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Commission approves Skookum 2 minor subdivision after discussion about accretion, floodplain and out-of-date benchmarks
Summary
The Petersburg Borough Planning Commission approved the Skookum 2 minor subdivision at 811 Sandy Beach Road and discussed shoreline accretion, the lack of recent local tide benchmarks, and the implications for floodplain mapping and elevation certificates.
The Petersburg Borough Planning Commission approved the Skookum 2 minor subdivision at 811 Sandy Beach Road after addressing questions about shoreline accretion and floodplain mapping.
A commissioner raised concerns about a portion of the plat that appeared close to a property line and about whether a portion of the property lies within a flood hazard zone. A surveyor or staff member who spoke at the hearing explained that portions of the property are in accreted land and that Petersburg lacks up-to-date local tidal benchmarks. He said the most recent semi-official benchmarks were established by the U.S. Army Corps of Engineers in 2008 for North Harbour and earlier tide readings date to 1978.
“That’s what’s going on,” the speaker said, and described tracking local uplift and using local tide readings to estimate the current mean high-water line. He said he has been recording local tide data and using those measurements to establish closer benchmark values; he told the commission he has observed “it’s pretty close to almost a half an inch a year of uplift,” and that accretion since 2001 has added land along the shoreline.
Commissioners asked whether a note stating that a portion of the lots lie within the floodplain could be placed on the plat; staff agreed that the note can be added. The speaker said he intends to cite his own local readings on future elevation certificates and noted FEMA previously accepted Corps of Engineers values for the area. The commission approved the subdivision with the staff findings and conditions of approval.
The discussion highlighted local technical uncertainty: the record shows the commission and staff relying on historical Corps of Engineers and NOAA information and locally gathered readings to determine accreted areas and mean high-water lines. Staff said they can add a plat note indicating floodplain extent where required; the record does not show additional formal actions to request new federal benchmarks or to alter FEMA mapping.
