District of Columbia Water and Sewer Authority (DC Water)
Washington, DC
Due to potential risks associated with transportation and handling of liquid chlorine, the District
of Columbia Water and Sewer Authority (DC Water), switched to the use of liquid sodium
hypochlorite as the disinfecting agent at the Blue Plains Advanced Wastewater Treatment Plant
(AWTP). The escalating cost of bulk purchased sodium hypochlorite prompted DC Water to
commission a study to evaluate disinfection alternatives that: 1) are compatible with existing
treatment processes; 2) meet all plant effluent disinfection requirements; and 3) reduce life cycle
costs of disinfection.
The study involved a detailed technical, economic and non-economic evaluation of the feasibility
of constructing and operating an onsite sodium hypochlorite generation facility in lieu of bulk
purchase. Economic analyses included capital and O&M costs, life cycle costs over a 30-year
time horizon, and sensitivity of price of bulk sodium hypochlorite and salt, electric power cost,
debt service on life cycle costs.
Metric Used:
Posted: May 20th, 2011 | Filed under: 100K-500K, Waste Water Treatment | Tags: Capital Savings, Improved Plant Reliability, O&M Cost Savings | No Comments »
Michelson Water Recycling Plant (MWRP)
Irvine, California
Recycled water corrosivity control is an important consideration in the design and operation of
wastewater treatment plants and recycled water distribution systems. Even mild corrosivity can
have significant long-term impacts on equipment and pipelines. Corrosivity control involves
adjustments to water chemistry (pH, alkalinity, hardness, etc.), but how adjustments are
implemented can vary based on existing treatment processes. For the Michelson Water
Recycling Plant, corrosivity control was achieved by modifying an existing process rather than
adding a new one. This paper discusses the investigation and evaluation of several treatment
alternatives for corrosivity control. The study resulted in replacing chlorine gas disinfection with
sodium hypochlorite disinfection, which offered the additional advantage of addressing
operational, regulatory, and safety concerns associated with the use and storage of gaseous
chlorine. The study highlights the connection between disinfection and corrosivity, an important
consideration for other agencies starting water recycling programs to meet increasing water
demand.
Metric Used:
Posted: May 20th, 2011 | Filed under: 100K-500K, Stormwater, Waste Water Treatment, Water Treatment | Tags: Corrosion Control, Cost Savings, Improved Plant Health/Safety, Improved Plant Reliability | No Comments »
Indianapolis Department of Public Works
Indianapolis, Indiana
The City of Indianapolis Department of Public Works (DPW) constructed eleven real-time
controls (RTC) in the operation of the collection system between 1995 and 2004 to reduce
combined sewer overflows (CSO). These eleven RTC facilities are part of the Early Action
Projects (EAP) to reduce CSO frequency and volume. In 2009, DPW completed a hydraulic
performance evaluation of each RTC facility using a computer hydraulic model simulation of
RTC operations, and successfully quantified their environmental benefits in CSO volume
reduction. This evaluation helped DPW to demonstrate the feasibility of utilizing RTC in the
collection system to reduce CSOs. This evaluation of the RTC facilities provided a basis for
DPW to further investigate additional CSO control projects that can utilize RTC. This technical
paper provides a case study on quantifying the environmental benefits of RTC in a large sewer
collection system.
Metric Used:
Posted: May 20th, 2011 | Filed under: 500K-1M, Sanitary Sewer, Stormwater, Waste Water Treatment | Tags: Enhanced Operational Efficiency, Environmental Improvement, Improved Plant Reliability, Reduced Combined Sewer Overflows | No Comments »
Sacramento Area Sewer District
Sacramento, California
The Sacramento Area Sewer District (District) is in the final stages of implementing a new
Supervisory Control and Data Acquisition (SCADA) system for their 103 pump stations. While
implementing this new SCADA system, the District faced many challenges and obstacles, such
as developing the SCADA system requirements, designing the networking system, testing station
communication, and cutover to the new SCADA system. Implementing a new SCADA system
has provided the District with valuable experience that can be shared with other sewer agencies
that may also be in the process of replacing their SCADA system.
Metric Used:
Posted: May 20th, 2011 | Filed under: >1M, Sanitary Sewer, Stormwater | Tags: Improved Plant Efficiency, Improved Plant Performance, Improved Plant Reliability, Reduced Communication Failure | No Comments »
Pump stations are an integral part of wastewater collection and treatment systems. Their
applications can be quite varied: lift stations in the collection network pump raw sewage up to a
level where gravity can take over; pumping systems within the treatment plant move effluent
through various treatment stages or deliver it from the plant to agricultural users and others.
While wastewater pumps have a common function––moving fluid where gravity can’t––the
design of any individual pump station can depend on many factors.
Choosing the right pump station design for the application is a matter of balancing personal
preference with the requirements of the job, the necessity for energy efficiency and the need for
pump station reliability. This presentation examines three very different pumping system
designs, and weighs the advantages and disadvantages of each in the context of real-world
applications.
Metric Used:
Posted: May 20th, 2011 | Filed under: Stormwater, Waste Water Treatment | Tags: Efficient Lift Station Design, Energy Efficiency, Improved Plant Performance, Improved Plant Reliability, Improved Wastewater Pumping | No Comments »
The current NPDES permit of an industrial aerospace complex located on Ventura
County, California requires to provide treatment to any stormwater overflows originated
at the complex typically during storm events. These overflows occur when the individual
capacities of a series of storage ponds located at different points of the site are exceeded.
A stormwater treatment system (STS) is required to avoid exceedances of certain
constituents of concern (COCs), especially certain heavy metals (iron, manganese,
copper, mercury, lead) and organics (dioxins and volatile organic compounds – VOCs),
that may washout from the soil during storm events. Coarse filtration (sand and
multimedia filters) was the basis of the STS, but did not achieve the required removal of
COCs to meet the permit. Additional analyses were required to increase filtration
effectiveness. Fractionation of the solids present in the water revealed the presence of
large fractions of silts and clays, which are too small to be removed by coarse filtration.
These small solids also had a significant fraction of the total COCs attached to them,
which prompted the exceedances of the permit limits. This analysis highlighted the need
for coagulation chemicals to clump these small particles together and form flocs that may
be further removed by coarse filtration while meeting permit limits. This analysis also
allowed to better characterize the raw water from different storage ponds and select the
location with the best water quality to feed the STS.
Metric Used:
Posted: May 20th, 2011 | Filed under: Stormwater, Waste Water Treatment | Tags: Improved Filtration Effectiveness, Improved Plant Reliability, Meet Regulatory Constraints | No Comments »
Stormwater discharges from an industrial aerospace complex located in Ventura County,
California require substantial treatment in order to meet the stringent NPDES permit
limits. Overflows are generated during heavy rain events when onsite storage pond
capacities are exceeded. Multiple treatment configurations have been tested to remove the
constituents of concern (COCs) below the permit limits. Past experiences have indicated
that chemical treatment with rapid clarification consistently produced water quality close
to the permit limits. Therefore, additional treatment is required to fully meet the treatment
goals. Ultrafiltration (UF) membranes were tested for this effect during a pilot study
conducted to determine performance of a submerged membrane unit. Effluent from the
rapid clarification unit (i.e., Kruger’s ACTIFLO) was further treated with multimedia
filters and used as influent to the membrane pilot. The submerged UF membrane was
able to remove approximately 99% of the influent turbidity. Ultimately, the submerged
UF membrane proved to be a viable treatment alternative that consistently removed
COCs below their NPDES permit limits, which in this particular case are even more
stringent than drinking water limits for certain COCs.
Metric Used:
Posted: May 20th, 2011 | Filed under: Stormwater, Waste Water Treatment | Tags: Improved Filtration Effectiveness, Improved Plant Reliability, Improved Total Suspended Solids Removal, Meet Regulatory Constraints, Turbidity Control | No Comments »
Montgomery County Water Services
Dayton, Ohio
Montgomery County Water Services (MCWS) is a regional water and sewer provider
with 11 water booster stations, 36 sewage lift stations, three equalization basins, and two
regional WWTPs (20 MGD and 13 MGD). MCWS provides an average 26 MGD
drinking water to 250,000 people. All drinking water is purchased from the City of
Dayton, OH. MCWS staff is comprised of 242 persons.
Responding to operational alarms and work requests at remote water and sanitary pump
stations often requires sending two people—one mechanic and one electrician. This often
creates unnecessary overtime as the corrective action usually requires either mechanical
or electrical repair—not both. In 2007, we began to study how to maintain core operation
and maintenance (O&M) responsibilities, save labor costs, provide improved mechanical
and electrical maintenance support using existing staff, and to develop better-skilled
maintenance employees. The ability to improve maintenance skills within the two
WWTPs was also examined.
Metric Used:
Posted: May 20th, 2011 | Filed under: 100K-500K, Stormwater, Waste Water Treatment, Water Treatment | Tags: Improved Employee Morale, Improved Maintenance, Improved Plant Reliability, Increased Equipment Service Life, Lobor Cost Savings, O&M Savings | No Comments »
Portland Water Bureau
Portland, Oregon
A key challenge faced by utilities in managing their infrastructure is the need to confidently
determine short and long term asset investment requirements without getting buried in the detail
or waylaid by the poor quality of data, for thousands of individual assets. The paper will discuss
an approach using management strategies to simplify the management effort, appropriately
model short and long term future investment needs for all assets, result in improved confidence
in the quality and confidence of the analysis, – even in situations of limited data – and enhance
improved capital improvement program programming. It presents the benefits, implications, and
applicability of using management strategies as described by the implementation for the City of
Portland Water Bureau on the development of their future investment needs.
Metric Used:
Posted: May 20th, 2011 | Filed under: 100K-500K, Stormwater, Waste Water Treatment, Water Treatment | Tags: Improved Maintenance Operations, Improved Plant Reliability, Optimized Decision Making, Reduced Modeling Processing Time | No Comments »
Johnson County Wastewater District
Olathe, Kansas
During the development of the Johnson County Wastewater District (JCW) Asset Management
Plan it became apparent the available data in the current system did not include sufficient
information on the force mains. To evaluate the condition of the force mains and provide the
missing information the District is embarking on a comprehensive and proactive approach to
prioritization and inspect their force main assets. With the growing environmental awareness
and ever increasing stringent environmental regulations, JCW took a proactive approach to
develop force main asset management protocols and develop an inspection prioritization matrix.
With nearly 40 miles of force mains, JCW’s inventory is comprised of pipes varying in size,
material type, age and condition.
This paper documents the implementation of asset management principles to develop an
inspection prioritization matrix based on risk analysis, recommended inspection technologies
and procedures for collecting data through scheduled routine physical inspections.
Metric Used:
Posted: May 20th, 2011 | Filed under: 500K-1M, Waste Water Treatment | Tags: Enhanced Asset Management Plan, Improved Plant Reliability, Optimized Force Main Inspection | No Comments »