Projects - Wastewater Systems

 

Obsolete Stehekin Wastewater Treatment Plant Replacement
 

North Cascades National Park, Washington

Stehekin, Washington is located along the northeast shore of Lake Chelan in the Lake Chelan National Recreation Area near the south end of North Cascades National Park.  The National Park Service owns and operates a physical-chemical wastewater treatment plant (WWTP), which was designed and constructed in 1974-76 to treat 25,000 gallons per day (gpd) of domestic wastewater from the community near Stehekin Landing.  HECO completed a Condition Assessment Report on the facility, identifying WWTP building and wastewater treatment system deficiencies in order to determine the scope and need for a new wastewater treatment system.  The Condition Assessment Report summarized the current operational capabilities and structural and unit process deficiencies that are expected to affect current regulatory compliance as well as compliance with anticipated discharge permit requirements.  HECO completed a Design Alternatives Report, developing design alternatives, which provide for a simple and efficient wastewater treatment process suited for the seasonal temperature and volume fluctuations at Stehekin.  It also identified potential strategies for land application of treated biosolids in Stehekin, and evaluated the economic feasibility for each alternative.  Finally, HECO completed a Value Analysis / Choosing By Advantages Study for the project alternatives and documented in a report.  The alternatives focused on technologies that would meet water quality parameters, handle the large seasonal fluctuations, fit within the space constraints of the existing site and treatment building, and be feasible to construct at the remote site, approximately 44 miles by boat or plane from Chelan, Washington.  Also, the technology needed to be reliable and consider the limited operator staff available for operation and maintenance.

Services Provided by HECO Engineers:

  • Civil Engineering
  • Project Management
  • Title I Report (Preliminary Engineering)
  • Condition Assessment

 




Stinson Beach Pressure Drainfield Replacement
 

Golden Gate National Recreation Area, California

Stinson Beach is the only swimming beach within Golden Gate National Recreation Area.  A popular recreational site, the beach area receives over 700,000 visitors on an annual basis and upwards of 5,000 visitors per day during the peak season.  The sewage from the restroom facilities are handled through typical septic tanks and drainfields.  HECO has completed the Title I services (preliminary engineering) to evaluate alternatives for the repair of the drainfield facilities.  HECO developed alternatives which provided for simple and efficient wastewater treatment and disposal.  The selected alternative was to utilize the existing septic tank, provide centralized secondary treatment and disposal through a large absorption field.  HECO is currently designing the selected alternative.

Services Provided by HECO Engineers:

  • Civil Engineering
  • Project Management
  • Title I Report
  • Condition Assessment
  • Construction Documents

 




Wastewater Treatment Facility Improvements

 Melba, Idaho


This project included the construction of improvements to the municipal wastewater facility to meet a DEQ issued consent order and to provide adequate capacity for existing connections.  The City’s existing facility was a non-discharging facility and had reached capacity requiring frequent pumping and transport of wastewater to other facilities.  This project designed 19 million gallons, total volume, of new HDPE lined reservoirs to allow for a fully evaporative system and not require any discharge.  The facility was designed utilizing property that was located approximately 110 feet below the existing facility, which eliminated the need for pumping facilities and thereby a very sustainable system with very low operating costs.  The project also included the design of new head works including a rotary screen and flow measurement equipment, a new 750,000 gallon aerated primary treatment pond, construction of 800 lineal feet of sewer collection system, and construction of concrete valve control boxes with depths ranging from 5 to 13 feet.

Services Provided by HECO Engineers:

  • Master Planning
  • Project Management
  • Preliminary Engineering
  • Construction Documents
  • Construction Management
  • Survey
  • Civil Engineering



 

Wastewater System Improvements

New Plymouth, Idaho

 
Improvements were made throughout the entire City and have prepared the City for increasing population growth until 2027.  Some work was within Highway District and Irrigation District right-of-way and required coordination with other agencies.  Replacement of the deteriorated sewer mains has resulted in considerably lower sewer flows due to the decrease in infiltration and inflow.  Because of low construction costs and the size of the available construction budget, the City was able to complete over 50% more work than originally bid.  This project was funded through Rural Development and City funds.
 
Services Included:

  • Approximately 10,230 linear feet of 8-,12 and15-inch PVC SDR
    35 gravity sewer pipe

  • Approximately 5750 linear feet of 6-, 8- and 12-inch CIPP liner 
    a screen building at the wastewater lagoons


Services Provided by HECO Engineers:

  • Preliminary Engineering
  • Construction Management
  • Survey
  • Civil Engineering
  • Construction Documents
  • Project Management
  • Condition Assessment


 



Sewer System Management Plans

Yosemite National Park, California


The purpose of this project is to develop individual Sewer System Management Plans (SSMP) for six sewer collection systems in Yosemite National Park that are subject to the requirements of the State of California Order No. 2003-2006.  The SSMPs for each individual systems include a Spill Prevention and Response plans (SP&R), Operation and Maintenance plans (O&M), Preventive Maintenance plans (PM), Capital Improvement Plans (CIP), Design and Performance Provisions, System Evaluation and Capacity Assurance Plan,  FOG Control Program, Monitoring, Measurement, and Program Modifications, SSMP Program Audits, Communication Program and Employee training.
 
The SSMPs will be used by Park staff to manage the sewer collection systems and track Sewer System Overflows (SSO) with the intention to reduce occurrences and provide the necessary oversight to improve performance of the sewer collection systems that over one mile in length.

Services Provided by HECO Engineers:

  • Civil Engineering
  • Project Management
  • Master Planning
  • Condition Assessment