1. Supply Augmentation Need Planning
NYWEA 2013
Water for the Future
Supply Augmentation Need Planning
Mark N. Page, Jr.
September 19, 2013

2. Background on Water for the Future Current Program Modeling Results
Agenda
Background on Water for the Future
Current Program
Modeling Results

3. Water Supply System Overview

4. Dependability Program
10 Critical Areas Have No ‘Back-up’ Infrastructure or Supplies
Below Kensico Reservoir
Kensico Reservoir and Connecting Tunnels to Eastview
Hillview Reservoir
City Tunnels #1 & #2
Catskill & Delaware Aqueducts between Kensico and Hillview Reservoirs
Richmond Tunnel (Brooklyn to Staten Island)
Above Kensico Reservoir
Rondout - West Branch Tunnel (Delaware Aqueduct)
West Branch – Kensico Tunnel (Delaware Aqueduct)
Ashokan – Kensico Reach (Catskill Aqueduct)
Rondout Reservoir
Ashokan Reservoir

5. Dependability Supply Needs Above Kensico
Ashokan
Reservoir
( MGD)
Ashokan
Kensico Reach
( MGD)
Rondout Reservoir
( MGD)
Rondout-West
Branch Tunnel
( MGD)
West Branch
Kensico Tunnel
( MGD)

6. Dependability Below Kensico
Pressurization of Catskill Aqueduct from Kensico Reservoir to the UV Facility at Eastview
Kensico – City Tunnel (Previously known as City Tunnel No. 3 Stage 3)
The Bronx – Queens Tunnel (Previously known as City Tunnel No. 3 Stage 4)
City Tunnel No.3
(Stage 2, Manhattan Leg)

7. 2007 RWBT Identified as Primary Area of Concern
RWBT conveys Delaware system water and is the primary source for Towns of Newburgh and Marlborough and approximately 50% of New York City’s supply

8. Project Background - Roseton Surface Expression
Roseton Leakage
Project Background - Roseton Surface Expression
A dozen or so surface expressions
Flow observed on west bank of Hudson River
Testing program and analysis estimates leakage of 15 to 35 mgd.
Zhenqi Notes – improve quality of slide / image resolution? Call-out font sizes… enhance tunnel lines

9. How Long will the Tunnel be Out of Service?
2007 Shutdown Schedule
How Long will the Tunnel be Out of Service?

10. 2008 Shortfall Curve

11. Potential Solutions for Dependability
Increase Aqueduct Capacities
Parallel Tunnels
Croton Pump Stations
Abandoned Sources (Westchester Co.)
Hudson River and Harbor Surface Water, Hudson Groundwater
Interconnections
Demand Reduction
Expand Groundwater Use

12. Augmentation Project Screening
Project Tiering/Prioritization – Focuses Effort on Best Projects and Combinations

13. Delaware Repair: Alternative water sources
Project evaluation to identify a group of projects to meet NYC’s alternate water supply needs (2008)
Factors:
Cost
Schedule
DEP Control
26 Projects
Key:
Redundant tunnels
Optimization of existing system
Groundwater
Desalinization of Hudson River or Harbor water
Interconnections to New Jersey or Connecticut
39 Projects

14. Delaware Repair: Alternative water sources
Top 26 Projects falls to 17 with the removal of mutually exclusive projects.

15. Duel path – Alternate Supply / Parallel Tunnel

16. Moving to Design
In 2008 and 2009 DEP hired new consultant team to develop parallel tunnel and bypass tunnel concepts to address the RWBT leaks

17. Repair of the Leaks Roseton Repairs Wawarsing Repairs:
Shaft 6 Tunnel
Unwatering Shaft
Shaft 2A 17
Rondout
Reservoir
Shaft 9
Shaft 8
EL 840
Shaft 1
Shaft 2
Shawangunk Mountains
Shaft 4
Shaft 5
Shaft 5A
Shaft 7
West Branch
Reservoir
Rondout Creek
Shaft 3
Walkill River
Hudson River
El 503 El
Wawarsing
Roseton Repairs
Not possible from within tunnel
Access requires new shafts
Best Solution is Bypass
Wawarsing Repairs:
Possible from within tunnel
Access via Shaft 2A
Confinement Relatively good
Roseton

18. Bypass Tunnel Construction18

19. Recent Modeling
In 2010 DEP shifted from evaluating a full repair of the RWBT to constructing a bypass around the leak in Roston, NY
This bypass included the use of inundation plugs to handle tunnel inundation, resulting in approximately a month shutdown period for the connection

20. OST Supply Curve ( )
OSTv _Aug-SC_000
Runs were conducted for these four supply levels

21. Threshold Approach - Objectives
Objectives (during an outage):
Provide advance notice of potential shortfall conditions
Provide DEP with enough time to take some preventive action
Objectives (now, during the planning process):
Accurately simulate operations during an outage
Provide a fuller picture of how various augmentation projects perform
Provide a framework to help support DEP’s risk analysis
Uncertainties in augmentation project capacity
Uncertainties in RWB repair duration

22. Likelihood of Emergency Actions for 15-Month Outage22

23. Big Break Through!!! Inundation Plugs not necessary!!!
This resulted in the following:
A shorter shutdown period for the connection of approximately 10 months
A phased connection of the bypass tunnel to the RWBT
Allowed for an evaluation of shorter shutdown periods and bailout contingencies
We evaluated four phased approaches:
Fixed Staging
4 month / 3 month / 3 month
5/5
6/4
Variable Stage (10 months total but can be broken and phased over 3 years)

24. Tunnel Outage Duration Evolution
The design of the connection work always considered outage duration and risk mitigation
Subsequent iterations improved risk picture
Base Plan
Preemptive Plug
Reactive Plug
Drainage Tunnel

25. Recent Modeling Results
Where we are now!

26. Water Demand and Dry Weather Wastewater Flows
Historic Flows and Future Projections 2012

27. Water Supply System Augmentation and Improvement
Conservation / Demand Management
Upper Catskill Aqueduct Optimization
Queens Groundwater Rehabilitation

28. Modeling Results End of 2012
As a result of three workshops, extensive modeling, and shutdown design updates:
Variable Stage Shutdown allows for complete shutdown in one phase
Includes a repair start on Oct 1 with augmentation starting June 1
Provides for a singular phase repair based on modeling using forecasted 60 day look ahead for continuation of shutdown or bailout from repair
Provides for allowance for remaining repair to be completed in subsequent years, if necessary
58 mgd of augmentation (33 mgd Groundwater + 25 mgd Demand Management)
Catskill Aqueduct maximum flow increased to 636 mgd via Catskill Rehabilitation Project
Croton WFP flow at 250 mgd to account for diurnal demand pattern.

29. Outage Surface Plot: Variable Outage
Index
560
Outage_Pattern
Var
SourceNY_Q 58
New_Crot_Aq_max
290
CatAq_max
636
Reserve_Buffer
10%
NYC_Demand_level
1070
Temp_vary_Demand
Most outages start in October
Substantially longer Stage 1 outage duration with 10% reserve and CAT 636
Year 1
Year 2
Year 3

30. Likelihood of Completion: Variable Staging
Month # 1 2 3 4 5 6 7 8 9 10
Likelihood of Completing x Outage Days
Shows probability of successfully completing the variable stage shutdown repair during a three consecutive year period
Allows for three chances to complete the 10 month (300 day) repair
Could complete entire 10 months in first year
Or could complete remaining repair period during subsequent one or two years if insufficient supply is available in first year
Fixed stage shutdowns do not allow for this flexibility since entire three year period is required for each repair period
4 lines for each color – these represent:
NCA 250 / Demand Pattern
NCA 290 / Demand Pattern
NCA 250 / Demand Regression
NCA 290 / Demand Regression
Why does this scenario appear to be more successful than the fixed outage scenarios here but appears to be less successful in the following runs...?
Should discuss this...
This plot shows the likelihood of completing 300 total outage days over a period of up to 3 years.

31. Likelihood of Completion: Summary Table
99% Probability of Success!

32. Next Steps Continue refining shutdown design and modeling
Continue thinking about issues that could arise
Develop operational plans for shutdown