Water Quality Management at Yard Waste Mulching and Composting Facilities

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Water Quality Management at Yard Waste Mulching
and Composting Facilities

• Or Into Every Life A Little Rain Must Fall

Craig Coker North Carolina Composting Council,
Inc.
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Why Is This An Issue?

• Oct. 2006 DENR/DWQ decided to require
  wastewater discharge permits at yard waste
  composting mulching facilities
• No longer possible to get storm water discharge
  permits at these facilities
• Policy shift based on limited sampling and
  impact assessment
• Impact to date over 1 Million in extra costs
  major delays in permit renewals a freeze on
  composting industry expansion in NC

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How New Program is Implemented

• DWQ will impose wastewater discharge permits upon
  renewal of DWM composting permits
• 2009 municipal Type 1 renewals
• Brunswick County
• Winston-Salem
• High Point
• 2010 municipal Type 1 renewals
• Greensboro
• Hickory
• CRSWMA

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Storm Water Management

• Historic perspective
• Manage water quantity only
• Post-Development runoff pre-development runoff
• Containment ponds with controlled releases
• 1987 Amendments to Clean Water Act
• Focus on water quality protection
  (non-degradation)
• New programs to address industrial storm water
  discharges
• New programs for municipal separate storm sewer
  systems (MS4s)

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Storm Water Management

• Industrial storm water discharges regulated by
  SIC Code
• Industries in same code have similar discharges
• Composters no SIC Code fits exactly
• SIC 2875 Fertilizer Mixing
• SIC 4873 Landfills
• SIC 2499 Wood Processing other

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Storm Water Hydrology

• Hydrologic Cycle

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Rainfall

• Rain varies in both time and space
• Storms described by recurrence interval or
  return period
• Defined by statistical frequency analysis

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Rainfall

• Recurrence intervals
• 25-year storm on average once in 25 years
  4 chance of occurrence any given year
• Storms can, and do, occur more often than once
  per year
• Stormwater systems based on both volumes of
  runoff as well as on flow rates
• Rain of 1.5/hour for 1 hour 0.25/hour for 6
  hours
• 1.5 of rain 5,445 cubic feet of water on 1
  acre 40,000 gallons

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Estimating Rainfall
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Runoff

• Runoff that portion of rainfall not evaporated
  or infiltrated
• Factors that influence amount of runoff
• Recent rainfalls, long-term soil moisture
• Type of compost pad, presence/absence of
  windrows, and spacing, age and moisture content
  of windrows
• 2004 Canadian Study
• 68 of rainfall on open air windrow facility
  became runoff
• Significant time delay in release (affects system
  design for flow rate)

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Methods for calculating runoff

• Non-Hydrograph Rational Method
• Q C x I x A
• Q flow (cfs), C runoff coefficient, I
  rainfall intensity (in./hr.), A area (sq.ft.)
• Better Method Unit Hydrograph Analysis
• More refined runoff coefficients
• Consideration of soil types
• Use NRCS TR-20 and TR-55 for hydrologic analysis

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Runoff Hydrographs

• Runoff hydrograph for 10-year, 1-hour storm of
  2.2/hr. falling on 13.25 acres of gravel compost
  pad

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Water Sources in Composting

• Run-on - runoff from uphill areas route around
  pads
• Washwater from washing equipment vehicles
• Nonprocess storm water rain that falls on site
  and runs off, but not from pad or storage areas
• Process storm water runoff from compost pads,
  curing pads, product storage
• Leachate liquid that drains through and out of
  windrows and compost piles

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Whats in the Runoff?

• Nutrients N, P, K, micronutrients
• Soluble salts
• Biological Oxygen Demand (BOD)
• Amt. of O2 reqd by bacteria to decompose organic
  matter in water
• Chemical Oxygen Demand (COD)
• Total amount of O2 needed to completely oxidize
  organics

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Runoff Ingredients, cont.

• Tannins and phenols from decomposing vegetation
  characteristic brown color
• Herbicides/pesticides/fungicides particularly
  from fresh yard clearing debris
• Fecal coliform bacteria
• All contaminants can have significant
  environmental impact
• Particularly in impaired waters
• Not surprising that runoff is becoming regulated

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Runoff Constituents, cont.

• Runoff Ranges - Four Facilities in Pacific NW
• Parameter Range (mg/l)
• BOD5 20 - 3,200
• Total solids 1,100 - 19,600
• Volatile solids 430 - 9,220
• Color (color units) 1,000 - 70,000
• Fecal (MPN/100ml) 200 - 24,000,000
• Copper (ppb) 33 - 821
• Zinc (ppb) 107 - 1,490
• Nutrients
• Ammonia N 32 - 1600
• Total Kjeldahl N 14 - 3,000
• Nitratenitrite N 0 - 8
• Total phosphorus 4 - 170
• Ortho phosphate 0 - 90
• pH (standard units) 6.7 - 9.5
• Conductivity 887 - 16,500
• Chloride 52 - 2,100
• Potassium 167 - 4,640

• Analysis of runoff from European open windrow
  composting facility (30 samples)
• Parameter Range (mg/l)
• Arsenic (As) lt0.001 0.044
• Lead (Pb) lt0.001 0.500
• Cadmium (Cd) lt0.001 0.172
• Zinc (Zn) 0.011 2.4
• Ammonium (NH4-N) 2.0 46.0
• Nitrate (NO3-N) lt0.1 96.4
• Nitrite (NO2-N) lt0.1 0.80
• Chlorides 106 445
• BOD5 lt2.0 513
• COD5 56 1768
• BOD5/COD5 ratio 0.01 0.37

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Water Quality Permitting

• Wastewater (End of Pipe)
• Discharge is assigned allowable effluent limits
• Derived from
• Allowable mass load (lbs) / Avg. Daily Flow (cfs)
  Allowable conc. (mg/L)
• Allowable loads determined by stream quality
• Impaired streams subject to Total Maximum
  Daily Loads
• Frequent monitoring required
• Stormwater
• Need Annual Benchmark Monitoring
• Need SWP2 Plan
• May need BMPs

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Oregon DEQ Storm Water Discharge Benchmark
Monitoring Requirements1

• Parameter Benchmark
• Total Copper 0.1 mg/l
• Total Lead 0.4 mg/l
• Total Zinc 0.6 mg/l
• pH 5.5 9.0 SU
• Total Suspended Solids 130 mg/l
• Total Oil Grease 10 mg/l
• BOD5 30 mg/l
• Total Phosphorus 2 mg/l
• Floating Solids (associated with composting
  activities) No Visible Discharge
• Oil Grease Sheen No Visible Sheen
• 1Proposed 2007, withdrawn in 2008 due to
  environmental group litigation

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How Should We Manage Storm Water?
Reduce Reuse Recycle Treat Pump and Haul
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Reducing Runoff

• No Exposure Exclusion if not exposed to
  rainfall producing runoff, then no permit needed
• Roofed areas, in-vessel containers
• Site design to segregate runoff
• Minimize volumes of truly contaminated runoff
• Grade site to divert upgradient runoff around
  facility
• Pad design to segregate runoff (à la Novozymes)
• Contain washwater runoff
• Storm water pollution prevention plans (SWP3)

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Novozymes-Natures GREEN-RELEAF Facility
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Design Considerations

• Leachate Management Pad Construction

Compost Windrow
8 oz Non Woven Fabric
6 inches ABC Stone
6 inches 67 Stone
10 oz Non Woven Fabric
COMPACTED CLAY
60 mil HDPE Liner
Drainage Trench
HDPE 6 inch Lateral Drain to leachate
collection pond
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Reuse Runoff

• Use it for moisture optimization during mixing
• Particularly important with ASP due to
  evaporative losses during composting
• Return it as irrigation water for moisture
  control in windrows
• Apply with water truck, sprinklers, or hose reel
• Use only on windrows that have not met 15A NCAC
  13B.1406(10)1
• Bacterial contamination likely, even with yard
  waste
• 1Compost process at Type 1 facilities - gt 55oC
  for 3 days

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Calculating Water Reuse Demand

• Water Mass Basis
• Determine tonnage of water in windrows, existing
  and desired
• Determine needed reuse by difference
• Volume Basis (courtesy UK Composting Association,
  2007)

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Exercise Calculating Reuse Demand

• Assumptions
• Stormwater system sized for 25-year, 24-hour
  storm of 6.62
• Compost/cure pad is 8 acres paved asphalt
• Methodology
• Calculate area-weighted runoff curve number (RCN)
• RCN for windrows RCN for aisles/roadways
  Total RCN
• Use NRCS Rainfall-Runoff Curves to determine
  runoff (inches)
• Convert inches of runoff to gallons of runoff
• Determine tonnage of water in windrows (existing)
• Determine tonnage of water in windrows (desired)
• Based on difference, calculate gallonage of water
  reuse needed

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Problem Solution

• Assumptions
• System sized to handle a 25-year, 24-hour storm
  of 6.62
• Compost/cure pad is 8 acres (348,840 SF) and is
  made of asphalt
• Pad has 35 windrows, each 14 wide and 400 long,
  volume 871 CY/windrow
• Bulk density 1,200 lbs/CY
• Assume non-windrow areas of pad are open aisles
  and/or roadways
• Conversion factors 1 cubic foot 7.48 gallons,
  1 gallon 8.4 pounds
• Methodology
• Calculate area-weighted runoff curve number
• Area occupied by windrows (SF)
• 35 ( 14 x 400 ) 196,000 SF
• Area occupied by open aisles and/or roadways
  (SF)
• 348,840 SF 196,000 SF 152,840 SF
• Curve number (CN) for area occupied by windrows
  681
• Curve number for area occupied by
  aisles/roadways 98
• Weighted Average CN
• (196,000)(68) (152,840)(98) 81.2

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Problem Solution, cont.

• Calculate the Volume of Runoff to be Controlled
• Runoff amount (inches) 4.52
• Runoff linear volume (inches x area, CF)
• 4.52/ 12/ft. x 348,840 SF 131,396.4 CF
• Runoff liquid volume (gallons)
• 131,396.4 CF x 7.48 gal/CF 982,845 gallons
• Determine Quantity Needed in Water Reuse
• Assume 50 of the windrows have not yet met PFRP
  and can be watered
• Assume measured moisture content of windrows is
  40 and desired moisture content is 55
• Volume (CY) of material on pad
• 17 windrows _at_ 871 CY/windrow 14,807 CY
• Weight (lbs) of material on pad
• 14,807 CY _at_ 1,200 lbs/CY 17,768,400 lbs
• Weight (lbs) of water in material on pad
• 17,768,400 lbs x 0.40 7,107,360 lbs H2O
• Weight (lbs) of water desired in material on pad

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Recycling Runoff

• Recycle runoff as spray irrigation water for
  crops
• Crops row, pasture, turfgrass, biomass
• Application methods overland flow, spray
  irrigation, drip irrigation, subsurface
  irrigation galleries
• Normally designed for hydraulic loading but may
  be subject to Nutrient Management Planning
• Pretreatment (disinfection) may be needed
• Extent or lack of disinfection may influence
  setbacks
• If recycling not possible, then consider
  treatment with Best Management Practices (BMPs)

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Best Management Practices (BMPs)

• Can be either structural or non-structural
• Structural
• Extended detention ponds
• Biofiltration pond/ rain gardens
• Engineered wetlands
• Non-Structural
• Housekeeping
• Appropriate Site Vegetation
• Prompt processing of feedstocks
• Shaping of piles

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Treating Storm Water with BMPs

• Non-structural BMPs helpful, but not enough
• Structural BMPs
• Used to manage both quantity and quality
• Regular maintenance essential
• Use BMPs that can handle nutrient loadings and
  that can reduce BOD/COD loads
• Mainly vegetative solutions (rain gardens,
  bioswales, wetlands, etc.)
• Use multiple types in series

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BMP Pollutant Removal Efficiencies

• Difficult to assess with storm water as influent
  concentrations vary
• Most BMPs have only been evaluated with respect
  to nutrients, TSS, metals
• Some data showing good bacteria removal with
  filtration-based systems
• Little data on BOD/COD removal, or removal of
  tannins/phenols, but vegetative (i.e. biological)
  solutions are inherently suitable

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NC DENR, Stormwater Best Management Practices
Manual, July 2007
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NC DENR, Stormwater Best Management Practices
Manual, July 2007
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NC DENR, Stormwater Best Management Practices
Manual, July 2007
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On-Site Stormwater Treatment

• Complications
• Degree of treatment needed (defined by receiving
  water quality)
• Secondary treatment at a minimum (BOD 30 mg/l
  TSS 30 mg/l TN 5 mg/l TP 3 mg/l)
• Tertiary treatment likely in nutrient-sensitive
  waters (BOD 3-5 mg/l TSS 3-5 mg/l TN 1
  mg/l TP 1 mg/l)
• Flow equalization normally needed

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Pollutants Treatment Processes
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Cedar Grove Composting-Everett WA
Information Courtesy of Cedar Grove Composting
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4 Phase Solids Separator
Information Courtesy of Cedar Grove Composting
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Lined Pond Primary Aeration
Information Courtesy of Cedar Grove Composting
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Lined Pond Secondary Aeration
Information Courtesy of Cedar Grove Composting
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Bioswale
Information Courtesy of Cedar Grove Composting
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Design Considerations
Receiving Building
Information Courtesy of Cedar Grove Composting
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Design Considerations
Sweeper truck picking up fines
Information Courtesy of Cedar Grove Composting
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Stormwater Operational Practices

• Sweeper Truck 75 per hour
• 4hr twice/wk 600 per week
• Keep Solid Separators and Catch Basins Clean
• 75 per hour
• 2 hr 150 per week

Information Courtesy of Cedar Grove Composting
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Cost of Each Treatment Unit at Cedar Grove

• Oil/Water Separator 41,000
• Solid Separator 58,500
• 46,000 Leachate Tank
• w/Secondary Containment,
• Cover, Pump and Line 150,000
• 2-500,000 gal Lined Ponds 83,000 100 mil
  liner
• Double bottom - 7,000 80 mil liner
• add 40K for excavation 40,000
• 3-Surface Aerator (stainless steel) 20,000 7
  hp
• 500,000 gal wet pond 25,000
• 600 ft Bioswale (add 2k for veg) 7,000
• Leachate pump to re-hydrate
• and plumb line from tank 9,000

Information Courtesy of Cedar Grove Composting
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Most Effective For the Least Cost

• Sweeper truck once per week
• Compost Berm of 1 Screen Material
• 1 ft High by 3 ft Wide
• 4 Phase Solid Separator
• 1 Wet Pond
• 1 Bioswale

Information Courtesy of Cedar Grove Composting
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Pump-and-Haul

• Not all WWTPs will accept trucked in liquids
• Could be forced to empty ponds several times per
  year
• City of Durham YWCF
• Must pump and haul pond contents of 100-yr,
  24-hour storm
• Max. pond storage 1.9 million gallons
• Will take over 300 6,500-gal tanker-trailers to
  empty full pond and haul to Durham WWTP

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Whats Next?

• NCCC proposed storm water sampling and analysis
  project to DWQ, scope negotiations underway
• House Bill HB 1100 Stormwater Control BMPs for
  Compost/Mulch
• Introduced April 7, 2009
• Sponsors Allen, Fisher, Harrison, Insko, Lucas
• Requires 3-yr moratorium on wastewater permitting
  requirements while DENR stakeholder group
  develop BMPs
• Stakeholders include NCCC and NC-SWANA

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Questions?
Craig Coker North Carolina Composting Council c/o
Coker Composting Consulting (540)
890-1086 cscoker_at_verizon.net www.cokercompost.com