Tuesday, February 9, 2010

Details of the New Detroit Sewage Plan

Coming off of one of the worst years for combined sewer overflows (CSOs) in awhile, the Detroit Water and Sewerage Department (DWSD) recently released its: "Alternative Rouge River CSO Control Program Executive Summary." This new plan explains the DWSD's alternative to the former Upper Rouge Tunnel project. The new plan is cheaper and takes place over a longer time period of 25-years and also includes green infrastructure measures as well as grey infrastructure measures.

Green infrastructure aims at limiting rainwater from getting into the sewers in the first place. The report recommends the following points that would be implemented by "multiple City agencies and departments, as well as private and non-profit stakeholders. A $50 million budget has been established to fund Green Infrastructure projects from sewer revenues..."

1. Disconnect residential and municipal downspouts.

2. Demolish and remove vacant structures and replace with pervious land cover.

3. Use bioswales and tree trenches along roadways and parking lots to intercept runoff and reduce stormwater inputs.

4. Plant trees for uptake and evapotranspiration along roadways and open spaces.

5. Implement activities on municipally-owned properties, focusing on managing stormwater runoff in underutilized parks.

Grey infrastructure is far more expensive and instead of being preventive like green infrastructure, it focuses on how the rainwater and sanitary waste will be treated before being released into the environment. The grey infrastructure also focuses on eliminating the CSO outfalls altogether. The DWSD plan has the following CSO control projects for grey infrastructure:

1. Complete the Oakwood District Sewer Improvement Program (three construction contracts totaling $59 million).

2. Install remedial improvements at the Baby Creek Screening and Disinfection (S&D) Facility including disinfection feed system renovations, new mechanical mixers, and emergency bypass channel ($3 million).

3. Complete the Total Residual Chlorine Minimization and In-Stream Assessment program for three Rouge River CSO Control Facilities ($1 million).

4. Initiate improvements at the Hubbell-Southfield CSO Basin to maintain the operational effectiveness of that facility ($2 million).

5. Modify two Lower Rouge Outfalls to eliminate existing CSO discharges ($1 million):

• Carbon Outfall elimination
• Fort St. East Outfall diversion to Oakwood Basin

6. Eliminate the Glenhurst Outfall by constructing flow control devices and a new pump station to direct this flow to the Oakwood Northwest Interceptor ($3 million).

7. Construct two new Pilot Projects to demonstrate the effectiveness of First Flush capture tanks in conjunction with disposable nets and innovative upstream disinfection injection systems at both the 7 Mile East and Pembroke outfalls ($41 million).

8. Re-invest in existing CSO control facilities on a phased basis over the 25-year program to ensure their continued structural integrity and operational viability as they approach their design life expectancies ($40 million).

9. Construct a new CSO storage tunnel (URT-2); a 5.5-mile long, 19-foot diameter; 63-MG capacity tunnel to control 14 CSOs between Warren Avenue and McNichols; plus associated drop shafts and outfall modifications, and a 35-mgd pump station to dewater the captured flow to the wastewater treatment plant after the storm event ($484 million).

10. Upgrade the wastewater treatment plant by constructing a new Rouge River Outfall (RRO-2) with the capability to chlorinate and dechlorinate primary effluent to eliminate the existing undisinfected Rouge River Outfall (RRO-1). This project will include improvements at the wastewater treatment plant to provide flow control including gates, regulators, hydraulic structures, and instrumentation and control, plus a new outfall conduit ($130 million).

The total cost for all of these CSO grey infrastructure projects will be $764 million.

The new 25-year plan will create an average yearly debt-load of $33 million a year as opposed to the old plan that had an average debt-load of $190 million per year. The project will be implemented in five different phases over the 25-year period.

Phase I: 2010-2014 = $101M
Oakwood Sewer Segments 2, 3 ($44 M) 2010-2011
Baby Creek Remedial Improvements ($3 M) 2010
7 Mile Pilot Project (FFT & nets, NaOCl) ($17 M) 2012-2014
Pembroke First Flush Tank ($15 M) 2013-2014
Glenhurst Outfall Elimination ($3 M) 2014
Carbon/Fort St. Outfall Elimination ($1 M) 2010
Hubbell-Southfield Re-investment ($2 M) 2011
TRC Minimization & In-Stream Evaluations ($1 M) 2010
Green Infrastructure Phase I ($15 M) 2010-2014

Phase II: 2015-2019 = $218M
Oakwood Sewers Segment 4 ($15 M) 2015-2016
Pembroke Outfall Nets & NaOCl ($9 M) 2017
WWTP Outfall Gates/I&C ($30 M) 2015-2016
Re-investment in Existing Facilities ($10 M) 2015-2020
URT-2 South Tunnel Segment ($139 M) 2017-2020
Green Infrastructure Phase II ($15 M) 2015-2019

Phase III: 2020-2024 = $158M
URT-2 S. Tunnel Drop Shafts & Near Surf ($83 M) 2019-2022
URT-2 35 MGD Pump Station ($55 M) 2021-2022
Re-investment in Existing Facilities ($10 M) 2019-2024
Green Infrastructure Phase III ($10 M) 2020-2024

Phase IV: 2025-2029 = $227M
URT-2 North Tunnel Segment ($133 M) 2026-2029
URT-2 N Tunnel Drop Shafts & Near Surf ($74 M) 2029-2031
Re-investment in Existing Facilities ($10 M) 2025-2029
Green Infrastructure Phase IV ($10 M) 2025-2029

Phase V: 2030-2034 = $110M
WWTP Outfall Conduit & Cl2+SO2 ($100 M) 2032-2034
Re-investment in Existing Facilities ($10 M) 2030-2034

The state will still need to approve this new proposal. A public meeting will take place Wednesday February 10 at 7 pm at::

University of Dearborn
Environmental Interpretive Center
4901 Evergreen, Dearborn MI

"Alternative Rouge River CSO Control Program Executive Summary."


Ian of the Great Lakes said...

Thanks for going into the details, I've included a link to your blog on one of mine summarizing the RRO-2 too.

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