Managing Tiverton s Water Resources

Transcription

1 Managing Tiverton s Water Resources Tiverton Town Hall February 28, 2018 Lorraine Joubert and Lisa Philo URI Cooperative Extension, RI NEMO

2 Nonpoint Education for Municipal Officials RI NEMO provides training and technical tools to help local decision makers manage impacts of changing land use on water resources. RI NEMO is part of the URI Cooperative Extension Water Quality Program

3 Topics Tiverton s water resources The link between land use and water quality State roles, Local responsibilities and best practices o Focus on OWTS, Wetland buffers and stormwater Discussion of local issues and management options

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8 Tiverton s Impaired Fresh Waters Waterbody Not Supporting Impairment Stafford Pond Fish & Wildlife Habitat Excess Algal Growth Dissolved Oxygen Phosphorous Pachet Brook Swimming & Boating Enterococcus Fecal Coliform Study Schedule Completed 2030 Sin and Flesh Brook & tribs Swimming & Boating Enterococcus 2030 Nonquit Pond Fish & Wildlife Habitat Public Drinking Water Supply Phosphorus Total Organic Carbon (TOC) Sucker Brook Fish & Wildlife Habitat Copper 2026 Swimming & Boating Enterococcus 2011 TMDL Completed Adamsville Brook & tribs Swimming & Boating Enterococcus 2030

9 Wellhead Protection Area The overlying land surface that contributes water to a pumping well. Land use in this area directly influences groundwater quality and quantity. Wellhead Protection Area

10 Bedrock Aquifers - Store water within fractures Yield and direction of water flow highly unpredictable Depends on size, amount and orientation of fractures

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13 Topics Tiverton s water resources The link between land use and water quality State roles, Local responsibilities and best practices Parting thoughts and discussion

14 Development Impacts on the Water Cycle 40% 30% 50% 10% runoff Forested Watershed Low runoff High recharge Healthy summer stream flow Natural pollutant treatment 15% runoff 55% Developed Watershed - High runoff, Low recharge - Nuisance flooding - Low summer stream flow - Bypass pollutant treatment

15 Water Quantity Impacts Erosion Flooding Increased runoff quantity Source: Alisa Richardson, RIDEM Low summer stream flow

16 Water Quality Impacts Nutrients Pathogens Sediment Toxic Contaminants Debris Thermal Stress More Runoff = More Pollutants

17 Threats to RI Surface Waters Contaminants in surface waters Bacteria Sediment Nutrients - Nitrogen in coastal waters - Phosphorus in fresh water Low oxygen Metals Sources Runoff Septic systems Fertilizers Water withdrawals and other changes in flow. RIDEM, 2002

18 Why not rely on drinking water treatment? Organic matter from aquatic weeds and algae is difficult to remove completely. Affects taste and odor. Complicates disinfection - combines with chlorine to create carcinogenic trihalomethanes.

19 Threats to RI Groundwater Common contaminants found in RI wells Petroleum products Organic solvents 15-30% of public wells report detects. bacteria in private wells often from improper seals nitrate pesticides Sources Leaking underground fuel tanks -leading cause of new contamination. Septic systems. Fertilizer and pesticide application. Spills & improper waste disposal. Hazardous and industrial waste disposal sites. Road salt RI DEM 2002

20 How much groundwater nitrogen is too much? Increasing pollution risk 1 mg/l Sign of impact to groundwater from wastewater or fertilizer. (USGS,2000) 5 mg/l Public drinking water action level. Triggers additional monitoring. Maximum in some towns. 10 mg/l Drinking water maximum level Acute health effects to infants. With blue baby syndrome nitrate replaces oxygen in blood mg/l or less Natural back-ground in RI groundwater in forested areas. Healthy shellfishing habitat 0.32 mg/l or less.

21 Topics Tiverton s water resources The link between land use and water quality State roles, Local responsibilities and best practices Parting thoughts and discussion

22 State Role in Environmental Regulation, generally Establishes minimum standards. Focus on large complex projects. Authority often restricted to specific pollution source or activity. Permit review may not begin until engineering design stage.

23 State Role continued Does not address existing water quality, future growth, or cumulative impacts - examples Jamestown and Charlestown. May grant variances from standards. Limited staff for field inspection and enforcement. Relies on municipalities for protective land use planning and standards.

24 Key areas for local drinking water protection 1. Onsite wastewater treatment system 2. Wetland buffer protection 3. Stormwater management

25 Need for Local OWTS Management to Protect Drinking Water Sources OWTS are often the major source of pollution to groundwater in unsewered areas with dense development. OWTS can be a significant source of Phosphorus to surface waters in shoreline areas with shallow water tables. Large OWTS can impair quality of nearby private and and public wells. RI municipalities are responsible for wastewater planning and for OWTs management.

26 Conventional septic system Does not treat Nitrogen or Phosphorus Relies on horizontal setback and vertical separation to groundwater for Bacteria removal and P adsorption by soil Relies on low density to dilute N, and also microbial denitrification in wetlands.

27 CESSPOOL Often sitting in groundwater. No aerobic separation for Bacteria and P removal May overflow at surface a public health threat All cesspools are more than 40 yrs old

28 Advanced treatment system Does not remove phosphorus Shallow pressurized drainfield can reduce P but requires deeper water table than bottomless sand filter. Requires routine maintenance with town oversight and enforcement.

29 Towns have Specific Authority for OWTS Management Strong State Enabling Legislation for Wastewater Management Districts(1987) and Local Zoning (1991) Authorizes the establishment of wastewater management districts for inspection and maintenance Zoning Act promotes innovative land management techniques Ground and surface water protection is a stated purpose Can require buffers and performance standards for septic systems.

30 Progress in other towns Charlestown and Block Island - Full wwmgt program with Cesspool phase out and active enforcement program. Jamestown Full wwmgt program. High water table ordinance establishes treatment standards. Adopted cesspool phase out in North Kingstown Mandatory inspection with pumpout as needed. Nitrogen standards in groundwater overlay district for commercial use.

31 Role of Wetland Buffers and hydric soils Bacteria and Phosphorus from OWTS treated in unsaturated soil Retain sediment and nutrients in stormwater runoff by sheet flow and Infiltration. Potential for conversion of nitrate to N2 gas in wetland soils

32 Preventing Stormwater Pollution Stormdrains and roadside ditches lead directly to local waters without any treatment. So when rain hits the pavement, it carries any oil, spills, pet waste, leaves, road sand, sediment, trash, and dirty water from washing your car directly to local waters that we drink, fish, or swim in.

33 Detention Pond Rooftop and Driveway Runoff Turf Runoff Road Runoff

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35 Low Impact Development (LID) Community Planning Larger Conventional BMPs LID Site Design LID BMPs Receiving Waters

36 LID Site Planning and Design Strategies Minimum Standard No. 1 (out of 11) Must be used to the maximum extent practicable. Avoid, reduce, manage runoff impacts Thorough site assessment in early review Protect water quality function of soils, wetlands Limit area of disturbance, restore veg and soils Greater design flexibility, compact design Reduce impervious cover Use nonstructural stormwater controls.

37 Example LID projects Cottages on Green, East Greenwich RI

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40 Example LID practices Bioretention Bioretention in parking lot islands, North Kingstown commercial development

41 Infiltration Trenches Infiltration trenches at roadsides intercepte roadway runoff. North Kingstown, RI

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44 Topics Tiverton s water resources The link between land use and water quality State roles, Local responsibilities and best practices o Focus on OWTS, Wetland buffers and stormwater Discussion of local issues and management options

45 References Jörg Schullehner, Birgitte Hansen, Malene Thygesen, Carsten B. Pedersen, Torben Sigsgaard. Nitrate in drinking water and colorectal cancer risk: A nationwide population-based cohort study. International Journal of Cancer, 2018; DOI: /ijc.31306

46 Acknowledgments RI NEMO is funded by the RI Department of Health, Office of Drinking Water to help build municipal capacity for source water protection, And the RI Department of Transportation, with support from RI Department of Environmental Management, to help municipalities implement effective stormwater management programs.

47 Resources: NEMO Contacts: Lorraine Joubert Tel: