Frequently Asked Questions

Frequently Asked Questions

Combined Sewer Overflow (CSO) Project

2. How does the CSO retention/treatment shaft work?

4. Why is a treatment shaft being constructed in our neighborhood?

5. I read that some of the similar projects that are in varying stages of construction have shifted or cracked, delaying the project. What assurances are there that similar problems will not affect the shafts still needing to be constructed?

6. How long will construction take?

7. Will restoration of the site happen only after construction is completed?

8. What is the plan for site restoration?

9. How will we know if construction is going according to schedule?

10. Why was permit parking implemented in all of Riverbend?

11. What are the permitted hours for construction?

12. Who do I contact if noise violations are taking place at the site?

13. I understand that a control building will be constructed with the treatment shaft. What will the control building look like, what operations will take place there and what chemicals will be stored there?

14. What dust control procedures will be implemented?

15. What if construction activity causes damage to my house or property?

16. Where can I get more information on this project?

Go back to CSO home page

1. What is the CSO Project?

It is a project to meet the requirements of the Federal Clean Water Act of 1972 pertaining to correcting water quality problems caused by discharges from combined sanitary/storm water sewers. The United States Environmental Protection Agency has cited combined sanitary/storm water sewer overflow (CSO) discharges as a significant source of pollution to the nation’s surface waters.

In our nation’s history, combined sanitary/storm water sewer systems were built in the mid to late 1800s and early 1900s at a time when wastewater treatment plants did not exist. Nearly all the combined sanitary/storm water sewer systems built in this era are still in use. At that time construction of combined sanitary/storm sewer systems was encouraged to help eliminate emerging widespread safety and health concerns in our growing urban centers. Construction of this type of sewer was abandoned in the 1940s-50s with the advent of construction of wastewater treatment plants built to handle separated sanitary sewerage. Approximately sixty six percent of Dearborn is served by a combined sewer system.

The Federal Clean Water Act of 1972 now requires the overflows from combined sewers to be eliminated or treated to meet federal water quality discharge standards for body contact and for supporting healthy aquatic life.

Dearborn’s CSO Project will meet the federal requirements by a combination of:

1. Separating combined sanitary/storm sewer where practicable and

2. Where separation is not practicable construct retention/treatment facilities that store and treat discharges to meet federal water quality standards for body contact and for supporting healthy aquatic life when discharges occur.

Dearborn’s CSO facilities are constructed using a large concrete cylindrical shaft that is sunk into the earth through a coordinated excavation process. The result is referred to as a “treatment shaft” that temporarily captures a large volume of the CSO discharge for later treatment at the Detroit sewage treatment plant. Any CSO volumes that exceed the capacity of the treatment shaft receive “settling, skimming and disinfection” prior to being discharged to the Rouge River. The result is that the vast majority of CSO discharges will no longer reach the river and the relatively small amount of remaining CSO volumes will be properly treated before entering the river.

2. How does the CSO retention/treatment shaft work?

Dearborn’s treatment shafts are about 100 feet in diameter and approximately 130 feet deep. About two-thirds of Dearborn is served by a combined sanitary/storm water sewer system.

The treatment shaft system is designed to reduce overflows from the existing 45-55 to 2-3 per year and provide treatment of those discharges to meet federal water quality standards for body contact and for supporting healthy aquatic life.

3. Were other approaches considered?

Yes. The City spent several years and thousands of hours working with federal and state officials and City residents reviewing numerous alternatives for addressing the combined sewer overflow problem, including sewer separation. The City selected partial sewer separation and the treatment shaft approach where separation was not practicable or economical. The treatment shaft design was selected because it met the federal CSO control requirements, provided the greatest environmental benefit with the least disruption to neighborhoods and businesses and was the best in terms of construction cost and long term operation. When the CSO Project is completed it will be the largest public works project in Dearborn’s history.

4. Why is a treatment shaft being constructed in our neighborhood?

The area along the Rouge River is a flood plain. The combined sanitary/storm sewer outfalls were placed there to direct overflows to the river.

Design of the CSO control system requires that the treatment shafts be located at or near the existing sewer overflows.

Some CSO projects currently under construction have encountered problems during the shaft sinking process, but steps are being taken now to resume work and make the necessary repairs. These are large and complicated projects and it is not unusual to encounter some difficulty during construction. Some of the contractors involved with the other projects are less familiar with the sinking process and it is taking them longer to complete. The contractors working near Outer Drive and Military have both been successful with similar projects in Dearborn. During construction, the city will conduct an extensive inspection process, with professional engineers on site to ensure proper compliance with the design specifications.

6. How long will construction take?

The treatment shaft installation will take 30-36 months to complete the construction and final restoration of the affected sites.

7. Will restoration of the site happen only after construction is completed?

No, some restoration can begin in various areas of the site as soon as work in those areas has been completed.

For example, final shoreline restoration along some portions of the Rouge River will be implemented in the winter and spring 2008. Temporary erosion control measures like filter fencing and straw bales along the perimeter of the construction at the Rouge River are installed at the beginning of the project and will remain in place until the project is finished and final stabilization measures are installed. Temporary seeding will be planted in all disturbed areas where possible to minimize erosion and dust. In addition the area to the south of the river will be planted this spring with both temporary and permanent plantings to improve the appearance while construction continues. The final plantings will be put in place in all areas as construction staging allows. The plantings and final restoration plans will be selected and installed to meet Michigan Department of Environmental Quality ( MDEQ) standards and the expressed needs of the neighborhood.

8. What is the plan for site restoration?

Each site is different and the final restoration plan is developed to meet MDEQ standards, the needs of the residents of the surrounding area and the City’s environment as a whole.

For CSO project #8, the draft final restoration plan was developed by JJR, Inc., a landscape architect firm retained by the City to obtain approval from the MDEQ to construct this project in a floodplain. The plan provides detailed site restoration drawings showing floodplain, river, wetland, forested and grassland features. It also describes plant stock consistent with native species that will provide habitat, attract songbirds and increase wetland and floodplain functions. Dearborn’s Department of Public works (DPW) will be working with the residents of the area and other interested individuals and groups in reviewing the draft plan and selecting the final restoration plan that meets citizens’ requests and conforms with MDEQ’s requirements. Full and final restoration is planned for spring/summer 2010.

9. How will we know if construction is going according to schedule?

Dearborn DPW has prepared a timeline of the critical path construction activities. The timeline will be updated quarterly.

Current Schedule and Progress (as of April 2008):

The site is proceeding as scheduled.

Treatment Shaft: The construction site activity occurring involving preparation to begin construction of the “treatment shaft” will remain at the current level for the next several months. In late August or early September traffic and construction activity will increase as steel sheet piling to encase the circumference of the shaft is installed and the shaft construction begins. The method to sink the sheet piling is a vibrating hammer. The noise and vibrations from this method is the least intrusive of the methods normally used. About 1 day per month there will be approximately 80-90 cement delivery trucks coming and leaving the site as the shaft is being poured. There will be several large trucks taking away the excavated soil removed as the caisson shaft is sinking. This level of activity will occur intermittently for about 12-15 months while shaft is being constructed.
Construction Traffic: All construction related traffic involving large vehicles can access and leave the site only from the south, i.e. Michigan Avenue.
Additional Sheet Piling Activity:

Additional sheet piling will occur when the Rouge River crossing occurs in July-August 2008.
Additional sheet piling will also occur when the sewer connections are made to the caisson after it has been sunk and is in place. This will not occur until the summer or fall of 2009.

Temporary Soil Erosion Measures: Construction of a perimeter filter fence along the north and south sides of the Rouge River has been installed to minimize erosion and off site sedimentation. This will be maintained throughout the duration of the project. In addition the area south of the Rouge River will be stabilized in the spring with temporary grass seeding as soon as weather permits. The north side of the Rouge River will have areas seeded as construction allows.
Military Road Crossing: During the next 3 months a sewer will be built under Military. The contractor has requested the City allow an open cut instead of the tunnel required in the contract. This request by the contractor was made since the soil investigation at the site found mostly fill material is under the road making tunneling dangerous. If the road is open cut it will necessitate closing Military Street for about 3-4 weeks. The Military Road crossing will be completed no later than August 1, 2008 and the road reopened. The City Engineering Division is reviewing the request to open cut and will make a decision the week of April 14, 2008.
Sewer Connection Chamber at Alexandrine and Reginald: The chamber has been reworked. The temporary cement patch will be removed and the final road cement and asphalt topping will be completed within the next 30-60 days depending on when the Asphalt plants, which are seasonal operations, reopen.
Site fencing and pedestrian safety: During construction the entire site will have a temporary cyclone fence with green fabric covering attached to help limit the visible impact, traffic ogling, and provide site security and pedestrian safety. The fence will remain in place throughout the duration of the project.
Project Completion and Final Restoration: Project completion and final restoration are scheduled for the summer of 2010. The final landscape restoration and control building architecture will be reviewed with neighborhood residents and other interested individuals or groups in the fall of 2009-winter 2010.

Updates to the schedule and construction activities will be posted quarterly.

10. Why was permit parking implemented in all of Riverbend?

Neighbors had voiced concern about construction workers parking on the residential streets during construction when more than 80 workers may be on site at a time. City officials and Riverbend representatives working cooperatively agreed that permit parking throughout the entire neighborhood was the best solution to prevent construction vehicles from merely moving from one street to the next. Those interested in securing parking permits or would like additional information please call the Dearborn Police Department at 313 943 2275.

11. What are the permitted hours for construction?

City ordinances restrict construction activities to occur between 7:00 a.m. to 7:00 p.m. Monday through Saturday. The contractors may also perform site maintenance operations between 7:00 pm and 10:00 p.m. but cannot cause elevated noise levels during that time.

12. Who do I contact if noise violations are taking place at the site?

Complaints can be made to the Dearborn Police Department by phone at 313 943 2241at any time. In addition, residents can also contact the Dearborn DPW from 8am to 5pm Monday through Friday at 313 943 2075.

An automated control building will be constructed at the treatment shaft site. The building is necessary to house the disinfection chemical (liquid chlorine bleach), and the electrical, plumbing and mechanical equipment needed to operate the facility.

The control building will be one story tall and approximately 40’ x 50’. The outside of the building will be brick, with roofing and trim material selected to fit with the architecture of the surrounding area. The residents of the area and other concerned individuals or groups will be invited to comment and review the final exterior design.

The chemical stored there will be sodium hypo chloride, better known as common household bleach. About 19,000 gallons of this liquid will be stored in two double wall tanks under the building with leak detection monitors. The bleach will be blended with the CSO flows to kill harmful bacteria when it is anticipated that an overflow to the river will occur, which is expected only 2-3 times per year. To keep the bleach at proper strength and to refill after treatment events, the tank will need to be replenished 3-4 times per year.

14. What dust control procedures will be implemented?

Temporary and permanent seeding, soil moisture control, street sweeping using vacuum or pickup-type equipment will all be used to control dust and soil that may be tracked out from the site and onto City streets on a daily basis.

15. What if construction activity causes damage to my house or property?

The City has taken every precaution to protect against public and private property damage that might occur due to construction. Seismic ground monitors have been installed along the perimeter of the property to insure ground vibrations remain below levels that may cause damage to adjacent structures. Air monitoring equipment and noise measuring devices are being used at the site. Prior to construction activity commencing the City required video and neighborhood inspection of all properties adjacent to the site.

Residents need to document any damage that they feel has occurred as a result of the construction activities at the site. Documentation that shows before and after conditions (i.e. pictures, videos, etc.) is the most valuable means of insuring claims can be adequately reviewed and resolved. Any damage or approvable loss that may be caused by construction of this project will be corrected as a project expense.

Please contact Dearborn DPW regarding any questions or claims pertaining to property damage you feel has resulted because of the construction of this project.

16. Where can I get more information on this project?

Persons requesting further information can contact:

James Murray

Deputy Director

Dearborn DPW

313 943 2073

jmurray@ci.dearborn.mi.us

Go back to CSO home page