1. 44 WE&T l JANUARY 2016 l WWW.WEF.ORG/MAGAZINE © 2016 Water Environment & Technology. All rights reserved.
Building bigg
Replacement design of pumping station for long-term
combined sewer overflow control
Chein-Chi Chang, Garry Brennan, and Bill Meinert
T
he Poplar Point Pumping Station has been
operating in Washington, D.C., since 1915.
Upon flow testing a few years ago, the
station, which has a design capacity of
170,300 m3
/d (45 mgd), only could pump
166,160 m3
/d (43.9 mgd). Couple this
finding with many operational and structural
issues, and DC Water (Washington, D.C.), which owns and
operates the station, decided to build a new station.
This new project also offered the chance to increase
capacity, enhance operation, and improve the building
aesthetics.
The need to rebuild
Like many older cities in the U.S., the sewer system in
D.C. includes both combined and separate sanitary sewers —
about one-third of the D.C. system is combined. Communities
with combined sewer systems must prepare long-term plans
(LTCPs) to address combined sewer overflows (CSOs) in
accordance with the 1994 CSO policy at Section 402 (q) of
the Clean Water Act. DC’s LTCP has received final approval
from the U.S. Environmental Protection Agency (EPA) and the
D.C. Department of the Environment (DDOE).
One of the principal components for the LTCP, which DC
Water has dubbed The DC Clean Rivers Project, is to replace
the existing Poplar Point Pumping Station (PP-PS) with a new
one. In addition to not meeting its design flow, the existing PP-
PS has equipment issues with mechanical screens, sanitary
pumps and motors, and bridge crane corrosion. Additionally,
the existing PP-PS has such structural issues as cracks in
support beams, chimney, and wet well walls; roof leakage; and
other deficiencies.
Additionally, the existing PP-PS is less than 2.4 km (1.5 mi)
from the National Mall and south of the U.S. Capitol, resulting
in additional scrutiny from the Council of Fine Arts. Also, a
new adjacent bridge is replacing an aging trundle bridge over
the Anacostia River — the existing PP-PS sits in the path of
associated roadway changes.

2. WWW.WEF.ORG/MAGAZINE l JANUARY 2016 l WE&T 45© 2016 Water Environment & Technology. All rights reserved.
er and better
The new plan
The new PP-PS station will have a firm capacity 208,000 m3
/d
(55 mgd) to accommodate additional build-out that may occur in
the Poplar Point area. According to the LTCP, the station also will
link to Blue Plains Advanced Wastewater Treatment Plant via an
underground CSO tunnel. The Blue Plains CSO tunnel stretched
between PP-PS and the treatment facility.
Due to the site constraint issues, DC Water conducted a
comprehensive search for a site suitable for the new PP-PS.
DC Water considered factors including hydraulics, proximity to
the new Poplar Point Junction Shaft, site accessibility, utilities,
and minimizing the disruption of high-traffic thoroughfares.
DC Water evaluated several alternative sites. Several
exhibited unsuitable soils to establish the station footprint and
foundation support. Ultimately, the location indicated in Figure
1 (p. 46) was found to be suitable.
The need to design well
DC Water also needed the new building to meet certain
aesthetic and sustainability requirements. In D.C., the Green
Building Act of 2006 requires that all district public buildings
meet U.S. Green Building Council’s (USGBC) LEED Silver
certification standards and EPA energy performance. Thus,
DC Water promotes that its nonindustrial structures meet or
exceed the verification requirements of LEED-NC 2.2 or LEED
CS 2.0 Standard.
The new PP-PS incorporates green design elements
equivalent to a LEED certification. Throughout the project’s
development, the management and design team kept asking
itself two questions:
■ Are we doing the project right?
■ Are we doing the right project?
These questions are the cornerstones of the green
infrastructure design process. In terms of LEED, this set of
questions encourages strategies that minimize effects on
ecosystems and water resources, promotes better building
energy performance, utilizes sustainable building materials,
and improves the workplace environment. Figure 2 (p. 46)

3. 46 WE&T l JANUARY 2016 l WWW.WEF.ORG/MAGAZINE © 2016 Water Environment & Technology. All rights reserved.
shows an architectural design concept of the
preliminary layout and rendering for permitting
review and approval.
The exterior factors to consider
The project designer used the USGBC
spreadsheet for estimating credits or points to
assess the project. (See Figure 3, below.) The
design goals for the architectural concepts and final
architectural design sought to
■ meet consent decree requirements;
■ demonstrate DC Water commitment to the
Poplar Point development and revitalization;
■ provide a low-maintenance, vandal-resistant,
and reliable facility;
■ provide a strong and appropriate aesthetic
presence at the gateway to Washington D.C.;
and
■ incorporate LEED and low-impact development
green design elements and principles.
These design elements included
■ indigenous landscaping with low irrigation and
maintenance needs;
■ solar power collection;
■ vegetated roof design to provide heat island
reduction, rainwater runoff reduction, and
increased lifespan of roof system; and
■ control of runoff using cisterns, permeable
pavers, and so forth.
Preliminary assessments of the intended
design features tallied as 110 possible points, with
a majority of the points for the pumping station
project in the categories
of Sustainable Sites and
Energy and Atmosphere.
Fewer points came from
the remaining categories of
Water Efficiency, Materials
and Resources, Indoor
Environmental Quality
(unmanned station),
Innovation and Design
Process, and Regional Priority
Credits.
Some of the main features
of the LEED Silver-certifiable
design include photovoltaic
solar panels, wind turbines,
extensive green (and “white”)
roof and low-impact design
elements (rain gardens and
underground storm retention /
recharge; pervious pavement;
agri-fiber products). DC
Water also studied wind
power collection in the
conceptual design stage but
Figure 1. Location of the new Poplar Point Pumping Station
Figure 2. Preliminary design concept for the new Poplar
Point Pumping Station
Figure 3. USGBC spreadsheet for estimating credits

4. WWW.WEF.ORG/MAGAZINE l JANUARY 2016 l WE&T 47© 2016 Water Environment & Technology. All rights reserved.
did not use it in the final design.
The unique and innovative PP-PS shape and architectural
shell was developed given the site constraints and proximity to
an adjacent highway and various features of the nation’s capital.
Figure 4 (above) shows a rendering of the final design, which
currently is under construction.
The interior designs to optimize
The new PP-PS’s process and mechanical design also
incorporates many lessons DC Water has learned elsewhere.
For example, the design of the wet well relied on applying current
design tools and techniques to assess flow conditions and swirl
potential at the pump intakes. DC Water used computational fluid
dynamics software to model the initial wet well layout. The model
enabled the authority to identify and implement corrective actions
to minimize velocities and swirl potential under various operating
conditions. The measures included baffling and flow vanes along
with adjustments in operating water levels and channel inverts in
the wetwell area.
Figure 5 (above) shows a 3-D rendering of the PP-PS interior,
its levels, and major process equipment. This includes mechanical
(catenary) screening, wastewater
pumps — four 112-kW (150-hp) units
— odor control, flow measurement, and
power and control systems.
The way to choose
To choose the station’s builder, DC
Water elected to evaluate Statements
of Qualifications from proposers in
advance of receipt of bids. Using
a self-developed scoring system,
Statements of Qualifications were
tallied and the three highest scoring
firms were selected to prepare bids.
DC Water evaluated the resulting
bids and awarded a general contract
to proceed. Construction began in
spring 2015 and is expected to be
completed in April 2017.
Chein-Chi Chang is structural
engineer in the Department of
Engineering and Technical Services at
DC Water (Washington, D.C.). Garry
Brennan is program manager, Tunnel
Construction in the Department
of Clean Rivers at DC Water. Bill
Meinert is vice president at O’Brien
& Gere Engineers (Bowie, Md.).
Figure 5. New Poplar Point Pumping Station interior
Figure 4. Final exterior design rendering