1. Manchester’s CSO Program: A Look Behind and a Look Ahead
Highway Commission Meeting
January 6, 2014

2. Presentation Agenda Background on CSOs Phase I CSO Program (1999-2009)
Phase II CSO Program ( )
Chestnut Street Sewer Separation Project ( )
Questions

3. What is a CSO?
A "combined sewer" system is when one subsurface pipe is used to covey both sewer and stormwater flows. During rain events, the capacity of this single pipe is exceeded due to the large amount of stormwater entering the system. Therefore, outlets into local waterways were constructed to allow for the combined sewer overflows (CSOs) to exit the system. This results in the discharge of raw sewage into our waterways. This was standard construction practice for environmental infrastructure from the 1800s to the 1950s.

4. Manchester’s CSO History
EPA issued national CSO Policy in 1994
Negotiations w/ EPA mid/late 1990s
Manchester’s CSO Compliance Order issued 1999
Two phase approach
Phase I: West Side
Phase II: East Side

5. Requirements of Phase I CSO Abatement Program
Separate 14 CSO Basins
Raise 2 CSO Weirs
Upgrade Wet-Weather Treatment Capacity at WWTP
Flow Monitoring
Program
Supplemental Environmental Projects Program (SEPP)

6. Phase I: 1999 – 2009 Scope of Work 10-year $58 million program
Fully separated 15 basins
8 construction contracts
Over 53 miles of new
or rehabilitated piping
up to 60” diameter

7. Phase I CSO Abatement Program– Surpasses all Goals!
Average annual CSO discharges decreases by 99% from 53.2 mgd to 0.2 mgd
Goal was three-month level of CSO control, program achieved two-year level of CSO control
Merrimack River water quality increases
Manchester’s west side received full infrastructure upgrade; sewer, drain, water, gas, road, sidewalks, and curb
Ten year program was completed on schedule and on budget

8. Additional Benefits and Upgrades
Road reconstruction (26 miles)
Other utility construction
Water (9 miles)
Gas (14 miles)
Surface reconstruction
Curbing (8 miles)
Sidewalks (6 miles)
Pedestrian Ramps (290)

9. Lessons learned from Phase I
- Biggest bang for $$$
Do all infrastructure work at once
How do our residents benefit?
Address sewer backups
Address street flooding
What do our residents want?
Roads, sidewalks, and curbing

10. Phase II Long-term Control Plan for East Side due to EPA in 2010
Evaluation of 7 CSO Basins on East Side of City
4,500 acre Cemetery Brook Basin
1,500 acre Pennacook Street Basin
640 acre Stark Brook Basin
15 Outfalls

11. Goals for Phase II Work Remove five brooks from system
5 mgd day weather flow
55 mgd peak wet weather flow
Achieve CSO reduction w/out off-site treatment facilities
Promote urban revitalization
Green infrastructures
Roads, sidewalks, plantings,

12. Proposed Plan for Future CSO Work – Submitted to EPA in 2010
Phase II - $165 million over 20 years
$20 million in WWTP improvements
$3 million in system optimization
$65 million for removal of Cemetery Brook
$73 million in sewer separation
$4 million in program assessment/reporting
Phase III - $177 million over next 20 years

13. Phase II CSO Program

14. Chestnut Street Sewer Separation Project14

15. Chestnut Street Sewer Separation Project
Design
Construction – 2013
4400 LF of new drain (15” – 60”)
1640 LF of new sewer (6” – 12”)
2670 LF of new water main (6” – 20”)
Final Paving – 2014
Total Project Costs - $6.60 million

16. Chestnut Street Challenges
New drain system designed for 50 year storm to account for climate change
60-inch drain pipe up to 26 feet deep
Keep Verizon Arena/local businesses operational and happy
Traffic control
Work in front of MFD for over one month
Unforeseen utilities/problems

17. 60-inch Pipe Moved into Place

18. 60-inch Pipe Lowered into Trench

19. Pipe Rammed “Home”

20. Pipe Installation 26 feet deep

21. Manhole Section being Lowered

22. Sidewalk, Curbing, Paving, and Striping

23. Next up - North Chestnut Street Sewer Separation Project23

24. Questions?
Frederick J. McNeill, PE