opinion of Probable Opinion of Probable Construction CostConstruction Cost

Construct/Create Middle Wetland $20,000

Construct/Create Lower Wetland $30,000

Alternate Stream Reconstruction/ Restoration (300 feet) $48,000

Bank Stabilization/Habitat Amendments $50,000

Exotic Plant Control/Re-establish Native Vegetation $30,000

Total of Opinion of Probable Construction Cost $638,000

Conceptual Plan Conceptual Plan Opinion of Probable Opinion of Probable Construction CostConstruction Cost

Phase I - $225,000 Construct Retention Pond and Forebays

Phase II - $75,000Construct Upper and Lower Wetlands

Phase III - $190,000Water Quality Upgrade of Parking Lot and Water Recirculation

Phase IV - $98,000Stream Restoration, bank Stabilization/ habitat Amendments

Phase V - $50,000Construct Middle Wetland and Exotic Plant Control/

Re-establish Native Vegetation

Opinion of Probable Opinion of Probable Construction Cost Construction Cost Breakdown by PhaseBreakdown by Phase

Nashville Zoo at Nashville Zoo at GrassmereGrassmere

Open DiscussionOpen Discussion