Karen Jensen

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Innovative Stormwater Management at the Empire
Wastewater Treatment Plant

• Karen Jensen
• Metropolitan Council
• Environmental Services

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Acknowledgements

• Pat Oates, Cammy Johnson, Rene Heflin, Linda
  Henning, Bill Moore, Jim Roth - MCES
• Friends of the Mississippi Karen Schik
• Minnesota DNR
• Dakota SWCD
• Washington Conservation District
• Applied Ecological Services Matt Lasch
• Greg Pates

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Note The Met Council does not yet have
monitored evidence proving the efficacy of
LID practices. This presentation includes
anecdotal and observational evidence only.
Future monitoring is planned.
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Metropolitan Council

• Transit system Metro Transit
• Wastewater system - MCES
• Metropolitan Housing Redevelopment Authority
• Livable Communities
• Comprehensive planning

17-member Policy Board 16 members representing
equal population districts and Chair
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MCES Wastewater System

• 7 treatment plants
• 610 miles of regional interceptors
• Estimated 3 billion-4 billion replacement value
• 358 million gallons per day treatment capacity
• 105 communities connected

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Trout Facts (Mn DNR)
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Empire WWTP Overview

• Constructed in 1979 with capacity of 3 mgd
  located in Empire Township
• Total land area 480 acres Process area 30
  acres
• Receives influent from Lakeville, Apple Valley,
  Farmington and surrounding areas
• from approx. population of 175,000
• Plant expansion (2007) capacity from 12 mgd to
  24 mgd Potential 48 mgd
• Includes septage receiving area, bio-P, anaerobic
  digestion, biosolids are landspread on MCES land
  and nearby farmland
• Effluent diverted in 2008 12-mile pipe to
  Mississippi River
• Soil sand, sandy loam, silty loam

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Empire Stormwater Planning
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Empire Innovative Stormwater Goals

• Meet (or exceed) Proposed Requirements for New
  MPCA
• NPDES Industrial Stormwater Permit
• Infiltrate at Minimum 2 Over Entire Site
• Test Operation, Performance, and Maintenance of
  LID Stormwater Practices
• at a Continuously Operating Industrial Facility
• Select Practices Particularly Appropriate to
  Trout Stream Watershed
• Select Practices Which Would Serve as Examples
  Projects for Surrounding
• Communities
• Initial Collection of Anecdotal/Observational
  Data on Performance
• Eventual Collection of Measured Performance Data
• Enhance Local Wildlife Habitat
• Protect the Vermillion River

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Timeline of Empire Expansion

• 1999 Commencement of Master Planning process for
  Empire/Rosemount (REMP)
• 1999 Contacted by Friends of Mississippi and DNR
  regarding Vermillion River Leads to preparation
  of Natural Resources Plan (FMR, SWCD, DNR)
• 2002 Completion of Natural Resources Plan
• 2003 Pre-Bid meeting for WWTP expansion project
• 2003 Stabilization of streambank at 11 sites on
  Vermillion River
• 2003 Restoration of 50-acre wet meadow wetland
• Late-2003 Commencement of Construction of WWTP
  Expansion
• 2004 Friends of Mississippi organizes volunteers
  to plant restored streambanks
• 2005 Friends of Mississippi organizes volunteers
  to plant restored wetland
• 2007 Expansion Completed
• Early 2008 Effluent Diversion to Mississippi River

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Low Impact Development (LID)

• Aka Better Site Design, Smart Growth Practices,
• LID practices attempt to replicate
  pre-development hydrology to reduce runoff
• rate, volume, and pollutant load
• Minimize impacts by reducing impervious areas,
  conserving natural drainage
• courses, enhancing infiltration
• Benefits reduce cost of infrastructure
• (pipes, manholes, etc) groundwater
• recharge, enhanced wildlife habitat,
• decreased thermal impact,
• Use of native plants increased
• soil permeability, less irrigation,
• decreased herbicide/pesticide
• use, reduced mowing,
• carbon sequestration

Burnsville Raingarden
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Low Impact Development (LID)
Pre-Development
Urbanized
Credit Chris May, U of Wash.
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Low Impact Development (LID)
www.api.ning.com
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Low Impact Development (LID) Implementation
Initial and Routine Maintenance
Planning and Design
Implementation/ Construction
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http//www.pca.state.mn.us/water/ stormwater/storm
water-manual.html
http//www.metrocouncil.org/ environment/water/BMP
/manual.htm
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• Vermillion River Facts (Vermillion River JPO)
• Vermillion River JPO (Dakota/Scott Counties)
• Watershed 335 sq mi
• Dakota and Scott Counties rapidly growing
• 40 population growth in 1990s
• 20 municipalities
• 49 miles of designated trout stream
• Only world class trout stream in a major metro
  area
• in the USA (Trout Unlimited)

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Trout Facts (Mn DNR)

• Native to Minnesota Brook (Salvelinus
  fontinalis) and Lake (S. namaycush)
• Stocked Brown (Salmo trutta) and Rainbow
  (Oncorhynchus mykiss) Trout
• Require cold, highly oxygenated water
• Food macroinvertebrates (mayfly, caddisfly,
  stone fly), insects,
• Crustaceans. Adult fish will eat other fish,
  small mammals, birds
• Typically feed in riffle/run stream features
  adults shelter during day,
• feed at night
• Shelter habitat logs, snags, pools, undercut
  banks, undercut rocks
• Brook Trout lay eggs in redd in gravel with
  upwelling of spring water
• Predation humans, birds (eagles, herons,
  kingfisher), mammals

www.caribouair.ca
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BMPs at Empire Overview
Credit Friends of Mississippi
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BMP Effluent Diversion

• Completed in early 2008
• Goal Reduce thermal impact on Vermillion River,
  aid in flood reduction, Regulatory Compliance
• Planning MCES, REMP Partners
• Implementation Contractor
• Cost 74 million

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BMP Pollution Prevention/Source Reduction

• Goal Implement site management to meet
  requirements of proposed NPDES Industrial
  Stormwater Permit, including SWPPP
• Planning MCES
• Implementation MCES
• Specifications Developed of map with impervious
  areas, BMPs, sensitive areas, material storage,
  stormsewer outfalls, spill kit locations
• Maintenance Regular updates to map regular
  inspections
• Outcome Created interactive map template

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BMP Pollution Prevention/Source Reduction
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BMP Streambank Stabilization

• Completed in 2003 by DNR
• Goal stabilize 11 areas of streambank reduce
  TSS/Turbidity
• to River enhance trout habitat restore native
  vegetation
• Planning Friends of Mississippi and DNR
• Implementation DNR, contractor, FMR volunteers
  98,000
• Maintenance minimal
• Outcome Banks successfully stabilized. Shading
  enhanced Trout
• habitat restored with lunker boxes

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Initial Bank Conditions
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Construction 2003
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Completed Project
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BMP Wetland Restoration

• Completed in 2003
• Goal restore wet meadow wetland on 50 acres of
  marginal farmland protect groundwater store
  runoff enhance habitat
• Planning Friends of Mississippi and DNR
• Implementation FMR, contractor, FMR
  volunteers 230,000
• Maintenance 2003-2005 FMR and contractor
  50,000
• Outcome Wetland restored additional bird and
  insect species
• Challenges Initial dry conditions due to
  dewatering, drought Disturbance during effluent
  diversion need for continuous maintenance

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Pre-Restoration
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2006
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BMP Vegetated (Green) Roof
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Green Roof Review

• Intensive Green Roof
• Deep growing media (greater than 6)
• Mix of hard and soft scaping
• Allow interaction of people and landscape
• Can include trees, water features, etc

• Extensive Green Roof
• Shallow growing media (2-6)
• Typically only soft scaping
• Usually not intended for interaction of people
  and
• landscape
• Typically 18-34 lb/sq ft wet weight

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Green Roof Overview

• Advantages of Green Roofs
• Stormwater interception evapotranspiration
  Extensive 2-5 storage
• Conversion of impervious surface
• Cooling of roof surface and building lowered
  cooling costs and energy use
• Reduction of temperature of urban heat island
• Filter and bind air born dust particles
• Longer life of roof membrane thru protection from
  UV Estimated 50 year lifespan
• Habitat aesthetic enjoyment
• Higher property values

• Disadvantages of Green Roofs
• May raise temperature of discharged runoff
  greater thermal mass
• Require structural strength
• Cost (25-30 per sq ft) approx 2x traditional
  industrial roof
• Does require regular maintenance weeding
• Does require irrigation during drought

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Green Roof Overview
Credit roofscapes.com
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Phillips EcoEnterprise Building
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Minneapolis City Hall
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Minneapolis Public Library
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Minneapolis Condominiums
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Empire Green Roof

• Completed in 2007
• Goal Install green roof assess maintenance
  requirements assess appropriate plant species
  create feature easily observable by public ADA
  compliant
• Planning MCES Luken Architects
• Implementation Contractor, MCES
• System American Hydrotech 6 growing medium
• Plants Dianthus June grass Prairie Onion
  Sedum
• Cost 25,000 above traditional roof (15 sq/ft)
• Maintenance Contractor 1,800/year Irrigated
  with treated effluent
• Outcome Successful implementation Attractive
  Killdeer nest in 2009
• Challenges Plant establishment, migrating
  hydro- seed irrigation (drip system to be
  installed in 2010) high-organic growing medium

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2007
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Late 2007
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Early 2008
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Early 2009
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Late 2009
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BMP Infiltration Basins
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Empire Infiltration

• Final seeding in 2009
• Goal Infiltrate runoff from 2 storm Use
  native plants
• Planning MCES Rani Engineering
• Implementation Contractor, MCES
• Plants Native grasses and forbs (flowers)
• Specifications 12 sand/compost/topsoil Scarify
  to 2 ft depth clean straw mulch drill seed
• Maintenance Contractor
• Outcome 0 discharge from infiltration basins
  since construction, even in 3 rain events
• Challenges Plant establishment, retro fit of
  forebay reconstruction of septage receiving
  basin

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North Infiltration 2005
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BMP North Infiltration Late-2009
Area 1.2 acres Assumed infiltration rate
0.5/hr Drainage area 11.8 acres
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Empire South Infiltration Pre-Construction
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Empire South Infiltration Post-Construction
Area 0.8 acres Assumed infiltration rate
0.5/hr Drainage area 10.6 acres 11.8 acres
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Infiltration Basins
West Infiltration (Septage Receiving)
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West Infiltration Basin Re-Design and
Construction (2010)
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BMP Pervious Pavers
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Pervious Paver Overview

• High durability lifespan of 50 years
• High load capacity 8,000 psi
• High infiltration rate 3 in/hr (conservative)
• Renewable if plugged with sediment
• May require less winter sand/salt due to thermal
  connection with ground

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BMP Pervious Pavers

• Completed in 2006
• Goal Install 6 pervious paver parking areas
  test durability to heavy truck traffic and
  plowing observe infiltration capacity create
  maintenance specs
• Planning MCES Contractor
• Implementation Contractor,
• System Uni EcoStone cast concrete
• Specifications 2 sand base 10 washed class 5
  gravel
• Cost 33,330 (4.37 sq/ft) excluding
  sand/gravel
• Maintenance Vacuuming and gravel replacement
  in 2010
• Outcome Successful implementation no
  dislodged or broken pavers infiltration rate
  high
• Challenges Timing of installation UV bulb
  transport

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Paver Challenge UV Bulb Transport
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BMP Grassed Swales
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Stormwater Surprises and Challenges
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Stormwater Surprises and Challenges
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Stormwater Surprises and Challenges
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Thank You!
Karen Jensen Metropolitan Council Environmental
Services 651-602-1401 karen.jensen_at_metc.state.mn.u
s
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Trout Facts (Mn DNR)
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Grassed Swales
Infiltration Basins
Vegetated (Green) Roof
Pervious Paver Parking
Native Plant Garden
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Trout Facts (Mn DNR)
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Title of Presentation

• Name
• Title
• Company Name