Problem

The Ash Mountain Wastewater Treatment Plant, serving over 1.6 million visitors annually along with park residences and facilities, faced significant deficiencies. A 2011 Condition Assessment Report highlighted the need for an extensive wastewater rehabilitation. The challenges included:

• Outdated and failing 17,500 gallons per day treatment system
• Deteriorating electrical systems and headworks
• Ineffective overflow and chlorination systems
• Deteriorated treatment dosing building and spray disposal fields
• Failing wastewater lift stations and force mains
• Difficult-to-access effluent spray fields requiring repairs

Solution

In July 2019, HECO Engineers conducted a detailed site visit and prepared a comprehensive scoping trip report. They updated the Class D Construction Cost Estimates, helping to validate the estimated costs identified in the Project Management Institute Statements (PMIS) for the rehabilitation projects, including:

• PMIS #184085: Rehabilitation and replacement of critical components installed in 1974 within the treatment facility. This involved replacing the failing existing 17,500 gallons per day wastewater treatment system, rehabilitating the electrical system, deteriorated headworks and overflow, installing a new floating cover for the detention pond, rehabilitating the deteriorated treatment dosing building and spray disposal fields, and replacing the chlorination system.
• PMIS #246176: Rehabilitation of the three wastewater lift stations and force mains in the developed areas of Ash Mountain and Buckeye Housing of the Park. This included the renewal of duplex pumps, motors, controls, float system, force main blow off, drain vaults, and other mechanical equipment.
• PMIS #181622: Repairs to the 3,000 square foot treated effluent spray field components, including sprinkler heads, risers, solenoid valves, and valve boxes. The repairs and replacements were conducted in challenging terrains such as secondary roadways, steep terrain, under creeks, and meadows, with varying pipe sizes buried at depths of two to eight feet.
• PMIS #229631: Replacement of metal signage that had become discolored and unreadable, and repairs to the perimeter security fencing at the Ash Mountain spray field. This also involved removing severely overgrown and invasive vegetation and fallen/dead trees.
• PMIS #257424: Rehabilitation of the Ash Mountain Buckeye employee housing road. This involved grinding and pulverizing 950 square yards of four-inch-thick existing asphalt to utilize as a four-inch structural road base and repaving with four inches of new asphalt. The project included minor safety restriping with traffic flow arrows, stop bars, and 100 lineal feet of parking.
• PMIS #257415: Rehabilitation of the Ash Mountain treatment plant service road. This included grinding and pulverizing 700 square yards of four-inch-thick existing asphalt to use as a four-inch structural road base and repaving with four inches of new asphalt.
• PMIS #256139: Replacement of controls and monitoring equipment for the treatment plant, following typical industry life-cycle replacement standards. This included replacing controls for the process batching and pumping to the disposal field and local monitoring equipment for pump and motor failures to prevent system overflows of wastewater.

Results

The efforts of HECO Engineers in scoping and cost estimation facilitated:

• Accurate budget allocation for the rehabilitation projects
• Validation of over $4.5 million in project costs
• A clear path for the rehabilitation of critical wastewater infrastructure
• Enhanced planning and resource allocation for the National Park Service

Accurate Scoping and Cost Estimation Ensure Successful Rehabilitation

HECO Engineers’ detailed scoping trip report and updated cost estimates played a pivotal role in validating the necessary funds for rehabilitating the Ash Mountain Wastewater Systems. This project underscores HECO Engineers’ expertise in providing accurate cost assessments and effective project scoping.

For similar needs or to schedule a free 30-minute review of your upcoming project, contact HECO Engineers today.