PROJECTS   ››   Selected Experience In Wastewater Projects

Wastewater Treatment Plant Improvements

City of Coquille, Oregon

As with many public works projects, this construction required a multi-step process which began with a new public works garage and demolition of the old public works building. Removal of contaminated soils from the old building was required, along with installation and removal of preload, rather than driving pile, in order to stabilize and compress soils on the construction site. Once these phases of the project were completed, construction of the plant began and proceeded while maintaining operation of the existing plant.

This $8.1 million plant, which is highly visible to the public at its location on State Highway 42, was completed just recently, financed in large part by the U.S. Department of Agriculture's Rural Development funds, Oregon Business Development Department Water/Wastewater Financing Program and Oregon Department of Environmental Quality Clean Water State Revolving Fund.

The funding of Coquille's new plant was typical of nearly all the major projects where Dyer has been involved. Dyer works with Owners from assessment of needs to design and funding, as well as construction management and inspection, and training of employees to operate the new facilities. Because these facilities are built in small rural communities with often severely limited economic means, they simply could not be built without the assistance of various types of funding, an area where Dyer provides many years of experience.

In addition, a biosolids dewatering unit included in a Wastewater Facilities Master Plan to be constructed as funds became available is currently in construction, five to ten years ahead of schedule.

This 6.12 mgd wastewater plant was completed in 2013.The existing influent pump station was rehabilitated, a new SBR was constructed along with a new ultraviolet disinfection system with flow control galley. Modifications were made to the solids treatment stream , including rehabilitation of the existing digester and addition of a new membrane sludge thickener (a new process proven to reduce volume for export), conversion of the secondary clarifier into an aerated sludge storage tank, rehabilitation of the existing sludge storage tank and conversion of existing chlorine contact tank into a third sludge storage tank. Plant site improvements included controls for the plant, a new operations building with laboratory, a new blower and storage building and conversion of the control building into a public works building, along with extensive improvements to the yard, paving, underground utilities and landscaping. Design was focused on removal of phosphorus from the waste stream as the city of Coquille was under a Mutual Agreement and Order with the Oregon Department of Environmental Quality.

This project won a 2014 Excellence in Concrete award for Craftsmanship for the team: Owner/Developer - City of Coquille; Civil Engineer - The Dyer Partnership Engineers & Planners, Inc.; Civil/Structural Engineer - VLMK Consulting Engineers; Architect Lon Samuels; General Contractor - Wildish Construction; Ready Mix Supplier - Knife River Corp.

Wastewater Treatment Plant

City of Gold Beach, Oregon

Completed in 2013 in two phases, this $8.5 million project for the city of Gold Beach involved a major upgrade to the drainfield located at the Gold Beach Airport, making the drainfield the largest one west of the Rockies. The city of Gold Beach was under a Mutual Order and Agreement with DEQ because undisinfected effluent overflowed at times into Riley Creek when the capacity of the drainfields was exceeded. The original drainfield had clogged with sand and algae growth which caused a continuing problem with the equalization basin. Subsequently, the drainfield was enlarged from a 1-million to a 2-million gallon subsurface, nonclogging field with cleanout ports; drain pipe was encased inside infiltrators. This drainfield is in an area designated as a Runway Safety Area (part of Gold Beach Airport) so the drainfield design was modified to include stone to support aircraft in the event of an excursion from the runway.

Many plant components needed modification or were so outdated as to need replacement, and the plant needed to be upsized to meet current and future flows. The facility lacked redundancy of key treatment processes. A new public works building with a new laboratory at one end was constructed, as were an access bridge, a new Fairgrounds Pump Station and significant improvements were made to the wastewater treatment plant such as sequencing batch reactors and a covered equalization basin (to prevent algae growth) with decanters, an ultraviolet disinfection facility, control building, generator room, sludge dewatering with screw press, and conveyor and sludge storage pit. Two new glass-fused steel digester tanks with a sky bridge were completed as were new digester blowers, three drainfield force mains, 21 drain fields and pumps (instead of the original 9). Phase 3 will be the construction of the Hunter Creek and County Pump Stations, to be completed soon.

Wastewater Treatment Plant

City of Yachats, Oregon

Design, bidding and construction administration preceded extensive upgrades to the city's wastewater treatment facility and five pump stations. This Rural Development funded project expanded Yachat's wastewater system as a result of a need to increase a system already at capacity. Because of multiple DEQ notices for noncompliant treatment violations, Yachats was under a Mutual Order and Agreement to upgrade facilities. The conventional donut-style activated sludge secondary treatment facility was at design parameters for hydraulic and mass loadings, and the five pump stations were at design capacity and/or were at the end of their useful lives. The main influent pump station wa a below-grade wet well/dry well configuration with severe corrosion and was an OSHA confined space for worker entry. BOD5 and TSS loads exceeded design capacity and the treatment facility was unable to achieve volatile solids reduction to meet DEQ requirements for Class B biosolids in the digesters. In addition, the facility was discharging chlorine residual into a marine environment and had violated bacteria limits for effluent discharge nor did it meet EPA redundancy requirements.

Existing City shops, sludge drying beds and existing headworks were removed. Construction of twin sequencing batch reactors and an equalization basin, new headworks, conversion of existing aeration basins to digesters, conversion of the existing clarifier to a sludge storage tank, and installation of a new UV disinfection system then followed. All five pump stations received upgrades to increase capacity and replace outdated and/or equipment that couldn't be repaired. Ocean View, Riverside and Main Pump Stations were upgraded with installation of new packaged pump stations with submersible pumps. A new Public Works building with a laboratory, office, electrical room, toilet, blower room, upper storage mezzanine and five garage bays were also constructed. Because of a very limited footprint for this facility, it was constructed so that one wall of the plant shared a wall with the Public Works building.

Pump Station

City of Waldport, Oregon

This project included a preliminary engineering report, design and bidding documents and construction management for a new wastewater pump station and wastewater treatment plant headworks upgrade. Ocean Hills Pump Station utilizes two 470 gpm submersible pumps with an aboveground piping gallery. A new building was constructed to house a standby generator and hydrogen sulfide control system. The pump station upgrades also included the installation of a 14,700 foot six-inch diameter force main.

Wastewater Treatment Plant

Bandon Dunes Resort - Bandon, Oregon

As the first operational flat membrane system installation in the United States, this plant was designed and constructed to replace the existing aerated lagoon and wetland system. The membrane bioreactor (MBR) process technology is capable of consistently producing an effluent with less than 1 mg/L BOD, 1 mg/L TSS and 5 mg/L nitrate. This membrane system is now in its eleventh year and is still in use with no replacements or repairs. Plant improvements included construction of an MBR basin, chlorine contact chamber, conversion of the aerated lagoons to a facultative sludge lagoon (FSL), and a new control building. Plant capacity is 125,000 gpd.

Wastewater Treatment Plant

City of Siletz, Oregon

With the first flow-through sequencing batch reactor (SBR) installation in the State of Oregon, Siletz is the only municipality allowed to discharge to the pristine Siletz River. This plant serves a community of 1,100 people. This project consisted of design and construction-period services for construction of a new SBR system to replace the existing lagoon system. Additional facilities included a headworks, surge overflow basin, ultraviolet disinfection, aerobic digesters, facultative sludge lagoon and control building.

Solar Sludge Drying Bed

City of Rogue River, Oregon

This project, completed in May 2002, included the design and installation of a solar sludge drying bed, drum thickener, solids storage tank, and transfer pump. The solar sludge drying bed consists of a greenhouse facility with microprocessor - controlled ventilation louvers and fans, and a "mole". The mole is an electronically controlled device that tills the sludge bed, bringing moist sludge to the drying surface. The City utilizes this facility to process sludge – collected in its facultative sludge lagoon (FSL) into a dry, granular end product for land application.


Confederated Tribes of Coos, Lower Umpqua and Siuslaw Indians (CTCLUSI)

The design/build process was used to create a flat membrane treatment system that will serve the new Three Rivers Casino Complex located in Florence, Oregon. The project was completed in 2007. The overall project included a waste-activated sludge holding tank, drain pump station, biosolids handling, headworks with mechanical bar screen and screenings wash down station, membrane bioreactor tank system, drain pump station, non-potable water pump station and control building.

Wastewater Treatment Plant

Spirit Mountain Casino, Grand Ronde, Oregon

Design and construction administration of an upgrade for Spirit Mountain Casino's wastewater treatment plant. The project added a sequencing batch reactor in parallel with the existing system and increased total plant hydraulic capacity to 0.43 mgd. The installation of a 3.5-acre spray irrigation system allowed for disposal of 120,000 gallons per day of treated effluent and required a medium-pressure ultraviolet disinfection system capable of meeting total coliform requirements for a Class IV spray irrigation system.

Wastewater System Improvements

Bay Cross - Horizontal Directional Drilling Sewer Line City of Coos Bay, Oregon

South Slough crossing improvements consisted of the installation of approximately 1,375 lineal feet of 10-inch HDPE force main under the South Slough of Coos Bay using horizontal directional drilling construction methods, connection of a new force main discharge to existing manhole, and cementitious lining system for new manhole sections.

Pump station improvements consisted of the retrofit of two existing wet pit/dry pit pump stations with two submersible pumping units, variable frequency drives, SCADA systems, and controls, and installation of valves, vaults, replacement of wet well sections and pump discharge piping.

Construction Management

Coos Bay-North Bend Water Board (HDR, Inc.)

The Dyer Partnership performed the construction administration, construction management, and on-site inspection of this project for the regional Coos Bay-North Bend Water Board, which upgraded the capacity of the existing finish water plant from 8 million gallons per day to 12 million gallons a day. This upgrade was constructed while keeping the existing plant operational at all times. Included were improvements to the Rapid Mix Vault, Floc/Sed Basins and filters to incorporate new and/or high-rate improved treatment processes and surge improvements. New facilities constructed as part of this upgrade included the Pre-Oxidation Vault, treated water chemical injection vault, new filter with associated filter gallery extension, new chemical building and ammonia storage building as well as a new emergency standby generator.