2017 Excellence in Environmental Engineering and Science® Awards Competition Winner

Honor Award - Planning

Miami-Dade Ocean Outfall Legislation Program

Entrant: CH2M
Engineer in Charge: Evelio Agustin, P.E.
Location: Countywide, Miami Dade County, Florida
Media Contact: Jamie Jackson

Entrant Profile

CH2M began working with the Miami‐Dade County Water & Sewer Department in 2014 as the program manager of the approximate $6 billion Ocean Outfall Legislation Program. The 11‐year program is the culmination of a 2008 regulatory mandate by the Florida Legislature to reduce wastewater discharge to the ocean by 2025 and implement reuse alternatives. CH2M is providing system wide planning, as well as managing the overall delivery of 63 capital projects, including upgrading a very complex conveyance system with more than 1,400 pump stations; upgrading three wastewater treatment plants and building a new resilient wastewater plant to account for climate change variables in Miami.

CH2M leads the professional services industry delivering sustainable solutions and providing consulting, design, engineering and management services for clients in water; environment and nuclear; transportation; energy and industrial markets.

Other OOL Program consultants include: Hazen; Parsons Brinckerhoff, Inc.; Gannett Fleming, Inc.; Nova Consulting, Inc.; CES Consultants, Inc.; ADA Engineering, Inc.; Milian, Swain & Associates, Inc.; Vital Engineering, Inc.; Rohadfox Construction Control Services of FL, LLC; GCES Engineering Services, LLC; Hadonne Corp.; G‐T Construction Group, Inc.; CLIMsystems, Ltd.; and the Miami‐Dade Chamber of Commerce.

Project Description

Holistic Wastewater System Master Planning For an Environmentally Integrated Project

2025 Facility Average Daily Flow is 400 mgd (total of 4 plants).

Miami-Dade's OOL program will dramatically decrease wastewater flows to ocean outfalls.

CH2M's flow analysis tool validates Miami‐Dade's hydraulic model based upon spatially varied rainfall and the projection of flows, producing more refined flow projects and greater confidence in the model.

Miami‐Dade Water and Sewer Department (WASD) is the largest water and sewer utility in the southeastern United States. Operating three large wastewater plants (WWTPs), WASD treats 320 million gallons per day (mgd), discharging approximately half to the ocean. Driven by efforts to protect the environmentally sensitive water body and coastal ecosystem, a 2008 Florida law mandated wastewater utilities using ocean outfalls to reduce nutrient discharges by 2018, cease normal use of outfalls by 2025 and reuse 60 percent of wastewater flows by 2025.

As a result, WASD initiated the Ocean Outfall Legislation (OOL) Program to meet service needs of its customers and accommodate future growth. The $5.7 billion program involves wastewater system master planning through 2035 and the design, procurement and construction of 63 major capital projects.

A key element of the OOL Compliance Plan is creating a new WWTP and re‐distributing the County's wastewater system flows, currently traveling west to east (to the ocean). Roughly one‐fourth of the wastewater will be rerouted west to a new membrane bioreactor treatment plant (which when completed will be one of the largest in the world). The normal ocean outfall discharge will be replaced with 24 new injection wells. By 2035, 440 mgd of high‐level disinfected treated effluent will be injected into wells for both reuse and disposal. Outfall use will be limited to wet‐weather conditions after 2025, with less than 5 percent of the treated volume being discharged to the ocean.

An initial validation evaluation was conducted for WASD's baseline Compliance Plan, assessing the existing WWTPs, the planned future western WWTP, flows, conveyance system upgrades to pump stations and force mains, injection well plans, schedule and costs. In parallel with the validation effort, flow projections were validated and updated, taking into consideration impacts of climate change and sea level rise. New estimates of future intense storm flooding and storm surge were also conducted, accounting for sea level rise and climate change.

After the initial validation, the OOL Program tackled various data gaps, refining the Plan through comprehensive master planning.

System flow modeling for 2015‐2025 with the new projects installed were conducted iteratively to improve project scheduling and coordinate WWTP upgrades. This model identified 427 pump stations in need of replacement or rehabilitation. An implementation schedule was developed to phase projects so that the system's capacity can be managed for intermediate growth and to spread out costs over time.

Quality

To date, the 20‐year programmatic master planning is complete, all OOL Program milestones are met and detailed designs are proceeding. The holistic planning that accounted for future climate change, as well as Florida's persistent growth, will provide for exceptional sanitary service for longer than the 20‐ year planning period. Implementing the OOL Program will:

Improve the environment and coastal ecosystem by eliminating ocean discharge
Continue ensuring Miami‐Dade County's 2.3 million residents and thousands of daily tourists receive quality, reliability and efficiency from a world‐class water and wastewater system
Deliver 63 capital projects to improve the County's wastewater system
Establish a local workforce program with community leaders and partners, such as the Miami‐ Dade Chamber of Commerce, Latin Builders Association and other business associations
Identify and encourage Community Small Business Enterprises to provide the trade support needed for project implementation

Social and Economic Advancement

The OOL Program is comprised of 15 local companies; small businesses will complete at least 25 percent of the design work, maximizing learning and technology transfer. Public outreach is being conducted to promote and educate local business agencies of upcoming work, and the Program is hosting networking events to connect suppliers and lending/bonding organizations with small‐ and minority‐owned businesses. It is estimated that the OOL Program will contribute 30,000+ jobs to the County during its implementation.

In addition to public outreach and job creation, the OOL Program will protect public health by rerouting its system to a new plant on the west side, and accounting for sea level rise and higher surges at facilities will make the utility sustainable well beyond 2035.

Innovation - Finding Solutions to Stay on Budget and Schedule

The OOL Program's Compliance Plan was altered to improve implementation and spread costs over time to facilitate financing. Alternative delivery approaches for potential savings and schedule benefits are considered. For example, the new west WWTP will be a design‐build contract to meet the aggressive schedule. In another instance, a major large‐diameter force main to move wastewater west would disrupt an important Miami business district. A detailed feasibility study has identified a deep gravity sewer alternative that will greatly reduce impacts to the community, which will avoid millions of dollars of economic impact.

Complexity/Summary

The OOL Program is very complex; with 63 capital projects planned to re‐plumb a complicated collection system of more than 1,400 public pump stations and 700 miles of force mains, WASD is making a major investment to completely transform Miami‐Dade's wastewater system to not only comply with federal, state and local mandates, but also to improve sustainability and resiliency through effective long‐range planning for climate change and sea‐level rise. The result of the programmatic master planning effort completed in 2016 is a new Compliance Plan for WASD.

Highlights of the 2025 plan include:

Constructing greenfield 70 mgd (Phase 1) membrane WWTP
250+- upgraded/replaced pump stations
Numerous conveyance projects
20 new injections wells
Hardening/raising coastal facilities to combat future storm surges
Installing additional disposal and aquifer recharge wells
Phase 2 expansion of western WWTP (100 mgd by 2035)

With an estimated completion of 2026, the OOL Program will require all of WASD's existing regional WWTPs to undergo extensive upgrades to hydraulics, treatment processes, high‐level disinfection addition and alternative/increased disposal capacity to meet future growth demands and improve performance and operations. Despite the complex nature of the program, when it is complete, WASD will have implemented its vision of renewing its whole system, utilizing master planning and cutting‐ edge technology to develop a modern, world‐class utility that will be sustainable throughout the 21st century.

Click images to enlarge in separate window.

West District Wastewater Treatment Plant

WDWWTP Preliminary Site Layout. The West District Wastewater Treatment Plant (WDWWTP) is a critical part of the Ocean Outfall Legislation (OOL) Compliance Plan. It will provide WASD with the additional capacity required to manage the projected 2035 average and peak system‐wide flows. The effluent will discharge to the boulder zone and would meet secondary treatment and high‐level disinfection. The biosolids treatment at WDWWTP is to produce a Class AA biosolids product..	West District Wastewater Treatment Plant (WDWWTP) Land Acquisition. Miami Dade Water and Sewer Department (WASD) is planning to develop a new wastewater treatment plant in the West District of the County as part of the OOL Program. The first step for this project was the evaluation of potential sites to construct the new facility. 18 sites were evaluated and one was chosen to be the best location, from a conveyance and hydraulic point of view, as well as the least impact to the surrounding environment. The OOL team has supported WASD in the land acquisition process for the multiple parcels within the selected site.

GISA Proposed Route. Gravity Interceptor Storage Alternative (GISA) to convey wastewater from PS-187 to the new WDWWTP. The GISA is a deep conveyance system projected to convey significant wastewater flow to the proposed WDWWTP. As an alternative to the shallow pipelines to be installed along residential and business communities, it will replace the big pipelines and high energy consumption pump stations. The underground construction of the GISA will significantly reduce the disruption to the communities, as well as to the environment, while potentially eliminating approximately 50 pump stations that could be converted to gravity sewers inflows to the GISA	Central District Wastewater Treatment plant High-Level Disinfection System and Peak Flow Treatment. Central District Wastewater Treatment Plant (CDWWTP) is WASD's oldest existing wastewater treatment facility. The plant is located on Virginia Key and was originally constructed in 1956. CDWWTP will address the OOL by eliminating the outfall discharge and using deep injection wells to impermeable zone 3,000 ft. below grade for treated wastewater disposal. Additional upgrades include: high level disinfection by considering tertiary treatment and chemical disinfection. The plant will manage the estimated peak flow of 368 mgd by year 2035 and reduce nutrients discharge by 2018.

Large Diameter Injection Well Drilling Rig. The success of the OOL Program relies on an alternative disposal method: deep injection wells capable of receiving more than 15 mgd of treated wastewater each. Large‐diameter (24‐36 inch) Class I deep injection wells, such as the approximately 30 planned for the OOL Program, are drilled with rigs that are more than 125 ft high and wide enough to hold thousands of feet of large‐diameter drill pipe for installation of large‐diameter steel casings 2,000 and 3,000 ft below the surface. The large diameter deep injection well drilling conditions and equipment are considerably different from those in oil well drilling. Whereas a 10,000 ft oil well may be drilled in 30 days, a 3,000 foot Florida injection well will require at least 180 days, due to difficult drilling conditions.	Schematic Injection Well Profiles. Miami‐Dade County also considers the protection of the Biscayne aquifer among its highest priorities. This potable water source has been designated a sole source aquifer by the U.S. Environmental Protection Agency (EPA) and is afforded additional protection as the primary source of drinking water for Miami‐Dade County under the Sole Source Aquifer Program authorized by the 1974 Safe Drinking Water Act. Injection wells that are not constructed properly could cause upward migration of waste streams into the Biscayne aquifer. Therefore, the Class I injection wells constructed for the OOL Program have been designed to progressively isolate aquifers and confine units such that the Biscayne aquifer is ultimately protected by four cemented steel casings. The injection zone - a saline, cavernous interval known as the Boulder Zone - is located more than 1,000 ft below the lowermost underground source of drinking water (USDW).

Plant Site Planning. SDWWTP is one of Miami Dade County's existing treatment plants that will upgraded from existing capacity of 112 mgd AADF/285 mgd PHF to 131 mgd AADF/368 PHF. The upgrades are planned to be completed in two phases, with the first phase upsizing the plant to 121 mgd AADF/305 mgd and the second phase to the ultimate capacity. These upgrades will enable the plant to meet future average flow increases and relieve the south district basin during peak flow events. Comprehensive planning and conceptual design of upgrades were recently completed for the proposed upgrades, with design to Commence in 2017.	RAS PS Upgrades. As part of the expansion of the SDWWTP, new peak flow management strategy of equalization and step feed at oxygenation trains will be implemented. This will include expansion of the Existing RAS pump station.
South District Conveyance Improvements

South District Conveyance Improvements. Pump Station 522. Upgrades to the South District Conveyance system are planned to meet future capacity growth, as well as remove peak flow bottle necks. Upgrades of existing booster pump station, new booster pump station and transmission line upgrades are being planned. One of the existing pump stations to be upsized is pump station 522.	South District Conveyance Improvements. Pump Station 1073. Miami Dade Country has various volume sewer customers like Florida City, Hialeah, Coral Gables, etc. Upgrades proposed under the OOL Program will enable the county to be able to transmit future average and peak flows from these areas, as well relieve bottle neck in the existing transmission system. Pump station 1073 is located in Florida City and transmits flows from Florida City to Miami Dade transmission system.
Pump Station Peak Flow Upgrades

System Flow Planning. In order to meet the OOL, WASD submitted to FDEP a Compliance Plan in 2013 with a planning horizon of 2035. This plan was refined to include climate changes and sea level rise to come up with updated peak and average flow projection for 2035. Review of existing and future sewer basin and impact of future average and peak flows was performed for this large interconnected system.	Flow Diversion Evaluation. In order to meet the OOL, WASD proposed a new greenfield West District WWTP to move flows away from the coast. New WWTP planning and movement of average and peak flow to this plant needed extensive system planning and evaluation to find the most operation friendly ways to transfer flows.