Horsley Witten Group                               Sustainable Environmental Solutions                Decision Makers Work...
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Summary Plan for Restoring the  Ponds in Roger Williams Park
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Restoring the Ponds in Roger Williams Park:                                      Summary Plan1.0 Introduction             ...
Roger Williams Park                                    The project Steering Committee established the following goals for ...
2.0 BackgroundWith the exception of Deep Spring Lake,the Park ponds are man-made, andconsist of a series of seven intercon...
Roger Williams Park                                                Pond System            Roger Williams Park Ponds Charac...
3.0 The Park Ponds are in Trouble TodayFor almost six months a year the Park ponds appear as envisioned when the Park was ...
Why should we care about the poor water quality in the Park ponds? The degraded water quality condition of the ponds in th...
Not only did the areas around the Park develop, but the area around Mashapaug Pond and its feederponds, Spectacle Pond and...
Roger Williams Park Ponds Watersheds                                     Upper Watershed                                  ...
Sources of Phosphorous                                                   in the Roger Williams Park Ponds                 ...
3.0 What Can Be Done: Best Management PracticesThe Horsley-Witten (HW) study of the Park ponds outlines scores of potentia...
   Curb Removal—Roger Williams Park, unlike the large state parks in Rhode Island, has miles            of curbing along ...
with nutrients and thus catch basins can potentially be a significant method for reducingstorm water pollution flowing int...
Park officials need to commit to letting a large amount of shoreline to go “natural” and not    mow up to the water’s edge...
need to be continually engaged to learn what they do on their properties affects the storm           water flowing into th...
   Chemical Treatment of Exiting Sediment in the Ponds—One of the issues unresolved by the           HW study is the exte...
south of the Calart Building) into a 72” pipe that bypasses the Park ponds. Currently all of            the low flows and ...
Water Quality Management Improvements Start at Home. There are a number of           operational and maintenance tasks tha...
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Summary of Watershed Management   Plan for Rhode Islands Salt Ponds
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Horsley Witten Group                    Sustainable Environmental Solutions                                90 Route 6A • S...
i.           EXECUTIVE SUMMARYINTRODUCTIONThis Watershed Management Plan for Green Hill and eastern Ninigret Ponds is an a...
Over the years, the water quality of Green Hill Pond and eastern Ninigret Pond hasdiminished. Scientists use a variety of ...
level of water quality. The management plan partners selected a nitrogen loading andmanagement approach based on a method ...
condition range and allow for a higher nitrogen loading target of 18,234 lbs/year orrequire a nitrogen load reduction of 1...
this approach. The potential disposal areas identified in this plan still need to beconfirmed with field testing, and may,...
and permitting process through the CRMC and the Army Corps of Engineers. Theanalysis would have to consider the benefits o...
•    Developing a wastewater management facilities plan (which is Pending);     •    Conducting a review of waterfowl/wild...
recommended monitoring indicators. The watershed management implementationmeasures are summarized in Table E2. Detailed de...
Table E2.           Watershed Management Implementation Plan SummaryAction Item                           Responsible Part...
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Strategies for effective stormwater management
Strategies for effective stormwater management
Strategies for effective stormwater management
Strategies for effective stormwater management
Strategies for effective stormwater management
Strategies for effective stormwater management
Strategies for effective stormwater management
Strategies for effective stormwater management
Strategies for effective stormwater management
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Strategies for effective stormwater management

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A resource document about strategies for low-impact development/green infrastructure techniques to effectively manage stormwater. Presented by Rich Claytor, engineer with Horsley Witten Group, during the Buzzards Bay Coalition's 2013 Decision Makers Workshop series. Learn more at www.savebuzzardsbay.org/DecisionMakers

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Strategies for effective stormwater management

  1. 1. Horsley Witten Group Sustainable Environmental Solutions Decision Makers Workshop Landscape Solutions: Strategies for effective stormwater management and fertilizer useMarch 20, 2013 - UMass Cranberry Station, East Wareham Stormwater Management at Taunton Mill River ParkSpeaker Profile: Workshop Packet Contents: Rich Claytor, Principal • Restoring the Ponds in Roger Williams Engineer at HW, has more Park Summary Plan than 28 years of practical • Summary of Watershed Management experience in civil and Plan for Rhode Islands Salt Ponds water resource engineering. • Summary of Pleasant Bay Fertilizer Rich has specific expertise Management Plan Final Report in watershed planning and management; stormwatermanagement practice design, policydevelopment and master planning; streamand river geomorphology; water supply andwastewater conveyance design; land useplanning, site design; drainage and erosion/sediment control design. He has authored avariety of publications on stormwater designand implementation and presented in morethan 100 training workshop and conferencesover the last 20 years. Sandwich, MA Boston, MA Newburyport, MA Providence, RI 508-833-6600 857-263-8193 978-499-0601 401-272-1717 www.horsleywitten.com
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  3. 3. Summary Plan for Restoring the Ponds in Roger Williams Park
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  5. 5. Restoring the Ponds in Roger Williams Park: Summary Plan1.0 Introduction Since the first plan for Roger Williams Park was developed in 1878 by landscape architect Horace Cleveland, the Park ponds have been considered essential visual and recreational elements in the Park’s design. Over the years, the ponds have provided boating opportunities, a place to fish, a home for wildlife, and a visual refuge for urban dwellers looking for relief from crowded city streets.The Park ponds, however, have been suffering from algae problems, aquatic weed growth, andsedimentation from road sand for many decades. In 1982 Park officials spent several hundred thousanddollars to dredge 3 of the ponds in the pond system, but it didn’t solve the algae problem in the pondsas phosphorous-laden storm water and road sand continued to flow unabated into the ponds. Theponds were first listed in the Rhode Island Department of Environmental Management’s (RIDEM)impaired water bodies list in 1992. The algae and aquatic weed growth in the ponds has been so severein the last 10 years, that RIDEM in 2007 released a report, Total Maximum Daily Load Report (TMDL), toanalyze 9 ponds in Rhode Island with the most challenging phosphorous problems. The Roger WilliamsPark pond system was one of the pond systems highlighted for its worsening problems. In 2010 with the urging and cooperation of the Narragansett Bay Estuary Program (NBEP), the Parks Department applied for and received an EPA Region 1 matching grant to comprehensively examine the pond’s pollution problems, to suggest remedial options, and to provide a plan for restoring the ponds’ water quality. With the assistance of a Technical Steering Committee, the firm of the Horsley-Witten Group (HW) was selected to develop a Water Quality Management Plan for the Park ponds. The Committee has helped guide the work of HW which began in July 2011.
  6. 6. Roger Williams Park The project Steering Committee established the following goals for the Ponds Restoration Project pond restoration project:Technical Steering Committee Roger Williams Park Ponds Restoration Project Goals  Providence Parks & Recreation  Narragansett Bay Estuary Program  Improve water quality, habitat, and biodiversity within the  U.S. Environmental ponds Protection Agency Region 1  Improve the overall environmental quality and user experience  US EPA Atlantic Ecology of the Park Division  Identify health risks associated with fish consumption; increase  RI Coastal Resources Management Council public awareness as warranted  RI Department of Health  Foster watershed awareness and environmental stewardship  RI Department of among Park users and surrounding residents through a public Environmental outreach campaign Management  RI Department of The first of these items—water quality restoration—is central to the Transportation project. The HW firm undertook extensive investigations and completed a water quality model and draft document for restoration of the ponds.  Save the Bay As a result of the HW work, it became clear that a significant reduction in  Save the Lakes phosphorus pollution to the Ponds is necessary to achieve water quality improvement. The sources of phosphorus include atmospheric  US Fish & Wildlife Service deposition, internal recycling within the Ponds, loading from waterfowl,  USDA Natural Resources and stormwater runoff from upland sources. The City and Steering Conservation Service Committee, therefore, established the following targets for phosphorus pollution reduction in the Ponds, in order to improve water quality,  University of Rhode Island Watershed Watch habitat quality and aesthetics:  RI Bass Federation Water Quality Restoration—Phosphorus Reduction Targets  Environmental Justice  Reduce phosphorous loadings to the ponds by 20% in five years League of Rhode Island  Reduce phosphorous loadings to the ponds by 42% in ten years  Serve Rhode Island  Pawtuxet River Authority  Over the long term, 20-25 years, reduce phosphorus loadings by up to 73%, a reduction which RI Department of  RI Natural History Survey Environmental Management suggests would allow the Park  Urban Ponds Procession ponds to achieve a water quality that would be significantly reduce seasonal algae and aquatic weed growth
  7. 7. 2.0 BackgroundWith the exception of Deep Spring Lake,the Park ponds are man-made, andconsist of a series of seven interconnectedponds. As the Park was developed in thelatter years of the 19th century,Mashapaug Brook that ran fromMashapaug Pond was used as the primarywater source to create the Park ponds.This former location of the Brook in areanow constituting the Park is shown above.The Brook was dammed near present dayPark Avenue at the southern end of whatis now Elm Pond. In conjunction withconsiderable dredging that was done bythe hands of many immigrant laborersover many years, several of the pondswere literally carved out of the landscape.Bridges were built to allow the ponds toflow continuously from one to the other,from Roosevelt Pond near the Casino toElm Pond near the Park Avenue entrance.The general pattern of flow through the Park ponds is from the southern end of Roosevelt Lake where a48 inch diameter pipe from Mashapaug Pond is located to the dam at the southern end of Elm Pond.Once the water leaves the Park, it flows into Bellefont Brook into the Pawtuxet River and eventually toNarragansett Bay.
  8. 8. Roger Williams Park Pond System Roger Williams Park Ponds CharacteristicsPond Average Depth Area Direction of Flow (feet) (Acres)Roosevelt 1.3 3.8 West to East then North to SouthWillow 2.0 3.4 South to North and North to SouthPolo 2.3 3.6 South to NorthPleasure 2.6 18.6 West to EastEdgewood 3.0 19.3 North to SouthCunliff 4.3 32.3 North to SouthElm 4.3 21.7 North to South
  9. 9. 3.0 The Park Ponds are in Trouble TodayFor almost six months a year the Park ponds appear as envisioned when the Park was built—free ofalgae and weeds and reasonably normal in color and clarity. But those six months are generally fromNovember to April when the ponds are not actively used and overall park visitation is low. Beginninggenerally in May every year, the shallow Park ponds began to heat up and to display a pea soup greencolor culminating with floating algae and acres of weeds in July-October, this is known as eutrophic orhypereutrophic conditions. Scientists typically look at a few key parameters to help assess water qualityconditions, including Chlorophyll a, total phosphorus concentration, and Secchi dish depth (a measure ofwater clarity). As seen below, water quality data reflects the extent of water quality degradation in theponds. Even the casual Park visitor, without the benefit of scientific water quality data for the ponds,can visually see the water quality degradation in the Park ponds.Summary of Water Quality Data for Roger Williams Park Ponds (URI Watershed Watch 1993-2012) Water Typical Average Value in Ponds by Year Quality Threshold Pleasure Lake Roosevelt Lake Cunliff Elm LakeParameter for Lake Eutrophic Conditions 1993 1994 2001 2002 2005 2012 1993 1994 2012 2003 2012 2005 2012Chlorophyll 7.2 to 30 22 28 20 46 57 55 17 26 31 54 55 56 58 a (ppm) Total P 25 to 65 85 105 76 64 140 100 65 69 76 120 87 97 82 (ppm) Secchi 6.5 to 2.5 5.2 4.6 3.0 2.0 1.6 2.6 5.2 5.2 1.6 2.3 2.6 2.0 3.0 Depth (ft)Red Font = value exceeds outside range of Eutrophic Threshold
  10. 10. Why should we care about the poor water quality in the Park ponds? The degraded water quality condition of the ponds in the summer and early fall months is troublesomefor many reasons:  The boating experience on the ponds is diminished  Biodiversity, particularly fish species, in the ponds is reduced  Nearby shoreline activities, such as picnicking and gatherings, are unpleasant  The overall perception of the park as an enjoyable family place to visit is negatively altered  Finally, Roger Williams Park is the primary recreational area for thousands of Providence families who do not have access to the state’s south county beaches and the restoration of the Park’s water resources is a matter of environmental justice.What is causing the water quality problems in the Park ponds?The answer to that question is both simple and complex. To properly understand what is happening tothe ponds, it is useful to remember that the ponds are man-made. They are not natural geologicallyformed deep lakes that you might find in western and northern Rhode Island. And because the Parkponds are shallow, the ponds heat up quickly when the summer ambient air temperatures increase.The shallow warm lakes when initially constructed probably did not exhibit today’s water qualityproblems. The Park when it was built in the 1880’s and 1890’s was at the southern end of Providencelargely surrounded by vacant land. As the city’s population grew, the areas around the park weredeveloped into dense residential neighborhoods. Thousands of acres of vacant land became houses,businesses, streets, sidewalks, driveways, and parking lots. And when it rained, city engineersprovided these nearbyneighborhoods with stormdrainage systems with storm wateroutfalls, many of which drainedinto the Park ponds. Even thePark’s principal source of flow—theMashapaug Brook—was at somepoint channeled into a large stormpipe before it enters RooseveltPond. Throughout the 20thcentury, park engineers alsodrained Park roads and parking lotsinto a storm drainage system whichtoday flows into the Park ponds viamany outfall pipes.
  11. 11. Not only did the areas around the Park develop, but the area around Mashapaug Pond and its feederponds, Spectacle Pond and Tongue Pond, also were urbanized. Mashapaug Pond was relatively pristinewhen its outflow from the pond, Mashapaug Brook was used to form the Park Ponds. Indeed, as late asthe early 20th century, Mashapaug Pond was a source of block ice for hundreds of Providence homes.The accompanying aerial photograph shows the Park’s two main watershed areas—areas that are thesources of storm water flowing into the Park ponds. The extent of development in the two watershedsis pretty dramatic. And the graphic below illustrates the relationship of the Park ponds to itswatersheds. Upper Watershed Tongue Pond Spectacle Pond Mashapaug Pond Watershed Watershed Watershed Water Tongue Spectacle Mashapaug Pond Pond Pond Park Property WatershedLower Watershed Roger Williams Adjacent Park Ponds Neighborhood WatershedOnce dependent solely on Mashapaug Brook for its water source, the Park ponds became theconvenient receptacle for storm water from hundreds of acres of two nearby watersheds every time itrained. This storm water is not clean. Anything on the impervious surfaces that drains into the Parkponds—dirt, bird waste, pet waste, car chemicals, fertilizer, trash—is carried by the storm water into thePark ponds.
  12. 12. Roger Williams Park Ponds Watersheds Upper Watershed Watershed AreasCranston/Providence Upper—977 acres Boundary Lower—649 acres Total—1,626 acres Lower Watershed The chemical culprit of particular concern in the storm water flowing into the Park ponds is phosphorous. A modest increase in phosphorous in a water body can, under the right conditions, set off a chain of undesirable biological events that can accelerate algal blooms, undesirable plant growth, depletion of dissolved oxygen, and the death of oxygen dependent fish. This process is known as eutrophication which may take centuries to occur in undeveloped areas, but which in the Park ponds is accelerated by the storm water entering the ponds after every rain event. The shallow warm Park ponds provide a perfect situation for the significant amounts of phosphorous entering the ponds to stimulate algal blooms and plant growth. See graphic below for the sources of phosphorous in the Park ponds.
  13. 13. Sources of Phosphorous   in the Roger Williams Park Ponds   Atmospheric Deposition   (64 lbs/yr)   Upper Watershed Storm   Water                                                                            (360 lbs/yr)  Roger Williams Park   Roger Williams Park Ponds  Waterfowl  Lower Watershed Storm   Water  (128 lbs/yr)  (154 lbs/yr)  (216 lbs/yr)  As seen above, a major source of phosphorous in the ponds is not just the drainage system, but the number of Canada geese that have taken up residence in the Park.  For decades Canada geese migrated south and stopped along their journey in the Park ponds.  Once the ponds began to freeze, the geese would continue their journey south.  Because of relatively recent climate changes, however, the Park ponds no longer consistently freeze in the December‐March months.  Gradually, large numbers of geese simply wintered over in Roger Williams Park.  As the resident geese population increased, park visitors unfortunately began to fed them bread from home.  And feeding the geese bread continued throughout all months of the year.  While well‐intentioned, public feeding of the geese in the Park is misguided and as recently as July 2012 resulted in over 700 resident geese living in the Park.  Unknown to most of the Park visitors, the gaggles of geese in the Park have been an environmental and public health nightmare for the Park because of the sheer volume of fecal matter produced by the geese on park lawns and in the park ponds.  Park officials began a comprehensive geese management strategy in the last 6 months of 2012, including signs instructing the public not to feed the geese.  This short‐term effort has drastically reduced the geese population.in the Park to approximately 60‐75 birds. 
  14. 14. 3.0 What Can Be Done: Best Management PracticesThe Horsley-Witten (HW) study of the Park ponds outlines scores of potential remedies to reducephosphorous loadings entering the ponds. The study recommends everything from cleaning the streetcatch basins more frequently to re-directing existing storm water flows to educating nearbyhomeowners to reduce pollution that washes into the Park ponds.Outlined below are some of the principal categories of best management practices that potentially mayimprove the water quality of the Roger Williams Park ponds:4.1 Structural Storm Water System Changes  Storm Water System Retro Fits—the HW study examined about 30 places in the Park where the existing storm water pipes could be diverted and re-engineered to enable storm water to flow into bio-retention vegetated areas and swales before entering the groundwater into the ponds. This technique essentially allows the storm water to be intercepted and to be treated before it enters the pond system. The graphic below illustrates a typical storm water treatment design. The picture below shows a bio retention area being constructed near the Carousel which now drains a major portion of the Carousel parking lot.  Pavement Reduction—A very basic method for reducing storm water pollution in the ponds is to reduce the amount of impervious surfaces—primarily parking lots and roadways—in the Park to reduce the amount of storm water flow. While the Park has many stretches of wide roads that could be narrowed, this type of structural change needs to consider parking and traffic issues very carefully. Thus, Park staff will examine where pavement can be reduced at a reasonable cost without affecting normal Park use. The current storm water retro fit project along Roosevelt Pond involves the removal of almost 40,000 sq. ft of road area.
  15. 15.  Curb Removal—Roger Williams Park, unlike the large state parks in Rhode Island, has miles of curbing along the sides of its roads. This curbing is a legacy of work done by the Works Progress Administration in the 1930’s and was a well intentioned effort to channel storm water into catch basins to flow into the ponds. There are lots of opportunities in the Park to selectively remove curbing to allow storm water to flow into existing grass areas and to be absorbed into groundwater.  Disconnecting Building Down Spouts—Another storm water practice implemented in Providence in the early 20th century was to have building down spouts connect directly into underground drainage lines that then directed storm water into the street drainage system. This practice also occurred in the Park and in the watersheds draining into the Park. The roof areas in the Park total over 100,000 sq. ft and thus send a lot of storm water into the ponds. These down spouts can be disconnected relatively easily from the underground pipes and then the down spouts can be altered to divert the storm water into adjacent planting areas. This has been successfully done in a demonstration at the Botanical Center already as seen in the accompanying photo. This practice also offers significant potential in the upper and lower watersheds where neighborhoods, according to the HW study, have generally 50-60% of houses with down spouts directly connected to underground storm water pipes.4.2 Non Structural PracticesWhile some of the above structural practices will involve considerable capital costs, there are scores ofnon structural practices, much less costly, that can be implemented in the Park and in the nearbywatersheds draining into the Park to reduce storm water loadings.  Operations and Maintenance Practices—Daily operations in Roger Williams Park and the abutting watersheds can be altered and adjusted to reduce storm water pollution. Here are the most significant practices that should be considered: --Catch Basin Cleaning: Catch basins in the street “catch” storm water flowing on the street and then through gravity flow discharge the flows from the catch basin through a pipe into a nearby water body. As seen in the accompanying sketch, catch basins are designed to settle out solids before the storm water flows into the discharge pipe. These solids are loaded
  16. 16. with nutrients and thus catch basins can potentially be a significant method for reducingstorm water pollution flowing into the Park ponds, if the catch basins are periodicallycleaned of the settled solids. If the catch basin solids are not cleaned in a timely manner, they eventually fill up the catch basin and storm water events flush the solids into the discharge pipe into the nearby water body. Roger Williams Park has approximately 45 catch basins and there are perhaps a few hundred in the upper and lower watersheds outside of the park. The Parks Department does not have its own vacuum truck to clean out catch basins—it depends on an already strapped Providence Department of Public Works (DPW) to periodically clean Park catch basins as well as the catch basins in the upper and lower watersheds. This catch basin cleaning does not consistently occur because does not have the resources to clean approximately 20,000 catch basins throughout the City. Park officials are examining how to become self-sufficient for catch basin cleaning.--Street Sweeping: One way to reduce the amount of solids and trash on Park andwatershed streets from flowing into the storm water drainage system is to sweep thestreets more frequently. The Parks Department does not own a street sweeper anddepends on Providence DPW to sweep the 10 miles of roads in Roger Williams Park twice ayear. Park officials need to figure out how to supplement the DPW services with privatevendors or how to contract DPW services more frequently.--Mowing Operations: When the Park was designed in the Victorian era of the late 19thcentury, the Park design emphasized grass lawns coming right to the edge of the water.Several thousand feet of shoreline in the Park have this look as seen in the photo below.Unfortunately, while this design and practice presents an aesthetically pleasing appearance,it is not a wise water quality managementpractice: it allows geese to easily gobetween the ponds and the shorelinemaking the Park an attractive place tostay; it provides no natural vegetativebuffer to absorb pond nutrients; and itleads to shoreline erosion in steep slopeareas that are difficult to mow.
  17. 17. Park officials need to commit to letting a large amount of shoreline to go “natural” and not mow up to the water’s edge. --Maintenance Operations “Hot Spots”: The HW study identified several areas in non- public maintenance areas where the operations required better “housekeeping” by Park staff to minimize pollution from entering the ponds after rain events. Both the area Grounds Maintenance yard and the Mounted Command facility on Noonan Island need to develop best management practices to avoid waste from flowing into the ponds. Geese Management—As pointed out in Section 2, the resident Canada geese have long contributed to the phosphorous loadings that are harming the Park ponds. In 2012 the first steps to comprehensively manage the resident geese were undertaken: addling all of the geese eggs in the Park nests; removing several hundred geese under contract with the US Department of Agriculture; installing “geese education signs” in key geese feeding areas of the Park; and public education of park visitors by summer high school interns. The 2012 effort has reduced the resident Canada geese in the Park to approximately 60 geese. This comprehensive effort needs to continue for several years to keep the resident Canada geese population in check. Shoreline Buffer Planting—To accelerate natural vegetation along the shorelines, it will be useful to pro- actively plant native plant species along many of the Park shorelines. This will have many water quality management benefits as discussed above under “Mowing Operations”. Steep Slope Stabilization—While most of the sediment that is in the Roger Williams Park Ponds is the result of sand washed into the ponds from the upper and lower watershed storm drainage systems, a small amount of pond sediment is from erosion of sloped lawn areas that have lost their grass cover for one reason or another. These steep slope areas with bare soil should be systematically re-seeded with appropriate erosion control matting in September of each year. Making a Difference: The Public—Clean water in Roger Williams Park is not just a municipal or public sector responsibility and it will not occur if total responsibility is left with government actions. Park users, and particularly upper and lower watershed residents, need to do their part to improve the ponds water quality. The HW study indicates that upwards of 60-65% of the phosphorous loads coming into the ponds causing the water quality problems come from outside the Park. Watershed residents and businesses will
  18. 18. need to be continually engaged to learn what they do on their properties affects the storm water flowing into the Park. Park officials also need to ramp up efforts to inform and inspire Park visitors about restoring the water quality and biodiversity in the Park ponds. A significant education and information program will need to be developed to develop a constituency for clean ponds.4.3 In-Pond OptionsWhile the above land-based options and public outreach will significantly reduce pollution loadsentering the pond, many of the actions will be expensive and will not make a major differenceimmediately in the ponds. The in-pond management options discussed below should be considered inthe mix of actions to be implemented.  Chemical Treatment of Aquatic Weeds and Algae—Park officials have been chemically treating aquatic weeds and algae, under RI DEM permit procedures, for approximately 20 years. Aquatic herbicides are used to treat rooted aquatic weeds and copper sulfate is used to treat algal blooms. The doses for these applications are governed by time of year and water temperature, are relatively inexpensive--about $5,000-7,000 per year, and provide temporary relief for algae and aquatic plants during the Park’s busy time of year.  Dredging of Pond Sediment—In the early 1980’s Park officials spent considerable funds dredging Roosevelt Pond, Willow Pond, and Polo Pond to address the water quality problems that existed in the ponds at that time. While well-intentioned, it was a very expensive short-term solution. Because nothing was done to control the sediment and phosphorous coming in from the upper watershed into Roosevelt Pond, all three ponds have long since lost the pond depth that was achieved in 1982. In addition, Pleasure Pond has also lost considerable pond depth. The lesson from the early 1980’s dredging effort is that water quality improvements have to be sequenced properly or else the cost benefit of these actions will be significantly reduced. Dredging will need to be done again at some point in at least 3 or 4 of the Park ponds, but land based efforts and upper watershed efforts need to be done first.
  19. 19.  Chemical Treatment of Exiting Sediment in the Ponds—One of the issues unresolved by the HW study is the extent to which existing sediment in the ponds releases phosphorous into the water column under certain depth and dissolved oxygen conditions. This phenomenon is called “internal recycling” and it may be a significant contributor to phosphorous in the Park’s deeper ponds, i.e., Cunliff, Elm and Edgewood. When existing phosphorous loads coming into those ponds from the lower watershed are substantially reduced, water quality testing will need to determine if internal recycling is an issue. At that point Park officials may consider treating the sediment with aluminum sulfate or sodium sulfate. This is a relatively expensive treatment—about $1,500/acre, however, and will require careful dosing to not harm existing fish in the ponds.4.4 Mashapaug Pond Flow into the Park: OptionsThe HW study recognized that the long term goal of reducing phosphorous from the upper watershedthat flows into the Park ponds via Mashapaug Pond will be daunting to achieve. Two cities are involved;three water bodies; scores of dense residential neighborhoods with no common identity or track recordof working together; one industrial park; and hundreds of stand-alone businesses. While all of theabove discussed structural, non-structural, and public outreach efforts need to be started and pushedforward, the pace of implementation in the upper watershed will likely be far more challenging than theefforts in the lower watershed.In the meantime, phosphorous loadings from Mashapaug Pond—the major source of pollution for RogerWilliams Park—will continue to diminish the other efforts in the lower watershed to reduce storm waterpollution in the Park ponds. What can be done in the interim, before the hundreds of pollutionreduction actions are implemented in the upper watershed? The HW study suggests three importantsmall scale solutions that will need considerably more study, but which appear to be promising.  Chemical Dosing Station—The 48” pipe that carries the Mashapaug Brook and the storm water flows from the upper watershed is essentially a point source of pollution for the Park ponds. The HW study recognized this and suggests chemical treating of the water coming out of this point source should be considered as an interim measure until solutions in the upper watershed to reduce pollution are implemented. Their suggestion: a dosing station that would treat the phosphorous and suspended solids. One or more aluminum compounds via a drip line feed dosing station, either at the discharge point in Roosevelt Pond or upstream of the Park, would bind up the phosphorous and suspended solids precipitating a resultant floc that would fall out of the flow into the pond. HW recognizes the need for a study to examine the permitting for such a dosing study, operational requirements, maintenance requirements, treatment protocol, and disposal of the precipitated floc.  Mashapaug Brook Weir Box Re-engineering—When Route 10 was constructed, some of the flows from Mashapaug Pond were altered to go through a weir box (just east of RT 10 and
  20. 20. south of the Calart Building) into a 72” pipe that bypasses the Park ponds. Currently all of the low flows and smaller storm flows are directed towards the Park ponds through the 48” pipe into Roosevelt Pond. The HW study speculates that if the weir box is modified to divert more of the storm events into the 72” pipe that bypasses the Park ponds this might reduce the phosphorous loads that come into Roosevelt pond after storm events. A detailed engineering study to examine the feasibility of this weir box modification is needed.  Chemical Treatment of Sediment in Mashapaug Pond—RI Department of Environmental Management indicates in its 2007 report on Mashapaug Pond that “internal recycling” of phosphorous in Mashapaug Pond maybe a a major contributor to the phosphorous loads originating from Mashapaug Pond and flowing into the Roger Williams Park ponds during the summer months. The conditions in Mashapaug Pond in the summer months—relatively deep pond, high water temperatures, and low dissolved oxygen levels—allow the release of phosphorous into the water column. Thus, treating portions of Mashapaug Pond during summer months with some type of aluminum compound may be able to inactivate phosphorous and bind to the pond sediment impinging the ability of the phosphorus to be released. A detailed study of this treatment is obviously needed since it may require several acres of Mashapaug Pond to be treated.4.0 What Can Be Done: RecommendationsWhile the Horsley-Witten study outlines an impressive array of best management practices for reducingstorm water pollution in the Park ponds, it is clear that some significant findings should guide Parkofficials in deciding how to proceed during the next eight to ten years. A Long-Term Commitment to Managing the Water Quality in the Park Ponds Is Needed. A year-by-year set of cost effective solutions for the next several years will be required that takes advantage of available scarce resources. There are no quick and easy solutions. Park officials need to plug away each year targeting a sequence of activities to reduce storm water pollution entering the ponds. Engineering Solutions Alone Will Not Clean Up the Park Ponds—Public Attitudes Need to be Changed. The Horsley-Witten looked at 35 structural storm water retro-fit projects to address the storm water pollution from existing storm water outfalls in the Park(not including the pipe from Mashapaug Pond) and the total cost was estimated at around $1.8- 2.0 million. The Park can’t simply buy its way out of the pollution problem in the ponds because these infrastructure projects are expensive and will not address all of the phosphorous loadings flowing into the ponds. Many of the sources of phosphorous coming into the Park ponds are the result of human behavior, such as feeding the geese and residential fertilizer practices in watershed areas near the Park. A consistent public outreach program is needed to change public behavior and attitudes about the Park ponds.
  21. 21. Water Quality Management Improvements Start at Home. There are a number of operational and maintenance tasks that Park staff need to focus on to help reduce pond pollution, including: o systematic catch basin cleaning o educating park visitors about geese feeding and littering o providing shoreline buffer vegetation o allowing leaves to remain in wooded hillside areas o diligently addressing slope erosion issues as they develop each year. We Will Need Additional Study to Determine Long Term Solutions for Some of the Pond Water Quality Issues. We not only need to provide an annual water quality sampling program in the ponds to monitor the effectiveness of our on-going efforts, we also need to look at the following un-resolved and/or on-going storm water issues:  Is it possible to treat the storm water coming into Roosevelt Pond from the Mashapaug Pond watershed to reduce phosphorous? What are capital and operating costs for such a system?  To what extent is the existing sediment that is in the Park ponds releasing phosphorous into the ponds and under what conditions? Is it cost effective to selectively treat the sediment in some of the ponds? Is it cost effective to treat sediment in Mashapaug Pond?  What would it cost to dredge selective Park ponds and what will be the pollution reduction from such an effort?  Can storm flows (and the resulting phosphorous loads) from Mashapaug Pond be diverted away from the 48” pipe entering Roosevelt Pond?  Is it feasible for the City to develop an overall Regional Storm Water Management District to fund city wide storm water flow and pollution reduction?The following Roger Williams Park Pond Restoration actions are recommended to be implementedduring the 2013 – 2020 period. Depending on the number of actions implemented and the ability toreduce phosphorous from the Mashapaug Pond inflow into Roosevelt Pond, these actions will reducethe phosphorous loadings into the Park ponds by 20 to 50%.
  22. 22. ..
  23. 23. Summary of Watershed Management Plan for Rhode Islands Salt Ponds
  24. 24. ..
  25. 25. Horsley Witten Group Sustainable Environmental Solutions 90 Route 6A • Sandwich, MA • 02563 Phone - 508-833-6600 • Fax - 508-833-3150 • www.horsleywitten.comFinal Watershed Management Plan Executive Summary for Green Hill and Eastern Ninigret Ponds, South Kingstown and Charlestown, Rhode Island April 18, 2007 Submitted to: Rhode Island Department of Environmental Management; the Salt Ponds Technical Advisory Committee; and the Salt Ponds Coalition
  26. 26. i. EXECUTIVE SUMMARYINTRODUCTIONThis Watershed Management Plan for Green Hill and eastern Ninigret Ponds is an actionplan to guide residents, watershed groups, and local, state and federal governments onhow to reduce both nutrients and bacteria loadings to Green Hill Pond and easternNinigret Pond in order to restore and maintain water quality levels suitable for fishingand swimming. This plan is also intended to provide a model for other salt pondwatersheds within the state.The plan includes an introduction section that describes the planning area, a descriptionof the watersheds, partners involved in development of the plan, and a water qualityanalysis that identifies water quality goals, sources of pollutants, and current loads and/orconcentrations. An assessment section documents existing programs and managementoptions for wastewater management, stormwater management, regulatory programs,public education and outreach, and increasing flushing to Green Hill Pond. Themanagement plan presents specific measures for reducing pollutant sources and presentsimplementation measures that specify what is required, who is responsible, a timeframefor implementation, and how such implementation might be funded. A monitoring planis provided to measure interim progress of plan implementation and to provide aframework for adjusting management measures in the future.A watershed quality improvement plan was developed by the Rhode Island Departmentof Environmental Management (DEM) that specifies maximum allowable bacterial levelsin the ponds and their tributaries. This is referred to as a total maximum daily load(TMDL) and the bacteria management recommendations are intended to support theTMDL (approved in 2006). Since a nutrient TMDL has not been developed for theponds, the nitrogen loading calculations and management recommendations presented inthis report are intended to be the equivalent of a TMDL.Watershed DescriptionThe so-called Charlestown lagoon system is located on the southern coast of RhodeIsland and consists of two major basins, Ninigret Pond and Green Hill Pond. Both ofthese shallow coastal lagoons receive restricted tidal flushing through one narrow man-made breachway between Ninigret Pond and the ocean.Green Hill Pond is located primarily in the southwestern corner of the Town of SouthKingstown, Rhode Island with a small portion of the pond extending into southeasternCharlestown, Rhode Island. Green Hill Pond has a surface area of approximately 380acres and a watershed area of approximately 3,400 acres. Ninigret Pond is locatedentirely within the Town of Charlestown and is bounded on its northern side by Route 1and the Charlestown end moraine. It has a surface area of approximately 1,600 acres anda watershed area of approximately 6,000 acres.Final Watershed Management Plan for i Executive SummaryGreen Hill and Eastern Ninigret Ponds Horsley Witten Group, Inc.South Kingstown and Charlestown, RI April 18, 2007J:4095 R.I. South Shore Salt PondsReportsFinal Management PlanFinal Executive Summary 4-18-07.doc
  27. 27. Over the years, the water quality of Green Hill Pond and eastern Ninigret Pond hasdiminished. Scientists use a variety of specific measures to gage water quality and/orchemistry including measures such as dissolved oxygen concentration, fecal coliformconcentrations, Secchi dish depth, nitrogen concentrations, or Chlorophyll aconcentration. Green Hill Pond and eastern Ninigret Pond are listed on the Rhode Island2006, 303(d) list as being impaired for pathogens and a final TMDL was developed bythe Rhode Island Department of Environmental Management (DEM) and approved bythe U.S. Environmental Protection Agency (EPA) in February 2006. Green Hill Pond isalso listed as impaired for dissolved oxygen (DO), a consequence of excessive nitrogenloading and poor tidal flushing.Bacteria Sources and Concentration Reduction RequirementsGreen Hill and Ninigret Ponds are designated as Class SA waters. Class SA waters aredefined as suitable for shellfish harvesting for direct human consumption, bathing andcontact recreational use, and providing habitat for fish and wildlife. Class SA watersmust meet a standard for fecal coliform (fc) bacteria of 14 fc/100 ml and no more than10% of samples can exceed 49 fc/100 ml and a dissolved oxygen standard of not less than4.8 mg/L at any place or time. Green Hill Pond and eastern Ninigret Pond do not meetthe required fecal coliform standard due to elevated levels of fecal coliform bacterialconcentrations.In 2002, as part of the TMDL development, DEM used a DNA-based technique toconduct a bacteria source tracking assessment. Sources of fecal coliform bacteria weredetermined to include humans, wildlife, waterfowl, and domestic pets with the majorpathway being the stormwater conveyance system. Septic systems were determined to bethe source from humans. Development of the TMDL utilized sampling stations that werelocated in several locations in Teal Brook, Factory Pond Brook, which are tributaries toGreenhill Pond, Green Hill Pond and eastern Ninigret Pond. The TMDL report citesrequired reductions in fecal coliform concentrations to comply with water qualitystandards. Factory Brook and Teal Brook need the greatest reductions in fecal coliformof 95% and 93% respectively based on a mean of all sampling locations.Nitrogen Loading and Water Quality AssessmentThe other major pollutant source to coastal lagoons such as Green Hill and NinigretPonds is nitrogen, which is acknowledged to contribute to impaired water quality bystimulating algae/plant growth in the water column and along the pond’s bottom. Severalresearchers have developed nitrogen loading estimates to the Salt Ponds over the pastseveral years that evaluate the sources of loads, that documented the elevated loading andconcentrations of nitrogen in the ponds, and that report the negative consequences of toomuch nitrogen loading.In October of 2006, DEM issued a report entitled Determination of Nitrogen Thresholdsand Nitrogen Load Reductions for Green Hill and Ninigret Ponds. This reportestablished an appropriate nitrogen loading “target” for each pond to ensure a predictiveFinal Watershed Management Plan for ii Executive SummaryGreen Hill and Eastern Ninigret Ponds Horsley Witten Group, Inc.South Kingstown and Charlestown, RI April 18, 2007J:4095 R.I. South Shore Salt PondsReportsFinal Management PlanFinal Executive Summary 4-18-07.doc
  28. 28. level of water quality. The management plan partners selected a nitrogen loading andmanagement approach based on a method originally developed by the Buzzards BayNational Estuary Program (BBNEP). The BBNEP method uses sampled water qualitydata to derive an empirical relationship between watershed mass loading of nitrogen asrelated to estuary flushing rate and water quality measures of eutrophication. TheBBNEP approach characterizes estuarine response as a Eutrophication Index (EI) that is afunction of five factors: the mean value of the lowest 20% of dissolved oxygen percentsaturation values, mean dissolved inorganic nitrogen (DIN) concentration, mean Secchidepth, mean chlorophyll a concentrations, and mean total organic nitrogen (TON).Eutrophication Indices, calculated using available physical and chemical data collectedfrom the Salt Ponds Coalition Volunteer Water Quality Monitoring Program (PondWatchers) and DEM were determined to be an average of 45 for Green Hill Pond and anaverage of 67 for Ninigret Pond.Eutrophication Index Scores of 65 to 100 are considered “good to excellent” waterquality, 35 to 65 are considered “fair to good” water quality, and less than (<) 35 areconsidered typical of eutrophic conditions. Both Green Hill and Ninigret Ponds havebeen designated by DEM as Special Resource Protection Waters (SRPW) and thereforeshould have an EI goal of 65 or greater (higher).Applying this approach to Green Hill and Ninigret Ponds, DEM calculated a targetnitrogen loading for Special Resource Protection Waters. These targets and existingloads are summarized in Table E1.Table E1. Nitrogen Loading Targets for Green Hill and Ninigret Ponds Parameter Green Hill Pond Ninigret Pond Pond Area (km2) 1.70 7.38 Average Pond Depth (m) 0.80 1.35 EI Goal1 65 65 1 Current EI 45 67 1 Current Annual Nitrogen Load (lb) 30,386 79,384 Target Load (lb)1 6,078 84,450 Required Percent Reduction1 80% 0%1 (DEM, 2006)The nitrogen loading target identified above was derived using an EI score of 65 which ispredictive of “good to excellent” water quality and is the ultimate objective of thismanagement plan. As it will take time and a significant investment to achieve an 80%reduction in nitrogen loading to Green Hill Pond, this plan also recommends a phased oradaptive management approach to watershed planning, where ultimate goals areestablished based on water quality standards and criteria and interim goals are alsodefined. An interim goal of reaching an EI score of 50 (associated with the Class SAwater use designation) would result in predictive water quality in the “fair to good”Final Watershed Management Plan for iii Executive SummaryGreen Hill and Eastern Ninigret Ponds Horsley Witten Group, Inc.South Kingstown and Charlestown, RI April 18, 2007J:4095 R.I. South Shore Salt PondsReportsFinal Management PlanFinal Executive Summary 4-18-07.doc
  29. 29. condition range and allow for a higher nitrogen loading target of 18,234 lbs/year orrequire a nitrogen load reduction of 12,152 lbs/year (or approximately 40%) belowexisting levels for Greenhill Pond. There is currently no nitrogen load reduction neededfor Ninigret Pond. However, it is prudent to continue to mange nitrogen loadings tomaintain good water quality.ASSESSMENT SUMMARYThis section provides a summary of the watershed assessment for the Green Hill andeastern Ninigret Ponds. Given the water quality impairment currently experienced in theponds, the assessment focused on two contaminants: fecal coliform bacteria and nitrogen.The assessment focuses on current and potential future wastewater managementprograms, stormwater management programs and options, regulatory programs, publiceducation and outreach methods, other pollutant sources, and the potential for increasedflushing of Green Hill Pond.A summary of the analysis for each of two primary contaminants is described below. Inaddition, a brief summary of recommended additional studies is provided at the end ofthis section.NitrogenNitrogen enters the ponds through groundwater and surface water, with groundwatersources representing approximately 75% of the total load to the ponds. Loadings fromindividual ISDSs within the watershed are the greatest contributor of nitrogen to theponds (approximately 74% of the load provided through groundwater and 60% of thetotal load to Green Hill Pond). As a result, a series of wastewater alternatives wereevaluated to develop recommendations to reduce nitrogen inputs. The options consideredinclude: • Upgrading all ISDSs according to current DEM regulations; • Upgrading all ISDSs with alternative nitrogen reducing systems; • Community or cluster systems for six service areas within the study area; and • The use of nitrogen treatment trenches along the pond shoreline.The nitrogen reductions provided by these options were then compared to the nitrogenloading target for Green Hill Pond (the pond most severely impacted by nitrogen). Noneof the wastewater options, on their own, reduce nitrogen loading enough to reach thetargeted 80% nitrogen reduction (although the load reduction of the nitrogen treatmenttrenches was not specifically quantified). The community or cluster treatment alternativecomes the closest, providing approximately 16,700 lbs/year of the necessary nitrogenreduction (36% of the total nitrogen load to Green Hill Pond). The community treatmentoption is similar in cost to the on-site denitrification system option. Both cost in therange of $20,000 to $35,000 per lot. The community system is more attractive because itprovides a greater reduction of nitrogen, and eliminates the need for management ofhundreds of different on-lot denitrification systems. However, there are still issues withFinal Watershed Management Plan for iv Executive SummaryGreen Hill and Eastern Ninigret Ponds Horsley Witten Group, Inc.South Kingstown and Charlestown, RI April 18, 2007J:4095 R.I. South Shore Salt PondsReportsFinal Management PlanFinal Executive Summary 4-18-07.doc
  30. 30. this approach. The potential disposal areas identified in this plan still need to beconfirmed with field testing, and may, or may not, provide adequate sites for disposal.The community system may foster the development of existing lots of record that arecurrently unbuildable given existing DEM regulations on ISDSs. There are significantpolitical and institutional hurdles to overcome regarding who would manage the system,who would pay for it, and how it would be financed.An alternative approach of nitrogen removal is also identified in the report. In thisapproach, a porous reactive “barrier” or treatment trench is constructed in the groundperpendicular to the direction of groundwater flow at a depth sufficient to intercept andinteract with the groundwater. The trench is filled with woodchips, which serve as acarbon or food source for denitrifying bacteria. As nitrate-bearing groundwater filtersthrough the trench, the bacteria denitrify the nitrate, causing a decrease in nitrateconcentrations. These nitrogen treatment trenches appear to offer a significant benefit toreducing nitrogen loading to the ponds. Further investigations are needed to see if thisapproach is feasible. There is a need for further data to define the watershed treatmentarea and the amount of groundwater that flows to the trenches, and there is a need formore research to confirm the long-term treatment efficiency they provide. Engineeringand maintenance considerations also need to be fully vetted. However, the trenches havethe potential to provide the greatest nitrogen reduction at the least cost. In addition, theapproach is attractive because it treats all sources of nitrogen in groundwater that passthrough the barrier and because it can have an immediate impact on the quality ofgroundwater entering the pond (as opposed to other options that will only affect waterquality over the long term). The towns of South Kingstown and Charlestown are in theprocess of further assessing the most appropriate wastewater treatment options in apending wastewater treatment facilities plan. This plan is scheduled to be completed byDecember 2007.Although stormwater is a major contributor of bacteria and other pathogens, nitrogenloading from stormwater is not as significant as the loading from other sources in thewatershed, particularly wastewater sources. The results of the MANAGE model showthat surface runoff load is not reduced significantly by the handful of structural end-of-pipe practices. However, the implementation of small-scale practices across thewatershed can make a significant reduction in nitrogen loading. Although there are few“centralized treatment options” for stormwater in this watershed, the small-scalesolutions, in conjunction with end-of-pipe solutions, will help reduce nitrogen loadsincrementally over time.Another option to reduce the impacts of nitrogen loading is to increase the flushingwithin Green Hill Pond. This could be done through the construction of a new openingfrom Green Hill Pond across the barrier beach into the ocean. This direct opening wouldallow a greater exchange of water than is currently provided through the single openingin Ninigret Pond. The opening could be permanent, or periodic (seasonal). The creationof a permanent opening would require significant armoring, at tremendous expense, toprevent the new entrance from closing, shifting or filling in with sediments from coastalerosion. The creation of a new opening would require a complex environmental analysisFinal Watershed Management Plan for v Executive SummaryGreen Hill and Eastern Ninigret Ponds Horsley Witten Group, Inc.South Kingstown and Charlestown, RI April 18, 2007J:4095 R.I. South Shore Salt PondsReportsFinal Management PlanFinal Executive Summary 4-18-07.doc
  31. 31. and permitting process through the CRMC and the Army Corps of Engineers. Theanalysis would have to consider the benefits of the increased flushing versus potentialchanges in habitat in the pond due to changes in water level, salinity, and other potentialfactors. A breachway would also require an suitable parcel of land. The parcel with thebest potential is owned by DEM, however it appears that the deed would precludeconstructing a breachway.Fecal ColiformResults from the Green Hill Pond bacteria source tracking project conducted by DEM inthe fall of 2002, suggest that waterfowl and wildlife are a major source of fecal coliformto the pond. Stormwater runoff can act as the delivery mechanism for much of thisanimal-derived bacteria. The study also found evidence of human sources of fecalcoliform but not at as high a frequency as other animal sources. The study wasconducted during a drier than normal period. Failing septic systems may play a moresignificant role in pollutant loadings to the ponds in wetter years and when groundwateris elevated.All of the wastewater management options will also help to reduce bacterialconcentration to the ponds, with the exception of the nitrogen treatment trenches.Currently, properly functioning ISDSs are already reducing bacterial concentration.Given the current relatively low hydraulic failure rate of ISDSs in both Charlestown andSouth Kingstown, it is unlikely that wastewater is the primary source of bacterialconcentration to the ponds. Future ISDSs failures, outbreak and overflow events, pipebreaks, as well as overflows associated with the community sewerage options maycontinue to contribute a modest level of bacterial concentration, but this contribution isprobably negligible when compared to the contribution from stormwater runoff.Bacteria can be removed to a certain extent through structural stormwater practices suchas infiltration, constructed wetlands, water quality swales, and bioretention, withinfiltration being the most effective structural control. However, since infiltration is notfeasible in areas adjacent to the end-of-pipe outfalls to Green Hill and Ninigret Ponds, themost effective method to reduce fecal coliform levels is by implementing a combinationof structural controls combined with source controls. Non-structural stormwater sourcecontrols and habitat modifications, including wildlife management, are thereforeimportant measures and receive significant attention in the watershed management plan.Recommendations for Additional StudiesWhile numerous studies have been performed for the Rhode Island South Shore SaltPonds, the watershed assessment revealed the need for other studies that would aid in thedecision making process for implementation of watershed plan recommendations. Apreliminary list of additional recommended studies includes, but is not limited to: • Further analysis of groundwater flow and capture amount to the nitrogen treatment trenches;Final Watershed Management Plan for vi Executive SummaryGreen Hill and Eastern Ninigret Ponds Horsley Witten Group, Inc.South Kingstown and Charlestown, RI April 18, 2007J:4095 R.I. South Shore Salt PondsReportsFinal Management PlanFinal Executive Summary 4-18-07.doc
  32. 32. • Developing a wastewater management facilities plan (which is Pending); • Conducting a review of waterfowl/wildlife management strategies that focuses on nuisance waterfowl and wildlife (e.g. raccoons, skunks, and foxes) and better control measures; and • A study that evaluates the effectiveness of existing regulations, such as determining how many existing sites comply with current CRMC buffer regulations.Regulatory programs and public education and outreach currently provide a range ofmeasures to minimize nitrogen loading and fecal coliform concentrations to the ponds.These include regulations at the federal and state level, including the total maximumdaily load (TMDL) program, the Rhode Island Pollution Discharge Elimination System(RIPDES) Phase II Stormwater program, Coastal Resources Management Council(CRMC) regulations for activities on or within 200 feet of a shoreline feature, the CRMCSpecial Area Management Plan (SAMP) for the Salt Ponds Region, and Rhode IslandDivision of Fish and Wildlife nuisance species control programs. Local regulationsinclude controls in the local zoning ordinances in both South Kingstown andCharlestown. Both towns have adopted local Watershed Management Districts thatprovide for mandatory inspection and maintenance programs of ISDSs, and both townsare subject to RIPDES Phase II requirements to implement stormwater controls to reducenitrogen loading.Public education and outreach programs are generally voluntary at the town level (withthe exception of Phase II stormwater program requirements). The Salt Ponds Coalitionprovides significant educational and outreach programming. Key educational areasinclude: • Waterfowl and wildlife management; • Lawn care management; • Pet waste management; • Stormwater management; and • Septic system maintenance.MANAGEMENT AND IMPLEMENTATION RECOMMENDATIONSThe watershed plan presents a phased or adaptive management approach to improvewater quality in the ponds. The first step is to increase water quality to a “good” level byimplementing near-term actions. The next step is to implement a second level of actions,such that “excellent” pond conditions that can be achieved by actions considered morelong-term.The watershed management plan presents a suite of available options pertaining towastewater management, stormwater management, regulatory mechanisms, publiceducation and outreach, and other management of pollutant sources. All of these optionsare presented in a Watershed Management Toolbox in Appendix L of this plan, with thepreferred recommendations presented as an implementation plan. This plan also presentsa Watershed Monitoring Plan that outlines existing monitoring programs andFinal Watershed Management Plan for vii Executive SummaryGreen Hill and Eastern Ninigret Ponds Horsley Witten Group, Inc.South Kingstown and Charlestown, RI April 18, 2007J:4095 R.I. South Shore Salt PondsReportsFinal Management PlanFinal Executive Summary 4-18-07.doc
  33. 33. recommended monitoring indicators. The watershed management implementationmeasures are summarized in Table E2. Detailed descriptions of the proposedmanagement and implementation measures are provided in Section 3 of the watershedplan.Final Watershed Management Plan for viii Executive SummaryGreen Hill and Eastern Ninigret Ponds Horsley Witten Group, Inc.South Kingstown and Charlestown, RI April 18, 2007J:4095 R.I. South Shore Salt PondsReportsFinal Management PlanFinal Executive Summary 4-18-07.doc
  34. 34. Table E2. Watershed Management Implementation Plan SummaryAction Item Responsible Party Term Target Pollutant Near Long Nitrogen BacteriaWastewater ManagementWastewater Facilities Town Councils of South X X XPlan Kingstown and CharlestownStormwater ManagementSite 3: Elm Road Retrofit South Kingstown Town Council X XSite 6: Dawley Road South Kingstown Town Council X XRetrofitSite 2: Shore Road Retrofit Charlestown Town Council X XSite 1: Arches Road Retrofit Charlestown Town Council X XSites 7&8: Matunuck South Kingstown Town Council X XSchool House Road and GHBeach Rd.On-lot, Community and Individual homeowners, X X XRoadway Stormwater Neighborhood or CondominiumTreatments Associations, Town CouncilsRegulatory ProgramsOverlay Districts Planning Commission/Town X X X Councils of each townSubdivision and Land Planning Commission/Town X X XDevelopment Councils of each townOrdinance/RegulationsPhase II Stormwater Planning Commission/Town X X XManagement Ordinance Councils of each townStormwater Management South Kingstown – Dept of X X XProgram Plan (in Public Services, Charlestown –accordance with Phase II) Dept. of Public WorksPerformance Based South Kingstown – Conservation X X XWastewater Treatment Commission, CharlestownStandards Wastewater Management CommissionPublic Education and OutreachEducation of Local Officials Salt Ponds Coalition, DEM, X X X CRMCAnnual Watershed Salt Ponds Coalition X X XAwareness DayAdopt-a-Pond Organization Salt Ponds Coalition X X XDemonstration Projects Town Public Service/Public X X X WorksSchool Watershed Science Town School Committees, X X XPrograms TeachersOther Pollutant SourcesWildlife Management Study DEM. X X X Final Watershed Management Plan for ix Executive Summary Green Hill and Eastern Ninigret Ponds Horsley Witten Group, Inc. South Kingstown and Charlestown, RI April 18, 2007 J:4095 R.I. South Shore Salt PondsReportsFinal Management PlanFinal Executive Summary 4-18-07.doc
  35. 35. wn to n stow Kings le Char South % [% [ % [ # Y % [ # Y % [% [ % [ # S #S[ S[ %%% % [ [#%[ % [ % %% [ [[ % [ % [ % [ # Y % [ % [ %[ [% % [ # % S [ % [Y % [ % [ # S % [ # Y % [ % # [ Y% [ % [ % [ Mautuncket Road 1 % [ % [ % [ % [ Factory % [ # Y% [ oa d % [ % [ Pond Pos tR %% [[ %# [S 1A Old %% [[ %%% [[[ % [ % % [ [ % [ % [ % % [ [ % %% % [ [[ [ % [ % %% [ %% % [[ [ % [ % [ [[ Factory l Hou se Road %%%# [[[Y %% [[ #% Y[ % [ Brook Scho o nuck % [ Teal %%# [[S% [ # Ma Y tu Brook %# # [S Y % [ % [ %# [Y Y # # Y Y % [ # S % [ # Y % [ % [ # # Y Y % [ # Y Green Hill % [ Be Trustom ach Road % [# Green Hill Pond YY# #Y Pond # Y % [ Ninigret %# [S % [ %% [[ %[ [% Pond % [ # % Y [ %% [[# Y Block Island SoundLegend Wetlands Outfalls Parcels Non-Community Wellhead Pipe Diameter Protection Areas # 4" Y Town Line Roadway # 6" Y Surface Water Forest # 12" Y Watershed Features Streams % Catchbasins # 15" Y N Rhode Island Eastern Ninigret Pond [ # S Inlets # 18" Y South Shore Salt Ponds Watershed Study Area Manholes # 24" Y Green Hill Pond Watershed # S 0 2000 Feet 7/21/05 R.I. South Shore Salt Ponds J:4095 ec Figure 6 Study Area # Y Culverts # 36" Y GISwastewater.apr

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