Of all the East Coast port upgrade programs aimed at luring cargo traffic from the newly widened Panama Canal, the Savannah Harbor Expansion Project (SHEP) may well be the most ambitious, and complex. Elements of the joint effort by the U.S. Army Corps of Engineers’ Savannah District and the state of Georgia—originally estimated to cost $706 million, but subsequently increased to $973 million—range from 40 miles of channel dredging and new water quality mitigation facilities to the addition of an upstream fish passage and the recovery of a Civil War-era relic.
The project’s intricacies—and approximately half its cost—represent a strategy developed over 17 years to mitigate myriad environmental impacts from dredging nearly 24 million cu yd of material to lower the Savannah River’s shipping channel by 5 ft, creating a mean low-water depth of 47 ft suitable for larger, deep-draft vessels to access Savannah’s port facilities year-round.
Not surprisingly, defining and crafting that strategy among multiple agencies demanded the same degree of balancing as the fragile environment it sought to protect, says Corps spokesman Russell Wicke. He cites a 2008 internal review that identified the need to reassess several of SHEP’s economic, engineering and environmental aspects, forcing a delay in starting construction.
“If the output of one study component changes, that change alters something in the analyses contained in the other two,” explains Wicke. “These revisions were time consuming, but were vital to the report’s credibility when it was reviewed by independent panels—both inside and outside of the Corps.”
Positive progress
It wasn’t until September 2015, with the permits finally in place, that the Corps could give the go-ahead to Great Lakes Dredge & Dock Co. of Oak Brook, Ill., to begin deepening SHEP’s outer harbor under a $134.5-million contract. The 18.5-mile-long project includes extending the entrance channel seven miles into the Atlantic Ocean. The contractor is using a mix of cutter suction and hopper dredges.
The project team scheduled dredging to coincide with the beginning of SHEP’s most technically complex mitigation project—a $99.9-million dissolved oxygen (DO) injection system designed to maintain the river’s oxygen levels, particularly during seasonal low-flow periods.
该系统从20多种潜在技术中选择以成本效益维护港口预淘汰的氧气水平，该系统利用Speece Cone技术，该技术将大量的水吸入锥形设备，从而迫使氧气进入水中。该系统每天将从河中抽出约1.5亿加仑的水，然后再将富含氧气的水返回到河流中。
佛罗里达州梅特兰的CDM构造函数开始在2016年4月在两个地点建造DO系统，这是由于一名失败的竞标者抗议导致了两个月的延迟。Robert Gilbert, CDM vice president, says the firm’s crews are using a crawler crane with 160 ft of boom to install 12 22-ft-tall, 12-ft-dia stainless steel Speece Cones at two sites, with a coffer system of sheet piling with beam and whaler construction protecting work areas from waves kicked up by the large cargo vessels.
“This coffer system was significantly more robust than a typical coffer system,” Gilbert says.
CDM Constructors endured a less successful battle against water intrusion in October 2016, when Hurricane Matthew delivered 11 in. of rain that subsequently flooded an intake structure at the downriver Speece Cone site and washed out an upriver site’s access road. Crews spent a week pumping out the water and cleaning the intake structure before work could resume.
“There was only a minor delay to the overall construction schedule,” Gilbert says, adding that the DO system is scheduled to be operational by the end of 2017.
Another safeguard against Savannah Harbor’s low-flow conditions is a 17-acre, 97-million-gallon raw water storage impoundment. The $40.2-million reservoir, which ties into the 48-in.-dia mains linking Savannah’s treatment plant and raw water intake, will also protect the city’s drinking water supply from seasonal chloride increases.
Beginning in mid-2016, Thalle Construction, Hillsborough, N.C., started moving approximately 440,000 cu yd of material to create the reservoir’s 29-ft-high walls and a 3,400-ft-long dike, both of which topped out in early April.
As at the DO site, Hurricane Matthew’s rains required some re-building of previously completed earthwork. But the biggest challenge was a single access point to the 40-acre site, which required routing dozens of dump-truck loads each day through a residential neighborhood, says Thalle project manager Paul DiMeo.
“We repaved a one-mile section of road before we got started to be sure it could handle the traffic, and took other measures to limit any effects on the residents,” DiMeo says. Installation of a 16mm thick HDPE liner and construction of pump and treatment facilities should be complete later this summer, allowing the Corps to begin filling the reservoir.
Also scheduled for completion this year is removal of a 1970s-era tidegate structure originally constructed to help reduce shoaling in the Savannah River’s main channel. That $21.3-million project, being performed by the Miami-based DeMoya/Continental Joint Venture, is the first step in a three-part plan to redirect the flow of saltwater to significantly reduce its impact on several hundred acres of freshwater marsh, determined by the Corps as the highest priority wetland natural resource in the Savannah River Basin.
Demoya/Continental将在乔治亚州和南卡罗来纳州的3,000英尺海岸线上拆除3,200吨混凝土和650,000立方英尺的土壤，并在3,000英尺的海岸线上放置约130,000吨的岩石。
Yet even with all the new infrastructure, Wicke considers the recovery of the sunken Civil War ironclad ship CSS Georgia, a designated historic site, to be one of SHEP’s most complicated elements. Scuttled as Union troops advanced on Savannah in 1864, the vessel lay for decades at the bottom of the Savannah River adjacent to the existing shipping channel. Recovery of the wreck has required divers to perform complicated rigging work in a dark-water environment during limited periods due to the area’s tides.
尽管自2014年以来，考古学家已经从船只中恢复了1,700多个小文物，但当船只的两部分证明太大而无法用可用的起重机去除时，打捞工作就停滞了。他们的历史价值也排除在将它们分为较小的碎片中。
“We plan to return to that work this summer with larger equipment that will allow us to raise those remaining sections onto a barge deck for documentation and collecting imagery,” Wicke says. The Corps will then develop a long-term conservation strategy.
An Uncertain Future
尽管SHEP的最初建设在头两年中进行了相对平稳的运行，但4月初出现了云，当时该军团宣布该计划的预期成本已从原始估计中增长了近40％。
Contributing to the increase, Wicke says, was the need to fund many of the contracts incrementally, a factor further complicated by the project’s high number of “one-of-a-kind” features. Demand for industrial dredging services increased significantly as well.
Wicke says the program’s original five-year time line, including completing other elements currently in design—such as dredging Savannah’s Inner Harbor, adding a $35-million fish passage at the New Savannah Bluff Lock and Dam and flow rerouting through tidal marshlands—will have to be extended until at least 2020 as funding becomes available.
他说：“当然，这有条件，包括每年需要获得最佳资金，合同奖励，避免其他抗议活动，没有任何改变或不可预见的情况。”谢普。
虽然目前不确定如何以及何时谢普funding issues will be resolved, the Georgia Port Authority expects to be ready for the program’s completion, having made a significant investment in its landside facilities. By this summer, the Port of Savannah will have four new Finnish-built cranes capable of serving the next generation of Panamax container vessels, with another four units scheduled to be commissioned in 2018.
GPA发言人爱德华·富尔福德（Edward Fulford）说，总共有30台起重机工作近10,000英尺，“该港口将能够每小时处理1,000多个容器移动。”
除了新的集装箱存储区域外，GPA还在佐治亚州西北部42英亩的内陆码头上破裂。旨在将GPA市场扩展到其他东南州的其他州，预计388英里的直接货运铁路连接将使亚特兰大卡车的交通减少50,000个行动。
“A greater reliance on rail at the GPA as Savannah’s container volumes grow will help avoid delays and ease traffic in congested areas,” Fulford says.
