The New Clark Well & Treatment Plant
Eastsound Water has been in active development of a well site and a treatment facility over the past 4 years. Located across from the medical center, and in front of OPAL’s Wild Rose Meadow development, this new site has the ability to fundamentally change our future access to water resources by doubling our total production capacity. Secondary benefits include creating opportunities to rehabilitate much-needed pieces of our own infrastructure and consolidate our operations to run more efficiently.
This email mini-series will explain both the historical context as well as technical detail of this new site. Our hope is that by the end of this series our members and customers will understand the significance of this project, learn about the technical and financial details, and get excited about the future ahead.
The Clark Well Treatment Facility
At this point in the Clark Well series, the focus shifts from understanding the source and validating the treatment approach to something more immediate and visible: the facility itself. What’s now under construction is not simply the activation of an existing well, but the creation of a simple but complete treatment system designed to operate as an integrated part of the Eastsound water system.
The Clark Well treatment facility is built around a single, continuous process. Raw groundwater enters the system, passes through treatment, and is injected directly into the distribution network without the need for storage or staging. The system is designed to operate at approximately 150 gallons per minute, equivalent to roughly 216,000 gallons per day when operating continuously. While testing showed the well is capable of producing closer to 250 gallons per minute, this operating rate was selected to limit aquifer drawdown, maintain positive head pressure, and reduce the long-term risk of saltwater intrusion. What is taking shape on site is the physical expression of that process.
At the center of the facility is the treatment building, which serves as the operational core of the system. The building measures approximately 28 feet in length, 16 feet in width, and 22 feet in height. It is a wood-framed structure set on a reinforced concrete foundation, sized just large enough to contain the full treatment process while maintaining access for operation and maintenance.
The building is engineered from the inside out. Its height is driven by the vertical filtration vessels (about 12 feet tall with working clearance) and overhead piping, while its footprint is constrained to efficiently house the treatment train without excess space. The primary equipment access opening is approximately 10 feet by 10 feet, allowing installation and removal of the pressure vessels and major components. Inside, the building is organized around a linear treatment process:
Raw water enters from the wellhead and is routed directly into the process piping. Sodium hypochlorite (aka chlorine) is introduced at controlled dosing rates typically ranging from approximately 2.6 to 3.0 milligrams per liter, providing both oxidation and primary disinfection. The chlorine is generated on site and delivered through 3/8-inch chemical feed lines tied to metering pumps sized for the plant’s 150 gallon-per-minute capacity.
Following chemical injection, water passes through a mixing zone designed to promote turbulent flow and ensure uniform oxidation. From there, it enters the filtration system.
The filtration system consists of four vertical pressure vessels, each 30 inches in diameter and containing approximately 42 inches of pyrolusite media. The system operates at a loading rate of approximately 7.65 gallons per minute per square foot, with flow distributed evenly across all four vessels.
Each vessel is capable of backwashing at approximately 137 gallons per minute for about five minutes. A full system backwash cycle uses approximately 2,700 to 2,800 gallons of water and typically occurs once every 24 hours of operation or based on differential pressure across the filters.
Backwash water is routed outside the building to a partially buried decant vault measuring approximately 8 feet by 8 feet in plan and about 7.8 feet deep. Within this structure, solids settle out while clarified water is returned to the front of the treatment process over a period of several hours. Residual solids are removed periodically through the septic system.
Downstream of filtration, the system incorporates a defined contact length for disinfection. A 24-inch diameter pipeline approximately 40 feet in length runs along the exterior of the building, providing the necessary volume to achieve contact time without the need for a separate tank.
Within the building, onsite chlorine creation and storage systems operate alongside the treatment process for maximum efficiency. Two 620-gallon storage tanks provide sodium hypochlorite supply, with average usage in the range of 35 to 40 gallons per day. This provides approximately two to four weeks of operational storage depending on demand for use in case of emergencies.
Outside the building, the full site layout becomes clearer when viewed as a system. The treatment facility occupies a relatively small footprint, with approximately 1,179 square feet of impervious surface. Total site disturbance during construction is on the order of approximately 3,000 square feet, including trenching for piping and utility connections.
The facility is set back approximately 40 feet from the centerline of Mt. Baker Road, with additional setbacks from property boundaries and surrounding features. A 100-foot radius well protection area surrounds the wellhead, defining the protected zone for the groundwater source.
The site includes a stabilized construction entrance, utility connections, and a clearly defined piping corridor connecting the well, treatment system, and distribution system. During construction, these appear as separate elements — exposed trenches, isolated structures, and partial installations — but they ultimately form a continuous hydraulic path.
One of the more visible elements is the large-diameter piping running along the building, representing the contact chamber in pipe form. Nearby, the partially buried decant vault appears as a concrete structure adjacent to the building. The treatment building itself anchors the site, with all systems either entering or leaving through it.
What is notable, when viewed against the earliest design work that was completed nearly two decades ago, is how much of this layout and process would still be recognizable. From the beginning, the Clark Well was envisioned as a straightforward groundwater treatment system: inject sodium hypochlorite, provide mixing and contact time, filter out oxidized iron and manganese, and deliver finished water directly into the distribution system. That fundamental treatment train — oxidation, mixing, filtration, and discharge — was already clearly established in the original concept drawings and remains intact in the facility being built today.
The 2006 plan also placed a compact treatment building adjacent to the wellhead, with short piping runs connecting directly into the existing main along Mt. Baker Road, and that same physical logic is still visible in the current site configuration. What has changed is not the underlying approach, but the level of execution.
The original concept assumed a smaller building of roughly 400 square feet (vs. 430sf for the new building), a single filtration vessel, and a simple chemical feed system relying on delivered chlorine. It reflected the understanding of the aquifer at that time and prioritized minimal capital investment. The modern facility builds on that same principle but expands it into a fully realized treatment plant. Multiple pressure vessels replace a single filter, providing operational redundancy. Defined contact piping replaces assumed mixing volumes. Automated controls and monitoring systems replace manual operation. On-site chlorine generation eliminates dependence on delivered chemicals. Even the backwash reclaim concept present in the original design has been carried forward and expanded into a dedicated decant and return system.
In this sense, the Clark Well facility now under construction is not a departure from the earlier plan, but a direct continuation of it. The original design established the correct treatment approach. What has evolved over time is the level of certainty, the understanding of water quality behavior, and the expectations for long-term reliability and resilience. As construction progresses, the individual elements on site resolve into a single system.
When complete, water will enter the facility, move through oxidation, filtration, and disinfection, and exit as finished drinking water without interruption. Every pipe, structure, and component on site supports that single path. For now, what is visible is the construction — the building, the piping, the pieces coming together.
Stay tuned for the next installment soon…
Dan Burke
General Manager
Eastsound Water