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Projected Use of Innovative/Alternative On-site Sewage Treatment Systems in Eastham, Under Current Regulations and Policies. Susan Rask Barnstable County Department of Health and Environment. Project funded by Barnstable County Wastewater Implementation Committee (WIC). Project Goals.

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Susan rask barnstable county department of health and environment

Projected Use of Innovative/Alternative On-site Sewage Treatment Systems in Eastham, Under Current Regulations and Policies

Susan Rask

Barnstable County

Department of Health and Environment


Project funded by barnstable county wastewater implementation committee wic

Project funded by Barnstable County Wastewater Implementation Committee (WIC)


Project goals

Project Goals

  • Examine existing regulations and Board of Health policies that require or encourage use of I/A systems

  • Use this information to project how many I/A systems might be installed over next 20 years, and where these might be installed

  • Provide information about initial and long term costs of I/A systems, so these can be compared to other alternatives


Project methodology

Project Methodology

  • 6152 lots in Eastham

  • Could not examine on case-by-case basis

  • Use of reasonable assumptions to compensate for missing information

  • Use of GIS to analyze parcels and graphically show results

  • Analysis linked to Eastham drinking water quality database


Criteria for installation of i a

Criteria for Installation of I/A

  • Criteria 1: Board of Health policy

    • For new construction or upgrades of existing systems

      • When SAS < 100 ft. to any drinking water well

      • When SAS < 75 ft. to edge of wetland resource


Criteria for installation of i a1

Criteria for Installation of I/A

  • Criteria2: Public Water supplies

    A public water supply is any well that serves more than 25 people for more than 60 days per year

    In Eastham, most are Transient, Non-Community wells at restaurants and motels

  • 39 in Eastham, primarily on Rt. 6


Criteria for installation of i a2

Criteria for installation of I/A

  • Criteria 3: Title 5 requirements

  • I/A required

    • For NEW CONSTRUCTION on residential lots with well and septic, if design flow exceeds 440 gpd/acre

  • Title 5 and DEP policy that BOHs consider requiring I/A

    • For existing systems at time of upgrade, if design flow > 440 gpd/acre and nearby wells showing elevated nitrates


Criteria 1 board of health policy

Criteria 1: Board of Health policy

  • When SAS <100 ft to any drinking water well

    • Could not be directly determined, due to lack of information on septic and well locations

    • Surrogate:

      • All parcels <10,000 s.f. were likely not to be able to meet 100 ft setback, and were projected for I/A

      • Parcels > 20,000 s.f. were assumed to generally be able to fit well and septic

      • Parcels >10,000 but <20,000: examined wetland coverage on parcel, size of surrounding parcels, bedroom density, and well water quality and made decision on lot-by-lot basis


Criteria 1 board of health policy1

Criteria 1: Board of Health policy

  • When SAS <100 ft to any drinking water well

    RESULTS:I/A projected on

    Parcels <10,000 s.f. = 276 I/A projected

    Shown in pink on Map 2

    Parcels >10,000 but <20,000 s.f. := 282 I/A projected

    Shown in blue on Map 2

    Parcels > 20,000 s.f. = 0 I/A projected

    but these parcels were examined under Criteria 3 to see if they met 440 gpd/acre standard


Criteria 1 board of health policy2

Criteria 1: Board of Health policy

  • When SAS <75 ft from edge of wetland

    • Could not be directly determined, due to lack of information on septic and house footprint

    • Surrogate: For each parcel

      • Mapped wetland coverage

      • Mapped 75 ft buffer zone beyond wetland boundary (BOH setback criteria)

      • Mapped 10 ft property line offset

      • Knew house foundation size from assessor data

      • Created “House Footprint” by adding foundation size plus a 20 ft border around foundation, to meet septic setbacks


Criteria 1 board of health policy3

Criteria 1: Board of Health policy

  • When SAS <75 ft from edge of wetland

  • Area available for SAS = Total lot size –(area of “House Footprint” + area covered by 75 ft wetland buffer + area covered by 10 ft lotline setback)

  • If Area available for SAS < 3000 s.f., projected I/A


Criteria 1 board of health policy4

Criteria 1: Board of Health policy

  • When SAS <75 ft from edge of wetland

  • RESULTS: I/A projected = 482

    • Shown in green on Map 1

    • Recognize that some of these are likely all wetland and unbuildable, more realistic number is probably 382


Criteria 2 public water supplies

Criteria 2: Public Water supplies

  • Regulated by 310 CMR 22.00—Drinking Water regs

  • Zone I: area immediately surrounding a well

    • For small volume wells, is minimum 100 ft radius

  • IWPA: “zone of contribution”, land area that may contribute water to well

    • For small volume wells, is minimum 400 ft radius around well


Criteria 2 public water supplies1

Criteria 2: Public Water supplies

  • 310 CMR 15.00—Title 5 requires I/A

    • When design flow >2000 gpd and septic system will be located in IWPA or Zone II of public drinking water supply well

    • When septic system is in IWPA and design flow exceeds 440 gpd/acre

    • For upgrades of existing systems, when septic components cannot be located outside Zone 1 of the well


Criteria 2 public water supplies2

Criteria 2: Public Water supplies

  • Most businesses with a public water supply well are located on relatively small parcels

  • 400 ft IWPA radius usually covers most or all of the parcel, making it difficult to locate septic outside this radius

  • Most have septic design flows > 440 gpd/acre

  • Most businesses will fit into one of the categories in previous slide

  • All are projected to have I/A systems installed = 39. Shown in blue on Map 1


Criteria 3 title 5 requirements

Criteria 3: Title 5 requirements

  • I/A required

    • For NEW CONSTRUCTION on residential lots with well and septic, if design flow exceeds 440 gpd/acre

  • DEP and Title 5 suggest that BOHs consider requiring I/A

    • For existing systems at time of upgrade, if design flow > 440 gpd/acre and nearby wells showing elevated nitrates


Criteria 3 title 5 requirements1

Criteria 3: Title 5 requirements

On residential lots with well and septic, Title 5 allows

440 gpd/acre = 4 bedrooms/acre

or 2 bedrooms/0.5 acre, etc.

i.e. 1 bedroom per 10,000 s.f. lot size


Criteria 3 title 5 requirements2

Criteria 3: Title 5 requirements

  • Why does Title 5 limit septic design flow to 440 gpd/acre in areas served by private wells?

    • Nitrogen loading model predicts that 440 gpd/acre results in groundwater nitrogen concentration of 7.1 mg/L on lot-by–lot basis

      • Protective, based on human health standard of 10 mg/L nitrate in drinking water

      • Does not address N loading to coastal embayments


Criteria 3 title 5 requirements3

Criteria 3: Title 5 requirements

  • I/A required for NEW CONSTRUCTION on residential lots with well and septic, if design flow exceeds 440 gpd/acre

    • Installation of these systems is usually voluntary, i.e. owner wants more bedrooms and is willing to install I/A system

    • Not predictable, so unable to project

    • Could result in a significant number over time

      Note: New Construction = addition of new design flow


Criteria 3 title 5 requirements4

Criteria 3: Title 5 requirements

  • DEP and Title 5 suggest that BOHs consider requiring I/A

    • For existing systems at time of upgrade, if design flow > 440 gpd/acre and nearby wells showing elevated nitrates


Criteria 3 title 5 requirements5

Criteria 3: Title 5 requirements

  • To approach this problem, we mapped:

    • Most recent water quality data for each lot

    • Bedroom density on each lot

      • Equivalent to 4,5,6,7,8+ BR/acre

      • Shown on Map 3


Criteria 3 title 5 requirements bedroom density and nitrate levels

Criteria 3: Title 5 requirementsBedroom density and nitrate levels

  • Results: Map 3

    • Lots showing elevated nitrates (> 2 mg/L) are widespread, esp in northern end of town

    • Number of water samples showing nitrates > 2 mg/L constitute 50.4% of all samples

    • Bedroom density is not directly correlated with nitrate level on its own lot

    • Wells showing nitrate > 5 mg/L are likely due to “short circuiting”


Susan rask barnstable county department of health and environment

Leach field

Downgradient well

NO3

Nitrate


Susan rask barnstable county department of health and environment

Drinking wells intercepting plume at different distances from plume source and therefore showing different concentrations of nitrate


Criteria 3 title 5 requirements bedroom density and nitrate levels1

Criteria 3: Title 5 requirementsBedroom density and nitrate levels

  • “Short circuiting” is occurring due to small lot size and large number of wells and septic systems;

  • High number of samples > 2mg/L validates that entire groundwater system is showing nitrogen impacts from septic systems


Susan rask barnstable county department of health and environment

Current Eastham Drinking Well Results


Historical trend of nitrate levels in wells 1981 2006 shown as percent of total samples

Historical Trend of Nitrate levels in Wells, 1981-2006shown as percent of total samples


Criteria 3 title 5 requirements bedroom density and nitrate levels2

Criteria 3: Title 5 requirementsBedroom density and nitrate levels

  • Results: Map 3

    • Lots showing elevated nitrates (> 2 mg/L) are widespread, esp in northern end of town

    • Lots showing nitrates > 5 mg/L appear to be randomly distributed

    • Bedroom density does not appear to be correlated with nitrate level on its own lot

    • Many lots exceed 440 gpd/acre


Criteria 3 title 5 requirements bedroom density and nitrate levels3

Criteria 3: Title 5 requirementsBedroom density and nitrate levels

  • How to deal with this information?

  • Developed scenarios for installation of I/A

    • Lots with >6 BR/acre and nitrates > 5 mg/L147 lots shown in light blue on Map 4

    • Lots of 10-20,000 s.f. with > 4 BR/acre and nitrates > 3 mg/L

      90 lots shown in pink on Map 4


Criteria 3 title 5 requirements bedroom density and nitrate levels4

Criteria 3: Title 5 requirementsBedroom density and nitrate levels

  • Results in very random distribution of I/A systems

  • Not recommended way to use these systems because

    • Does not address groundwater N loading in a coherent way

    • Will likely not solve problem of lots with elevated nitrates

    • Expensive for homeowners

    • Management issues with single family I/A s


Bedroom density

Bedroom Density

45% of total parcels in town exceed 4 BR/acre or 440 gpd/acre guideline (this doesn’t include analysis of commercial flow vs. lot size)


Criteria 3 density vs lot size

Criteria 3: Density vs. lot size

45% of total parcels in town exceed 4 BR/acre or 440 gpd/acre guideline

  • If 440 gpd/acre = 7.1 mg/L N in groundwater, its not surprising that Eastham has a number of lots showing elevated nitrates

  • Unlikely that groundwater quality will improve


Summary of projected i as

Summary of Projected I/As

  • 93Currently permitted

  • 276Criteria 1A: parcels <10,000 s.f.

  • 372Criteria 1B: insufficient setback to wetlands

  • 39Criteria 2: public water supplies

  • 90Criteria 3: parcels 10-20,000 s.f. with > 4BR/acre and nitrates>3 mg/L

  • 147Criteria 3: parcels with >6 BR/acre and nitrates >5 mg/L

  • 1017TOTAL


Summary of projected i as1

Summary of Projected I/As

  • 1017Projected

  • Shown on Map 4

  • Randomly distributed around town

  • Random distribution will do little to address groundwater nitrogen in a coherent way


I a systems considerations

I/A Systems: Considerations

  • Perception that I/A systems are quick and inexpensive fix

  • Not True

    • Costly over life of system

    • Stringent O&M and sampling requirements when used for nitrogen reduction

    • Variable performance

    • At best, remove 50% of nitrogen

    • Impose management burden on town


I a systems economics

I/A Systems: Economics

  • Individual I/A on-sites are not inexpensive

  • Installation cost: $10,000 above cost of Title 5 system

  • Significant Annual Costs

    • Operation and Maintenance contract ($1200)

    • Electricity costs ($350)

    • Effluent Sampling ($400, included in cost of O&M)

    • Total annual cost to operate= $1550


I a systems economics present value cost of i a system

I/A Systems: EconomicsPresent value cost of I/A system

  • Present value analysis brings all costs associated with system installation, maintenance and operation of the system, over the entire life of the system, into present dollars

    i.e. How much money would I have to set aside today to cover all costs associated with the system over it’s life span?


I a systems economics present value cost of i a system1

I/A Systems: EconomicsPresent value cost of I/A system

  • Assumptions:

    • Installation cost $10,000

    • Annual O&M contract $1200/yr

    • Electricity to operate $350/yr

    • Quarterly inspection and effluent sampling

    • 20 year life of system

    • 5% interest rate

      Yields present value of roughly $35,000.


I a systems economics present value cost of i a system including title 5 components

I/A Systems: EconomicsPresent value cost of I/A system including Title 5 components

Initial costs:

I/A unit $10,000

Title 5 components $10-20,000

Brings total initial cost to $20-30,000

Brings present value cost to $45-55,000


Economics of i a systems

Economics of I/A systems

  • Assume present value for each I/A system is $45,000

  • Use conservative assumption of 1000 I/A installed

  • Total projected wastewater infrastructure cost present value =$45,000,000.

  • Is this the best use of $$$?


Economics of i a systems vs sewering to small collection plant

Economics of I/A systems vs. sewering to small collection plant

  • Falmouth New Silver Beach Project:

    • 220 homes, gravity collection system to small treatment plant; plant and effluent disposal on town owned property

    • Total cost estimate: $12.2 million

    • Per home cost: $55,000

      • Payable as betterment over 20 years at 5% interest


I a systems individual residential use performance

I/A Systems Individual Residential Use Performance

  • Most I/A systems remove nitrogen and organic matter (BOD) from wastewater, but are only somewhat effective in removing pathogens, unless additional components—such a UV treatment—are used.

    • I/A systems are not a substitute for meeting Title 5 setback requirements.


I a systems individual residential use performance1

I/A Systems Individual Residential Use Performance

  • How well do various systems work?

    • Only 2 technologies have been granted General Use Approval for nitrogen reduction by DEP— recirculating sand filters (RSFs) and RUCK systems

    • 2 technologies (Bioclere, FAST) that had Provisional Use Approval for nitrogen reduction may no longer be installed and DEP has not granted them General Use Approval for nitrogen reduction.


I a systems individual residential use performance2

I/A Systems Individual Residential Use Performance

  • At present, only 2 technologies may be installed, under Piloting Use Approval, for nitrogen reduction—Amphidrome, Waterloo Biofilter.

  • Only a small number of these systems will be allowed, per the terms of Piloting Approval


I a systems individual residential use performance3

I/A Systems Individual Residential Use Performance

  • To keep costs low and to keep maintenance minimal for homeowners, most are designed to be as simple and as passive as possible

  • Gravity flow where possible

  • Water flows through system by hydraulic displacement

    i.e. Water In = Water Out


I a systems individual residential use performance4

I/A Systems Individual Residential Use Performance

  • No Surge Capacity results in varying amounts of residence time and therefore treatment of individual “slugs” of water

  • Results in inconsistent levels of treatment


I a systems individual residential use performance5

I/A Systems Individual Residential Use Performance

  • Residential Wastewater is highly variable in strength and composition

    • From residence to residence

    • From hour to hour and day to day within one residence

    • Results in inconsistent levels of treatment


Susan rask barnstable county department of health and environment

Average TN=18.4 median=15.2 mg/L

66% of samples met 20 mg/L limit but 33% did not


I a systems for individual residential use seasonal use

I/A Systems for Individual Residential UseSeasonal Use

  • Seasonally occupied homes

    • All technologies work by biological treatment of wastes. It takes at least 4-6 weeks after start up to bring the bacterial populations that digest the sewage up to effective levels.

    • Full nitrogen reduction is not achieved until 4-6 weeks after seasonal start-up.


Management issues

Management Issues

  • Homeowners resist paying annual costs, so maintenance contracts lapse, O&M and sampling are not performed

  • People want to put these systems in the ground and forget about them, the way we’ve always been able to do with our Title 5 systems.


Management issues1

Management Issues

  • Owners have financial incentives to turn systems off and to discontinue O&M contracts.

  • Many systems do not always operate optimally and, unless followed up by Health Dept. staff, many operators seem to show little interest in re-visiting a system to “tweak” its performance.

  • Extra visits by the system operator to “tweak” the system cost homeowners extra operator and laboratory fees.


Management issues2

Management Issues

  • I/A treatment systems are performance based

  • EPA recommends that performance based systems be managed by Responsible Management Entity (RME)

  • RME can be

    • Town wastewater district

    • Municipal operators

    • Regional wastewater district


Bigger picture concerns

Bigger Picture Concerns

  • Installation of I/A systems may preclude better wastewater solutions

    • Once owners have spent the money to upgrade their system to I/A, they are unlikely to support cost of sewering their neighborhood


Bigger picture concerns1

Bigger Picture Concerns

  • How do I/A systems fit in with larger water and wastewater planning efforts in town?

    • Comprehensive Wastewater Facilities Plan

    • Where will I/A systems fit in this plan?

    • From management and financial standpoint, a planned approach is more effective than installing systems randomly all over town.


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