Objective: To help communities appraise the current value of their navigational and port infrastructure, allowing them to project the potential costs of maintaining or replacing these resources in the face of changing water levels and storm conditions caused by climate variation.
Authors: Gene Clark, David Hart (Wisconsin Sea Grant); Jeff Stone (ASFPM)
Publication Date: January 31, 2014
Update Note: April, 2016 - The "Infrastructure and Dredging Cost Estimate Matrix Tool" described in this case study is the same as it was when this study was written in January, 2014. There is nothing new concerning the tool. Attempts to obtain grant funds to update the tool costs as well as add new infrastructure (such as marina docks, etc) have been unsuccessful. The "Tool" was originally used in analysis of the harbors in Duluth, MN, Superior, WI and Toledo, OH. Later it was used in harbor analysis in Green Bay, Milwaukee and Manitowoc, WI.
Ports, harbors, and marinas on the Great Lakes are vulnerable to a number of predicted climate change conditions. The most dangerous of these conditions are extreme water level variability and increased storm frequency and intensity. Both rising and falling water levels can impact infrastructure stability and strength and require additional dredging of harbor navigation channels and interior facility slips. A major impact of lower lake levels is the potential for decay of harbor infrastructure as wooden structural elements are exposed to oxygen (Clark, 2012).
Projected increases in storm severity and precipitation levels, higher winds, and a greater number of storm events put harbor infrastructure at risk. More severe storms can damage port and harbor infrastructure, requiring costly rehabilitation or replacement. In addition, increased storm frequency and intensity may increase channel silting and sedimentation, compounding dredging problems and creating conditions analogous to those of lower water levels.
Climate model predictions for specific weather outcomes vary greatly throughout the Great Lakes Basin, and include both higher and lower water level scenarios (Angel and Kunkel, 2010; Lofgren et al., 2013). However, all models seem to forecast an increase in both the number and intensity of major storm events. This combination can result in unanticipated water level change, larger waves, more dramatic seiches and greater storm surges than considered in original design parameters—all of this compounded with the antiquated and sometimes dilapidated state of our Great Lakes infrastructure.
Figure 1. View Map of the Port
Taken from: http://tourtheport.com/
The purpose of this case study is to describe the "Infrastructure and Dredging Cost Estimate Matrix Tool" (The Matrix) and the general process by which a community would valuate its navigational and port infrastructure. With some basic training, port authorities and others on the Great Lakes can use The Matrix to estimate the costs of repair and/or replacement or dredging for most port infrastructure. Maintenance costs for these assets are then extrapolated in relation to changing water levels and projected storm conditions due to climate variation in order to determine the associated economic risk. (Clark and Bergeron, 2010; Bergeron and Clark, 2010).
For the purpose of this case study, the Port of Toledo will be analyzed using The Matrix in order to demonstrate how the tool is used in practice. The port lies at the mouth of the Maumee River in northwestern Ohio, at the southwestern tip of Lake Erie. The City of Toledo is the seat of Lucas County, Ohio and its metropolitan area is home to over half a million people. The Port of Toledo handles over 12 million tons of cargo and 700 vessel calls annually, while its shipyard is one of the only full service shipyards on the U.S. side of the lower lakes with graving or "dry" docks.
Cost Components for Ports & Harbors
The Matrix consists of two components and follows a careful process (described in Analysis section below) for examining current value and maintenance costs based on:
- Structure Repair and Replacement Cost vs. Depth Ranges – Identifies the current "market value" of the navigation and port infrastructure.
- Harbor Dredging Cost – Identifies potential dredging and dredged material disposal costs for maintaining navigation channels and adjacent facility slip depths due to increased siltation from changing water levels and storm conditions.
Structure Repair and Replacement Cost vs. Depth Ranges
The Matrix structure cost tables are divided into two categories of common Great Lakes navigation and port infrastructure types: 1) entrance structures and 2) interior harbor structures. The tables include information for either repair/rehabilitation or total replacement of structures and can be scaled to three different depth levels. For convenience, structure depth is categorized into three ranges: shallow = 8-13', medium = 14-25', deep = 26-35'. Typically, costs increase with greater depths.
Bayfield Harbor Entrance
Courtesy of Gene Clark, WI Sea Grant
Photo Credits: 1. Rubble Mound Breakwater Courtesy of UW-Madison Breakwater Wave Energy Modeling Project, 2. Bulkhead Courtesy of Ohio DNR, 3. Steel Sheet Pile Cell Courtesy of Gene Clark, WI Sea Grant.
Entrance structures (see above images) are built to withstand impacts from large waves, significant storm surges, and seiche events. Entrance structure types include steel sheet pile bulkheads with a variety of structure caps, rubble mound breakwaters, timber or steel cribs with a variety of structure caps, and closed steel sheet pile cells.
Example of Interior Pilings
Courtesy of Gene Clark, WI Sea Grant
Harbor interior structure types (see above images) include slip wall designs, standard steel sheet pile walls, timber or steel cribs, soldier-pile walls with timber or concrete, and open dock structures with piling supports.
Cost estimates do not include variables such as site investigations, design work or permitting. These three additional factors could add 25% or more to the overall cost and vary greatly depending upon individual ports and specific infrastructure condition and location. To ensure a complete harbor assessment, it is important to include both public and private infrastructure since port terminals are frequently leased to private companies by the Port Authority, which retains responsibility for their repair and maintenance. These costs are not included in The Matrix because it was designed to be a regionally relevant tool that can be used to provide a general framework for cost evaluations or be customized by users to reflect specific local circumstances.
Harbor Dredging Costs (per ft. of depth dredged)
Great Lakes dredging costs can vary greatly depending upon the location and size of the project. Dredging costs were thus separated out in The Matrix based on the location of the harbor and on the size of the dredging project, that is, a large scale harbor project or smaller individual slip project.
The dredging cost data was collected from the U.S. Army Corps of Engineers dredging database. This data included archived projects for FY 1993-2009 and was divided into actual port regions: the Buffalo, Chicago and Detroit districts. The information was further sorted by size—large, commercial harbors vs. small recreational harbors. To gain a better understanding of how the range of dredging costs varies with size of project and location, Great Lakes dredging contractors were also contacted for typical costs of both large scale and small scale projects. The contractor information is especially valuable when estimating dredging costs for smaller ports and harbors as well as for individual slip dredging projects. Recently, the U.S. Army Corps of Engineers dredging database has been updated and now includes archived projects for FY 1998-2012.
Note that if climate change impacts require the dredging of depths deeper than currently authorized, new federal authorization would be required.
Cost Calculation Process
Structure Repair and Replacement Cost Calculation Process
The steps below outline the process for identifying the current "value" to repair, rehabilitate, or replace the port or harbor structures.
- Inventory all port structures.
Create an inventory of port structures for Toledo by accessing the Great Lakes Maritime Research Information Clearinghouse. To select out just the Toledo structures, click the "Docks" tab and select "OH" for State and "Toledo" for Town, then click the "Search" button.
2. Identify specific port structures for valuation.
Refine the specific data listed for each port facility to select those features that would be needed to determine both structure repair/replacement costs and slip dredging details. Important dock details include characteristics such as type of dock wall construction, total berthing length, depth of slip, and maximum height of dock deck above the waterline. To acquire these data an engineer may need to be hired to inspect the facility, depending on the expertise of the individual tasked with its maintenance.
3. Validate specific port structure data.
After port structure data has been acquired, efforts to validate or corroborate this information must be made by working with port officials. This is done in an effort to ensure that available data actually reflects the most current local port information.
4. Create repair and replacement cost vs. depth tables.
Prepare tables showing the costs for either repair or total replacement of the structures, subdivided into three ranges of typical depths: shallow = 8-13', medium = 14-25', and deep = 26-35' plus. Cost tables are prepared for two distinct categories of typical Great Lakes port and harbor structures as follows:
This table provides the cost estimates for eleven different harbor entrance structure types.
This table provides the cost estimates for nine different harbor interior structure types.
5. Calculate costs in harbor structure inventory tables.
Assign each harbor structure record from the inventory table (Step 2) with the appropriate structure designation (entrance structure or interior structure) and assign the appropriate repair and replacement cost per foot of berthing length. Then calculate the required cost for each individual facility and sum the total for the entire port. View the Port of Toledo cost estimates.
The cost ranges used for this analysis were collected from the following sources:
- The U.S. Army Corps of Engineers Great Lakes district offices provided structure cost estimates based upon actual project bid prices. The USACE Civil Works Construction Cost Index System was used to normalize historic costs to June 2010 levels.
- Three nationally known coastal engineering design firms with offices and projects in the Great Lakes provided 2010 cost estimates derived from actual construction, contract/bid costs that were readily available, or from design or study estimates.
- Three Great Lakes construction firms also provided cost estimates for several of the structures most commonly constructed in the Great Lakes.
Dredging Cost Calculation Process
This process identifies potential costs for maintaining navigation channels and adjacent facility slip depths. It includes costs for dredging and dredged material disposal.
1. Acquire channel dimensions.
Obtain the total authorized federal channel dimensions from either the port itself or the appropriate U.S. Army Corps of Engineers District office for each port. Assume a typical dredging cost as given by the Dredging Cost Tool for that specific port.
2. Acquire facility slip depths.
To determine the individual facility dredging costs, each port was asked to state whether it was possible for a 1000-foot vessel to dock at any of its facilities. For those docks, the expected vessel width was assumed to be 105', while other docks were assumed to have a conventional Great Lakes vessel width of 75'. These widths were then multiplied by the total slip berthing length and also by a factor of 1.2 (20% overage factor) to account for vessel maneuverability and connection of the dredged slip channel to the authorized federal channel. Since individual slip dredging costs can vary greatly, each port's costs were calculated at $5, $10 and $15 per cubic yard of material dredged, which were then added to the costs for the federal channel dredging.
3. Determine current conditions.
Structural information can be determined by the port owner or manager or by a coastal consultant inspection in which channel depths are determined by hydrographic surveys.
4. Create dredging cost value tables. Dredging costs can be viewed at the U.S. Army Corps of Engineers Navigation Data Center; however, it is recommended that the appropriate U.S. Army Corps of Engineers District office be contacted for updated archival dredging contract bids awarded.
Great Lakes dredging contractors were also contacted for typical costs of both large and small scale dredging projects. This information is especially valuable when estimating dredging costs for smaller ports and harbors as well as for individual slip dredging projects.
5. Validate dredging data.
Note that each port's dredging data was determined to be incomplete. Local U.S. Army Corps of Engineers offices thus reviewed the database information for each port and updated dredging contracts as needed. Determining the cost of dredging the entire authorized federal channel could then be easily calculated.
6. Calculate dredging costs in spreadsheet.
The costs per foot of depth for dredging the entire federal channel were calculated by multiplying the total cross-sectional area of the authorized federal channel by the dredging costs per cubic foot. View the Port of Toledo dredging cost estimates.
Results, Implications and Actions
Adaptation strategies for Great Lakes ports, harbors and marinas to address potential climate change impacts must be considered and implemented where needed. Otherwise, structure failures are only a matter of time. New structures must be designed with these impacts in mind. For the Port of Toledo, the results below provide a starting point for developing a detailed risk assessment that compares the economic, social and natural resource risks of such structures with the potential impacts and timing of climate change variables. These cost estimates generated by The Matrix also provide the Port of Toledo with the data necessary to make a strong argument for their need for additional investments from the state and surrounding community.
Toledo Harbor Results
The Port of Toledo's harbor consists of 28 individual facilities and a total of 55,590,500 square feet of federally authorized channel. Therefore, by utilizing The Matrix the following summarized results were obtained:
Total Dredging Costs for All 28 Slips + Entire Federal Channel (per foot of depth):
@ $5/cy for slips = $4,717,350
@ $10/cy for slips = $9,434,350
@ $15/cy for slips = $14,152,050
Infrastructure Costs for All 28 Slips:
Repair of all vertical slip walls = $69,599,125
Replacement of all vertical slip walls = $118,192,700
Matrix and Dredging Database Results for Toledo Harbor
Taken from: Bergeron and Clark, 2010
Implications and Benefits
Using this baseline economic data for the Port of Toledo, the repair/replacement and dredging costs can be shared with the public to create awareness and an appreciation for the investment and opportunity that exists in their harbors. Additionally, these estimated values serve as baseline information that can be modified to reflect actual future conditions in order to plan and budget for adaptation and mitigation strategies that address predicted climatic changes. The information can also help ports demonstrate the value of their infrastructure and the costs associated with operations and maintenance, which is essential for developing grant or funding proposals.
Taking Action in the Great Lakes – So Now What?
Prior to employing The Matrix it is recommended that an actual inspection of the port, harbor or marina be completed to help identify channels that need dredging and structures that need repair or replacement. Engaging in this process will ultimately inform a better estimate. Additionally, when seeking to apply The Matrix to a small marina or harbor, special considerations must be made when assessing the value of interior infrastructure. Unlike large ports, which typically contain slips and pilings, smaller marinas or harbors contain docks and landings. These differences must be accounted for when using The Matrix as they will greatly influence the outcomes of the analysis due to differences in size, frequency, and cost for repair or replacement.
Below is a list of organizations and/or potential funding sources that can be leveraged based on the characteristics and needs of a given port, harbor or marina.
Facility repair or replacement:
Larger Ports and Harbors
- Entrance Structures – U.S. Army Corps of Engineers
- Interior Structures – The Port Authority, State Coastal Management Program, or state permitting programs which might have funding available.
Small Recreational Marinas
- State Coastal Management Program or state permitting programs which might have funding available.
Larger Ports and Harbors
- Seek grant and engineering help from the U.S. Army Corps of Engineers. Due to its size and designation as a port, Toledo initially would seek federal grants or engineering help from the U.S. Army Corps of Engineers and also seek help from state programs.
Small Recreational Marinas
- Grants are available from the Ohio Department of Natural Resource's Recreational Harbor Evaluation Program – select "Boating Facility Grants". The program provides reimbursement grants to public entities for dredging of the Ohio River, Lake Erie, and their tributaries.
- State Coastal Management Program or state permitting programs which might have funding available.
Infrastructure Repair, Construction, and/or Dredging
- Grants for harbors, ports and marinas of all sizes are available through the USFWS Boating Infrastructure Grant (BIG) Program; states may apply for funding on grants.gov. The BIG Program is targeted towards the construction, renovation or maintenance of tie-up facilities that are capable of housing non-towable recreational vessels (26 feet in length or more).
Other Dredging Links
At-risk and high-risk port, harbor and marina facilities can be identified with respect to potential dredging problems. Facility owners and managers should develop strategies to adapt to changing lake levels and identify alternatives to dredging, such as relocation of critical facilities or exploring new options for additional dredged material disposal or beneficial use.