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

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

Water Supply System Overview

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

Dependability Supply Needs Above Kensico Ashokan Reservoir (35 - 135 MGD) Ashokan Kensico Reach (35 - 135 MGD) Rondout Reservoir (335 - 435 MGD) Rondout-West Branch Tunnel (335 - 435 MGD) West Branch Kensico Tunnel (385 - 485 MGD)

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)

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

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

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

2008 Shortfall Curve

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

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

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

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

Duel path – Alternate Supply / Parallel Tunnel

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

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 -600.0 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

Bypass Tunnel Construction 18

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

OST Supply Curve (2012-02-01) OSTv1.3.7.1_Aug-SC_000 Runs were conducted for these four supply levels

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

Likelihood of Emergency Actions for 15-Month Outage 22

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)

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

Recent Modeling Results Where we are now!

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

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

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.

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

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.

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

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