1.) Are there other communities with CSO tunnels (besides Portland, OR)?
Yes, there are many; some shallow soft ground tunnels like First St. Tunnel, others deeper rock tunnels All require dropshafts and diversion structures. A few examples would be South Boston, MA; Richmond, VA; Chicago, IL; Atlanta, GA; Milwaukee, WI. Federal EPA keeps a relatively up to date running list of all Federal CSO enforcement actions.
2.) I request that any additional report or information from DC Water examine these alternatives, and explain, with a factual basis, what the community and environmental impact would be.
a. McMillan Storage and Flagler Pumping Station
b. Replace portions of the Flagler Trunk sewer to increase capacity
Under the DC Environmental Policy Act of 1989, DC Water has completed a Final EA (soon to be released) that examines alternatives and impacts to the community and environment. A McMillan Storage and Flagler Pumping Station alternative was discussed in this report as well as other neighborhood suggested alternatives that were not deemed feasible for further analysis.
3.) If a diversion chamber can be built in 6-8 months on First Street, explain why Flagler will be required to be closed for 18 months.
The 18 months for the Construction Staging Area at Flagler includes construction of the drop shaft, approach channel, adit, and diversion structure. The 6-8 month for the one diversion structure at First St is part of the 27 month schedule to build 3 diversion structures (including First St), the drop shaft and adit. The 6-8 month window for the First St. diversion structure was broken out separately to show impacts to traffic on First St., a major accessway to the hospitals to the north.
4.) Could the Flagler construction be more like 7-10 months?
After constructability reviews by 3 very qualified design build firms, the consensus was that 18 months was the shortest duration that can be built in a safe manner in the very limited amount of staging area being provided to minimize impacts to residences.
5.) If the two structures were built concurrently couldn’t the construction be limited to 6-8 months?
The 18 months currently assumes that several elements would be constructed concurrently.
Thanks much, and please let us know of any other questions, comments or concerns.
Have a great evening.
Emanuel D. Briggs | Manager, Community Outreach, External Affairs | District of Columbia Water and Sewer Authority | firstname.lastname@example.org
5000 Overlook Avenue, SW | Washington, DC 20032 | (202) 787-2003 | (202) 787-4122 (fax)
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