City of Monmouth Main Street Park

Monmouth, Oregon
Rainwater Harvesting
Owner:
City of Monmouth
Engineer:
KPFF - Portland
Contractor:
Superior Excavation Inc.
Technical Description:
  • CDS® Hydrodynamic Separator (pretreatment)
  • DuroMaxx® Steel Reinforced Polyethylene Tank
  • Mechanical Skid
 
Installation:
Spring 2016

Monmouth Oregon is a city of 9,620 residents and the home of Western Oregon University. The city is located 20 minutes west of Salem, the state capitol, and the Pacific Ocean and the Cascade Mountains are just an hour’s drive from the city. 
 
City planners and business owners recognized the value of the numerous events being held in Main Street Park, located in the heart of the downtown area.  The building of an amphitheater was seen as the next logical step in the continued development of the park. The amphitheater project entailed several structures including new bathrooms, storage facilities, and a rainwater harvesting system (RWH) that reuses water from the park’s splash fountain to irrigate the park.
 
Landscape architects from Cameron McCarthy led the process of creating unique design options for replacement of the original concrete fountain structure. Engineers from KPFF Portland worked with Contech Engineered Solutions to design a RWH system comprised of a CDS hydrodynamic separator, a DuroMaxx steel reinforced polyethylene tank, and a mechanical skid. Contech was chosen because we provided a turn-key rainwater harvesting system and design support between the civil engineer, owner, landscape architect, and contractor to deliver a system that fit their site constraints.
 
Water from the splash fountain is first sent to the CDS for pretreatment. Pretreating the water removes trash and sediment that may harm downstream pumps, filters, and fixtures. The treated water is then stored in a 36’ long, 120” diameter steel reinforced polyethylene tank that provides 20,000 gallons of storage.  Using a large diameter tank provides storage at a lower cost per cubic foot and reduces excavation costs.
 
When needed, water is pumped from the tank through the mechanical skid where it is filtered with a 25 micron automatic backflush filter and disinfected using UV disinfection. A pump then delivers 28 gpm at 60 psi for spray irrigation to water the park grass and landscaping, including the amphitheater lawn.
 
Both the CDS and the tank are located under the lawn where guests gather for concerts and other events, while the mechanical skid is located in a storage room in the new restroom facility.

"The City’s innovative idea of collecting water from the fountain during the day so that it could be used to irrigate the lawn at night was pretty straight forward, but how to do it wasn’t as clear. Working with Contech we were able to design the right system for the job and have the confidence that it would work well and be easily maintainable,” said Joshua Lighthipe, of KPFF Portland.  “Contech was super helpful and key to the project’s success. We’ll definitely use them on our next water harvesting project.”

The installation of the tank and mechanical skid was performed by Superior Excavation. "Throughout the process we received excellent communication and prompt responses to any questions or concerns we had," stated Dan Loscar, President of Superior Excavation. "The product is a high quality product. We so appreciate the training Contech provided for the use and maintenance of the tank. We look forward to working again with Contech on our future projects."

During the first month and a half of operation, the City saved 368,000 gallons of potable water and has only used 3,000 gallons of potable water for landscape irrigation. The splash fountain is getting lots of use from kids, and they have weekly concerts in the park throughout the summer in the amphitheater

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