GOULDSBORO — The town’s decision to challenge the federal government’s new maps designating which shoreline homes are in a flood zone and which are not appears to have paid off.
The accuracy of the mapping is critical because insurance premiums for homes in a flood zone are costly and are required for all homeowners with federally backed mortgages.
Ransom Consulting Engineers and Scientists of Portland determined that about half of the 95 to 100 homes in the areas under appeal are not in a flood zone or the base flood elevation level is lower than what was determined by the Federal Emergency Management Agency (FEMA).
“The specific value added because of the appeal is sizeable,” said Code Enforcement Officer Ed Brackett.
Leila Pike, project engineer for Ransom, said FEMA is accepting her company’s findings.
“FEMA is changing the flood zone elevations to match what we determined in our analysis,” she said.
Pike said letters with the new base flood elevations are expected to be mailed to homeowners in January 2016 and the new designations will likely become official in late spring.
FEMA undertook the remapping to determine new base flood elevation levels in the wake of Hurricane Sandy in 2012.
FEMA released its new proposed maps about one year ago.
Gouldsboro, as well as several other municipalities in Maine, voted to spend $28,000 to have Ransom conduct its own survey.
Pike, from Ransom, said FEMA anticipated “storm surges” in drafting the new maps.
“FEMA bases their elevations on deep shore waves propagating towards the shore,” she said. “They look at the wave set-up and the wave run-up. The run-up is that increase in elevation before a wave breaks.”
Pike said that following Ransom’s survey 15 homes were taken out of the flood zone and another 30 to 35 are still in the flood zone, but the base flood elevation levels are reduced.
“A reduced elevation flood zone is accounted for in insurance premiums,” she said.
Both FEMA and Gouldsboro require that homes be 1 foot above the designated base flood elevation level.
The four areas under appeal were Paul Bunyan Road in Corea, Corea Harbor, Inner Harbor in Prospect Harbor and Prospect Point.
Some homeowners on Paul Bunyan Road saw their base flood elevation drop from 19 feet down to 14 or 15 feet.
Pike said the changes are due to the additional transects — additional measurements — and added wave models Ransom included to get a more detailed look at specific areas.
In Corea Harbor, FEMA had a flood zone of 15 feet, but Ransom decreased the height to 14 and 13 feet in different areas of the harbor, Pike said.
She said FEMA based its calculations for Corea Harbor on a single transect outside the harbor.
“We used more sophisticated methods showing that the elevation will decrease as you move into the harbor,” Pike said.
The base flood elevation level in Inner Harbor decreased from 16 to 15 feet as determined by FEMA down to 15 feet and as low as 12 feet along the shore.
Pike said there was one area along Prospect Point where Ransom determined the base flood elevation was actually higher — 21 feet instead of FEMA’s 19 feet — but Ransom also decreased the level closer to shore down to 13 feet.
She said FEMA is likely to issue its finalized letter in January 2016 and institute the new flood zones sometime next year, possibly in the spring.
Pike said Ransom was not surprised by the changes.
“Before we do any analysis we look over what FEMA has done to see if it is flawed,” she said. “We have a good idea before we begin the work that we will be able to make a difference.”
Brackett, the code enforcement officer, said homeowners with federally backed mortgages and whose properties are in a flood zone will be required to buy flood insurance.
Any property determined to be in a flood zone will carry restrictions on what and how new structures can be built on the land.
“You can still build, but you are required to come up with a construction method that will mitigate the potential damage,” Brackett said.