Portland Harbor Commercial Revitalization Project

Project Overview

Boats in South Portland Harbor
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Without a reliable, well-maintained berth, with proper water depth at all tides, we do not have anything to offer the marine businesses.

— Charlie Poole, Owner, Union Wharf

Many Portland Harbor piers have not been dredged in over 70 years and are slowly filling in with sediment, decreasing water depths and causing a steady decline in available berthing for our working waterfront.

The piers have not been dredged in so long because the sediment accumulating around Portland’s piers contains modern-day pollution from storm water runoff, and “legacy contaminants” from long-departed factories and shipyards.

The presence of these contaminants prohibits sediment placement at sea, which is the most economical method of removal, and expensive alternative methods will be required.

Private and public wharf owners have been stymied by the exorbitant costs associated with the testing, dredging, and transfer of these sediments they were not responsible for contaminating. There are few placement options and, unfortunately, most are prohibitively expensive- and some have negative environmental impacts.  Wharf owners have been hesitant to spend tens of thousands of dollars on the required testing and regulatory permitting, only to find out that the sediment disposal required will be cost prohibitive.

The dredging stalemate in Portland Harbor has had significant economic and environmental consequences. To maintain their piers, owners have been forced to look at other uses for revenue, such as restaurants, hotels and office buildings, which has caused a decline to our once vibrant working waterfront.

The environmental impact is also significant.  Boat propellers and big storms can disturb the contaminated sediments, damaging water quality in the Fore River and exposing pollutants to fisheries and wildlife.

The problem only gets worse as sediments continue to accumulate.

The dredge and CAD cell  project goal is to provide the testing, engineering, and permitting required to determine a cost effective and environmentally responsible way to remove the contaminated dredge materials currently located in Portland Harbor.

Boats at the dock in Portland Harbor Maine

Dredging Documents

Scientists, environmentalists, businesses, lobstermen, government agencies and other stakeholders have long been working together to find an environmentally and financially responsible solution to the dredging dilemma.

In a collaborative effort to advance the pier dredging initiative, the cities of Portland and South Portland form a Non-Federal Dredge (NFD) work group to assess and recommend options for the placement of contaminated sediments.

NFD Work Group Website

The NFD work group recommends that the city issue a Request for Proposal (RFP) for the design and permitting of a Confined Aquatic Disposal (CAD) cell in Portland Harbor. The recommendation for CAD cell arose because The United States Army Corps of Engineers (USACE) and U.S. Environmental Protection Agency (USEPA) will not allow contaminated sediments to be placed at sea. Based on past testing, most of the sediments involved in this project will not likely meet qualifications for offshore placement.

Location Sub-group Notes

The Portland Harbor Commission applies for a $350,000 federal Brownfields grant, which would provide the funding necessary for the testing and permitting phase for the dredging project.

The State of Maine Department of Transportation (Maine DOT) allocates $250,000 to the City of Portland to fund the design and permitting of a CAD cell in Portland Harbor.

The Harbor Commission is awarded the federal Brownfields grant and hires Campbell Environmental Group to complete design and permitting for the dredging of the Portland and South Portland wharves.

The City of Portland issues a Request for Proposal (RFP) for the design and permitting of a CAD cell in Portland Harbor.

Stantec is awarded the CAD cell contract.

A CAD cell work group composed of approximately 30 Portland Harbor stakeholders is formed to review the site recommendations made by the Non-Federal Dredge work group and provide additional insight regarding possible locations.

The project team completed a bathymetric survey of Portland Harbor to aid in determining dredge need and associated dredge volumes.

The project team completed a sub-bottom profile survey of proposed CAD Site to determine depth to bedrock.  Based on survey results, Site C has sufficient depth to bedrock for a CAD cell.

Stantec completed a geotechnical boring at the proposed CAD Site C to determine depth to bedrock and sediment characteristics. The geotechnical boring determined depth to bedrock was over 70 feet below the mud line and the bulk of the sediments consist of marine clay. These results indicate that this site is suitable for construction of a CAD cell.

The CAD cell project received an additional $75,000 from MaineDOT for additional CAD cell site investigation, environmental testing and permitting.

Mapping: Preliminary design drawings for individual wharfs and waterfront properties were developed depicting the bathymetry survey data, proposed dredge depths, and thickness of required sediment removal required.

The Process

After almost a decade of collaboration and research, a responsible solution was found that will safely isolate the contaminated dredge materials in a sealed hole deep in the harbor floor.

The CAD cell Solution

A CAD cell is constructed by digging a deep hole into the harbor bottom, filling it with the contaminated sediments, and capping it with a thick layer of clean sand. The EPA considers Confined Aquatic Disposal (CAD) Cells to be an environmentally safe and permanent solution for isolating contaminated sediments.

CAD cells are becoming an increasingly common solution for the clean up and isolation of contaminated dredge sediments. There are 11 CAD cells in Boston Harbor alone, and CAD cells are also found in Hyannis, Rhode Island, Connecticut, and California and as far away as Hong Kong.

CAD Cell Location

The engineering firm Stantec has been working with stakeholders to determine a location for a CAD cell in Portland Harbor.  In December of 2016, Stantec produced a scoring matrix based on stakeholder feedback, technical and environmental testing. The top scoring site, site C,  is located outside the federal channel between South Port Marine and the Coast Guard Station, just southeast of the Casco Bay Bridge. This potential site will undergo further study and testing before a final  recomendation is made for permitting.  View Siting Map and Scoring Matrix

Project Cost

The cost of the project will vary greatly depending upon final siting, design, and size of the CAD cell. Once the final site is selected and the amount of dredged materials that need to be isolated int the CAD cell has been calculated, an exact cost will be determined.

Project Funding

Funding will come from a combination of public and private sources and through a variety of funding mechanisms.

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Our priority is to protect and improve the water quality of Casco Bay. CAD cells have been used successfully around the world, including in Massachusetts and Rhode Island. The plan here is to remove contaminated sediment from around Portland’s and South Portland’s wharves and place it in a much smaller, confined space, which will be capped with clean fill. This measure should keep the polluted sediments underground so they cannot contaminate shellfish and other aquatic life. This solution will help clean up the harbor and benefit our economy.

— Ivy Frignoca, Casco Baykeeper, Friends of Casco Bay

Revitalization News

Press, Articles and Blogs

Frequently Asked Questions

The project will move through three phases: permitting, funding, and implementation, and is expected to take approximately six years to complete.

WASN'T THE HARBOR DREDGED IN 2014?

The United States Army Corps of Engineers dredged the navigational channel in the middle of the harbor. This was a “maintenance dredge” that the federal agency undertakes every decade. The navigational channel runs between 400 and 1,000 feet wide. The areas near the piers were not dredged as part of this project.

WHY HAVEN'T THE PIERS BEEN DREDGED FOR ALMOST 70 YEARS?

Public and private pier owners have been not been able to afford the high cost of testing, permitting, dredging, and contaminated sediment disposal. The costs are exorbitant and can be as much as a half million dollars for some piers. The decline of available berthing space due to sediment build up further decreases the value of the piers over time, making dredging increasingly unaffordable.

View Friends of Casco Bay Article Digging Into Dredging

CAN WE DISPOSE OF THE DREDGED PIER SEDIMENTS OUT AT SEA?

No. The United States Army Corps of Engineers and U.S. Environmental Protection Agency have rigorous qualification standards for an open sea disposal of dredged materials. Based on past testing, most of the sediments involved in this project will not likely meet these qualifications

CAN WE HAUL THE CONTAMINATED SEDIMENTS TO A LANDFILL?

Yes, but it is cost prohibitive. Hauling the spoils upland could run as high as $200 per cubic yard, which would put the cost of the project at approximately $60 million. The cost of a CAD cell is between $40 and $50 per cubic yard.

WHERE WILL THE CAD CELL GO?

The engineering firm Stantec has been working with stakeholders to determine a location for a CAD cell in Portland Harbor. In December of 2016, Stantec produced a scoring matrix based on stakeholder feedback, technical and environmental testing. The top scoring site, site C, is located outside the federal channel between South Port Marine and the Coast Guard Station, just southeast of the Casco Bay Bridge. This potential site will undergo further study and testing before a final recommendation is made for permitting.

View Siting Map and Scoring Matrix

HOW MUCH WILL THE PROJECT COST?

The project cost will be determined once a CAD cell site is selected and the volume of dredged materials has been calculated.

WHO IS GOING TO PAY FOR THE PROJECT?

Funding will come from a combination of public and private sources and through a variety of funding mechanisms.

IS A CAD CELL SAFE?

Yes. The United States Environmental Protection Agency has determined that a CAD cell is a safe, permanent solution for disposing of contaminated harbor sediment. The agency’s conclusion is supported by data collected and evaluated at CAD cells around the nation.

View EPA article Why CAD Cells Often Make Sense

WILL THE PROJECT HARM THE ENVIRONMENT?

No. The project will undergo significant environmental review to ensure it does not impair water quality or harm marine life. Steps will be taken during the construction to minimize short term risks. “We will continue to carefully monitor the entire process to protect and improve the environmental health of Casco Bay.” – Ivy Frignoca, Casco Baykeeper, Friends of Casco Bay

WILL THIS PROJECT HARM LOBSTERS?

The dredging and construction of the CAD cell is expected to have minimal impacts on lobsters. The dredging would take place in winter when lobster fishing effort is least and most of the harbor’s lobster population has moved to deeper waters offshore. Additional efforts to mitigate lobster impacts will be evaluated during the design phase.

WHEN WILL THE PROJECT BE COMPLETED?

The project will be completed in approximately six years.