Forest Park Linear-Connected Waterway System, Post-Dispatch Lake, and Grand Basin

Elise Ibendahl, P.E.
Water Resources Engineer
CH2M Hill
St. Louis, Missouri
Presenter, 2006 APWA Congress

At 1,370 acres, Forest Park is the seventh largest urban park in the United States. Its major cultural institutions (including the Zoo, Art Museum, Municipal Opera, Science Center, and History Museum), recreational activities and special events attract over 12 million people to Forest Park each year.

Forest Park was founded in 1876 and hosted the 1904 World's Fair. The World's Fair resulted in major environmental changes to the park, which included clearing thousands of trees, forcing the River des Peres into underground tunnels, and construction of new structures that would require maintenance in the years to come. While usage of the park increased over the years, the Great Depression and World War II made park maintenance more difficult. By the early 1980s, Forest Park had fallen into widespread disrepair. In 1993 the City of St. Louis began the effort to develop a master plan to restore Forest Park and obtained voter support for a sales tax increase to benefit city parks with half of the proceeds going to Forest Park.

Two years later, the estimated $86 million master plan to restore Forest Park was completed and adopted by the city with goals to maintain the balance of existing park uses, repair decaying infrastructure, improve neglected natural systems, and implement the plan by 2004, the anniversary of the 1904 World's Fair. Today, over $94 million has been raised for the master plan implementation with public and private funds.

Project Overview
The main waterbody through the park, River des Peres, was temporarily moved underground for the 1904 World's Fair. This was done because River des Peres had a history of severe flooding in the park and to provide more open space for the World's Fair. By 1930 two permanent 32-foot horseshoe-shaped tunnels were constructed to house the River des Peres, leaving behind lakes and lagoons with no hydraulic connection to each other or the river, causing a new flooding problem during heavy rains. Surface runoff in the park now had nowhere to go other than the depressional areas, lakes and lagoons.

During the master plan and schematic design phase, the project team evaluated ways to transform the park's many lakes and lagoons into one continuous river in order to improve water quality, eliminate flooding, support wildlife, and support fishing. A design team consisting of architects, the public and park staff worked to determine how the waterbody would look and function during ordinary, drought and flood conditions.

Post-Dispatch Lake and Grand Basin
Restoration of "The Heart of the Park" was a top priority throughout the master plan process. This 90-acre area includes Art Hill, Grand Basin, and Post-Dispatch Lake, which historically has been the symbolic center of the park and major gathering space for public events. Over the years, the Grand Basin had deteriorated. The basin walls had crumbled, most of the overlooks removed, the waterbodies were stagnant and full of sediment, and the surrounding landscape was in poor condition.

As the initial step of the $10.9 million restoration, the basin was drained and dredged, the walls demolished, and golf holes across the basin and along Art Hill were removed. The basin walls were reconstructed with boat landings, balconies and overlooks. Tree-lined pedestrian promenades were created and dramatic-lighted fountains reminiscent of the 1904 World's Fair fountains, decorative lighting and landscaping were provided.

Post-Dispatch Lake was dredged and expanded, and two new islands were created. Lagoons connecting to Grand Basin were dredged to improve water quality and boating opportunities. Natural stone outcroppings were creatively provided to enhance the naturalistic cascading character at the spillways area where lake volume is used as a reservoir to attenuate the rate of stormwater runoff through the park's extensive system of lagoons and lakes. This riffle area replaced an existing concrete v-notch spillway.

The Linear-Connected Waterway System (LCWS)
Forest Park's restored river begins near the clubhouse of the new Norman K. Probstein Golf Courses. Underwater city water inputs provide 550 gpm to feed the system. Several waterfalls and naturalistic riffles are actually control structures that provide the engineered control required by the system. Riffles and waterfalls also provide extra oxygen to the system, while riparian plantings provide further water quality benefits.

Downstream of the golf courses, the rocky spillways of Post-Dispatch Lake provide an additional 500 gpm to the system. The waterway winds through Langenberg Field where it splits into two branches—one that flows beneath the stage of the Muny Opera and the other that flows around the Bandstand in Pagoda Circle. The renovated Pagoda Circle boasts several new bridges and concrete weirs with sharp drops for visual effect and added water quality benefits.

The waterway next flows into Deer Lake and the Deer Lake Wetland area. Deer Lake is accentuated at its downstream end by a series of rocky riffles, constructed from 2,000 tons of Wisconsin "holey stone." The surrounding landscape was restored to the meadows, swamp white oaks and riverine plantings of the historic savanna. The Deer Lake Wetland receives flow from both Deer Lake through a gravity feed and the lower LCWS via a pump system. The wetland treats the water before returning it to the LCWS downstream of Deer Lake. An emergency overflow, designed to convey extra storm event flow to the River des Peres tubes below, is located downstream of Deer Lake.

The LCWS next flows by the Fish Hatcheries, although it does not have a hydraulic connection to the hatcheries. A recirculation system boosts the flow through the reach. Downstream of the fish hatcheries, the river flows onward towards its end at Steinberg Rink where the water is dropped down to the River des Peres tubes. This reach features riparian plantings, riffles, boardwalks over the water and a restored prairie area. An aeration system is also present, along with another recirculation loop.

A resourceful action by the planners and design team was to increase the sustainability of the system and reduce dependency on city water input. Prior to the renovation, the park fed almost 3 MGD of city water into the park's many separate waterbodies. The schematic design specified 1.6 MGD, and during the actual design process the city water usage was decreased to 1.5 MGD.

The LCWS was completed in 2004, and the system is maturing. A Water Quality Management Plan and Water Systems Operations Manual provide guidelines on maintaining good water quality through customized best management practices and a monitoring program. Wildlife has returned to the system, and the renovated park is enjoyed by all.

Elise Ibendahl will give a presentation on this topic at the 2006 APWA Congress, accompanied by Roger Allison, P.E., Chief Engineer, Design Division, City of St. Louis, Missouri, and John Hoal, Ph.D., AICP, Principal, H3 Studio, Inc., St. Louis, Missouri. The session is entitled "The River Returns: Forest Park's Youthful Heart Beats Again" and takes place Tuesday, September 12, at 1:00 p.m. The three presenters will relate their experiences during the presentation from the master planning phase, through funding, design, construction and post-construction. Elise Ibendahl can be reached at (314) 421-0313 or Elise.Ibendahl@CH2M.com.