Sep 06, 2016

Storm Water Harvesting Revamps St. Louis Gateway Arch Park

After World War II, civic leader Luther Ely Smith conceived of building a memorial to help revive the St. Louis riverfront and memorialize the nation’s westward expansion. A nationwide design competition was held in 1947 and 1948, and Eero Saarinen’s stainless steel arch was chosen as the design for the memorial. After groundbreaking on June 23, 1959, Saarinen spent the next few years perfecting his design. Excavation of the grounds began in 1961.

In 2009, the CityArchRiver 2015 project envisioned a major upgrade to the St. Louis Gateway Arch park’s grounds to celebrate the arch’s 50th anniversary. The plan was to connect the Gateway Arch grounds with the riverfront and surrounding region to attract locals and visitors alike. 

In December 2009, an international design competition commenced, and in September 2010, landscape architecture firm Michael Van Valkenburgh Associates’ design was selected. The firm’s design created new and expanded spaces for events and public education, performance venues, museums, park acreage, bicycle trails, children’s play areas, and an invigorated riverfront near the Gateway Arch.

One of the design challenges was irrigation for the new park acreage. Harvesting and treating storm water to make it safe for spray irrigation requires special consideration along the entire treatment train. Runoff can include hydrocarbons, nitrates, organic matter and animal waste. Treated water would need to be clean and free from pathogens. The park service was insistent that the harvesting equipment not interfere with the sight lines of the park.

Water Harvesting Solutions Inc. (Wahaso) provided the solution, incorporating two additional partners to complete the project. 

It was critical in the treatment train to remove most of the suspended solids coming from the storm water runoff before they entered the storage system. SunTree Technologies Inc. recommended its Nutrient Separating Baffle Box system to remove sediment, organic material and hydrocarbons from large storm flows entering the cistern. The system holds trash above the standing water line and uses a series of baffles to remove suspended solids of less than 350 µ.

Oldcastle Precast Inc. supported the design and engineering of the StormCapture system, which holds 37,000 gal of pretreated storm water below-grade in nine precast modules. The company also helped resolve the sight lines challenge by providing an additional module to contain all the harvesting equipment below grade. An 8-by-10-ft precast equipment room was delivered with ventilation, sump pump, ladder and large access doors to avoid confined space restrictions.

Wahaso’s filtration and sanitation skid was designed to minimize maintenance on the system. A 50-µ filter is capable of self-cleaning during operation, eliminating the need to replace bag filters. High-intensity ultraviolet units are able to eliminate pathogens even if the water is slightly cloudy.

Wahaso’s solution was installed and started in time for the opening of Luther Ely Smith Square in the fall of 2015. Harvested water was provided for lawn and landscaping irrigation in the spring of 2016. 

The system delivers clean, safe water for spray irrigation at 40 gal per minute and 70 psi. It is expected to require service only at the beginning and end of each irrigation season. The belowgrade water storage system and equipment room ensures that the park will remain clear of obstructions, enabling visitors to focus on the Gateway Arch.

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