HCF’s Official Comments on Army Corps’ 3 x 3 Study
Posted: June 18, 2020
The Foundation has submitted the following comments to the Army Corps regarding the 3 x 3 Study:
As an organization dedicated to preserving Charleston’s historic resources, HCF feels strongly that we should consider every possible option for the long-term protection of Charleston from storm surge flooding and sea level rise. HCF is generally supportive of perimeter protection, if our concerns about design, aesthetics and impacts to historic resources can be alleviated. We have categorized our comments, concerns, and questions by subject area below.
Visualizations:
- In advance of the next public input period planned for early 2021, it is incredibly important for the public to understand the look and feel of the wall and how it interfaces with the peninsula and the water. The Corps and City must collaborate on developing some graphic renderings to help the public to conceptualize this system from different, key vantage points
- The Corps and the City should engage with the City’s Design Center to provide the public with some human-scale visualizations of height, engineering, design and aesthetics of the types of walls that may be constructed
- Provide some renderings so the public can appreciate how the wall height will change in different areas because of topography
- The same applies for the wave attenuating structure – provide some renderings from various viewpoints (e.g. view from the High Battery, the harbor looking toward the peninsula, from James Island)
- A better explanation is needed for the gated access points, particularly for those affecting private property (e.g. docks on the west side of the peninsula in Wagener Terrace)
- We look forward to engaging with Diane Perkins and others on the VRAP analysis as part of the Section 106 review process
Address Areas of the Peninsula Differently:
- The analysis should drill down as locally as possible to better understand the wall and its impact on different zones of the peninsula
- Ensure the Tentatively Selected Plan is not a “one size fits all” design approach and respects individual neighborhood characteristics
- The wall design and appearance should interface residents differently in different zones (e.g. a recreational/park space may be appropriate for one neighborhood and not another, while a more industrial approach might work for another)
- Recommend dividing the peninsula into logical ‘character areas’ of wall sections
- Suggested wall sections to consider from the east side of the peninsula circling around to the west: Morrison Drive/upper East Bay to Charlotte Street; Aquarium Wharf/Union Pier; Cumberland Street to the Carolina Yacht Club; High and Low Battery to Broad Street; Lockwood Boulevard; Brittlebank Park to The Citadel; and Wagener Terrace
Quality of Life and Livability:
- The wall design must be both beautiful and multi-functional, per the Dutch Dialogues Charleston recommendations
- The wall must contribute to Charleston’s character and quality of place – it cannot be an obtrusive monolith and overly disruptive of the relationship of the peninsula to the water
- The path the wall follows, along with its height, must interface logically and sensitively to surrounding property
- Assess wall sections for ability to double as active park/recreational space (High Battery is an exemplary case of what a protective wall can and should be for certain zones)
- Improve access and connectivity for residents and visitors to the waterfront
- The wall should not adversely affect viewsheds both from the peninsula to the rivers, harbor, and surrounding areas but also views from those surrounding areas to the peninsula
- Protect our community, but also bridge connections within our community – the wall cannot create divisions within our City neighborhoods and pose disconnections in community culture. If the proposed wall should intersect a street, then special care should be taken to ensure a connection between the sides of the street on opposite sides of the wall
- The wall’s alignment should avoid permanent mobility impacts (street and sidewalk closures), and intersections of the wall with the public right of way should occur logically for traffic flow
Adhere to the Specific Recommendations Made for the Peninsula, East Side and Medical District in the Dutch Dialogues Charleston Report:
- Again, perimeter protection must be multifunctional and beautiful – alignments should take a multiple benefit approach that contributes to Charleston’s character and quality of place. Alignments must create stormwater storage opportunities, manage groundwater and be logical, practical and forward-looking
- Align with the City’s future stormwater management plans – ensure that robust stormwater management through drainage basins is created and that proper drainage to rivers occurs, via adequately-sized permanent and mobile pump stations and collecting basins
- Assess public spaces for water storage and water infiltration opportunities, including exposing existing creeks for storage and drainage
Design, Engineering and Aesthetics:
- Borrow design and aesthetics from the City’s architecture and history – make the wall look local and responsive to context, especially in more sensitive historic areas
- Design and aesthetics should reflect the unique characteristics of different zones of the peninsula (perhaps based on HCF-recommended wall sections)
- Charleston, in its early years, was a walled city – borrow design and appearance cues from the Walled City, particularly for the wall section from Cumberland Street to the Carolina Yacht Club
- Assess continuation of the High and Low Batteries north to Brittlebank Park along the Lockwood Boulevard wall section to create a “West Battery”
- Can the height of the wall and the size of the wave attenuator be decreased to mitigate historic resource impacts and still achieve defensible storm surge protection goals? Can the wave attenuator be located further than 230 feet from the Battery to reduce its visual impacts?
- How do the Corps’ predictions for sea level rise interface with the City’s predictions made in the Sea Level Rise Strategy? Are the City and the Corps working from the same set of projection data for sea level rise over the next 50 years? If not, how do we marry the two to produce the best, most-integrated approaches for Charleston?
- Reassess areas not included in the interior of the wall and consider inclusion (Bridgeview Apartments, Aquarium Wharf, Union Pier, The Cooper Hotel, etc.)
- Should more pump stations be included in the plan to alleviate additional stormwater flooding, i.e. the “bathtub effect”?
- Identify areas of the peninsula inside the wall where water can be collected and stored to pump outside the wall
- Assess whether the sections of wall proposed to run through the marsh can be moved to land to mitigate environmental impacts to wetlands
- Assess whether “nature-based” solutions (NNBFs) can be incorporated into the design to enhance ecological benefits
- Construction materials for the wall should be assessed and selected for their long-term durability and endurance, particularly under harsh, saltwater conditions. Examine construction materials of the High Battery sea wall and consider usage of similar. Also, much like the Low Battery retrofit, the system should be designed to be raised at a later date, when necessary
Historic and Cultural Resource Concerns:
- How the wall interfaces with the Historic District and City neighborhoods is critical – mitigating impacts to the historic assets of the City must remain paramount, as they remain the defining features of the peninsula
- Analyze the specific affects (aesthetic and structural) on NRHP-listed and eligible properties located on the peninsula through the Section 106 environmental review process
- How will the non-structural measures (elevations and buyouts) included in the plan affect historic properties and neighborhoods? Which properties are affected?
- Visual intrusions to historic viewsheds caused by both the wall and the wave attenuating structure (both from the peninsula outward and toward the peninsula from the water and surrounding areas) require greater attention in the study
- The study should better analyze and identify a mitigation plan for impacts to Charleston’s vitally important historic and cultural resources
Economic Concerns:
- How will the proposed wall affect property values? Particularly for those properties whose view could be obstructed or water access inhibited
- How will the proposed wall affect the City’s tourism and hospitality industry? The historic districts and water access are an important draw for visitors
Temporary Construction Concerns:
- Visual intrusions from construction of the barrier wall and the wave attenuator
- Ground disturbance to historic and archaeological resources
- Vibration damage caused by construction and equipment
- If vibration damages occur, how will properties be repaired and who is responsible? How do owners seek reparations?
- General noise disturbance caused by construction
- Mobility impacts due to temporary road and sidewalk closures
HCF is proud to be invited to participate as a consulting party for purposes of the National Historic Preservation Act Section 106 Process and appreciative of the opportunity to provide comments and questions on the 3×3 Study. We look forward to continued work with the Corps and the City of Charleston in the optimization phase and beyond to ensure that the final flood risk management plan adheres to the recommendations of Dutch Dialogues Charleston, contributes to Charleston’s quality of place, and is sensitive to the historic and cultural integrity of our neighborhoods, while accomplishing the goals of storm surge protection to reduce damages and loss caused by coastal storm flooding.
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Before considering a perimeter flood barrier of any height from 8 to 12 feet above MSL 88 NGVD, prepare topographical exhibits based upon existing LIDAR data that indicate the area of the Peninsula that will be flooded within the barrier perimeter. If produced on a foot by foot increase from 8 to 12 feet elevation, such exhibits will provide an early understood visual image of the areas within the perimeter flood wall that will be protected for each specific elevation, and more importantly, the areas flooded by surge events higher than each prevressive barrier elevation. The unintended consequence of any barrier elevation will be to quickly pump out the interior impounded volume of detained flood water after an overtopping event.
There has also been very little discussion about the life-cycle cost of operating and maintaining a flood barrier system and the massive pumping facilities required. Emergency pump power requirements are another worthy topic.
Thank you for your interest and insight into the project. I hope you were able to submit your comments in an official capacity to the Army Corps during their public comment period.
-Cashion Drolet, Chief Advocacy Officer