Features
November
2012, Vol.
24, No.11
New approach to project delivery
Managing the challenges of a tunnel rehabilitation and sewer
pipeline replacement project
David M. Jurich and Joseph N. McDivitt
The South Coast Water District
(Laguna Beach, Calif.) operates the Beach Interceptor Sewer Tunnel in South
Laguna, Calif. The pipeline running through the tunnel conveys, on average, 4.7
million L/d (1.25 million gal/d) of wastewater. Approximately 85% of the
interceptor’s flow comes from an upstream force main; the remaining flow enters
the pipe through 80 residential connections along the tunnel. But the tunnel
itself is in an advanced state of deterioration.
To rehabilitate the tunnel before it deteriorated any further, the district adopted a risk management approach. This led to an emergency repair project for a 230-m (750-ft) length of the tunnel, as well as a full rehabilitation plan for the tunnel's full 3,192 m (10,474 ft.). Read full article (login required)
Coordinated monitoring for stream condition
Multiple indicator assessments in the San
Gabriel River watershed improve efficiency and provide a solid context for
decision-making
Kristy Morris, Scott Johnson, and Raphael Mazor
Before 2005, stream condition monitoring in the
San Gabriel River Watershed involved numerous agencies independently collecting
data from defined portions of the watershed — mostly around major discharges
for permit compliance purposes. Inconsistencies among the programs, including
differences in the constituents sampled and the frequency of measurement,
resulted in limited data comparability, redundancies, and major data gaps. For
more than 7 years now, a coordinated effort (the San Gabriel River Regional
Monitoring Program) has been integrating permit-mandated and ambient
monitoring. Read full article (login required)
Know your options
A Florida utility selects the right remote-site wireless
communication technology for its wastewater treatment systems
Dustin Sayre
The Collier County (Fla.) Public
Utilities needed to remotely monitor and control lift stations close to its
wastewater treatment plant. The utility wanted to prolong the life of its
existing equipment at these stations and operate pumps more efficiently.
Because Collier County is located in a hurricane-prone region, backup power and
local data storage in case of power and communication loss also were important
to the organization, as well as timely notification of equipment failures or
alarms.
The utility had many things to consider before making
its purchase. It required an understanding of its remote wireless communication
needs, which equipped the organization with the knowledge needed to ask the
right questions prior to selecting technology. Collier County carefully
addressed the many factors any utility must consider when purchasing a wireless
communications system. Read full article (login required)
Operations Forum Features
Bursting with possibility
Applicability of NESHAP to rehabilitating asbestos-cement
pipelines
Bill Thomas and Edward Alan Ambler
Asbestos, a naturally occurring
mineral fiber, was used extensively in many building materials prior to the
adoption of the National Emission Standards for Hazardous Air Pollutants
(NESHAP). Its properties, such as fire and chemical resistance, flexibility,
high strength, and a long and thin fibrous shape, made it a desirable component
for many construction materials, including pipe.
Now, as these pipes reach the end
of their useful lives, replacing them becomes a costly challenge. Today,
asbestos-containing materials are controlled carefully under NESHAP
regulations; its jurisdiction includes demolition and renovation activities.
Pipe bursting, however, could be an effective
technique to replace asbestos-cement pipe. Some states already allow
pipe-bursting of asbestos-cement pipe. However, pipe bursting has been severely
limited by widely varying interpretations of NESHAP nationwide. But an example
from Florida could hold the model for a solution. Read full article (login required)
Less leaks, more
capacity
City of Manassas targets infiltration and inflow
Tony H. Dawood and Mike Nicholson
Manassas, Va., covers approximately
26 km2 (10 mi2) near Washington, D.C. The city is not
only historic, but also one of the fastest-growing suburban areas in the United
States. This combination of age and rapid growth sets Manassas apart from many
other municipalities, and creates unique challenges for sanitary sewer
maintenance.
The City of Manassas Public Works Department continues
to assess and resolve problems associated with excessive infiltration and
inflow (I/I) into its sanitary sewer system. The sewer system assets are a
critical element of the city’s infrastructure, and the proper operation of its
wastewater collection and conveyance systems are vital to the city’s the health
and welfare. Read full article (login required)
Bolstering the first
barrier
Pilot testing by a Nevada utility finds that membrane filtration will greatly assist efforts to protect downstream water supplies
Douglas D. Drury, LeAnna Risso, and Bill Shepherd
Located in southern Nevada’s Las Vegas Valley,
the Clark County Water Reclamation District (CCWRD; Las Vegas) is among the
largest dischargers of wastewater to the Colorado River, the most critical
waterway throughout the arid southwestern United States. CCWRD discharges into
the Las Vegas Wash, which enters the Colorado River — or Lake Mead, as it is
known at that point — upstream from the drinking water uptakes operated by the
Southern Nevada Water Authority (SNWA; Las Vegas). Although this example of
large-scale indirect potable reuse has been practiced since the early 1970s,
concerns arose in recent years regarding the need to control concentrations of
total organic carbon (TOC) and endocrine disrupting compounds entering Lake
Mead. Read full article (login required)