SHEP's water impoundment nearly 30% complete

Photo By Russell Wicke | A backhoe loader fills a toe drain with coarse sand as two workers from Thalle Construction level the fill material on Sept. 8, 2016. The sand is fine enough to maintain the integrity of the ditch but coarse enough to all water to pass through. The ditch runs around the perimeter of the Raw Water Storage Impoundment, a feature of the Savannah Harbor Expansion Project that mitigates impacts to city water.  

PORT WENTWORTH, GA, UNITED STATES

09.13.2016

Story by Russell Wicke 

U.S. Army Corps of Engineers, Savannah District

Now almost 30 percent complete, the raw-water storage impoundment dike walls are currently four feet above ground level. With a circumference of two-thirds of a mile, they will be 29 feet high, encircle 17 acres and hold 97 million gallons of water when complete.

As part of the Savannah Harbor Expansion Project (SHEP) this water impoundment will be turned over to the City of Savannah as an additional source of municipal water supply to supplement water drawn from the city intake at Abercorn Creek.

Constructing the impoundment dikes involves hauling in enough soil to fill 135 Olympic swimming pools, or a material volume of approximately 440,000 cubic yards. The effort will take 40,000 round-trip dump truck runs from borrow pits in the local area.

The impoundment is part of the harbor deepening because the SHEP’s final report predicted deepening the harbor five additional feet would result in chloride increases near the city’s water intake.

Since the increases would come from salt water moving further upstream, the increases in chloride would only occur at high tides during summer drought conditions.

The Raw Water Storage Impoundment will mitigate the impact from increased chlorides. During periods of high tide and summer drought the city can suspend drawing water from Abercorn Creek and draw instead from the impoundment.

After a few hours pass and tides recede, the city can begin drawing water again from Abercorn Creek and refill the impoundment.

Building the impoundment is part of the $706 million harbor expansion project, known as the SHEP.

Deepening the harbor from 42 to 47 feet will enable newer and larger container ships to call on the Garden City terminal with greater ease, heavier cargoes and fewer tidal restraints than they currently experience.

• Date Taken: 09.13.2016
• Date Posted: 09.14.2016 08:53
• Story ID: 209530
• Location: PORT WENTWORTH, GA, US