Waterford Climate Vulnerability, Risk Assessment and Adaptation Study (PDF)

CDBG-DR 2015 
CLIMATE CHANGE RISK VULNERABILITY, RISK 
ASSESSMENT AND ADAPTATION STUDY 
WATERFORD, CONNECTICUT 
 
 
 
Prepared For: 
Town of Waterford 
15 Rope Ferry Road 
Waterford, CT 06385 
 
 
 
 
 
 
Prepared By: 
Kleinfelder Northeast, Inc. 
215 First Street 
Cambridge, MA  02142 
 
 
 
 
 
 
 
 
 
November 16, 2017 

 
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CLIMATE CHANGE RISK VULNERABILITY, RISK ASSESSMENT AND ADAPTATION STUDY 
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TABLE OF CONTENTS 
 
 
INTRODUCTION ........................................................................................................................ 1 
A. 
PROJECT TEAM .................................................................................................................... 2 
B. 
CITIZEN PARTICIPATION ...................................................................................................... 2 
C. 
ACKNOWLEDGEMENTS ....................................................................................................... 3 
FLOOD MAPPING ..................................................................................................................... 4 
A. 
PARAMETERS ....................................................................................................................... 4 
Time Horizons ......................................................................................................................... 4 
Tide and Storm Surge ............................................................................................................. 4 
Heavy Precipitation ................................................................................................................. 6 
B. 
COASTAL FLOODING ........................................................................................................... 7 
C. 
RIVERINE FLOODING ........................................................................................................... 8 
Limitations ............................................................................................................................ 10 
Vulnerable Areas in Waterford .............................................................................................. 10 
VULNERABILITIES AND ADAPTATION STRATEGIES ......................................................... 15 
A. 
METHODS ............................................................................................................................ 15 
Data Collection ..................................................................................................................... 15 
Vulnerability Assessment ...................................................................................................... 16 
Risk-Based Prioritization ....................................................................................................... 16 
B. 
VULNERABILITY ASSESSMENT RESULTS ........................................................................ 17 
Vulnerable Buildings/ Facilities ............................................................................................. 17 
Vulnerable Roads ................................................................................................................. 22 
Vulnerable Natural Resources .............................................................................................. 25 
C. 
STAKEHOLDER ENGAGEMENT ......................................................................................... 27 
D. 
ADAPTATION STRATEGIES - GENERAL ........................................................................... 31 
Protection ............................................................................................................................. 32 
Accommodation .................................................................................................................... 34 
Retreat .................................................................................................................................. 34 
Cost Estimating ..................................................................................................................... 34 
E. 
ADAPTATION STRATEGIES - BUILDINGS/FACILITIES...................................................... 35 
Base Flood Elevations .......................................................................................................... 35 
Design Flood Elevations ....................................................................................................... 35 
Impacted Wastewater Pump Stations ................................................................................... 36 

 
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Adaptation Strategies for Buildings and Facilities .................................................................. 43 
F. 
ADAPTATION STRATEGIES - ROADWAYS ........................................................................ 49 
Adaptation Strategies – Gardiners Wood Road ..................................................................... 51 
Adaptation Strategies – Oswegatchie Road .......................................................................... 55 
Adaptation Strategy – Rope Ferry Road / Avery Lane / Great Neck Road ............................ 57 
Adaptation Strategy – Niantic River Road ............................................................................. 59 
Adaptation Strategy – Evacuation ......................................................................................... 59 
Adaptation Strategy – Waterproofing Wastewater Manholes ................................................ 60 
G. 
ADAPTATION STRATEGIES - NATURAL RESOURCES..................................................... 63 
Town Beach and Marsh ........................................................................................................ 64 
Pleasure Beach/White Point Marsh ....................................................................................... 67 
Mago Point Marsh ................................................................................................................. 67 
Millstone/Jordan Cove Marsh ................................................................................................ 68 
Goshen Cove Marsh ............................................................................................................. 69 
Ridgewood Marsh ................................................................................................................. 70 
Mamacoke Cove Marsh ........................................................................................................ 71 
POLICY RECOMMENDATIONS .............................................................................................. 72 
A. 
ZONING REGULATIONS ..................................................................................................... 72 
B. 
SUBDIVISION REGULATIONS ............................................................................................ 74 
C. 
INLAND WETLAND AND WATERCOURSES REGULATIONS ............................................ 75 
D. 
LAND/RESOURCE ACQUISITION ....................................................................................... 75 
E. 
POTENTIAL POLICIES FOR PUBLIC PROJECTS ............................................................... 76 
F. 
COASTAL FLOOD AND EMERGENCY OPERATIONS PLAN ............................................. 76 
G. 
NATIONAL FLOOD INSURANCE PROGRAM COMMUNITY RATING SYSTEM ................. 77 
H. 
TIDE GAUGE INSTALLATION ............................................................................................. 79 
I. 
POTENTIAL FUNDING SOURCES ...................................................................................... 80 
Connecticut Institute for Resilience and Climate Adaptation (CIRCA) Municipal Resilience 
Grant Program ...................................................................................................................... 80 
National Oceanic and Atmospheric Administration (NOAA) Regional Coastal Resilience 
Grants ................................................................................................................................... 80 
Federal Emergency Management Agency (FEMA) ............................................................... 81 
US Army Corps of Engineers (USACE)................................................................................. 82 
U. S. Department of Housing and Urban Development (HUD) .............................................. 83 
Natural Resources Conservation Service (NRCS) ................................................................ 83 

 
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FIGURES 
Figure 1 - Observed Acceleration of Sea Level Rise in Waterford ...................................................... 4 
Figure 2 - Predicted Relative Sea Level Rise Scenarios in Waterford from 2016 (feet) ....................... 5 
Figure 3 - Daily High Tide (MHHW) with Sea Level Rise Factored In ................................................. 6 
Figure 4 - Baseline and 24-Hour Design Storms Projected Rainfall .................................................... 7 
Figure 5 - Quaker Hill Area Looking North Along Old Norwich Road - 1% (100 Year) Coastal Floods
 ......................................................................................................................................................... 12 
Figure 6 - Ridgewood Area Looking North Along Shore Drive – 1% (100 Year) Coastal Floods ....... 13 
Figure 7 - Avenues Area Looking South Between 1st and 2nd Avenues – 1% (100 Year) Floods .... 14 
Figure 8 - Illustration of Critical Building Elevation ............................................................................ 18 
Figure 9 - Wastewater Pump Station Interconnectivity in the Town of Waterford .............................. 20 
Figure 10 - Wastewater Service Areas Served by Vulnerable Pump Stations ................................... 21 
Figure 11 - Delineated Flood Hazard Zone at Evergreen Pump Station (source: FEMA FIRM 
09011C0503J) .................................................................................................................................. 22 
Figure 12 - Major Roads in Waterford Vulnerable to Coastal Flooding (SLR and Storm Surge) ........ 23 
Figure 13 - Major Roads in Waterford Vulnerable to Riverine Flooding ............................................ 24 
Figure 14 - Natural Resource Areas Vulnerable to Coastal Flooding ................................................ 26 
Figure 15 - Workshop Participant Adaptation Recommendations for Central Waterford ................... 28 
Figure 16 - Workshop Participant Adaptation Recommendations for Jordan Cove ........................... 29 
Figure 17 - Workshop Participant Adaptation Recommendations for Quaker Hill .............................. 30 
Figure 18 - Conceptual Illustration of Protect, Accommodate and Retreat Strategies Approaches ... 32 
Figure 19 - Seawall and Stone Revetment along Niantic River Road ............................................... 33 
Figure 20 - Concrete Flood Wall and Raised Electrical Panels at Bolles Court Pump Station ........... 33 
Figure 21 - Examples of Accommodation Strategies ........................................................................ 34 
Figure 22 - Photos of Mago Point Wastewater Pump Station ........................................................... 37 
Figure 23 - Cross-Section of Mago Point Wastewater Pump Station ................................................ 38 
Figure 24 - Example of Sliding Flood Door (left) and Floodproof Double-Door (right) ....................... 40 
Figure 25 - Photos of Gardiners Wood Wastewater Pump Station.................................................... 41 
Figure 26 - Photo and Cross-Section of Gardiners Wood Wastewater Pump Station ....................... 42 
Figure 27 - Potential Adaptation Strategies to Strengthen Evacuation and Emergency Access Routes
 ......................................................................................................................................................... 50 
Figure 28 - Gardiners Wood Road Adaptation Strategy No. 1 - 2070, 100-Year Coastal Flood 
Scenario ........................................................................................................................................... 53 
Figure 29 - Gardiners Wood Road Adaptation Strategy No. 2 - 2070, 100-Year Coastal Flood 
Scenario ........................................................................................................................................... 54 
Figure 30 - Proposed Conceptual Road Improvements at Oswegatchie Road – 2070, 100-Year 
Riverine Flood Scenario ................................................................................................................... 56 
Figure 31 - Proposed Conceptual Road Improvements at Rope Ferry/Avery Lane/Great Neck Road – 
2070, 100-Year Riverine Flood Scenario Shown .............................................................................. 58 
Figure 32 - Examples of Potential Rescue Vehicles ......................................................................... 60 
Figure 33 - Distribution of Recommended Wastewater Manholes to be Waterproofed Overlaid on 
Service Areas Associated with Each Pump Station .......................................................................... 62 
Figure 34 - Climate and Environmental Drivers Influencing Vertical and Horizontal Wetland 
Development (Source: USGS and Cahoon and others 2009) ........................................................... 63 

 
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Figure 35 - Examples of Thin-Layer Deposition (left) and Ouster/Clam Shell Bags for Marsh Edge 
Protection (right) ............................................................................................................................... 64 
Figure 36 - Town Beach and Marsh .................................................................................................. 65 
Figure 37 - Areas of Potential Marsh Migration at Town Beach ........................................................ 65 
Figure 38 - Pleasure Beach/White Point Marsh ................................................................................ 67 
Figure 39 - Mago Point Marsh Area .................................................................................................. 68 
Figure 40 - Millstone/Jordan Cove Marsh ......................................................................................... 69 
Figure 41 - Goshen Cove Marsh ...................................................................................................... 70 
Figure 42 - Ridgewood Marsh Area .................................................................................................. 70 
Figure 43 - Mamacoke Cove Marsh Area ......................................................................................... 71 
Figure 44 - U.S. National Climate Assessment Sea Level Rise Curves (NOAA 2012) ...................... 72 
Figure 45 - Temporary Flood Panels (left) and Flood Wall with Temporary Flood Gate (right) .......... 74 
 
TABLES 
Table 1 - Areas in Waterford Vulnerable to Coastal and Riverine Flooding ....................................... 11 
Table 2 - Facilities Vulnerable to Coastal and/or Riverine Flooding .................................................. 18 
Table 3 – Buildings and Facilities Prioritized by Risk ........................................................................ 19 
Table 4 - Potential Future Base Flood Elevations (BFEs) for 1% (100-Year) Probability Flood ......... 35 
Table 5 - Proposed Design Flood Elevations (DFEs) for 1% (100-Year) Probability Flood ............... 36 
Table 6 - Adaptation Recommendations for Buildings and Facilities ................................................. 44 
Table 7 - Recommended Wastewater Manholes to be Waterproofed ............................................... 61 
 
APPENDICES 
A. Flood Maps 
B. List of Roadways Vulnerable to Flooding 
C. Citizens Participation Plan 
D. Public Comments and Responses 
 
 

 
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CLIMATE CHANGE RISK VULNERABILITY, RISK ASSESSMENT AND ADAPTATION STUDY 
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INTRODUCTION 
The effects of climate change present themselves in a variety of ways, including an increase in extreme 
precipitation, sea level, and storm surge resulting in heightened risks of flooding. The Town of Waterford 
has already experienced impacts to its infrastructure, natural resources, and economy from these 
hazards.   Hurricane Sandy (2012) resulted in widespread power outages, disrupting daily life and 
municipal services. During Sandy, waves overtopped the dunes at the Town Beach and other south 
facing beaches changing the characteristics of the Alewife Cove and Goshen Cove channels due to 
siltation, along with impacts to other natural resource impacts.  Roadway and drainage infrastructure were 
also damaged by flooding from extreme rainfall during Tropical Storm Irene (2011) and in March 2010 
from an unnamed storm.     
The Town of Waterford recognizes that future changes in climate patterns will have significant 
ramifications for its infrastructure and natural resources affecting its residents, businesses, and 
government.  The Climate Change Risk, Vulnerability Assessment and Adaptation Study project allows 
the Town to proactively identify the risks associated with these changes, and to develop prioritized 
strategies to address them. 
The Town of Waterford applied for and was awarded a $175,000 Community Development Block Grant 
- Disaster Recovery (CDBG-DR) grant to fund this study.  The grant was awarded through the 
Connecticut Department of Housing. Abby Piersall, AICP, the Town of Waterford’s Planning Director, 
was the Town’s Project Manager responsible for administering the grant on behalf of the Town. 
This project had five primary goals: 
1. 
Develop appropriate rainfall, tidal, sea level rise and storm surge scenarios for the Town of 
Waterford for present, near-term and long-term time frames. 
2. 
Produce high-quality maps and graphics showing the likelihood, extent and magnitude of flooding 
impacts. 
3. 
Identify critical infrastructure, facilities and natural resources in Waterford that are vulnerable to 
present and future flooding events. 
4. 
Develop and prioritize potential short-term and long-term adaptation strategies, with order-of-
magnitude cost estimates where appropriate, including regulatory and policy changes, to help the 
Town manage its infrastructure and natural resources in the face of increasing flood risks. 
5. 
Engage the public and government officials to solicit feedback on proposed strategies so that the 
Town can make informed decisions that will help to avoid future costly impacts to public and 
private property.  
It is important to note that this vulnerability assessment and adaptation planning study is in no way 
connected with flood risk studies and mapping efforts periodically conducted by the Federal Emergency 
Management Agency (FEMA) to produce Flood Insurance Rate Maps (FIRMs) for the Town of 
Waterford. The coastal flood maps prepared as part of this study were developed for long-term planning 
using very different methods, scenarios, and data than are used by FEMA to prepare FIRMs. Data from 
this report should not be used in any way as a substitute for FIRMs as the legally-binding basis for 
determining flood insurance premiums and the minimum required inputs for the design and permitting 
of projects within the floodplain. 
 
 

 
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A. 
PROJECT TEAM 
The Town of Waterford selected the team of Kleinfelder Northeast, Inc. (Kleinfelder) through a Request 
for Proposal process. Kleinfelder, located in Cambridge, MA, was the prime consultant responsible for 
client liaison, modeling, vulnerability assessment, adaptation planning, and public process. Woods 
Hole Group, located in Falmouth, MA, was a subconsultant to Kleinfelder responsible for coastal flood 
modeling. Martinez Couch & Associates of Rocky Hill, CT, another subconsultant to Kleinfelder, was 
responsible for surveying, vulnerability assessment and aerial drone photography used to develop 
rendered videos simulating future flooding impacts.  
The team’s primary members included:  
 
Andre Martecchini, PE – Kleinfelder - Project Manager, Adaptation Planning, Public Process 
 
Nasser Brahim – Kleinfelder - Project Scientist, Vulnerability Assessment, Adaptation Planning 
 
Kirk Bosma, PE – Woods Hole Group – Coastal Flood Modeling  
 
Dr. Indrani Ghosh, PhD – Kleinfelder – Riverine Hydraulic Modeling 
 
George Pendleton, PE – Martinez Couch Associates – Surveying, Vulnerability Assessment 
Kleinfelder worked closely with a Town Working Group consisting of the following individuals: 
 
Abby Piersall, AICP – Planning Director and Town Project Manager 
 
Maureen Fitzgerald – Environmental Planner 
 
Kristen Zawacki, Public Works Director (through June 2017) 
 
Brian Long – Public Works Director 
 
Neftali Soto – Utility Director/Chief Engineer 
 
Jeff Sims – Chair, Conservation Commission 
 
Bert Chenard – Waterford Planning and Zoning Commission 
 
Dan Matheson – Assistant Director of Public Works 
 
Jim Bartelli - Assistant Utilities Director 
 
Steve Bellos – Emergency Manager 
 
Bruce Miller – Fire Services Director 
 
Peter Schlink – Fire Marshal 
 
B. 
CITIZEN PARTICIPATION 
 
As noted above, one of the primary goals of the project was to raise public awareness of increasing 
flood risks posed by extreme precipitation, sea level, and storm surge, and the potential strategies 
available to adapt to those changes over time.  
The Town established a Citizen Participation Plan to provide a framework for citizen participation in the 
planning and implementation of the project. It includes policies on providing public notice, outreach to 
vulnerable populations, access to meetings and information, opportunities for public comments, and 
mechanisms for complaints and grievances. 

 
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Five Working Group meetings were held over the course of the project to review interim findings and 
to solicit feedback from members of the Working Group. All meetings of the Working Group were posted 
and open to the public.  
 
September 28, 2016 – Presented project overview, introduction to climate change parameters, 
draft Citizen Participation Plan, and goals for stakeholder meetings.  
 
October 31, 2016 – Presented and discussed results of the climate change parameters 
analysis, and data needs for the vulnerability assessment. 
 
February 16, 2017 – Presented and discussed coastal and riverine flood mapping results, 
identification of vulnerable areas, and vulnerability assessment methods. 
 
April 18, 2017 – Presented and discussed vulnerability assessment results, site selection for 
flood animations, and public workshop planning.  
 
August 9, 2017 – Presented and discussed preliminary adaptation recommendations, and 
public meeting planning. 
 
On October 18, 2016, a presentation was made to the Town of Waterford Board of Selectmen 
describing the project goals and objectives, the general process that would be undertaken, and the 
tentative schedule. 
On October 31, 2016, a presentation was made to the Town of Waterford Planning and Zoning 
Commission to review potential changes to regulations and policies. 
Two general public meetings were held at the Waterford Town Hall to present interim findings to the 
public and to solicit comments. 
 
May 24, 2017 – Presented project goals and objectives; description of parameters used for 
coastal and riverine flood projections; coastal and riverine maps and vulnerabilities; and 
conducted breakout groups to introduce adaptation strategies.  
 
August 29, 2017 – Presented potential adaptation strategies, order-of-magnitude costs, and 
recommendations for potential regulatory/policy changes.   
Kleinfelder also attended, staffed a table, distributed a project leaflet, and talked with interested citizens 
at the Waterford Free Summer Concert Series at Waterford Beach Park on July 26, 2017. 
 
C. 
ACKNOWLEDGEMENTS 
We would like to thank members of the Town of Waterford Working Group who provided valuable 
guidance, information about historic flooding events, local knowledge of facilities, roads and natural 
resources and important feedback to data presented at the various Working Group and public 
meetings.  Their valuable input helped improve the accuracy of our conclusions and helped make our 
recommendations more meaningful and implementable. 
We would also like to thank the Connecticut Department of Housing for funding this important project 
through a CDBG-DR grant. 
 
 

 
 
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FLOOD MAPPING 
A. 
PARAMETERS 
The establishment of parameters was critical to developing appropriate climate change scenarios 
for heavy rainfall, sea level rise, and storm surge.  
Time Horizons 
The Working Group selected 2016, 2030, and 2070 to be the data collection time periods for the 
climate parameters. Multiple time horizons were investigated to demonstrate that, in general, 
climate change is expected to accelerate and cause increasing impacts over time.  Present day 
climate conditions, determined by sources of historic, local climate data, were used to identify 
priority adaptation projects. Parameters for 2030 and 2070 were based on climate change 
projections to identify incremental and opportunistic adaptation strategies.  
Time horizons are important for communities to determine what adaptation actions need to be 
taken and how soon. In general, flooding issues that occur today are a high priority. Changes in 
future temperatures and sea level rise are dependent on multiple factors, including rates of 
greenhouse gas emission and natural system responses to those changes.  Uncertainties related 
to future climate predictions are managed by using reasonably reliable data sources and methods 
to develop the projections of future impacted areas.  
Tide and Storm Surge 
 
 
Figure 1 - Observed Acceleration of Sea Level Rise in Waterford 
Figure 1 above shows monthly mean sea level in Waterford, as measured at the NOAA tide gage 
in New London since 1938. Data from the period 1938-1976 is shown in light blue, and 1978-
2015 is in dark blue. In total, mean sea level has risen about 0.65 feet since 1938. While on 
average it has risen at a rate of 1.0 inch per decade, a closer look at the data reveals that sea 
-0.8
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
0.8
1938
1945
1952
1959
1966
1973
1980
1987
1994
2001
2008
2015
FEET
Mean Sea Level (1938-1976)
Mean Sea Level (1978-2016)
1.7 inches per year 
0.9 inches per year 

 
 
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level rise has accelerated over time. From 1938 to 1976 the rate of sea level rise was slightly 
below 1.0 inch per decade, but from 1978 to 2015 it rose at a rate of 1.7 inches per decade, or 
84% faster. Most sea level rise projections for the future anticipate a similar and worsening 
acceleration trend over time as climate change becomes more pronounced. 
To determine how much additional sea level rise Waterford should plan for in the future, the study 
uses sea level rise projections derived from the National Climate Assessment’s global sea level 
rise scenarios. Several Connecticut laws mandate that these scenarios be used for coastal 
planning and infrastructure design. The National Climate Assessment provides three global sea 
level rise scenarios: Highest, Intermediate-High, and Intermediate-Low. The scenarios reflect 
different assumptions about how much and how fast key factors will contribute to sea level rise in 
the future.  Figure 2 shows the relative increase in sea level in feet from 2016 for Waterford for 
the Highest, Intermediate-High, and Intermediate-Low scenarios. 
 
                     Time horizons (year) and projections (feet) 
               Scenarios 
2020 2030 2040 2050 2060 2070 2080 2090 2100 
Highest SLR 
0.1 
0.6 
1.1 
1.7 
2.4 
3.2 
4.2 
5.2 
6.3 
Intermediate-High SLR 
0.1 
0.4 
0.7 
1.1 
1.5 
2.0 
2.5 
3.2 
3.8 
Intermediate-Low SLR 
0.0 
0.1 
0.1 
0.2 
0.3 
0.4 
0.4 
0.5 
0.6 
Figure 2 - Predicted Relative Sea Level Rise Scenarios in Waterford from 2016 (feet) 
 
As glaciers and ice sheets on Greenland and Antarctica melt, water is added to the ocean’s 
volume causing sea level to rise relative to land. In addition, as the ocean heats up, its volume 
expands further. The Highest scenario assumes maximum melting and significant thermal 
expansion. The Intermediate scenarios assume more limited melting and different degrees of 
thermal expansion. More information is provided in the NOAA Technical Report on Global Sea 
Level Rise Scenarios for the US National Climate Assessment (2012). 
In 2017, the Connecticut Institute for Resilience and Climate Adaptation (CIRCA), at the University 
of Connecticut, released the Sea Level Rise and Coastal Flood Risk in Connecticut (2017) report. 
It estimates 1.7 feet of sea level rise in Connecticut by 2050. This projection is consistent with the 
Highest scenario in Figure 2. 
Tide is a key parameter being studied in this project. The concern is that, as sea level rises, 
certain areas in town could eventually flood during daily or astronomical high tide cycles. Higher 
tide at the discharge-end of a drainage system could also chronically reduce that system’s ability 
to drain properly. In Waterford, there are two high tides each day. The higher of the daily high 
tides is averaged over longer periods of time to estimate the Mean Higher High Water (MHHW) 
elevation. The three labeled points on the Highest sea level rise curve shown in Figure 3 are the 
MHHW elevations in 2016, 2030, and 2070. These present and projected MHHW elevations were 
used to develop sea level rise flooding maps. While it is not certain that the Highest scenario will 

 
 
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accurately predict future sea levels, it is the safest scenario to plan for and it provides the most 
flexibility as a planning tool. 
 
   
 
Figure 3 - Daily High Tide (MHHW) with Sea Level Rise Factored In 
 
Heavy Precipitation 
A robust set of measures were used to develop climate change projections for heavy rainfall in 
Waterford to manage the uncertainties inherent in projections. Two different climate projection 
data sources were evaluated, which rely on different downscaling methods. One source was the 
USDOT CMIP5 Climate Data Processing Tool, and the other was the University of Idaho MACA 
Statistically Downscaled Climate Data from CMIP5. The University of Idaho data more closely 
reproduced the rainfall design storms from NOAA Atlas 14 for the baseline period. In addition, the 
downscaled results are provided at a higher resolution than the USDOT data, meaning they are 
more localized. Based on these factors, University of Idaho data was used to develop Waterford’s 
heavy rainfall projections. 
 
1.4
2.0
4.6
1990
2000
2010
2020
2030
2040
2050
2060
2070
2080
2090
2100
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
9.0
MEAN HIGHER HIGH WATER 
(MHHW) ELEVATION (FT. NAVD88)
Highest SLR
Intermediate-High SLR
Intermediate-Low SLR
Observed

 
 
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Figure 4 - Baseline and 24-Hour Design Storms Projected Rainfall 
  
Figure 4 above shows the baseline 10-year, 25-year, and 100-year 24-hour design storms from 
NOAA Atlas 14 and the projected future design storms for Waterford. Note that the baseline 100-
year storm is roughly equal to the 25-year storm in 2070. That is a four-fold increase in the 
frequency of these very heavy rainfall events. Similarly, the present 25-year storm is roughly equal 
to the 10-year storm in 2070. 
 
B. 
COASTAL FLOODING 
The Town of Waterford is highly vulnerable to coastal flooding and to the longer-term impacts of 
sea level rise and increasingly extreme storm surge.  
The vulnerability assessment for Waterford utilized existing information available from Woods 
Hole Group and dynamic models developed by the United States Army Corps of Engineers. 
These models incorporate the dynamic factors of tides, waves, winds, storm surge, and sea level 
rise and extend throughout all the water bodies and rivers surrounding Waterford.  
The model results were used to generate flooding probabilities and associated water depths, and 
flooding pathways, for Waterford under current day conditions as well as future sea level rise 
scenarios in 2030 and 2070. Additionally, an analysis was conducted to evaluate the change in 
Mean Higher High Water (MHHW) expected in 2030 and 2070 (no hydrodynamic modeling was 
required for the MHHW increase assessment). Flood extents, depths, and probabilities are 
illustrated on a series of GIS-based inundation maps. 
The results of simulations for 2016, 2030 and 2070 were used to generate maps of potential 
flooding probabilities and associated water depths throughout Waterford. Two different map types 
are produced. 
 
Percent Risk of Flooding Maps - These maps can be used to identify locations, structures, 
assets, etc. that lie within different flood risk levels. For example, a building that lies within 
the 20% flood exceedance probability zone would have a 20% chance of flooding in any 
10-Year
10-Year
10-Year
25-Year
25-Year
25-Year
100-Year
100-Year
100-Year
0
4
8
12
Baseline
2030
2070
Precipitation Depth (in)

 
 
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year under that climate projection (e.g., 2030-timeframe). Stakeholders can then 
determine if that level of risk is acceptable, or if some action might be required to adapt. 
 
 
Depth of Flooding Maps – These maps show the estimated difference between the 
projected water surface elevation for a given percent risk of flooding and existing ground 
elevation derived from the 2014 Sandy LiDAR (Light Detection and Ranging) survey.  For 
this study, we produced Depth of Flooding Maps for the 1% Probability of Exceedance 
which has approximately a 100-year recurrence interval. 
 
Depth of flooding maps were also developed for the effects of sea level rise alone, which do not 
include any effects from storm surge.  These maps were developed as “bath-tub models” by 
creating a planar water surface consisting of the predicted sea level rise (global SLR plus land 
subsidence) for the years 2030 and 2070 plus the current Mean Higher High Water (MHHW) 
elevation. 
The following town-wide coastal flood maps can be found in Appendix A: 
 
Present, 2030, 2070:  Percent probability of flooding maps (total of 3) 
 
Present, 2030, 2070:  Depth of flooding for 1% (100-year) storm maps (total of 3) 
 
Present, 2030, 2070:  MHHW depth of flooding maps (total of 3) 
 
More detailed flood map books can be found on the Town’s website at the following link:   
 
http://www.waterfordct.org/planning-development/pages/climate-change-vulnerability-risk-
assessment-and-adaptation-study 
 
C. 
RIVERINE FLOODING 
The Town of Waterford is already experiencing riverine flooding, which will likely become more 
severe with climate change. The following flood maps, included in Appendix A, assess the 
probability of riverine flooding: 
 
Riverine flooding: Present FEMA, 100-yr 2030 and 2070 (total of 3 maps) 
 
Riverine comparison: Present FEMA, 2030 and 2070 comparison (1 map)  
 
Comparison of coastal and riverine: present, 2030 and 2070 maps that shows difference 
in extent between the 1% probability of coastal flooding and the 100-yr riverine flooding (3 
maps) 
The riverine flood mapping analysis focused on the eight drainage basins in the Town of 
Waterford:  
 
Hunts Brook 
 
Jordan Brook 
 
Latimer Brook 
 
Niantic River 
 
Oil Mill Brook 
 
Southeast Shoreline (East) 
 
Southeast Shoreline (West) 
 
Thames River.  

 
 
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These same drainage basins were also the focus of the Town’s 2013 FEMA Flood Insurance 
Study (FIS). 
Peak flood flows for seven of the eight drainage basins were calculated using the CTDOT 
standard USGS Regression Equations (CTDOT Drainage Manual Chapter 6, 2000) for 10-, 25- 
and 100-yr recurrence intervals for present, 2030 and 2070. These regression equations were 
developed from 10-45 years of records from stream gaging stations in Connecticut used to predict 
a stream’s capacity during storm events. These regression equations were selected to be 
consistent with the 2013 FIS, because detailed riverine flood modeling is outside the scope of the 
current study.  
Peak flood flows were calculated using the following parameters: 24-hr rainfall depth, drainage 
area, stream length, streambed slope, and percent drainage area underlain by coarse-grained 
stratified drift. Rainfall depths were based on climate change projections for various 24-hr design 
storms developed as part of this current study. The drainage area and stream length for each of 
the drainage basins were estimated using GIS. If a watershed lay partially outside of the Waterford 
Town boundary, a ratio of the area within the Town line to the total watershed area was used. 
Streambed slopes within each watershed were calculated from corresponding profiles provided 
in Vol. 3 and 4 of the FEMA 2013 Flood Insurance Study. If profiles were not available in the FIS, 
elevations were determined from 2-ft contours (downloaded from CT-DEEP website) using GIS 
waterbody boundaries and average slope calculated along the stream length. 
Results of the above analysis estimate that peak flood flows in the rivers increase by 
approximately 12% (2030) and 34% (2070) for the 10-year storms, 10% (2030) and 26% (2070) 
for the 25-year storms, and 7% (by 2030) and 26% (by 2070) for the 100-year storms.  
The 100-year peak flood flows were then used to determine the corresponding depths of flow for 
present, 2030 and 2070 based on an empirical relationship that was determined and used by 
FEMA in a nationwide study. The percent change in depth of flow for the 2030 and 2070 100-year 
flood, in relation to present, was estimated, and the same ratio was applied to determine the 
change in existing and future 100-year flood elevations, or in other words, determine the 100-year 
riverine flood elevation by 2030 and 2070. The change in the 100-year depth of flow between 
present and future scenarios was also used to determine the corresponding change in the 100-
year floodplain area (referred to as the Special Flood Hazard Area - SFHA). This is defined on 
Flood Insurance Rate Maps as the area inundated by the 100-year, or 1% annual chance flood.  
Results of these analyses estimate that the 100-year flood elevation and 100-year floodplain area 
increase 3-4% by 2030 and approximately 10% by 2070, compared to present FIS elevations.   
This change in extent of the SFHA by 2030 and 2070 was mapped in GIS by proportionally 
increasing the area of the existing SFHA and by determining the intersect of the future SFHA with 
the projected 100-year flood elevation for 2030 and 2070. For existing FEMA 100-year flood 
zones that do not have a flood elevation defined, the extents of the future SFHA areas were 
mapped by only proportionally increasing the present SFHA areas by the change in present and 
future depths of flow.  
A limitation of this approach is that it is mainly applicable in areas that are relatively flat and do 
not have abrupt slope changes in the vicinity of the floodplain. This is true for most of the drainage 
basins, except the upstream reaches of Jordan’s Brook. However, considering the scale of this 
present study, we believe that this level of approximation is appropriate. If critical vulnerabilities 

 
 
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are discovered in these areas, the Town may wish to carry out a more refined analysis of those 
areas in future studies. 
D.  RESULTS 
Limitations 
The sea level rise and storm surge predictions made in this report are based on some of the most 
recent developments in the science of regional climate change.  However, it should be noted that 
the scenarios investigated in this limited study represent only some of the possible scenarios and 
combinations of sea level rise and storm surge.  It should also be noted that there are many 
uncertainties involving the science of climate change.     
The flood maps in Appendix A show flood levels over land only.  For this level of study, it was not 
possible to create accurate 3D modeling of every building to show how flood waters would actually 
flow around or through buildings.  For example, if a building is raised on pilings, water could be 
covering the land below the building footprint, but not actually touching the occupied first level of 
the building.  The intent of the inundation maps is to illustrate the impacts, extent, and general 
water depths of potential sea level rise and storm surge scenarios, but not to indicate any specific 
damage scenarios for a particular building or structure. 
Information shown on the coastal flood maps illustrates predicted flooding resulting from coastal 
flooding caused by storms (such as hurricanes and nor’easters) combined with sea level rise 
estimates developed by NOAA for the stated time periods.  These flood maps expressly do not 
include flooding attributed to wave run-up, overtopping of seawalls, and backups within municipal 
drainage infrastructure.  These flood maps shall not be used to represent the extent of 
flooding for which flood insurance is required.  
Projections depicted on these flood maps are the best judgment of Kleinfelder and the Project 
Team, but, in no way shall the flood levels depicted be interpreted as any guaranteed predictions 
of future events, and they shall only be used for general planning purposes. 
Vulnerable Areas in Waterford 
The results shown in Table 1 below identify coastal and riverine flooding exposure in different 
areas of Waterford. 
 

 
 
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Table 1 - Areas in Waterford Vulnerable to Coastal and Riverine Flooding 
 
   
 
Using flood maps and data collected to assess the infrastructure impacted allows one to consider 
both how likely a damaging flood event is, and also, when to take action regarding future 
infrastructure upgrades. Identifying vulnerable infrastructure allows the Town to prioritize 
spending of their capital funds. The Town-owned infrastructure assets that are subject to flooding 
in either or both the 2030 and 2070 scenarios are identified in Table 2 (buildings and facilities) 
and Appendix B (roadways). 
Three animated videos were created using unmanned aerial vehicle (drone) imagery and 
topography collected specifically for this project along with the project flood model results to 
illustrate the extent of possible future coastal flooding in the Quaker Hill, Ridgewood and Avenues 
areas of Waterford.  Figures 5, 6 and 7 below show “still” shots from the videos depicting the 
areas today with no flooding, and simulated flooding in 2030 and 2070 for a 1% probability (100 
year) storm and sea level rise.  Links to the videos can be found at the Town’s website: 
 
http://www.waterfordct.org/planning-development/pages/climate-change-vulnerability-risk-
assessment-and-adaptation-study 
 

 
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Figure 5 - Quaker Hill Area Looking North Along Old Norwich Road - 1% (100 Year) Coastal Floods 

 
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Figure 6 - Ridgewood Area Looking North Along Shore Drive – 1% (100 Year) Coastal Floods 

 
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Figure 7 - Avenues Area Looking South Between 1st and 2nd Avenues – 1% (100 Year) Floods 

 
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VULNERABILITIES AND ADAPTATION STRATEGIES 
A. 
METHODS 
 
The Town of Waterford owns various properties, infrastructure, 
and facilities. These assets serve important public functions, 
including public safety, transportation, wastewater, stormwater 
management, education, recreation, historic preservation, and 
environmental conservation. 
A vulnerability assessment was performed on Town-owned 
assets. The purpose was to determine which assets may 
experience flooding in the future, what the resulting impacts 
could be, and which assets could be adapted to minimize the 
effects of flooding. 
Once priority vulnerabilities were identified, adaptation 
strategies were developed. Adaptation strategies include 
physical, regulatory, and operational changes that can reduce 
the impact of flooding on important public functions. 
Data Collection 
Kleinfelder reviewed as-built drawings and various local and state reports and records provided by the 
Town of Waterford for infrastructure assets.  The Town also provided Geographic Information Systems 
(GIS) layers for some assets.  Kleinfelder staff then made several field visits with Town personnel to 
visually observe and photograph critical assets.  If these assets were not on the GIS layers provided 
by the Town, they were added in.  Asset information included their location, condition, use, importance, 
and past flooding issues.  
The following resources, some provided by Town staff, were reviewed as part of the data collection 
effort:  
 
GIS data from the Town of Waterford, CT, UConn Connecticut Environmental Conditions 
Online, Connecticut DEEP, US Census Bureau, FEMA, and Esri. 
 
Hazard Mitigation Plan Update Annex for the Town of Waterford. Town of Waterford. 2012. 
 
Wastewater Pump Station Flooding Vulnerability Evaluation for the Waterford Utility 
Commission. Wright-Pierce. 2016. 
 
Wastewater Facilities Plan Update. Waterford Utilities Commission. 2011. 
 
Elevation certificates for various wastewater pump stations and Quaker Hill Fire Station. 
 
Adapting to Coastal Storms and Flooding: Report on a 2014 Survey of Waterford Residents. 
Clark University and The Nature Conservancy. 2015. 
 
Town of Waterford Hazards and Community Resilience Workshop Summary of Findings. The 
Nature Conservancy. 2015. 
 
Evacuation Routes Map, Emergency Planning Zone for Millstone Station. 
 
Engineering drawings for various bridges. 
Town Assets: 
 
Roadways and bridges 
 
Wastewater pump stations 
 
Fire stations 
 
Police stations 
 
Schools 
 
Town offices  
 
Maintenance facilities 
 
Historic properties 
 
Recreational facilities 
 
Beaches 
 
Marshes/Wetlands 

 
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 
Map and narrative of flood vulnerability from prior storm events in 1982, 2010, and 2012 in 
Waterford, CT. Town of Waterford. 
 
Map of drainage issues during the 1970s-1980s in Waterford, CT. Town of Waterford. 
 
Flood Insurance Study, New London County, Connecticut. Federal Emergency Management 
Agency. 2013. 
 
Town of Waterford Zoning Map  
 
Beebe Brook watershed map 
 
Assessing the Impacts of Hurricane Sandy on Coastal Habitats. National Fish and Wildlife 
Foundation. 2012. 
 
A Salt Marsh Advancement Zone Assessment of Waterford, CT. The Nature Conservancy. 
2013. 
 
Stabilization of Goshen Cove Outlet Feasibility Study at Harkness Memorial State Park, 
Waterford, CT. Woods Hole Group. 2015. 
 
Vulnerability Assessment 
The coastal and riverine flooding maps developed for the project were overlaid on the asset maps in 
GIS. Each asset was assessed to determine the type, probability, and depth of flooding that the asset 
could be exposed to in present, 2030, and 2070 scenarios. The impacts from these flooding conditions 
were evaluated using information gathered in the data collection process. 
In some cases, additional field work was carried out to verify vulnerabilities. Buildings and their utilities, 
for example, are sometimes elevated above predicted flood levels. Though maps may show them as 
being located in a flood zone, they may not be subject to significant flood damage.  
After an initial screening to determine assets vulnerable to flooding, surveyors from Martinez Couch & 
Associates surveyed critical elevations of wastewater pump stations and other potentially vulnerable 
buildings. To make the most of this field work, the surveyors created new elevation certificates for 
several pump stations that are raised above ground levels.  
 
Risk-Based Prioritization 
The identified vulnerable assets were further prioritized based on 
their levels of risk. Risk takes into account both the probability 
(likelihood) of an asset being impacted, and the resulting 
consequence of that impact.  
Decision-makers are encouraged to consider both of these 
factors when setting priorities for limited funding. That way, when 
faced with limited resources, they can focus on addressing 
issues that are relatively more likely and more consequential 
than others. 
 
 
 

 
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