The document discusses the Narragansett Bay Commission's Combined Sewer Overflow Control Facilities Program. It describes Phase I facilities including the Main Spine Tunnel for CSO storage and diversion. The tunnel is 61.8 MG in design capacity and 66.5 MG in actual capacity. It connects to drop shafts and a pumping station. The pumping station facilities lower the flow to the tunnel depth and pump the stored flows after wet weather events.

1. Narragansett Bay CommissionNarragansett Bay Commission
Combined Sewer OverflowCombined Sewer Overflow
Control Facilities ProgramControl Facilities Program
The Biggest Project You will NeverThe Biggest Project You will Never
SeeSee
Paul Pinault, P.E. Former Executive Director NBCPaul Pinault, P.E. Former Executive Director NBC
Client Service Leader CDM SmithClient Service Leader CDM Smith

4. NBC CSONBC CSO
ProgramProgram
Combined Sewer OverflowCombined Sewer Overflow
Control Facilities ProgramControl Facilities Program

5. Phase I Facilities...Phase I Facilities...
CSO Diversion andCSO Diversion and
CollectionCollection
CSO Storage - MainCSO Storage - Main
Spine TunnelSpine Tunnel
Tunnel Capacity:Tunnel Capacity:
– 61.8 MG Design61.8 MG Design
– 66.5 MG Actual66.5 MG Actual
Tunnel PumpTunnel Pump
StationStation

6. SITE S1 AND OUTFALL 067

7. CSO Diversion and CollectionCSO Diversion and Collection
COMBINED SEWAGE
OVERFLOW - DIVERSION AND STORAGE
TUNNEL1.PRS
DIVERSION STRUCTURE
(APPROX. 22'L X 12'W)
INTERCEPTS EXISTING CSO
OVERFLOW
GATE & SCREENING STRUCTURE
(APPROX 35'L x 20'W)
CONTROLS FLOW INTO TUNNEL
APPROACH CHANNEL
ORGANIZES FLOW TO
CREATE VORTEX
DE-AERATION CHAMBER
REMOVES ENTRAINED
AIR FROM FLOWS
RECIRCULATION PIPE
DE-AERATED AIR IS
DRAWN BACK INTO
DROP SHAFT
CONNECTING ADIT
(APPROX 72" DIA; LENGTH
VARIES)
EXISTING SEWER SYSTEM
CURRENTLY OVERFLOWS
INTO RIVERS AND BAY
DURING WET WEATHER NEAR SURFACE
FACILITIES WITHIN
25' OF GROUND
SURFACE
SOIL / ROCK
INTERFACE
- DEPTH VARIES
BETWEEN 40'
AND 160'
MAIN SPINE TUNNEL
(APPROX 26'DIA; 16,000'
LONG & 62 MG STORAGE)
CONVEYS FLOW TO
PUMPING FACILITIES
DROP SHAFT
(5' - 9' DIA; DEPTH 250')
TRANSFERS FLOW
FROM SURFACE TO
TUNNEL DEPTH
VENTILATION SHAFT
(2'-3.5' DIA.)
ENABLES DE-AERATED
AIR TO LEAVE CHAMBER

8. SUCTION LINE - TRANSFERS
WATER FROM TUNNEL TO
PUMPS
SCREENS
GRITS AND SCREENING
REMOVAL BY GANTRY
CRANE
FORCE MAIN TO
FIELDS POINT
SITE S1
CONFIGURATION OF
PUMP STATION OPERATING
FACILITIES
200' ±
TPS1.PRS
UPPER LEVEL - PUMP FLOOR
LOWER LEVEL
PUMP FLOOR
TPS OPERATION &
CONTROL BUILDING
110'±
68'±
Soil
Depth
155'±
Rock
150'±
TOTAL DEPTH TO
INVERT 305'±
SUMP
SAFE
ROOM
32-FEET DIAMETER
ACCESS SHAFT
MAIN SPINE
TUNNEL
62 MG
11-FEET DIAMETER
EQUIPMENT
HOISTING SHAFT
SAFE
ROOM
SITE S1
CONFIGURATION OF PUMP STATION OPERATING FACILITIES

9. CSO StorageCSO Storage
Main Spine TunnelMain Spine Tunnel
Tunnel capacity:Tunnel capacity:
– 61.88 MG (Design)61.88 MG (Design)
– 66.5 MG (Actual)66.5 MG (Actual)
Seven dropshaftsSeven dropshafts
divert flow to the tunneldivert flow to the tunnel

10. BRINE
PUMP
MOBILE REFRIGERATION PLANT
EXPANSION
VALVE
LIQUID
REFRIGERANT
FREEZE
TUBES
COOLING
WATER
LOW PRESSURE
REFRIGERANT GAS
HIGH PRESSURE
REFRIGERANT GAS
COMPRESSOR
CHILLERCONDENSER
DEVELOPING
FREEZEWALL
BRINE FREEZING SYSTEM

11. Developmental Phases

51. 1
2
3
4
5
6
9
7
8
10
11
2
3
4,5
6,7,8
9,10,11

60. The End of the TunnelThe End of the Tunnel