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 Rhode Island Coastline Coastal Storm Risk Management Project

Purpose

The Rhode Island CSRM study was conducted due to frequent flooding from high tides, spring tides, and coastal storms in the study area. The study’s purpose is to identify a plan to reduce the risk of coastal storm damage along a large portion of the Rhode Island coastline while contributing to the resilience of communities, important infrastructure, and the natural environment. The study area includes significant critical infrastructure at risk of damage from future flooding and coastal storms including police, fire, and emergency support service facilities; schools; energy production facilities; water and wastewater facilities; nursing homes and assisted living facilities in addition to communities and businesses. These areas that experience frequent flooding are considered at high risk of coastal storm flooding with an associated threat to life safety; and are susceptible to relative sea level change.

Scoping meetings were held with Rhode Island Coastal Resources Management Council (RI CRMC), which is the non-federal sponsor, and with representatives from municipalities located within the study area early on the scoping of the study in order to better understand the region. The RI CRMC, with the assistance of stakeholders, identified eleven key focused study areas within the regional study area. These areas included Barrington/Warren, Block Island, Bristol, Jamestown, Narragansett, Newport Downtown, Newport/Middletown Reservoirs, North Kingstown, Portsmouth, Providence, and Warwick/Cranston. Focus areas for the study were identified based on elevation data, structure density, and discussions with town and state officials regarding high damage-prone areas and history of coastal storm damages. Using information from these meetings, USACE concentrated on developing alternative solutions for the focused study areas. Additionally, nonstructural measures were considered for the entire study area (i.e., the shoreline from Point Judith to the Massachusetts border).

A range of measures were considered to manage the risk caused by coastal storms to properties within the study area. Structural (floodwalls, river closure structures, living shorelines, etc.) and nonstructural measures (wet/dry flood proofing and elevation of residential structures) were considered, and alternatives were formulated, evaluated, and compared against each other in order to establish the Tentatively Selected Plan.

Study Background

The study area of the Rhode Island Coastline, shown in Figure 1, runs from Point Judith eastward to the Massachusetts border, including the majority of Narragansett Bay, which is a major feature of the state’s topography. The study area also includes Block Island, which is not located in Narraganset Bay. The area covers more than 457 miles of coastline as shown in Figure 2. All or part of 19 municipalities are included in the study area, with more than 650,000 people currently residing within the study boundaries.

Figure 1: The study area of the Rhode Island Coastline Study

Figure 2: The coastline included in the study area

 

Recommended Plan

Figure 1 shows the locations of the structures recommended for elevation or floodproofing in the Recommended Plan (RP). The RP consists of elevating the first floors of 290 single family residences in the study area. The elevation design height was determined separately for each structure. Elevation can be performed using fill material, on extended foundation walls, on piers, post, piles, and columns (Figure 2). Elevation is also a very successful technique for houses that sit on a slab foundation.

In addition, 2o7 non-residential structures will be floodproofed. Floodproofing was considered for non-residential structures and large multi-family structures without a basement. Floodproofing measures consist of dry floodproofing or wet floodproofing. Dry floodproofing makes a structure watertight below the level that needs flood protection to prevent floodwaters from entering. An example of a dry floodproofing measure is to apply a waterproof veneer, such as a layer of brick backed by a waterproof membrane, directly to the outside surface of an existing structure (Figure 3). Wet floodproofing allows floodwaters to enter an enclosed area of a structure without damaging the structure or its contents. All construction materials and finishing materials are water resistant and all utilities elevated above the design flood elevation in the areas of structures proposed for wet floodproofing (Figure 4).

Figure 1 - Locations of the Structures Recommended for Elevation or Floodproofing in the Tentatively Selected Plan

Figure 2 - Elevations: Elevation involves raising a building in place so that the habitable space is located above the anticipated height of flood waters.

Figure 3 - Dry Floodproofing: Dry floodproofing involves sealing building walls with waterproof materials or coatings to make the building watertight. (Image source: https://accd.vermont.gov/sites/accdnew/files/documents/CD/CPR/CPR-VERI-Toolkit-Floodproofing.pdf). 

Figure 4 - Wet Floodproofing: Modifying a structure to allow floodwaters to enter it in such a way that damage to the structure and its contents is minimized. (Image source: https://emilms.fema.gov/is_0280/groups/19.html).   

 

Contact

All inquiries should be directed to Janet Cote by mail at the address below, by telephone at 978-318-8728, or by email at nae-pd-pn@usace.army.mil. 

U.S. Army Corps of Engineers, New England District
Attn: Janet Cote, Planning Division
696 Virginia Road
Concord, MA   01742

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