2018 Excellence in Environmental Engineering and Science™ Awards Competition Winner

E3S Grand Prize

Grand Prize - Design

Northern Treatment Plant Facilities

Entrant: Metro Wastewater Reclamation District
Engineer in Charge: Steve Patterson, P.E.
Location: Brighton, Colorado
Media Contact: Scott Vanier, P.E., MBA


Entrant Profile


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Metro Wastewater Reclamation District's service area in Denver, Colorado.

Metro Wastewater Reclamation District (Metro District or District) is a wastewater authority providing wastewater services to about 1.8 million people in a 715-square-mile service area throughout greater Denver. The District currently handles 130 million gallons of wastewater each day (mgd) at the 220-mgd Robert W. Hite Treatment Facility-the largest wastewater plant between the Mississippi River and the west coast.

In 2016 the District commissioned the Northern Treatment Plant (NTP) located in Brighton, CO to provide 24 mgd of capacity for connectors northeast of Denver. The NTP uses advanced treatment prior to discharge to the South Platte River. The NTP Facilities Project is a regional project helping solve wastewater treatment needs for the northern Denver metropolitan area and highlights how a progressive design-build (PDB) delivery achieved schedule savings and cost certainty for the Metro District. The District and its Owner Advisor, Carollo Engineers, worked with the Design-Builder, CH2M now Jacobs (CH2M), to develop a project partnership that promoted team collaboration and project risk assignment that met the District's facility, budget, and schedule goals.

The Metro District's treated water makes up more than 85 percent of the South Platte River nine months of the year and is suitable for agriculture, fish and aquatic life, industrial use, water supply, and recreation.

The District land applies stabilized biosolids at private farms and the District's METROGRO Farm. The award winning Resource, Recovery, and Reuse programs at the District serve as a national example of stewardship of our nation's agricultural and prairie lands.

Project Description

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The District's NTP is the largest "greenfield" wastewater treatment facility to date in the U.S.

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The 78-inch South Platte Interceptor delivers wastewater to the NTP where influent pumps convey water for primary and secondary treatment. Located 50 feet below ground, the Headworks Building is the deepest facility in the NTP.

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Three-dimensional modeling during design facilitated interdisciplinary collaboration and more efficient cost estimate and quality reviews.

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The NTP was designed to meet the most stringent effluent standards in Colorado to protect the State's natural resources. The treatment was selected to not only to meet these limits, but also to improve long-term operability, maintenance, and reliability and has consistently met permit discharge limits since commissioning.

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The Administration Building at the NTP Facilities includes a Visitor's Center with interactive displays to provide educational opportunities to the public.

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The project encountered several challenges in dealing with groundwater. A slurry wall was installed around the site to accommodate construction activities and long-term operations.

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Dissolved oxygen in the effluent is increased prior to discharge to the South Platte River through a series of waterfalls-the centerpiece of the natural wetland buffer visitors can explore via paved trails connected to the river.

Our staff is very pleased with the Facility. We believe it is quite an accomplishment for a facility of this size and complexity to be compliant from Day One!

Orren West, NTP Superintendent

The Largest "Greenfield" PDB WWTP in the United States

After three decades of wastewater planning, the Metro Wastewater Reclamation District's $475M Northern Treatment Plant Program, including its $280M NTP Facilities, embody the spirit of regional, intergovernmental, and regulatory cooperation, and provide a consolidated approach to wastewater management. It is one of Colorado's largest and most complex wastewater projects to be contracted by alternative delivery. The project also represents the largest "greenfield" water or wastewater treatment facility in the U.S. to-date to be constructed using progressive design-build (PDB). Accordingly, the project demonstrates the collaborative spirit of PDB to meet scope, quality, budgetary, and schedule goals, and is referenced as Best Practice in the Water and Wastewater Industry.

CH2M was selected as the Design-Builder based on qualifications to provide design, permitting, construction, and startup/commissioning services. Notice-to-Proceed for design was granted in August 2011 and a stipulated price was agreed upon between CH2M and the District after 14 months of design progression.

The project consisted of:

  • 24-mgd advanced treatment (expand.able to 60-mgd).
  • 7-mile, 78-inch diameter interceptor.
  • Visitor's Center and Facilities Support Building (FSB).
  • 12 acres of natural channels, wetlands, and community trails.

Integrated Approach

A guiding principle throughout project delivery was collaboration across all project partners. Starting with the District and its Owner Advisor, the program's vision and goals were developed and included for the entire design-build team. Partnerships across local and regional entities were created through intergovernmental agreements. Collaboration and management systems, work flows, decision-making, and issue escalation procedures were defined to integrate all program partners into an enterprise delivery.

This theme of integration also carried through the design.-optimizing treatment while minimizing construction and operation costs. The design met the District's commitment to enhance the South Platte River while minimizing impacts to the community and environment through:

  • Odor control throughout the facility.
  • Cogeneration.
  • Natural effluent channel provides benefit of cooling the effluent.
  • Architecture and landscaping blend with the surrounding community.
  • Noise and traffic control through construction and operation.

Quality

Quality was an important project component in every step of delivery. The Design-Builder's Quality Management Plan (QMP) was paramount. Although QA/QC was led by the Design-Builder, established quality objectives were the responsibility of everyone. The design QA/QC manager ensured QMP processes were properly implemented and that all requirements were met. Construction personnel were also responsible for QC and third-party testing and inspections were performed as a redundant quality check.

User Satisfaction

At the 30 percent design, the team initiated a series of steps to ensure the project met budget expectations. This resulted in a 19 percent cost reduction at 70 percent design. Construction was completed under budget and on-schedule with a change order rate of 1.3 percent. Additionally, early delivery and occupation of the FSB lowered operation costs.

Performance

Since commissioning, the NTP has consistently met permit requirements.

Originality and Innovation

The project had many innovative features to minimize operational costs and maintain flexibility for future regulations including:

  • Two-pass, 5-stage Bardenpho bioreactors with dis.solved oxygen probes optimize phosphorus, nitrogen, and ammonia removal.
  • Tertiary filtration for chemical phosphorus removal and future denitrification.
  • One of two North American installations of post-aer.obic digestion (PAD) removes ammonia and nitrate, provides struvite stabilization and additional VSS destruction.
  • Natural effluent channel provides the benefit of cool.ing the effluent while offering recreational opportuni.ties for the community.

Elements of Project Delivery

  • Co-location of the Owner and Design-Builder from design through commissioning.
  • BIM 3D modeling allowed virtual design with disci.pline collaboration and efficient cost estimation.
  • PlanGrid enabled real-time punch list creation and updating with mobile tablets.

The FSB and Visitor's Center are additional original and innovative project elements. The FSB is unique in that it includes the plant controls and laboratory and also has a library, locker rooms, private offices, open office area, vehicle and maintenance shops, and a warehouse.

Complexity

Some of the project challenges met included:

Schedule constraints, which were alleviated by:

  • PDB delivery.
  • Co-location during design.
  • Permitting activities during planning.
  • Site preparation before selecting the Design-Builder.

To gain public support for the project, and ensure NTP becomes a community asset, the team established a communication and outreach plan to obtain input from the surrounding community.

Gaining regulatory approval was unchartered for the first and largest PDB in the State. The team worked closely with the Colorado Department of Public Health and Environment to coordinate on the review and appropriate approvals.

A portion of the site was located within the 100-year floodplain. Coordination with regulatory agencies began during planning, allowing the District to minimize requirements of the Design-Builder.

The site's high groundwater table had elevated concentrations of naturally occurring metals. To alleviate impacts on construction and long-term operations, a slurry wall was installed around the site. To alleviate impacts from the metals, dewatering discharges from different areas of the site were blended to meet the groundwater discharge parameters.

Risk allocation was a concern for the District's first experience with PDB. The District and Design-Builder engaged in a detailed risk analysis that identified and quantified, and appropriately allocated over 150 risks for the project.

In September 2013, during construction, Colorado experienced historical flooding that impacted the project site and construction activities, including significant flooding of the deepest excavation on the site. The Design-Builder worked diligently to dewater and clean the impacted areas while keeping the project scope and schedule on track.

Social and Economic Advancement

Early in the project, the District made a commitment to deliver a facility that would be viewed as an asset to the community and continue their environmental stewardship. The team met this commitment in several ways:

  • With the potential to eventually eliminate up to 9 lift stations, critical infrastructure was provided to support ongoing regional economic growth and development.
  • A Visitor's Center with interactive displays provides public education.
  • The effluent channel and wetlands include more than a mile of paved trails connecting with the regional trail system.
  • Advanced treatment technologies minimize the use and transportation of hazardous chemicals.
  • Over 700 trees and shrubs were planted, often replacing invasive weed species.

Click images to enlarge in separate window.

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Crews work on piping installation of the Post Aerobic Digester (PAD). Being the largest installation in the U.S., PAD allows reduction of ammonia concentrations in centrate returns to liquid stream processes, thereby significantly reducing additional treatment costs.

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The Administration Building includes a Visitor's Center with interactive educational displays. The displays are designed to provide information on the water cycle and how the Metro District helps protect the South Platte River.

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Members of the project team gathered to watch and celebrate the first treated flow over the Facility outfall structure.

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An integrated and well-coordinated start-up/operations team of District and CH2M staffs was critical for successful commissioning. As a result, the "greenfield" NTP has met stringent permit limits from the first day of operations.

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The influent pump gallery is located 50 feet below grade allowing regional wastewater to flow by gravity to the Facility. Gravity flow to the NTP Facilities allows elimination of up to 9 lift stations thereby greatly reducing wastewater O&M transmission expenditures.

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The high-rate flocculation/sedimentation facility was designed to optimizate capital and O&M costs. Combined with biological phosphorus removal, the NTP Facilities can treat to some of the lowest phosphorus concentrations in the U.S.

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Investments in odor control and treatment facilities demonstrate the District's "good neighbor" commitment.

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The architecture of the NTP Facilities, such as the Solids Processing Building, was based on a campus approach and integrated architectural themes of the surrounding City of Brighton community.

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More than a mile of paved trails around a wetland area on the southwest corner of the site provide an additional community resource. These trails serve as a connection to a regional trail system.

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NTP outfall with the Headworks Building and primary clarifiers in the background.


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