Submitted by Paul A. Bucich, P.E., Public Works Engineering Director, City of Lakewood.
Recent articles published in the Suburban Times regarding Waughop Lake have not included all the facts around how the City arrived at its decision to apply alum treatments to the lake to control toxic algae blooms.
There are many opinions on what to do about the lake, from do nothing to dredge it and start over. We believe we have found a solution through a management strategy that addresses the issue in a reasonable manner that is affordable and has the smallest impact on Fort Steilacoom Park, park users, and surrounding neighborhoods.
As most users of Fort Steilacoom Park know, toxic algae in Waughop Lake is a decades-long problem. In its search for a solution, the City consulted with national experts and state ecology officials, held extensive discussions with University of Washington professors and others with expertise in lakes and aquatics issues, and listened to residents.
In an effort to make sure the City had all the information before proceeding with a treatment option, two independent consultant firms were hired to provide recommended treatment options.
The suggested solutions proposed by Mr. McClellan (Jan. 14 “Lakewood is on the wrong path for its biggest environmental problem“) and Mr. Russell (Jan. 11 “Letter: Council should reconsider Waughop Lake plan“) fail to mention key information that led the City Council to its final decision.
That information is outlined below:
Nationally recognized consultants have evaluated options for addressing the algae blooms in Waughop Lake, including treatment with Aluminum Sulfate (alum) or hydraulic dredging of the bottom sediments. Consultants hired by the City, Brown and Caldwell as well as Tetra Tech, independently assessed the feasibility of treatment options and the costs of alum treatment vs. dredging. The 2017 Brown and Caldwell report recommended the following management strategy: “Conduct further lake sediment assessments to provide more accurate costs for sediment removal; if costs are higher than City can fund, conduct whole-lake alum treatment to remove phosphorus from the water column and inactivate phosphorus in the sediment; evaluate if sediment removal long term is feasible in regards to permitting requirements, costs for operations, impacts to park users.”
This is the strategy the City has followed since 2017. In 2018 the City hired Tetra Tech to conduct another review, this time asking specifically about dredging costs. Work done in 2018 and already in 2019 revealed the high cost of sediment removal and the impacts it would have on the park and adjacent neighborhoods.
Removal of sediments from a lake bottom is challenging even when a suitable location for disposal of that sediment is adjacent to a lake. In the case of Waughop Lake, it is even more challenging because the City is not able to dispose of the sediment within Fort Steilacoom Park without having a significant impact on existing park uses and features.
The 2018 study by Tetra Tech determined that the costs to dredge the lake ranged between $7.9 Million and $34.5 Million depending on the depth of materials removed. With a shallow removal, the probability of success was estimated at 20 percent. With a deeper dredging effort, the probability of success was estimated at 90 percent. Success is viewed as significant reduction or elimination of algae blooms.
The significant impact of dredging was not relayed in the recent articles in the Suburban Times. It is important for the public to understand all the impacts the City Council considered when making its decision.
Dredging requires a significant operation including pumping the materials, drying the materials, and transporting them off-site.
It was estimated a 20-acre “pond” would be needed as a drying facility to dry the materials. This facility would be six feet deep and would be built on top of the existing ground so as to not disturb any potential artifacts in the park.
The facility would be lined with an impermeable layer to ensure stability to hold the liquid/solids. As the dredged material dried, we would expect an odor to develop (think of the beach at low tide but worse) that would affect park users, nearby neighborhoods, Western State Hospital, and the commuting public. Hydraulic dredging of the material with the expected branches, rocks, and other debris would be challenging. Further, we anticipate the dredging/drying/removal process would require significant closures of large areas of the park for up to two years. The lakeside trail would be closed to public access during the dredging operation which would most likely occur during the summer season(s).
Disposal is Problematic
It was suggested that this material is equivalent to Tacoma’s Tagro product based on an analysis of the nutrient loadings alone and that it has a market value. What is missing from this assertion is the complex nature of the bottom sediments. We fully expect to find organic materials such as logs, branches, bones from fish, waterfowl, and potentially detris from the historic use of the lake by Western State Hospital such as bones, bottles, bricks, etc. These materials would need to be separated in the removal process, some by the hydraulic pumping system installed to move the loose bottom sediments, the rest by any product manufacturer prior to sale. It is unclear if the dry material can be used freely or if there is additional processing that would be needed.
Tagro is a product that the City of Tacoma has spent over 30 years perfecting and is a blend of bio-solids and other weed free garden products composted to rigorous standards prior to sale. It is unrealistic to expect any topsoil manufacturer to take on the lake sediments at no or minimal cost without additional processing. The market for this product is unclear and as such, we have to anticipate disposal at a landfill.
‘Alum is Toxic and Short Lived’
Statements have been made that alum treatment is dangerous, environmentally toxic to the lake, will lead to an explosion of aquatic weed growth, is limited in life span, will not work in a shallow lake, and not a preferred option by experts. These statements are misleading and in some cases outright wrong.
Alum treatment is a nationally recognized treatment process and deemed safe by state and federal agencies after extensive testing and review. Alum is a nontoxic material commonly used in water treatment plants to clarify drinking water. In lakes, alum is used to reduce the amount of the nutrient phosphorus in the water. Yes, there have been instances where applications in lake environments have failed. These are almost exclusively due to applicator error. To address this, the City will contract with our design firm to ensure a qualified expert is on hand to oversee the application to Waughop Lake. The expert we are working with from the consulting firm of Tetra Tech has over 40-years’ experience, is a nationally recognized Ph.D water quality scientist and expert who has designed and overseen the treatment of over 200 lakes.
Failed alum treatments are usually due to a lack of understanding of the sources of nutrients leading to the algae blooms. Waughop Lake has no external sources other than runoff from the park and the adjacent college and we expect a successful application. We are currently evaluating the sediment concentrations and refining the treatment needs of the lake to more accurately plan the alum concentrations needed for the treatment.
The City understands that alum treatment is not a one-time event. The typical treatment life span is between 5-10 years at which time a smaller treatment is likely going to be needed. This known aspect of alum treatment, when compared to the costs and impacts associated with dredging the lake, is deemed acceptable. Alum has not been determined to be environmentally harmful to any of the number of lakes treated over the past decades of use.
But What About…
It has been suggested that the City treat the lake with algaecides and herbicides in lieu of an alum treatment; that this is a viable management approach for the lake.
When we hired Tetra Tech, the City specifically asked for this option to be reviewed. The expert we are working with said:
“Given the level of ‘production’ within Waughop Lake, algaecides are not a sustainable approach for reducing and controlling” the algae blooms. The City was told repeated use will affect the food chain abundance leading to reduced water quality and affect the fisheries food base. It will also likely lead to groundwater and sediment contamination — the issue being presented by some as the reason not to use alum. Algaecide would have to be applied repeatedly throughout the summer, likely every 14 to 21 days, due to the reproduction cycle of algae. Aquatic herbicides would only be used if the clarity of the water reaches the point where aquatic plant growth impacts lake uses; this strategy would be applied even with the alum treatment strategy.
The City was approached by Mr. Russell who asked we try a new process being used on a lake in Federal Way. We informed him that in our opinion, this was an experimental process with an uncertain potential for success. We declined and explained that we were not set up to do the required testing for an experimental process. We encouraged him to contact larger agencies dealing with similar issues on lakes to see if they would be willing to have their lakes be the testing grounds for this treatment. Should it be successful and develop a proven track record, we would consider this new treatment process on future applications. At this time, we are unaware of any agencies taking on this new treatment alternative.
Funding for Treatment
Treatment with alum has been estimated to cost between $300,000 and $750,000. Current tests of Waughop Lake will provide a more refined plan for treatment and a better cost estimate. The City has applied for a $50,000 grant from the Department of Ecology to assist in treatment of Waughop Lake and received confirmation from Pierce County that a $300,000 Flood Control Zone District allocation for Lakewood can be used for this application. In our application for the Ecology grant, we were clear the money was to be used for alum treatment. Additional funding, if needed, would come from the City’s Storm and Surfacewater Utility fund.
The State Should Do It
In 1967 the State of Washington transferred the operational responsibilities for Fort Steilacoom Park to Pierce County through a lease. That lease was subsequently transferred to the City of Lakewood. The agreement releases the State of Washington from any and all responsibilities for virtually anything related to the park lands. There are improvements the City plans on making to the park and we have been very successful obtaining state grants for past and current improvements. There are no established grants we could apply for to dredge the lake, and if there were, the impacts to the park and surrounding properties would still remain.
The Answer is Clear
Removal of the bottom sediments through hydraulic dredging or other means is difficult, expensive, and fraught with significant unknowns. Impacts to the park users and adjacent neighborhoods are likely to be high. Impacts to the park will be extensive. When compared with the alternative of alum treatment, a well-known and permissible process, the choice is clear, alum treatment is the viable solution at this time.Print This Post