Pour Performance

By Kelly Barrington

California’s East Bay Regional Park District was conceived during the Great Depression. In 1929, when the local water utility declared 10,000 acres of hillside property surplus, residents of communities on the eastern side of San Francisco Bay organized to create a special district to preserve these open spaces as public lands for all time. The campaign was triumphant, and in a November 1934 election the regional agency became a reality. Today, 8 decades later, the district has grown to encompass 114,000 acres, 65 parks, and over 1,100 miles of intra-park trails.

Temescal Regional Recreation Area, an oasis set in the bustling city of Oakland, was one of three initial East Bay regional parks. Nestled in a small canyon, a reservoir provides opportunities for fishing and swimming. In 1940 the federal Works Projects Administration designed, commissioned, and constructed the park’s picturesque stone beach house and its adjacent waterfall.

An Aging Treasure
During its heyday years in the 1940s and 1950s, the Temescal waterfall was a beautiful outdoor feature, enhancing visitors’ enjoyment of the surrounding gardens and park. An electric, centrifugal pump surged lake water to a 25-foot fall, where it cascaded into an artificial creek and down a second 40-foot fall, before returning to Lake Temescal. Once a scenic backdrop for park visits, special events, and even a bathing-beauty contest, by 2012 the waterfall was in poor condition, and water flow had diminished to a trickle. A major renovation would be required to restore the historic waterfall to its original flow and capacity.

Restoration and Renewal
The park district’s sister non-profit organization, the Regional Parks Foundation, sponsored a $35,000 capital-improvement project for the renovation. The first stage was completed in 2012 for $10,000. The structural stability and integrity of the lower ponding areas were improved, and additional repairs were made to surrounding stone pathways.

Initially, park staff thought these repairs would be sufficient since water loss throughout the cracked and leaking watercourse seemed so significant. But subsequent assessments by the maintenance department revealed further problems. In the antiquated pumping system, underwater debris frequently blocked the intake structure and the plumbing to and from the pump was in poor condition and leaking in several places—places difficult to find due to the low-pressure, high-volume condition on the discharge side of the pumping system.

The existing pump, dating from the late 1950s or early 1960s, needed to be replaced as well because it was functioning poorly, which required staff to spend needless hours on temporary repairs that only marginally improved performance. Further, a fallen tree had damaged the electrical panel and overhead wiring that served the system. While the waterfall was still salvageable, it would clearly take a significant effort to return the historic water feature to its original splendor.

In 2012, the district’s maintenance department received informal bids between $200,000 and $450,000 for the total restoration of the waterfall. A more economical solution was required, and after careful consideration of project goals and available funding, the district decided to make the key repairs to extend the life of the historic waterfall and return water flow to the system. These goals were accomplished through the following means:

  1. Properly sizing and installing a new self-priming pump. The new pump is designed to improve efficiency and reduce the need for daily/weekly maintenance. It is an energy-efficient, three-phase model that will reduce the park’s electrical costs. The pump system is on a simple analog timer, shutting off flow from dusk to dawn when the park is closed. Two foot valves hold water in the intake and distribution systems while the pump is off, so it is always primed. This saves energy, extends the life of the pump, and reduces or eliminates the amount of time spent by park staff starting the waterfall. Additionally, fittings that are compatible with the district’s fire-suppression apparatus were installed on both the intake and discharge sides of the pump. If needed, water may be drafted into a fire engine from the intake side of the system. A second fitting may be used to clear the system of any debris or algae build-up that may occur as a result of normal operation or changes in water quality.
  2. Improving the pump intake structure in the lake. The new intake system is designed to reduce the amount of lake detritus entering the pump, thus reducing potentially excessive wear to the motor and impeller.
  3. Installing a secondary strainer assembly on the intake side of the new pump. This provides staff members the ability to remove debris from the intake side of the pump. The new strainer is located in the newly constructed pump house. The old intake required divers to access the submerged portion of the structure, even for minor maintenance.
  4. Installing new plumbing, from the pump to the top of the cascade, increasing flow and efficiency. The original pipes were steel and quite rusty. The district chose to install high-density polyethylene plastic, which is durable and unattractive to metal scavengers. The pipes are concealed by vegetation or buried wherever practical.
  5. Completing needed repairs to the electrical panel and main service that supplies electricity to the pump and critical switchgear. The electrical lines were installed underground and/or in a manner that better protects them against theft.  
  6. Constructing a new secure pump house. The old pump house was not secure, nor was it a “house.” In fact, the old pump was housed in an at-grade wooden box that was in very poor condition. It didn’t keep out rainwater and was difficult to open and close. And located next to the park’s busiest trail, it didn’t fit in with the park’s aesthetics. District skilled-trades staff built an attractive new shed with improved security features and convenient access for park staff. The shed houses the pump, timer, and other critical operational equipment.

Further Adjustments
Every retrofit or new design installation comes with at least a problem or two. This project was no exception, but the problems have been minimal. Upon completion of the restoration, the intake designed to feed the new pump presented staff with an unforeseen issue. The intake sits close to the bottom of the lake, and sucks in water through a pipe fitted with both coarse and fine screens to keep out debris. But the new screen was too fine—it clogged a couple of times with silt and algae, creating minor intake blockages and impeding flow to the pump. The district worked with its contractor to improve the design; solutions included angling the pipe upward, extending the intake farther above the silt bed, and changing the intake filter system so that it sucks water in from the sides of the pipe, using more inlet holes and coarser screens. So far, so good; this seems to have solved the problem.

Another ongoing challenge is that the outflow basin at the bottom of the 40-foot cascade is fully exposed, and thus subjected to falling leaves, litter, and other debris that occasionally clogs the outfall screen. There is no engineered solution to this problem that the district can employ due to the age of the waterfall and the district’s desire to retain the historic appearance. For these reasons, park staff must rake the outflow screens from time to time to keep the water recirculating without overflowing the last catch basin.

Takeaways
For those who are looking to take on a similar project, consider the following:

  • Leverage resources by looking into any available local, regional, or private grants for which an agency may be eligible; use agency staff when appropriate to save costs—but don’t be afraid to look outside of the organization for expert help.
  • Look at the restoration challenges from a multitude of angles and with an open mind. What was once thought to be a matter of repairing leaks turned out to be far more complex.
  • Invest in durable and theft-resistant materials for long-term life and the public’s enjoyment of the final product.
  • Match the historic materials (such as stonework) to the degree that is practical to retain the unique charm and aesthetics of historic features.

On March 28, the park district and the Regional Parks Foundation held a dedication at Temescal Regional Recreation Area to celebrate the restoration of the park’s historic water feature. With the repairs and improvements in place, and the water flow restored to its full vigor, the historic Temescal waterfall will provide a refreshing enhancement to the park for many years.

Kelly Barrington is Chief of Maintenance and Skilled Trades at the East Bay Regional Park District, in the San Francisco Bay Area, Calif. He may be reached at KBarrington@ebparks.org.

East Bay Regional Park District Administrative Analysts Nate Luna and Michael Stangl contributed to this article.