Peyton Manning –
Not the Only Big Thing
in the Mile High City
Sports Authority Field at Mile High is expected to sell out every
Sunday as rabid Bronco fans pack the stadium and await
quarterback Peyton Manning’s arrival to the Denver gridiron. That
thirsty crowd will generate a lot of weekend wastewater flow to the
220 mgd Robert W. Hite Treatment Facility (RWHTF) just north of
downtown. While Peyton prepares the Broncos for his 2012/13
debut season, Carollo has also done some big things in the
Rockies through our design and construction management of the
$150 Million South Secondary Improvements Project for Denver’s
Metro Wastewater Reclamation District (MWRD).
MWRD, like many agencies throughout the country, is upgrading their facilities to meet more stringent
effluent nutrient requirements. In fact, our recently developed Draft Wastewater Practice Business
Plan identifies nutrient reduction and recovery as one of the top five national trends of the wastewater
industry. For MWRD, this means decommissioning the South Secondary High Purity Oxygen System
(HiPOS) that was built in the mid 1970s and constructing a new 114 mgd biological nutrient removal
(BNR) facility. The new South Aeration Complex, designed by Carollo in four different offices (DENB,
DENL, OCO, PHX), includes six parallel aeration basins with an Average Day Max Month (ADMM)
capacity of 19 mgd each and three Centrate and RAS Re-aeration Basins (CaRRB) for side stream
treatment of high strength ammonia return flows from dewatering anaerobically digested sludge. CaRRB
was first incorporated into the RWHTF by Carollo in 2004 as part of the $50 Million North Secondary
Complex Improvements. The new MLE + CaRRB process is designed to produce effluent ammonia of
less than 2 mg/L and effluent nitrate+nitrite less than 8.6 mg/L on a 7-day average basis. Anaerobic
selectors can be operated in the Bio-P mode to achieve less than 1 mg/L of Total Phosphorus (TP).
Innovations include the CaRRB process, aeration blowers controlled through direct on-line ammonia
readings, repurposing of six of the eight existing HiPOS aeration basins to serve as RAS/WAS pump
stations, final aerobic polishing basins, and mixed liquor distribution for peak flows up to 250 mgd. Ten
140-foot secondary clarifiers will also be retrofitted with unique maze type EDIs and hydraulic suction
header sludge withdrawal mechanisms.
The entire complex, including the underground utilities (over 4000 drawings in 13 volumes of documents),
was designed in 3D MicroStation software. The 3D CADD files have now been tied to the contractor’s
construction schedule to provide 4D virtual construction sequencing of every element of the project.
A full time Carollo construction management team of nearly 15 people are working in the field each day
to oversee construction activity. Another 10 to 15 people are stationed in the DENB/DENL and OCO
offices to provide submittal review, design interpretation, startup and testing planning, O&M Manual
preparation, and operator training. The total value of Carollo’s five-year CM services contract will exceed
May 2012 Construction Progress of Denver’s RWHTF 114 mgd
South Secondary Complex
$25 million. The CM team must oversee
the placement of over 74,000 cy of
concrete, three large piping and utility
galleries and tunnels, large piping ranging
from 24- to 134-inch diameter, many
miles of cable tray and wiring, installation
of five 56 mgd - 450 Hp PE pumps, five
2,000 Hp single stage centrifugal aeration
blowers, twelve 25 mgd MLR pumps,
ten new clarifier mechanisms, and
fourteen RAS pumps. Strict and complex
construction and startup sequencing and
constraints are required to keep portions
of the existing plant operational during
construction. Sequencing culminates in a
6-month by pass pumping sequence for
up to 60 mgd during the final tie in and
startup phase.
This showcase project is critical to the successful growth of Carollo’s wastewater practice. Not only
does it highlight our capabilities for design of innovative nutrient reduction, but it also is a prime example
of large work effort projects identified as critical to Carollo’s success in our 2020 Vision Strategic Plan.
What make this even more exciting is that the MWRD RWHTF plant is just one of many similar facilities
built in the 1970s to conserve site space by using high purity oxygen. The challenge today is that these
plants do not remove nutrients very well and will have to either be completely remodeled or replaced
with BNR plants as more stringent nutrient criteria becomes the norm. The MWRD South Secondary
Improvements project is the largest conversion of a HiPOS plant to BNR in the nation. Other large
agencies around the country are considering similar conversions of HPO plants to BNR including: the
Sacramento Regional County Sanitation District (SRCSD), San Francisco Public Utilities Commission
(SFPUC) Southeast WWTP, San Diego, Point Loma, Los Angeles, Seattle, and Miami-Dade (Florida)
Central Plant, just to name a few.
Our experience with MWRD unlocks a world of opportunity for Carollo in helping others take the next step in
nutrient reduction. To accommodate the future needs of HPO plants around the country, the Draft Wastewater
Practice Business Plan calls for the development of marketing and technological strategies to leverage the
MWRD experience to assist other agencies in converting HPO facilities to BNR as the needs arise.
With a few of these high profile conversions under our belt, Carollo could quickly become the nation’s
premiere consultant in the design of HPO transitions to nutrient reduction. But we need your help to do
that. If you know of a plant facing similar challenges or with similar needs, John Fraser (DEN-B), Carollo’s
Wastewater Technical Practice Director, is the guy you need to talk to about putting together a technical
plan and business development strategy to bring that project home. Meanwhile, if you find yourself
checking in on a Broncos game to see how Peyton is doing, be sure to look for Goodyear Blimp aerial shot
of the South Platte River and find the three tower cranes that mark Carollo’s Mile High accomplishments.