Environmental Degradation Due To Intensity Of Development
Recently a member of the Charlestown Town Council proposed an increase in the number of lots and dwelling units that would be allowed per acre in large subdivisions. The proposal would have allowed up to a 100% increase, or a doubling of the number of lots and dwelling units allowed per acre.
These proposals were suddenly dropped from consideration at the start of a special meeting of the Town Council to discuss subdivision regulations in August, and, as a result, the testimony of experts assembled for the meeting was not allowed.
However, their testimony is very relevant because there is a push from the Rhode Island Legislature to force the doubling of overall densities throughout town, nor just for large subdivisions, and what appears to be an acceptance on the part of the current Town Council to adopt these provisions in the state legislation even though a doubling of densities throughout a town that depends entirely on wells and septic systems is not reasonable.
Even though none of the expert testimony was heard in August because the subdivision proposals were suddenly dropped, some documents were received and remain relevant. One of those communications was from Weston and Sampson’s James Riordan—a planner and water quality scientist with approximately 30 years of experience. His discussion of the impacts of increased density of development in Charlestown are worth reading because the issue of changing zoning to allow more dwelling units has not gone away.
The letter from Mr. Riordan, below, is not a full analysis of the environmental impacts of development intensity, but it does identify issues that should be fully analyzed before Charlestown changes zoning regulations that allow any increases to overall density.
You can read the full text of the original letter as a PDF file and the same content is pasted below with any bolding added by us.
Thank you for requesting this letter of comment on a recent proposal for updating the Charlestown’s Conservation Development regulations, which are part of the Town’s Zoning Ordinance specifically under sections 218-52 and 218-41. The proposed changes are related in part to how yield plans are defined and calculated. These changes will allow for significantly increased density of residential development. I have been asked to comment on the potential environmental implications of the proposed changes, especially as they relate to water quality.
I am a planner and water quality scientist with approximately 30 years of experience. I previously worked as a principal environmental scientist at the Rhode Island Department of Environmental Management (RIDEM) in the Office of Water. For six of the 12 years that I worked at RIDEM, I was the Coordinator of the Nonpoint Pollution Management Program. For the last 18 years, I have worked as a consultant on environmental and planning projects. I now lead a team of planners at Weston & Sampson. My specific areas of expertise include land-use planning, climate resiliency, onsite wastewater management, wetlands, stormwater, and water supply management.
Surface water and groundwater in Charlestown already experience significant adverse effects from development. In my professional experience, increased density of development invariably results in increased nitrate-nitrogen and pathogens from wastewater and stormwater, even with the most diligent application of best management practices.
The remainder of this letter discusses specific concerns related to the proposed zoning changes. Major concerns that are discussed are as follows:
- Environmental degradation as well as health and safety concerns due to the intensity of development in Charlestown have been documented extensively. Water quality impairments were identified as early as the 1990s and these concerns have trended for the worse. Adding density will worsen the problem.
- The proposed zoning changes do not include an analysis of potential harm or an analysis of regulatory alternatives. Charlestown would be well advised to consider both potential harm and regulatory alternatives before adoption.
Conditions in Charlestown
Charlestown is a growing agricultural and residential community, but some areas of town have already been developed beyond environmental carrying capacity. Carrying capacity refers to the natural capacity of land areas to support development without showing signs of environmental degradation. One land-use development threshold for environmental degradation, which is often cited by water quality scientists and land-use planners, is density of impervious surface (e.g., roads, sidewalks, and rooftops) that exceeds 10% of land area. Another threshold commonly used by onsite wastewater management professionals is one dwelling unit relying on an onsite wastewater treatment system (OWTS) per two acres of land. Much of Charlestown has exceeded both thresholds.
Documentation of related water quality degradation in Charlestown can be found in numerous studies. Some examples include:
- “Determination of Nitrogen Thresholds and Nitrogen Load Reductions for Green Hill and Ninigret Ponds” (RIDEM, 2006)
- “Nitrogen Inputs to Rhode Island Coastal Salt Ponds—Too Much of a Good Thing” (Nixon, S.W. and Buckley, B.A., 2007)
- “Hydrogeology and Simulated Ground-Water Flow in the Salt Pond Region of Southern Rhode Island” (US Geological Survey, 2006)
Moreover, the Town has recently completed its own study of nitrate-nitrogen in groundwater, which provides further evidence of environmental decline due to nitrate-nitrogen inputs related to over development.
Charlestown’s drinking water, which is supplied by a sole source drinking water aquifer, is of particular concern. EPA defines the term sole source aquifer (SSA) as an aquifer that supplies at least 50 percent of the drinking water for its service area and where there is no reasonably available alternative drinking water source were the SSA to become contaminated. In the case of Charlestown, all drinking water comes from an SSA.
EPA has set the maximum contaminant level (MCL) for nitrate-nitrogen in drinking water at 10 parts per million (ppm) due to the potential for nitrate-nitrogen to severely effect human health (e.g., blue baby syndrome). As the level of nitrate-nitrogen in drinking water begins to trend upward, the trend becomes more and more difficult to reverse. EPA has also established an action limit for drinking water of 5 ppm, which is intended to prevent environmental conditions from reaching a point of irreversibility. Nitrate-nitrogen concentrations in Charlestown’s drinking water already approach 5 ppm in many parts of town and in some cases exceed the action limit.
RIDEM has identified bacterial impairments to several fresh and salt water bodies in Charlestown, including Green Hill Pond and the Pawcatuck River. Total maximum daily load (TMDL) studies completed by RIDEM and approved by EPA cite sources including OWTS, stormwater, and intensity of land-use development as issues needing attention.
Recommendations
Charlestown may wish to move forward with a change in its Conservation Development regulations despite the environmental implications of doing so. If this is the case, I would recommend considering the following prior to making such an update:
- If the Town wishes to consider more intensive development, it should be done with eyes open. Modeling of environmental resources could be used to build an understanding of likely consequences. I understand that University of Rhode Island (Lorraine Joubert) and the Town (Matthew Dowling) prepared a nitrogen-loading analysis related to onsite wastewater treatment systems in 2014. I would recommend doing an analysis of impervious cover under current and proposed land-use and build-out conditions.
- One policy approach to consider is the use of a performance standard based on potential nitrate-nitrogen contributions from projects as they are proposed. Many communities on Cape Cod and in Southeast Massachusetts, which face similar environmental issues, have adopted—or are considering—such standards. A model policy was developed for the Buzzards Bay area, which can be found at this URL: https://buzzardsbay.org/wareham/wareham-nitrogen-overlay-draft.pdf.
Thank you for the opportunity to be of service.
Yours very truly,
WESTON & SAMPSON
M. James Riordan, LEED AP
Team Leader
The banner image is a photo of a sunset over Quonochontaug Pond by Leo Mainelli. Quonochontaug is one of the coastal ponds that will be negatively impacted by any increase in the intensity of land-use development.
October 11, 2023 @ 8:47 am
A further workshop style meeting, giving the Planning Commission and Town Council an opportunity to discuss some remaining areas of concern re Conservation design of subdivisions will be held at Town Hall 6 pm tonight Oct 11 th. These are still important issues to be reckoned with but dialogue is important.
September 24, 2023 @ 2:28 pm
The citing of one dwelling per 2 acres can be misunderstood. I think one misunderstanding of the issue at hand is that even though lots might be slightly smaller than the zoned designation they are clustered providing a greater acreage set aside as undeveloped and undevelopable close by that can offset the impact and be permanently protected from being made impervious thus enabling recharge and cleaning of water. The areas that are “Beyond Carrying Capaity” do not have any or very little undisturbed acreage to offset that density. When large lots are required there is no protection from the impacts of impervious cover or lawns rendered impermeable with compaction, wetland buffers being rendered non-functioning or forest being cut down and no protected open space that is undisturbed to offset the impacts. In conservation development as approved and alllowed currently, the slightly smaller lots or the flexibility to adjust sizes with a minimum size available but not mandatory is what aids in the protection of the groundwater on which we depend. The siting and distribution of lots would be on the most suitable soils for that purpose and the most environmentally and ecologically valuable land set aside to aid in protecting water recharge. There are a number of larger lots already existing to satisfy those who wish for larger lots but going forward we need to be more proactive on protecting groundwater. Many appreciate a smaller lot for less maintenance. The Planning Commission would make sure that septic and well are separated appropriately so as to avoid impacts on the groundwater and use the best scientific information to aid in that while maintaining the integrity of the zoning. Utilizing the studies and experience of Matt Dowling our excellent Waste Water staff member, and URI that has done extensive studies on water pollution, or other studies, helps the Planning Commission in making their apoprovals or decisions. Protecting our natural Resources for future generation is imperative. How we do it is the question. Utilizing current best practices is a good start. Less impervious cover, more undisturbed land to offset the development.
Frances Topping Vice Chair of Charlestown Planning Commisison.
September 24, 2023 @ 10:20 am
Wow, Mr Riordan really explains the issue very clearly, potential problems and potential solutions. I hope that his valuable input and advice will be heeded.