DRAPER WATER TREATMENT PLANT REDUNDANCY AND REINFORCEMENT OF RESILIENCE FOR WATER TREATMENT AND STORAGE
Oklahoma City
BEST PROJECT
Sent by: Carollo Engineers Inc.
OWNER City of Oklahoma City
RESPONSIBLE/STRUCTURAL/MEP DESIGN COMPANY Carollo Engineers Inc.
GENERAL CONTRACTOR Archer Western Construction Co.
CIVIL ENGINEERING Olsson Engineering
STRUCTURAL ENGINEERING White Engineering Associates Inc.
With a treatment capacity of 150 million gallons per day, the Draper Water Treatment Plant is the largest in the state of Oklahoma and has a more drought-resistant supply than the other water treatment plant city water
The primary goal of this $71 million project was to replace Draper’s clear wells with new ones designed to meet modern seismic resistance standards, improving the facility’s resiliency.
The scope also included the construction of a 120-in. transmission pipe up to 40 feet below grade for a redundant means of transporting filtered water to the new clear wells.
The design team performed a geophysical analysis of the subgrade, which indicated inadequate soils and periodic groundwater at the intended location for the clear wells. A delegated design utilizing ground improvements and a crushed stone transfer pad was implemented as a cost-effective means of accommodating the foundation loads and desired seismic resistance level.
Photo by Skylar Skaggs/Archer Western Construction Co.
The owner, engineer and contractor thoroughly assessed site conditions through selective excavation to better inform the delegated design. This resulted in a reduction in both cost and schedule for this design element and improved overall design efficiency.
Recognizing the risk to existing clearwells from recent seismic events, the team designed and built a contingency structure and developed an operational plan to divert leachate away from the clearwells in the event of a major failure.
During the planning process, the design team evaluated several options for providing both disinfection and transmission of filtered water from the filters to the new clearwells.
Computational fluid dynamics modeling helped the team evaluate the efficiency of chlorine contact for disinfection, using an innovative pump mixing design.
During construction, the team worked with local manufacturers to build an efficient, robust, and easy-to-operate-maintain chlorine injection and diffusion system within 120 inches. pipe contactor.
Photo by Skylar Skaggs/Archer Western Construction Co.
With increased transfer efficiency and the ability to disinfect post-filtration, the Draper WTP is able to reduce the total trihalomethanes entering the distribution system, benefiting the customer and the community as a whole.
This project had several security challenges. The first was the safety of the trench for the 120-foot pipeline that ran beneath the existing feed pipe banks feeding the plant. The Archer Western-led project team used a pier and beam system to bridge the conduit bank in order to open the 40-foot excavation into the bedrock beneath that conduit bank while keeping it in service.
Another safety concern was installing the liners in the filter effluent channel while maintaining flow downstream of the work area. Archer Western installed a series of bulkheads to protect the workers and to keep water out of the section of canal being repaired. The work has been carried out in a small space with a dangerous environment (coatings and sand). Permit entry, constant air monitoring, competent training and daily bulkhead inspections were part of the standard operating procedures, work plan and occupational hazard analyzes for this work.
