Engineers are optimistic a flood protection system can shield the entire Schoharie County office complex above and beyond the height floodwaters reached during Tropical Storm Irene.
Plans to rebuild the Main Street complex and add flood mitigation measures came to a halt last month when the county’s recovery coordinator, William Cherry, announced initial designs put movable floodwalls nearly 2 feet below the height of last summer’s floods.
Using historical, 500-year flood levels, engineers from LaBella Associates initially drafted plans for movable flood walls that would reach 612 feet above sea level.
That was considered a serious snag because the Schoharie Creek reached 613.5 feet above sea level at the county office building and historic Courthouse when it inundated the village of Schoharie on Aug. 28.
Engineers went back to the drawing board and reported to county supervisors Friday that a modified system being designed will provide full protection reaching 10 inches higher than last year’s flood level.
As designs come closer to completion, engineers are also outlining additional flood protection plans likely to double the anticipated cost of flood mitigation that officials hope will be covered by state and federal disaster aid.
HVAC, electrical and structural work, and building repairs are already estimated to cost between $5 million and $6 million and mitigation, earlier estimated at about $3.1 million, could reach $5.5 million.
Cherry said FEMA is expected to provide flood mitigation costs up to the same level of post-flood reconstruction costs, but plans have not yet been completed and presented for approval.
LaBella Associates architect Mark E. Kukuvka outlined a host of flood-blocking plans now in the design phase that will include self-activating flood barriers, 6-foot concrete walls and an underground system requiring a wall between 10 and 20 feet deep that will form a soil barrier.
Seven sections of floodgates similar to those used at Lourdes Hospital in Binghamton — which protected the hospital against 8 feet of water last summer — would be installed around the office complex under plans now being considered.
The seven sections, about 295 feet in total, would be installed and butt up against 11 exterior retaining walls.
Kukuvka said architects are working to design the big concrete walls in a way that may be “decoratively pleasing.”
The flood gates stay at ground level and will look like a grated sidewalk but will begin moving upward when activated by water to shield the buildings, Kukuvka said.
These gates won’t rise to their full height immediately, but rather elevate only high enough to block the level of floodwater present, as little as 2 feet.
The tentative plans also call for the addition of swing flood gate doors at two entrances to the county building, fitted with rubberized sweeps to keep them watertight. Kukuvka said these doors are “not aesthetically pleasing” — they will be a bit ugly.
One of the most labor-intensive elements of the work will be a massive underground “curtain” that engineers want to install around the entire complex foundation.
The curtain is aimed at preventing groundwater seepage from entering the building, and it will require boring holes 3 to 4 feet in diameter, between 10 and 20 feet deep, around the entire circumference of the complex before filling them with a grout mixture.
The curtain will keep the soil solid between it and the county building’s foundation, Kukuvka said.
Some windows will also have to be retrofitted to ensure the building itself is floodproof.
Officials are already considering the look of the building once it’s complete, and architects are drawing plans to develop a landscaped atrium on the Main Street portion of the complex for community events.
Cherry said several details remain to be reviewed before final mitigation measures are agreed on.
The plans have to be cleared by the state Historic Preservation Office to ensure there is no impact to the historic 1870 Courthouse.
Geological studies and test borings have to be done on the soil and then FEMA has to approve the design and confirm funding.