PORTLAND — Resurfacing of the Deering Oaks pond floor has moved out of a City Council committee after plans to add vegetation in a ravine area were added to the proposal.
A compromise proposed by the city Public Services Department and engineers Woodard & Curran received a favorable recommendation Nov. 19 from the Transportation Sustainability and Energy Committee, led by Councilor David Marshall.
The city Planning and Historic Preservation boards will also review the proposed pond work, Public Services Director Michael Bobinsky said Nov. 26.
The project would be funded with a $611,000 U.S. Environmental Protection Agency grant and $500,000 in city fiscal year 2013 capital improvement bonds. But it drew initial objections from people concerned the plans would harm the pond habitat, especially for ducks.
The work to restore the ravine area, which Bobinsky said could include removing some of the stone lining the channel, is expected to add $25,000 to the project cost. Once completed, maintenance of the pond will cost $59,000 annually, according to the project presentation.
The plan to remove sediment from the pond floor and replace the surface with concrete mats and gravel was presented to the committee on Sept. 17, and had the blessing of the nonprofit Friends of Deering Oaks Park.
But a group called Save the Deering Oaks Ducks said the work could harm the habitat and that the city was not doing enough to stop the flow of contaminated water into the pond.
The committee ultimately postponed its recommendation.
Following the Sept. 17 meeting, Bobinsky said a landscape architect and wetland biologist working independently from engineers at Woodard & Curran were engaged to consider more alternatives.
The restored wetlands setting will extend back from the pond toward a footbridge and try to stabilize the banks while adding plantings. The estimated $25,000 cost also includes design and permits, Bobinsky said.
“We are pleased to reach a compromise that seems to be workable,” he said.
The revised Woodard & Curran presentation on pond maintenance still asserts pond resurfacing is the most viable and cost-effective method to maintain water quality, and remove litter and vegetative growth.
Removing the retaining walls and adding natural plantings to the entire pond would mean possible removal of the duck house and end ice skating on the pond, according to the report.
The pond is drained twice annually by the Public Services Department, and was last dredged in 2010. At least six tons of accumulated sediment was removed, and dredging could be required once a decade if the pond is left in its current condition, according to the report.
The 55-acre park between Deering and Forest avenues was acquired by the city about 125 years ago. The 3.5-acre man-made pond was created after sewer construction on State Street led to damming nearby tidal flats, according to the report. The current pond water sources include storm water outflows, groundwater and some water from the Portland Water District.
The 2008 elimination of a combined sewer overflow diverted waste water to the Portland Water District treatment plant near East End Beach and enhanced pond water quality, Bobinsky said, but the pond is still vulnerable to overflows from the Deering Avenue area.
The bottom of the pond at Deering Oaks Park could be replaced with concrete mats and gravel, a restoration seen as a cost-effective way to manage the pond by city officials.
The outlined area of the pond in Deering Oaks Park could be restored as a natural wetlands while the remainder of the pond’s bottom will be concrete mats and gravel.