A new federal consent decree imposes the Metropolitan St. Louis Sewer District (MSD) to make more efforts to reduce sewer overflows.
The MSD operates and maintains the sewer system for the City of St. Louis and most of St. Louis County. It is the fourth-largest sewer system in the United States. The collection system delivers flow to seven wastewater treatment plants. A combined sewer system serves approximately 75 sq mi of the MSD’s service area and discharges 13 billion gal of overflows per year.
The MSD has spent $2.3 billion during the past 20 years to reduce overflows; however they will have to spend twice as much over the next 20 years. In 2007, the MSD was sued by the US Department of Justice and the State of Missouri for violating the Clean Water Act. Portions of the system are over 150 years old, and infiltration and inflow from old pipes lead to water quality problems.
The Missouri Coalition for the Environment tried to find a solution to resolve the Clean Water Act violations and came to an agreement on August 4. This agreement was a consent decree that imposes the MSD to spend $4.7 billion over the next 23 years to upgrade its sewer infrastructure to reduce overflows. The MSD has some requirements to observe and some measures to take:
- Reduce overflows and eliminate sanitary sewer overflows. The MSD must complete a ‘’master plan’’ before 2013 for eliminating approximately 200 overflows from its sanitary sewer system.
- Address Combined Sewer Overflows (CSOs): this measure starts with the submitting of a long-term control plan to the State of Missouri. The MSD has to increase the storage capacity of the combined sewer system and has to find a way to send stored flows to wastewater treatment plants after peak volumes. To reduce CSOs, the MSD will separate the sanitary and storm sewer functions in some sections of the combined sewer systems.
- To increase the storage capacity, the MSD must spend at least $20 million on efforts to mitigate the effects of wet-weather surcharging and overland flooding caused by the insufficient capacity of the combined sewer system.
- Implement primary treatment and disinfection to overflow before they are discharged to the environment.
- Expand secondary treatment capacity.
- Implement a mix of ‘’green’’ infrastructure (rain gardens, bioswales) with traditional ‘’gray’’ infrastructure. The consent decree requires spending at least $ 100 million on projects intended to reduce stormwater runoff from impervious surfaces. The MSD has created a five-year pilot program to implement green infrastructure on a large scale in its combined sewer area.
The consent decree and its cost will have consequences on the MSD’s rates. The District will increase its rates and will spend more than $ 1 billion on capital improvements.
If you have any questions about sewer overflows, please contact John McAllister at firstname.lastname@example.org or at (508) 747 - 7900 x 117.
Information in this article taken from November 2011, article ‘’St. Louis MSD to spend $4.7 billion over 23 years to reduce sewer overflows‘’ by Jay Landers, published in Civil Engineering.
An innovative new groundwater modeling tool called MODular ALLocation, or MODALL, can be used to shorten remediation projects and for assessing project performance. This program developed by ARCADIS / Malcolm Pirnie, was used at Reese Air Force Base in Texas and it proved efficient at remediating groundwater contamination.
Reese Air Force Base opened in 1941 as a pilot training facility and was closed in 1997 because of its high level of contaminants. Contamination at the site consists mostly of hydrocarbons and chlorinated solvents, which were used to clean aircraft. These contaminants degrade local groundwater resources and drinking water. A conventional pump-and-treat system was adopted in 1990 to try to remove the contaminants from the groundwater. In 2004, ARCADIS / Pirnie started a Remediation Program with two main goals:
- Cleanup the base
- Optimize the system and reduce the time required to complete the remediation objectives
How does MODALL work exactly?
This new pumping model was completed in 2005. It captures and treats more contaminants of concern than before, and in less time. This tool can capture the plumes and provide information on the plumes which can enable more efficient treatment. The groundwater system enables the model to examine flow allocations and the model can then generate contour maps depicting the capture of treatment systems remediating the plume. Thus, ARCADIS figures out exactly where the existing treatment system is operating effectively. As a result, ARCADIS can reduce the amount of groundwater extracted for treatment while still capturing the plume. The plume is better driven toward the extraction point, by better targeting the injection points.
What were the results of the model ?
- A reduction of the rate of groundwater extraction from 651 gallons per minute (gpm) to 350 gpm
- An improvement of the speed with which the plume is captured. ARCADIS captured the plume at a rate of two to three acres per week
- A major cost savings by more than $ 22 million
- An acceleration of remediation elsewhere at the site. The deadline for the remediation program is 2014 but ARCADIS expects to complete the work before. The firm already shortened the program by 20 years.
If you have any questions about groundwater systems, please contact John McAllister at email@example.com or at (508) 747 - 7900 x 117.
Information in this article taken from November 2011, article ‘’Groundwater Model shortens remediation projects by 20 years ‘’ by Jay Landers, published in Civil Engineering.
Rainwater harvesting (RWH) is a stormwater management and re-use concept that focuses on water conservation, re-use and reduction in public water supply usage for irrigation. This practice was initially only used on a small residential scale. Using a RWH system for conservation is a good tool to reduce water consumption but it can’t be seen as a cost-savings measure, because the price of water is very low in the US compared to most other nations. It can be an effective tool for guarding against water shortages or water restrictions.
The goals of RWH have evolved and with the expansion of the green movement, RWH systems were used to reduce the environmental impact of development and population growth. This is a Low Impact Development (LID) practice. LID practices reduce impervious area and infiltrate wherever practical in order to provide runoff reduction.
Engineers have to observe requirements when they use RWH as a Best Management Practice (BMP):
- Have storage capacity to catch the next storm event
- Have demand in the water budget to empty the storage cistern
The challenges of RWH during the wet season result from:
- Irrigation demand is low
- Water supply is high
Thus, there is a need to find additional applications to use the harvested runoff
The United States Green Building Council (USGBC) created a plan, the Leadership in Energy and Environmental Design (LEED), for responsible development and reducing the impacts of development. RWH and water conservation strategies are both good means to reach some of the goals and to earn points in order to receive the LEED certification.
RWH is used more frequently as building codes are changing and many include provisions for RWH. New requirements have to be observed including catchment, first flush diversion and pretreatment, storage, installing a re-use water line, and separating the RWH system from municipal supplies, in order to prevent water contamination and reduce runoff and water consumption.
Even as RWH systems are spreading, it is not always easy to regulate harvesting runoff. Stormwater management regulations aim at reducing runoff. But there are water laws as well, which particularly in arid areas, tend to limit upstream runoff reduction to protect the owners of water claims downstream. Stormwater regulations and water law are in conflict. This conflict needs to be clarified in order for RWH to grow as a BMP.
Reducing annual runoff by using harvested water is a particularly common application in irrigation. This practice is frequently used but RWH systems do not have to be limited to this application to reduce annual runoff. Engineers can use harvested water beyond irrigation for:
- Toilet flushing
- Washing machines
- Hose bibs and outdoor washing (vehicles, windows)
- Process water for commercial or industrial projects
- Potable applications, but this is not really the best way to reduce runoff, treatment costs are high and monitoring is required
The components of a RWH system:
A RWH system consists of common building blocks and incorporates:
- Catchment: rooftops contain less sediments and nutrients than hardscape surfaces
- First flush diversion and pre-treatment : diversion structures are required initial runoff building codes. The first flush diversion is useful because runoff from the beginning of a rainfall event is thought to carry more pollutants. Pretreatment cleans the water before the storage, protects downstream pumps, filters and fixtures from damage and keeps pollutants out of cistern and filters. Pretreatment is useful when RWH is employed as a BMP.
- Storage : aboveground cisterns for smaller systems, belowground cisterns for larger sites and additional storage features
- Day tanks, pressure tanks, make-up water : can provide an air gap between potable and re-use water and can ensure the end use application has a consistent water supply
- Pressurization : pumps are used for all combined applications
- Treatment : consisting mostly of filtration, to treat after storage
- Disinfection : UV Radiation, Clorination, Ozone and Reverse Osmosis, possible disinfection processes dependent on end-use.
- Controls : controls of the cistern, back-flushing of filters, disinfection dosing, ongoing monitoring and communication
RWH is an effective way to turn runoff into a valuable resource, to implement sustainable development, to reduce runoff efficiently, to reduce municipal water consumption, and to save energy. By incorporating RWH, engineers can meet stormwater regulations, earn points toward LEED, and reduce demand on municipal water supplies.
If you have any questions about rainwater harvesting or water re-use, please contact John McAllister at firstname.lastname@example.org or at (508) 747 - 7900 x 117.
Information in this article taken from September 2010, article by Greg Kwalsky and Kathryn Thomason, published in CE News.
Water has been considered as an inexhaustible resource for a long time. Its use was not really controlled or limited. The overusage inevitably led to shortages, and scarcity of potable water is now a reality that our world has to cope with. Only 1% of the world’s water is suitable for consumption and one-third of the world’s population lives in a region experiencing water shortages and does not have access to fresh drinking water, which accounts for 1.1 billion people in developing countries.
This scarcity comes from:
- Drought and unusually dry conditions, like in 2007 in the Southeastern United States
- Population growth, above all in regions where there are a few inches of rain per year like in the Sun Belt
The scarcity of potable water has led to a rise in water prices throughout the United States. It has become obvious and inevitable that there is a need to find another way to use water in order to spare this resource.
The first practice affected by new restrictions and conservation measures is landscape irrigation. Landscape-watering restrictions were introduced in the US: just one-third of all domestic water use can be allocated for irrigation. However, landscapes are valuable properties: they increase property values, decrease pollution and boost tourism. A solution had to be found in order to balance a decrease in potable water and the desire for irrigation. The best solution seemed to substitute the water supply with an alternative source: non-potable water.
Non-potable water is a term that includes: water from air-conditioning condensate, rainwater, stormwater runoff, treated residential wastewater, and brackish water (combination of sea and fresh water).
There are different ways and reasons of using non- potable water:
- The United State Green Building Council’s (USGBC) Leadership in Energy and Environmental Design program (LEED), part of the Green Building Movement, made the use of non-potable water for landscape irrigation a popular practice. This program gives the opportunity of sites who want to have LEED certification to receive six to ten certification points by using recycled water and implementing efficient irrigation systems. Having the LEED-certification is advantageous to properties because they save money and energy. This program aims at giving site the incentive to use non-potable water for irrigation, but it is completely voluntary.
- Using non-potable water is now required by some states and local agencies for new commercial properties and government facilities.
- There are tax incentives and rebates for residential and commercial buildings if non-potable water is used. This is always an appealing means at a time when the cost of municipal water and sewer services are increasingly high.
Using non- potable water for landscape irrigation includes some requirements to observe:
- Brackish water : may require a reverse osmosis to remove excess salinity, which can be very expensive
- Harvested water : systems to collect, filter, store and recycle stormwater
- Reclaimed water: in Massachusetts, must be treated to the Massachusetts Department of Environmental Protection (MA DEP) water re-use standards.
If the type of water used for irrigation changes, the irrigation system itself is going to change. Specifiers, landscape architects and contractors are going to design and implement new irrigation systems because non-potable water has different chemical properties than fresh water and non-potable water affects differently irrigation system components and design.
Research and development has revealed the components and priorities of reclaimed water. This water is unfit for consumption and can have a harsh effect on water transfer lines and irrigation system components. The challenge in designing irrigation systems for use with non-potable water is to make products that withstand all sources of non-potable water. Reclaimed water’s composition has been carefully analyzed by engineers and they found out that chemicals and compounds have a damaging effect on the performance of products like valves, rotors or sprays and they reduce their life expectancy. Engineers know that they now have to design and specify efficient and more durable products.
The use of reclaimed water for landscape irrigation is not just a trend, it is a new practice that will keep on spreading all over the world in order to face the shortage of potable water. Architects, specifiers, builders, legislators, and programs like the LEED program, will all contribute to promoting this new way of using water efficiently and wisely, and to educating customers. This new practice enables the customer to save water and money, and to act sustainably. Water savings and sustainable design meet an increased demand and this is not going to stop, because everyone recognizes the benefits of these products.
Norfolk will follow this blog posting with a posting providing more information on rainwater harvesting.
If you have any questions about rainwater harvesting or water re-use, please contact John McAllister at email@example.com or at (508) 747 - 7900 x 117.
Information in this article taken from November/December 2011, article by Lynette Von minden, published in Water Efficiency.
The East Boston Branch Sewer Relief project is a $85.4-million project that was completed in 2010 by the Massachusetts Water Resources Authority (MWRA). This project is part of the federally mandated cleanup of Boston Harbor. The sewer system in East Boston was built 110 years ago. It is in an area of reclaimed waterfront and the goal of this project was to control combined sewer overflows entering the harbor.
To reach the goal of controlling combined sewer overflows entering the harbor, the MWRA planned to upgrade to 4.5 mi of the aging interceptor system serving East Boston and to employ a combination of cured-in-place pipe (CIPP) lining, microtunneling, pipe bursting, and open-cut excavation methods. The project included three different construction contracts:
- The rehabilitation of approximately 1 mi of existing egg-shaped brick sewer by the addition of a CIPP lining
- The installation of approximately 2. 5 mi of 24 to 66 in. diameter pipes by a combination of micro-tunneling, in-line microtunneling, and traditional cut-and-cover excavation
- The expansion of approximately 1 mi of vitrified clay pipes 12 and 15 in. diameter to high-density polyethylene pipe 16 and 20 in. diameter by pipe bursting, with some reaches installed by means of cut-and-cover excavation
Numerous pipes installation methods were proposed during design, and microtunneling was selected. This method would affect the surface less and utility relocations would be required only at each shaft location. 17 microtunneling runs were completed for a total of more than 12,000 ft.
A quick timeline for the project is as follows:
- 2001 : the design process began
- 2004 : the CIPP construction contract completed
- 2008 : remaining construction work began (microtunneling and pipe bursting)
- 2010 : court-ordered completion date
For locations in which seawalls and abandoned foundations were likely to be encountered, pipeline was installed by open-cut excavation.
For areas in which the existing pipes were made of material that could be broken apart, the installation method selected was pipe bursting.
This project was a challenge for project participants because of the court-ordered deadline for completion, the major design, and the densely populated and heavily urban area where the project took place. East Boston is comprised of busy streets, a complex system of overhead and subsurface utilities, a unique geological history, and a mixture of commercial properties and residential houses. Coordination and communication with residents of the area and the community (noise control, traffic management, preconstruction and postconstruction surveys) proved challenging. The MWRA was able to complete its critical East Boston Branch Sewer Relief project on time and they greatly reached their goal by increasing the system’s storage capacity and facilitating the delivery of wet-weather flows. They reduced the volume of combined sewer overflows entering Chelsea Creek and the inner part of Boston Harbor by 79 % as well.
Figure 1 – East Boston Branch Sewer Layout
If you have any questions about sewers or combined sewer overflows, please contact John McAllister at firstname.lastname@example.org or at (508) 747 - 7900 x 117.
Information in this article taken from August 2011, article by Phillip Lanergan, Peter Mcgovern, Paul Savard, P .E., David McKiernan, and Lisa Hamilton, P.E., M.ASCE, published in Civil Engineering News.
Norfolk Ram, working with the Town of Harvard with Tim Bragan, the Town Administrator, organized a ceremony on Wednesday, the 26thof October 2011, to commemorate the start of a new sewer and wastewater treatment facility upgrade project.
This project is a $2.5 million town center sewer system and facility upgrade, which was approved by Town Meeting voters in August.
The ceremony gathered two dozen attendees including:
- Wayne Perry, Associate, engineer at Norfolk Ram Group
- Jennifer Bensen, State Representative
- David Ankener and Dave Boyer of the Department of Environmental Protection
- Chris Ashley, chairman of the current sewer building committee
- Tim Clark, Selectman
Ricciardi Brothers was selected as the general contractor for the project.
Weekly, meetings have been organized weekly to review progress with engineers, town officials, department heads, and contractor representatives.
From left: John Potts of Weston & Sampson; David Boyer, Mass DEP; State Representative Jen Benson; Wayne Perry of Norfolk Ram Group; Chair of Town Center Sewer Building Committee Chris Ashley; Selectman Liaison Tim Clark; David Ankener of the State Revolving Fund; Jim Ricciardi, Ricciardi Bros., Inc; and Sewer Commissioner Cindy Russo pose in front of the water treatment plant on Massachusetts Avenue for the Oct. 26 groundbreaking ceremony for the new town center sewer. (Photo by Lisa Aciukewicz)
For more information about this ceremony and this project, see the link below : http://www.harvardpress.com/News/NewsArticles/tabid/2176/ID/7593/PageID/7593/Ceremony_marks_start_of_sewer_work.aspx
Due to a century of industrial activity – steel manufacturers, and chemical companies - along its riverbanks, the Buffalo River has become very polluted. The levels of contamination were so high that in 1987, the Buffalo River was designated as ‘’ an area of concern’’ by the International Joint Commission. Due to the chemicals and contamination present in the sediment, dredging the Buffalo River has become a necessity.
Last August, the US Army Corps of Engineers started a $50 million project to dredge contaminated sediment from the River and to restore aquatic and riparian habitat.
As part of the project, many steps had to be taken to lead up to the dredging:
- The New York State Department of Environmental Conservation created a remedial action plan for the River
- In 2003, the EPA selected Buffalo Niagara River–keeper to coordinate the work involved in implementing the plan
- Since 2007, Buffalo Niagara River–keeper and its four partners (the Army Corps of Engineers, the EPA, The Department of Environmental Conservation, and Honeywell International, Inc., of Morristown, New Jersey) have worked to remediate the Buffalo River in a unique public – private partnership. The five partners together are known as the Buffalo River Restoration partnership.
Their work enabled them to put forward four main contaminants to be addressed by the dredging:
1. Polycyclic aromatic hydrocarbons
2. Polychlorinated biphenyls
The cleanup of the Buffalo River includes two phases in order to reach the following goals:
- Reduce human exposure to contaminated sediment, as well as the exposure of wildlife and aquatic organisms
- Restore habitat and supporting wildlife
The first phase is led by the Corps and consists of dredging portions of the navigation channel within the river and the City Ship Canal to a depth of 24 ft., 1 ft. deeper than the Corps normally dredges. This phase aims at helping the Buffalo River be removed as an ‘’area of concern’’.
The second phase is led by the EPA and includes different actions:
- Remove contaminated sediments from areas in the river outside of the navigation channel
- Cap contamination located at the terminus of the City Ship Canal
- Conduct 6 habitat restoration projects along the riverbanks and within the capped section of the canal
In late August, the dredging operations began hoping to remove 600,000 cu yd of material by clamshell dredging. The method used minimizes the dredged material reentering the water by sending it to a nearby confined disposal facility.
The Corps received increased federal funding to remove even more material than normal. The estimated cost of the dredging associated with the first phase will be approximately $5.9 million. Funding for the project comes from two sources:
- $4.6 million from the Federal government’s Great Lakes Restoration Initiative, which will fund the removal of 450,000 cu yd of material
- $1.3 million from the Corp’s annual appropriations for routine operation and maintenance dredging which will pay for the removal of the remaining 150,000 cu yd of material.
The project participants expect the river to return to a healthier state as its long term goal. The second phase with the additional dredging will enable them to cap in place the contaminated material located in a 7–acre area at the far end of the City Ship Canal. This phase will include six habitat restoration projects as well and this capped area is expected to become one of these six restoration projects.
If you have any question about dredging, please contact John McAllister at email@example.com or at (508) 747 - 7900 x 117.
Information in this article taken from October 2011, article by Jay Landers, published in Civil Engineering News.