Pascoag Utility District Source Water Assessment

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Pascoag Utility DistrictSource Water Assessment

• Clay Commons, Environmental Scientist
• RI Department of Health
• Office of Drinking Water Quality

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Pascoag Assessment Results

• USGS Statistical Analysis Findings
• Source Water Assessment Program
• Vulnerability Can contaminants move toward the
  well?
• Susceptibility Are contaminants present in the
  recharge area?
• In Pascoag, the answers are Yes, and Yes.

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USGS Vulnerability Assessment "A Vulnerability
Assessment of Public-Supply Wells in Rhode
Island" (Water Resources Investigations report
99-4160.)

• Nutrients 4 (Fertilizers, wastewater)
• Solvents 4 (Fuels, industrial uses)
• Pesticides 4 (Residential and Ag.)
• Road-Deicing Chemicals 4 (Road De-Icing)
• Fluoride 3 (Naturally occurring)
• Radionuclides 2 (Naturally occurring)
• Sum of Ranks 21

4 High Risk 3 Moderate Risk 2 Low Risk 1
Very Low Risk
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Background on SWA

• 1996 Amendments to Safe Drinking Water Act
• Assess the threats to all sources of public water
• for the protection and benefit of public water
  systems, and to support monitoring flexibility.

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Elements of Assessment

• First, determine recharge area the land surface
  that contributes water to the well
• Second, inventory all land uses within the
  recharge area
• Third, assign a risk ranking to the source
• Fourth, publish results

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Factors of an Assessment

• Soil permeability how rapidly can contaminants
  move toward the well?
• Land use the presence of potential contaminants
  in the protection area. What facilities and land
  uses are present?
• High-intensity land use on highly permeable soils
• Sampling history what has been found in the
  water?

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Pascoag Assessment

• Burrillville had just completed a Resource
  Protection project with Lorraine Joubert of URI
  Cooperative Extension
• Local Advisory Committee was already in place
• Citizens and suppliers were anxious to move
  forward
• Pascoag was assumed to be at high risk of
  contamination because of existing land uses

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1997 Aerial Photograph of the Pascoag Recharge
Area
Boundary in green
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Pascoag Well 3

• 90 of the Recharge Area soil is either highly
  permeable or well-drained.

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PERMEABILITY OF SOILS IN THE RECHARGE AREA
Most of Recharge Area is served by public sewers.
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Pascoag Well 3

• 90 of the Recharge Area soil is either highly
  permeable or well-drained.
• Over 75 of the Recharge Area is high-intensity
  land use.

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LAND COVER IN THE PASCOAG RECHARGE AREA
Mostly High-Density Residential and Commercial
land uses.
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High-Risk Land Use on High-Risk Soils
High-Risk soils include urban soil categories,
such as parking lots and roadways.
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Pascoag Well 3

• 90 of the Recharge Area soil is either highly
  permeable or well-drained.
• Over 75 of the Recharge Area is high-intensity
  land use.
• 62 individual sites are either commercial
  -industrial or have a UST on site.

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Potential Point Sources of Contamination
Many point sources are on high-risk soils.
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Pascoag Well 3

• 90 of the Recharge Area soil is either highly
  permeable or well-drained.
• Over 75 of the Recharge Area is high-intensity
  land use.
• 62 individual sites are either commercial
  -industrial or have a UST on site.
• Sampling History 1999 1.0 ppb MtBE. Sodium,
  Nitrates, some naturally-occurring substances
  otherwise clean.

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Assessment Results

• Combined 77 of WHPA is in moderately high to
  very high risk land use.
• Much high-intensity land use is on highly
  permeable and disturbed soils, and close to the
  wells.
• Many high-risk facilities yet in Recharge Area.
• Highest risk of any system assessed.

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CONCLUSIONS

• The wells are vulnerable - contaminants can
  reach them.
• The wells are susceptible - there are
  contaminants present.
• This has not changed since 2001.
• Results would have been the same for 3A (unless
  recharge area was re-drawn).