Monday, Feb 26th

Letter to the Editor: Writer Calls for a Comprehensive Review of Scarsdale Stormwater Management System

SHSParkingLot(The following letter was submitted by Scarsdale resident Cathy Liu)

Dear Mayor and Trustee,

My name is Cathy Liu and I am a 6 year resident as well as a licensed professional engineer specializing in drainage with extensive experience in both suburban and urban planning. I would like to provide my comments regarding the code review during the 6-month moratorium.

I have had the privileges of contributing to the prevention of flooding in various residential developments within the New York Region. The suburban and the city have different approaches to prevent flooding.

As a plan reviewer for stormwater pollution prevention plans at NYCDEP (New York City Department of Environmental Protection), I have dedicated several years to overseeing residential developments, including mansions and subdivisions, in towns such as Bedford, North Salem, Chappaqua, and Somers to prevent surface runoff from impacting the New York City water supply. A stringent process is followed before any architectural review takes place. Developers are required to submit a comprehensive stormwater management plan to our department before proceeding to the town planning board. This serves as the initial step in the development process. This site plan include the size and location of the house and impervious area and it also include essential components such as stormwater management calculations, number and locations of infiltrations, and other stormwater management practices.

Before the submission of the plan, a crucial step involves scheduling soil testing to assess soil quality. Our office are required to be on-site to witness the excavation and soil testing. This thorough examination is imperative, as it often takes the builder's engineer multiple attempts to identify a location with suitable soil conditions for constructing proposed infiltrators. The infiltration rate must adhere to the New York stormwater management standards, requiring it to be above 0.5 inches per hour, with no groundwater present in the first five feet. Failure to locate suitable soil renders the development unfeasible, and the landowner bears the responsibility for associated costs.

Currently, I am working in capital program management at NYCDEP, where my role involves overseeing and executing infrastructure upgrades throughout New York City. The urban landscape presents a distinct scenario—New York City grapples with aging infrastructure but recognizes the necessity to accommodate development. Understanding that such development is impractical without concurrent infrastructure enhancements, the NYC Department of City Planning collaborates with NYCDEP during the planning stage of developments or rezoning. This collaboration involves reaching out to NYCDEP to ascertain the timeline for drainage analysis, specifically evaluating the capacities of the sanitary sewer and storm sewer systems to accommodate the proposed development. Additionally, the infrastructure improvement timeline is a crucial aspect integrated into the considerations for rezoning and development. Notably, the city bears the responsibility and cost associated with averting flooding and preventing sewer backups. This collaborative effort ensures a harmonious balance between urban development and the preservation of essential infrastructure in New York City.

If Scarsdale intends to amend the zoning code to accommodate downtown development or comply with federal mandates for affordable housing apartments, similar approach should be adapted. A comprehensive evaluation of our existing infrastructure is imperative. Before implementing any new development plans, it is essential to conduct a thorough investigation and subsequent upgrade of the current infrastructure to ensure it aligns with the proposed changes and can adequately support the envisioned developments. This proactive approach will help address potential challenges and ensure that the infrastructure is robust enough to sustain the needs of the community and any mandated housing initiatives.

Both approaches hold the potential to facilitate increased development. Currently in Scarsdale, our stormwater management permit process involves submission after the Board of Architecture Review, a process that, unfortunately, proves too late. By the time the permit is considered for final approval alongside the building permit, homeowners and developers have already invested significant time and resources in the intricacies of the house design. Denying the stormwater permit application at this stage becomes unlikely, as builders often find ways to present a stormwater management plan that meets the criteria. Which then will be self-certified for the soil condition and effectiveness of the infiltrators. Our small engineering team lacks the capacity to witness soil conditions and perc rate tests, rendering our stringent stormwater code less enforceable. In certain areas of Scarsdale with poor soil conditions, the code's enforcement becomes even more challenging, leading to potential hardships, even for replacing a new house with the same footprint. The situation becomes more critical when considering subdivisions that call for a doubling of house footprints; these cases warrant careful examination.

To address these challenges, I propose a fundamental shift in the process. A stormwater management permit should precede the application to the planning board for subdivision or house expansion beyond a specific threshold. Given the strain on the current public system, it becomes imperative that the proposed house's stormwater management plan is not only submitted early but is also feasible and robust before any increased development can be further considered.

Builders often claim that new houses will have superior drainage systems compared to old houses, a fact applicable to the house itself. However, the assertion may not hold true for the broader environment, including streets and neighboring properties. New systems, if not approved robustly, may divert flow to the street, causing potential issues. Many recent developments have been allowed to have infiltrators to be installed in the front yard and under the driveway, with a release mechanism diverting flow to the street when storage is full. This practice, driven by a reluctance to reduce house footprints and allocate space for infiltrators in the backyard, raises concerns about the potential impact on the community. The village faces limitations in issuing violations to these houses, as approvals were granted under existing practices. Even with the introduction of a new code, there is a need to anticipate potential issues and limit the development of future houses to prevent a recurrence of similar problems. Recent housing developments have triggered ongoing complaints among neighbors, underscoring the urgency for the village to address these issues promptly and comprehensively.

It is imperative for the village to actively enforce our existing code. The engineering department, given its relatively small size, faces challenges in adequately serving the village's needs. As mentioned earlier, they are unable to witness soil testing and are sometimes absent during the backfill of infiltrators due to staffing issues. Additionally, the village typically refrains from intervening when issues such as a neighbor's roof leader redirecting water towards another house or a clogged drain causing severe downstream flooding arise. These issues demand immediate attention, irrespective of any potential changes to the existing code.

Furthermore, the recent amendment to our building code in 2020, limiting the height of new buildings, is commendable. However, there are currently no restrictions on the elevations at which houses should be built. A concerning trend has emerged where new houses are constructed at significantly higher elevations relative to neighboring properties. This has the potential to divert surface runoff from these houses onto neighboring properties. I recommend that a consulting company thoroughly examine and address this issue.

In 2015, we engaged the services of consultant Phillips Preiss to examine the matter concerning bulk regulations. The findings indicated that the concept of "bulk" is minimally associated with the Floor Area Ratio (FAR) and instead relies heavily on factors such as design, façade, and garage location. I am keen to discover the insights our new consultant will provide on this matter.

Additionally, in 2002, Scarsdale introduced the concept of floor area ratio to control the size of houses. This had a significant impact on numerous existing houses in Edgewood on small lots, constructed around the 1920s, rendering them nonconforming. The temporary moratorium implemented further reduced setbacks for a period of six months, resulting in an additional 160 square feet reduction in floor area ratio for these houses. For instance, a house built in 1928 for 2400 sqft on a lot of A5 (5200 sqft) could only adhere to a 2200 sqft limit as per the 2002 code if a redevelopment is needed, and this have been further reduced to 2000 sqft for new houses temporarily. Careful consideration is warranted in evaluating the necessity of further reducing the floor area ratio. If the issues outlined in the preceding paragraphs are not effectively addressed by the village, a reduction in floor area ratio may not contribute to alleviating flooding concerns but may instead lead to a decrease in property values.

Just my 2 cents,.

Thank you for your consideration,

Cathy Liu

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