Welcome to the Flood Zone is a nationally distributed resource for those interested in flood zone issues, land surveying, real estate, history, and educational opportunities. This newsletter has been proudly featured by the Association of State Floodplain Managers, the National Society of Professional Surveyors, and the Maine and New Hampshire Floodplain Management Programs. Please feel free to share with your friends and colleagues!

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In this Issue of Welcome to the Flood Zone:

Maine NFIP Corner: A message from Sue Baker, the State NFIP Coordinator - "Use of Fill in the Flood Hazard Area"
In the News: "Floods Are Increasing in Supposedly Low-Risk Areas"
Resources: "Green Infrastructure" and "Building Codes Save: A Nationwide Study of Loss Prevention"
Climate Corner: "New US Weather Data Shows ‘Obvious’ Effects of Climate Change"
Real Estate Corner: "Stanford Researchers Reveal that Homes in Floodplains are Overvalued by Nearly $44 Billion"

Banner Image: The north fork of Turkey Creek overflows its banks in Farragut, Tennessee, on Sunday, March 28. Image from "Nashville Flash Flood Leaves Six Dead and Dozens of Homes and Businesses Destroyed" (CNN, 2021)


Maine NFIP Corner

Sue Baker, CFM, State NFIP Coordinator

There are many important regulations guiding the use of fill in a Special Flood Hazard Area, and now you can find them all in one place! See below to learn more.

For future reference, this information is also available on the Maine Floodplain Management Program website.

Use of Fill in the Flood Hazard Area

Collated by Sue Baker, State NFIP Coordinator

Floodplain Management Requirements (FEMA-480) (page 5-28)
Where fill is the method of choice, it should be properly designed, installed in layers and compacted. Simply adding dirt to the building site may result in differential settling over time.

The fill should also be properly sloped and protected from erosion and scour during the flooding. To provide a factor of safety for the building and its residents, it is recommended that the fill extend 10-15 feet beyond the walls of the building before it drops below the BFE.

FEMA Technical Bulletin 10-01 Ensuring that Structures Built on Fill In or Near Special Flood Hazard Areas are Reasonably Safe from Flooding, Placement of Fill (page 5)
Properly placing fill requires an understanding of soil mechanics, local site conditions, and the specific characteristics of the soils being placed, the methods used to place and compact fill, and soil testing procedures. Standard engineering and soil mechanics texts cover these subjects in detail. The performance of these filled areas should consider, but is not limited to, the following:
• the consolidation of the fill layers and any underlying layers
• the effect of this consolidation on either excessive settlement or differential settlement
• how the permeability of the soils affects water infiltration on any structures built on the site.

ASCE 24-14 Flood Resistant Design and Construction
2.2 Development in Floodways
Structures and fill shall not be constructed or placed in floodways unless it is demonstrated that those structures and fill will not (1) increase the flood level during occurrence of the base flood discharge, and (2) reduce the conveyance of the floodway.

If the design flood elevation has been determined and a floodway has not been designated, structures and fill shall not be constructed or placed unless it has been demonstrated that the cumulative effect of proposed structures and fill, combined with all other existing development, will not increase the base flood elevation more than one foot.

2.4.1. Structural Fill
Structural fill shall not be used unless design and construction of the structural fill accounts for (1) consolidation of the underlying soil under the weight of the fill and the structure, (2) differential settlement due to variations in fill composition and characteristics, and (3) slope stability and erosion control during conditions of the design flood.

Fill used for structural support or protection shall be suitable for its intended use. Structural fill used to support or protect a structure shall be placed in lifts of not more than 12-inch loose thickness, with each lift compacted to at least 95% of its maximum standard proctor density (ASTM2012f) or 90% of its maximum modified proctor density (ASTM2012e), unless otherwise required by the building code or specified in a geotechnical investigation report or a soils engineering report prepared by a qualified registered design professional and approved by the authority having jurisdiction.

The side slopes of structural fill shall be no steeper than 1 on 1.5 (vertical/horizontal). Structural fill, including side slopes, shall be protected from erosion under flood conditions up to and including the design flood.

Coastal High Hazard Areas (V Zones) and Coastal A Zones
4.5.4. Use of Fill
Fill material used for structural support shall not be permitted in Coastal High Hazard Areas (and coastal A Zones if your community has adopted the ICC building codes). Placement of non-structural fill for minimal site grading and landscaping and to meet local drainage requirements shall be permitted. Placement of nonstructural fill under and around a structure for dune construction or reconstruction shall be permitted if an engineering report documents that the fill will not result in wave run-up, ramping, or deflection of floodwaters that cause damage to structures.


In the News

Floods Are Increasing in Supposedly Low-Risk Areas

By: Thomas Frank, E&E News, April 13, 2021

More than one-third of the claims payments last year were for properties located outside areas that FEMA considers at the highest risk of flooding. That continues a trend of flood damage occurring in supposedly low-risk areas and raises concerns about both the accuracy of FEMA’s flood maps and climate change making flooding more widespread and less predictable.

In the past decade, 36% of the flood claims were for properties outside the so-called 100-year flood zone.

In the 1990s, for example, just 24% of flood claims were for properties outside a zone where FEMA says there is a 1% annual chance of flood damage.

Click here to read the full article.




Bioretention systems capture and store stormwater runoff and pass it through a filter bed of engineered soil media composed of sand, soil, and organic matter. Rain gardens are a common example of bioretention. Image from "Types of Green Infrastructure" (Dept. of Energy & Environment, 2021)

Green Infrastructure

Green infrastructure is a cost-effective, resilient approach to managing wet weather impacts that provides many community benefits. While single-purpose gray stormwater infrastructure—conventional piped drainage and water treatment systems—is designed to move urban stormwater away from the built environment, green infrastructure reduces and treats stormwater at its source while delivering environmental, social, and economic benefits.

Click here to learn more about green infrastructure from the Environmental Protection Agency.


Building Codes Save: A Nationwide Study of Loss Prevention

FEMA’s landmark study, “Building Codes Save: A Nationwide Study,” shows that modern building codes lead to major reduction in property losses from natural disasters. The FEMA report calculates losses from three types of natural hazard (earthquakes, flooding, and hurricane winds) for each state and Washington, D.C.

Click here to learn more from FEMA's website.

Click here to watch a brief YouTube video called "Mitigation Matters: Building Codes Science Short Presentation."


Climate Corner

New US Weather Data Shows ‘Obvious’ Effects of Climate Change

Al Jazeera, May 4, 2021

The United States is getting warmer and parts of it are getting wetter, according to weather data released on Tuesday by the National Oceanic and Atmospheric Administration (NOAA).

NOAA, a US scientific agency that tracks weather data, has released a “new normals” set of data that tracks changes in the US climate. The report details data from 1991 to 2020 and updates what is defined as climate normals over the past 30-year period – allowing weather conditions to be put into “historical context”.

Click here to read the full article.

for sale

Real Estate Corner

Stanford Researchers Reveal that Homes in Floodplains are Overvalued by Nearly $44 Billion

By: Rob Jordan, Stanford Woods Institute for the Environment, April 26, 2021

Buyer beware: Single-family homes in floodplains – almost 4 million U.S. homes – are overvalued by nearly $44 billion collectively, or $11,526 per house on average, according to a new Stanford University-led study(link is external). Published in Proceedings of the National Academies of Sciences, the study suggests that unaware buyers and inadequate disclosure laws drive up financial risks that could destabilize the real estate market. The threat is likely to grow as climate change drives more frequent extreme weather.

Click here to read the full article.


June Flood Funny


Image by Alex Hallatt, March 12, 2011

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