Archers Creek Stormwater Plan Town of Emerald Isle/CWMTF Town of - - PowerPoint PPT Presentation

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Archers Creek Stormwater Plan Archers Creek Stormwater Plan Town of Emerald Isle/CWMTF Town of Emerald Isle/CWMTF July 10, 2012 Archers Creek Stormwater Plan Town of Emerald Isle/CWMTF

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Archers Creek Stormwater Plan Town of Emerald Isle/CWMTF

  • Archers Creek Stormwater Plan

Town of Emerald Isle/CWMTF

July 10, 2012

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Archers Creek Stormwater Plan Town of Emerald Isle/CWMTF

Watershed Characteristics Watershed Characteristics

  • Archers Creek Is 3 Miles Long and Runs East/West with

the Divide at Old Ferry Road

  • Watershed Area Is ~500 Acres

Mix of Residential and Commercial Land Use

  • Water Quality Is an Issue

Both Sides Discharge to Bogue Sound (SA and ORW Classification – Very High Standard) Fecal Coliform Is the Main Contaminant of Concern Only Area of Town Where Water Quality Use Is “Not Supported”

NCDEH Monitoring Data

Town Received CWMTF Grant to Complete Study to Develop Options to Improve Water Quality

  • Archers Creek Is 3 Miles Long and Runs East/West with

the Divide at Old Ferry Road

  • Watershed Area Is ~500 Acres

Mix of Residential and Commercial Land Use

  • Water Quality Is an Issue

Both Sides Discharge to Bogue Sound (SA and ORW Classification – Very High Standard) Fecal Coliform Is the Main Contaminant of Concern Only Area of Town Where Water Quality Use Is “Not Supported”

NCDEH Monitoring Data

Town Received CWMTF Grant to Complete Study to Develop Options to Improve Water Quality

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Archers Creek Stormwater Plan Town of Emerald Isle/CWMTF

Watershed Characteristics Watershed Characteristics

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Archers Creek Stormwater Plan Town of Emerald Isle/CWMTF

Data Collection Data Collection

  • Rainfall – NOAA Website
  • Soils – USDA Website
  • Topography

Mix of State LIDAR and Joyner Keeny Survey of Pipe Networks

  • Land Use

County GIS Data Mix of Residential, Manufactured Home, Commercial and Undevelopable Areas Approaching Full-Buildout Conditions

  • Water Quality

NCDEH Data at Two Creek Mouths & Data Collected Along Creek To Help Determine Potential Issues and Prioritize Sites

  • Rainfall – NOAA Website
  • Soils – USDA Website
  • Topography

Mix of State LIDAR and Joyner Keeny Survey of Pipe Networks

  • Land Use

County GIS Data Mix of Residential, Manufactured Home, Commercial and Undevelopable Areas Approaching Full-Buildout Conditions

  • Water Quality

NCDEH Data at Two Creek Mouths & Data Collected Along Creek To Help Determine Potential Issues and Prioritize Sites

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Archers Creek Stormwater Plan Town of Emerald Isle/CWMTF

Data Collection Data Collection

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Archers Creek Stormwater Plan Town of Emerald Isle/CWMTF

Water Quality Data Water Quality Data

  • Location of the Sampling Station within Sound for

NCDEH Data Has a Big Effect on Results

  • West Site Nearly Always Meets Standard
  • Location of the Sampling Station within Sound for

NCDEH Data Has a Big Effect on Results

  • West Site Nearly Always Meets Standard

10 20 30 40 50 60 70 80 90 100 110 120 130 140 9/20/2002 9/20/2003 9/19/2004 9/19/2005 9/19/2006 9/19/2007 9/18/2008 9/18/2009 9/18/2010 Fecal Coliform (Col/100 mL) Date

NCDEH Fecal Coliform Data (West Watershed)

Standard=14 col/100 mL

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Archers Creek Stormwater Plan Town of Emerald Isle/CWMTF

Water Quality Data Water Quality Data

  • East Site More Variable – Better Towards Mouth
  • East Site More Variable – Better Towards Mouth

25 50 75 100 125 150 175 200 225 250 275 300 325 350 375 10/21/1992 10/21/1994 10/20/1996 10/20/1998 10/19/2000 10/19/2002 10/18/2004 10/18/2006 10/17/2008 10/17/2010 Fecal Coliform (Col/100 mL) Date

NCDEH Fecal Coliform Data (East Watershed)

Station 30 Station 30A Station 30B

Standard=14 col/100 mL

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Archers Creek Stormwater Plan Town of Emerald Isle/CWMTF

Water Quality Data Water Quality Data

  • No Sampling Available for Creek So M&N Completed

Detailed Sampling

  • However, Only for One Event Due to Time and Budget

Constraints – Supply at Least a “Snapshot”

  • Results Were Mixed

TKN and TSS Were Below Typical Stormwater Concentrations Nitrate/Nitrite, Phosphorus, Fecal Coliform and Enterococci Were Above Typical Concentrations

  • Points to Possible Surfacewater and Groundwater

Sources

Fertilizer Runoff, Wildlife, Possible Septic Tank Failures

  • No Sampling Available for Creek So M&N Completed

Detailed Sampling

  • However, Only for One Event Due to Time and Budget

Constraints – Supply at Least a “Snapshot”

  • Results Were Mixed

TKN and TSS Were Below Typical Stormwater Concentrations Nitrate/Nitrite, Phosphorus, Fecal Coliform and Enterococci Were Above Typical Concentrations

  • Points to Possible Surfacewater and Groundwater

Sources

Fertilizer Runoff, Wildlife, Possible Septic Tank Failures

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Archers Creek Stormwater Plan Town of Emerald Isle/CWMTF

Water Quality Data Water Quality Data

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Archers Creek Stormwater Plan Town of Emerald Isle/CWMTF

Water Quality Data Water Quality Data

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Archers Creek Stormwater Plan Town of Emerald Isle/CWMTF

Water Quality Data Water Quality Data

0.00 0.25 0.50 0.75 1.00 1.25 1.50 1.75 2.00 2.25 2.50 2.75 3.00 3.25 3.50 3.75 4.00 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 TKN (ppm) Site Number

Total Kjeldahl Nitrogen (TKN)

West Watershed East Watershed West East Typical Stormwater Concentration=1.4 mg/L

5 10 15 20 25 30 35 40 45 50 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 TSS (ppm) Site Number

Total Suspended Solids (TSS)

West Watershed East Watershed West East Typical Stormwater Concentration=50mg/L

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Archers Creek Stormwater Plan Town of Emerald Isle/CWMTF

Water Quality Data Water Quality Data

0.00 0.25 0.50 0.75 1.00 1.25 1.50 1.75 2.00 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 TP (ppm) Site Number

Total Phosphorus (TP)

West Watershed East Watershed West East Typical Stormwater Concentration=0.2-0.3 mg/L

0.00 0.25 0.50 0.75 1.00 1.25 1.50 1.75 2.00 2.25 2.50 2.75 3.00 3.25 3.50 3.75 4.00 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 NO3+NO2-N (ppm) Site Number

Nitrate/Nitrite Nitrogen (NO3-N)

West Watershed East Watershed West East Typical Stormwater Concentration=0.6 mg/L

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Archers Creek Stormwater Plan Town of Emerald Isle/CWMTF

Water Quality Data Water Quality Data

250 500 750 1000 1250 1500 1750 2000 2250 2500 2750 3000 3250 3500 3750 4000 4250 4500 4750 5000 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 Enterococci (col/100mL) Site Number

Enterococci

West Watershed East Watershed West East Human Health Standard=35 mg/L

250 500 750 1000 1250 1500 1750 2000 2250 2500 2750 3000 3250 3500 3750 4000 4250 4500 4750 5000 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 Fecal Coliform (col/100mL) Site Number

Fecal Coliform

West Watershed East Watershed West East Typical Stormwater Concentration>4000 mg/L Human Health Standard=14 mg/L

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Archers Creek Stormwater Plan Town of Emerald Isle/CWMTF

Development of Potential BMPs Development of Potential BMPs

  • Broken Into Three (3) Zones: Western, Central, Eastern
  • Zones Based On Watershed Characteristics and BMP

Opportunities

  • BMPs Ranged From Simple Culvert Removal to Large

Scale Expensive BMPs with Land Purchase Required

Based On Water Quality Data and Watershed Assessment, Infiltration and Filtration BMPs Show Most Promise Hydraulic Modification to Allow More Flushing Also Is Promising But May Have Habitat Change and Adjacent Resident Concerns

  • Broken Into Three (3) Zones: Western, Central, Eastern
  • Zones Based On Watershed Characteristics and BMP

Opportunities

  • BMPs Ranged From Simple Culvert Removal to Large

Scale Expensive BMPs with Land Purchase Required

Based On Water Quality Data and Watershed Assessment, Infiltration and Filtration BMPs Show Most Promise Hydraulic Modification to Allow More Flushing Also Is Promising But May Have Habitat Change and Adjacent Resident Concerns

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Archers Creek Stormwater Plan Town of Emerald Isle/CWMTF

Western Zone Western Zone

  • Culvert Replacements Along Main Creek to Improve

Tidal Flushing

  • Infiltration BMP at Emerald Plantation Townhomes
  • Emerald Plantation Shopping Center (Catch Basin

Inserts or Underground Infiltration/Storage

  • Removal of Selected Woodpecker Lane Culverts
  • Reed Drive/Boardwalk Avenue Bioretention/Wetland
  • Marsh and Buffer Restoration Throughout
  • Culvert Replacements Along Main Creek to Improve

Tidal Flushing

  • Infiltration BMP at Emerald Plantation Townhomes
  • Emerald Plantation Shopping Center (Catch Basin

Inserts or Underground Infiltration/Storage

  • Removal of Selected Woodpecker Lane Culverts
  • Reed Drive/Boardwalk Avenue Bioretention/Wetland
  • Marsh and Buffer Restoration Throughout
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Archers Creek Stormwater Plan Town of Emerald Isle/CWMTF

Western Zone Western Zone

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Archers Creek Stormwater Plan Town of Emerald Isle/CWMTF

Western Zone Western Zone

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Archers Creek Stormwater Plan Town of Emerald Isle/CWMTF

Western Zone Western Zone

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Archers Creek Stormwater Plan Town of Emerald Isle/CWMTF

Western Zone Western Zone

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Archers Creek Stormwater Plan Town of Emerald Isle/CWMTF

Central Zone Central Zone

  • Underground Infiltration/Storage In Existing Commercial

Areas

Will Require Property Owner Coordination and Permission to Install

  • Removal of Selected Drainage Systems Along Dogwood

Circle and NC 58

NC 58 Systems Will Require NCDOT Approval – Systems Not Functioning As Designed But Still Likely Difficult to Remove

  • Buffer Restoration Throughout
  • Underground Infiltration/Storage In Existing Commercial

Areas

Will Require Property Owner Coordination and Permission to Install

  • Removal of Selected Drainage Systems Along Dogwood

Circle and NC 58

NC 58 Systems Will Require NCDOT Approval – Systems Not Functioning As Designed But Still Likely Difficult to Remove

  • Buffer Restoration Throughout
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Archers Creek Stormwater Plan Town of Emerald Isle/CWMTF

Central Zone Central Zone

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Archers Creek Stormwater Plan Town of Emerald Isle/CWMTF

Central Zone Central Zone

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Archers Creek Stormwater Plan Town of Emerald Isle/CWMTF

Central Zone Central Zone

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Archers Creek Stormwater Plan Town of Emerald Isle/CWMTF

Eastern Zone Eastern Zone

  • No Recommendations

Appears to Have Adequate Buffers – No Significant Outfalls

  • Depth Is Very Shallow and Dredging May Improve Tidal

Flushing

Costs and Permitting Issues Rendered This Option As a Non- Starter

  • Aeration Was Also Considered But Creek Is Too Shallow

to Be Effective

  • No Recommendations

Appears to Have Adequate Buffers – No Significant Outfalls

  • Depth Is Very Shallow and Dredging May Improve Tidal

Flushing

Costs and Permitting Issues Rendered This Option As a Non- Starter

  • Aeration Was Also Considered But Creek Is Too Shallow

to Be Effective

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Archers Creek Stormwater Plan Town of Emerald Isle/CWMTF

Eastern Zone Eastern Zone

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Archers Creek Stormwater Plan Town of Emerald Isle/CWMTF

Summary of BMP Costs & Prioritization Summary of BMP Costs & Prioritization

  • Wide Range of

Costs - $4K - $719K

  • Initial

Prioritization Completed Based

  • n Cost per Cubic

Foot of Volume Captured

  • Wide Range of

Costs - $4K - $719K

  • Initial

Prioritization Completed Based

  • n Cost per Cubic

Foot of Volume Captured

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Archers Creek Stormwater Plan Town of Emerald Isle/CWMTF

Plan Recommendations Plan Recommendations

  • Final

Recommendations Based on Total Cost As Well

  • Complete Cost-

Effective Options First and Can Complete More Expensive Options As Funding Allows

  • Final

Recommendations Based on Total Cost As Well

  • Complete Cost-

Effective Options First and Can Complete More Expensive Options As Funding Allows

1 2 3 4 5 6 7

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Archers Creek Stormwater Plan Town of Emerald Isle/CWMTF

Overall Findings Overall Findings

  • Watershed Development Is Close to Full-Buildout
  • Already a Number of BMPs Installed
  • Water Quality Monitoring Results Highly Dependent On

Location of Sampling

  • Fertilizers, Wildlife, Possible Failing Septic Systems, and

Lack of Tidal Flushing Appear to Be Largest Issues to Tackle

  • Removal of Non-functioning Culverts, Installation of

Infiltration BMPs and Buffers Would Likely Provide Best Treatment for Contaminants of Concern

  • Improved Tidal Flushing Is A Viable Option on West Side

(Habitat and Resident Concerns Are Issues) – More Difficult On East Side Due to Dredging Requirement

  • Watershed Development Is Close to Full-Buildout
  • Already a Number of BMPs Installed
  • Water Quality Monitoring Results Highly Dependent On

Location of Sampling

  • Fertilizers, Wildlife, Possible Failing Septic Systems, and

Lack of Tidal Flushing Appear to Be Largest Issues to Tackle

  • Removal of Non-functioning Culverts, Installation of

Infiltration BMPs and Buffers Would Likely Provide Best Treatment for Contaminants of Concern

  • Improved Tidal Flushing Is A Viable Option on West Side

(Habitat and Resident Concerns Are Issues) – More Difficult On East Side Due to Dredging Requirement

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Archers Creek Stormwater Plan Town of Emerald Isle/CWMTF

Discussion Discussion