Staff file photoTwo crews that ran up on the sand bar at Conomo Point try to rejoin the Essex River Race in May 2013. Officials have said realigning and dredging the river channel could prevent such circumstances in the future.

Study: Cities, town should mull buying dredge equipment

ESSEX, MASSACHUSETTS — Should North Shore communities consider buying their own regional dredging equipment or outsource the work to a private company?

This was the question contemplated at Friday’s Northeast Coastal Coalition gathering at Essex Town Hall. Representatives from various coastal Essex County municipalities met with NCC Chairman and state Senate Minority Leader Bruce Tarr to discuss a recently completed study on the issue by Woods Hole Group, an international environmental consulting group based in Bourne.

The study was conducted “to maintain navigable depths in places such as channels and mooring areas,” according to Tarr’s office. It was paid for through a $50,000 state grant administered by the Merrimack Valley Planning Commission, which managed the study.

Leading the study was Woods Hole Group coastal scientists Adam Finkle and Katherine Lavallee. They based their research on historic dredging data from Gloucester, Rockport, Manchester and Newburyport harbors, as well the upstream Merrimack River, and the Ipswich, Essex and Annisquam rivers, all federal-managed waterways. Through these records, they estimated around 42,800 cubic yards of material is dredged per year from these areas. In addition, about 351,000 cubic yards of sediment is available to be dredged from them currently, according to surveys conducted by the U.S. Army Corps of Engineers. These figures did not factor in 21 other waterways within the regional area, as there were no federal records documenting past dredging projects in them.

At Friday’s meeting, the two scientists presented three possible courses of action for the municipalities:

Purchase a hydraulic cutter suction pump. The machine excavates and transports soft sentiment using a variety of pumps and a rotating cutter head. There would be a one-time payment of $1.8 million and $700,000 in annual payments for operational costs. For this option to be fiscally feasible, Woods Hole Group recommended that around 57,000 cubic yards of sediment be dredged per year.

Purchase a hopper dredging ship, the most expensive up-front option. Such a ship trails large suction pipes to pick up soft sediment. It costs $10.5 million to acquire on top of $1.1 million in annual operational costs. With it, the region would need to dredge around 104,500 cubic yards of sediment per year for it to pay off, according to Woods Hole Group.

Finkle said he believes there is enough sediment in the unstudied waterways to meet these annual quotas. The definite amount, however, would require more research.

Hire a private dredge contractor. Woods Hole Group said contractors can charge anywhere from $10 — an “extreme” low estimate, according to Finkle — to $40 per cubic yard of dredging. If the NCC wished to sign a three-year contract with a contractor to remove the 351,000 cubic yards of material in the waterways right now, WHG estimates pumping costs could range from $1.16 million to $4.68 million. An estimated annual $580,000 charge would also be required for mobilization/demobilization and pre- and post-dredge survey costs.

Pros and cons

WHG found purchasing dredging equipment would “(reduce) uncertainty and (prevent) scheduled projects from being delayed” and “(allow) individual municipalities to exercise a high degree of autonomy in managing waterways” under market averages. However, “purchasing and operating dredging equipment is a long-term investment” that would require “a sufficient volume of material annually for the lifetime of the dredging equipment.”

Projects that carry “significant amounts of gravel or cobble” would not work using hydraulic or hopper dredging equipment. In addition, owning the equipment would expose the municipalities to liabilities and risks.

Likewise, hiring contractors would “allow municipalities to utilize the best available dredging technology and equipment” and “avoid the need to recruit, train and retain a skilled dredge crew.” But, it “would not allow municipalities to retain fully depreciated assets, which may retain value” and is “contingent on identifying, permitting and dredging a sufficient volume of material annually to ensure a cost-effective dredge rate.” Rates fluctuate, too, as is “ensuing equitable access to private contracting services.”

Going forward, Woods Hole Group recommended the Northeast Coastal Coalition form a regional dredge steering committee to further evaluate the three plans available. Also, it encouraged the coalition to find more information on permitting and acquire more environmental data on the waterways.

Tarr dismissed the group around noon, saying there was “a lot to digest” from this presentation. The next Northeast Coastal Coalition meeting is not scheduled at the moment.

Michael Cronin may be contacted at 978-675-2708, or mcronin@salemnews.com.

See Salem News article . . .