New York City s Operations Support Tool: Motivation, Use Cases, and Components

Transcription

1 New York City s Operations Support Tool: Motivation, Use Cases, and Components AWRA Annual Conference Tysons VA November 4, 2014 Grantley Pyke, PE, Hazen and Sawyer James Porter, PhD, NYCDEP

2 NYC Water Supply System Overview Surface water supply from 2,000 mi 2 watershed in 8 upstate counties 19 reservoirs and 3 controlled lakes 580 BG storage capacity Serves 9.4 million people (½ of population of New York State) Delivers ~1.1 BGD Operated and maintained by NYCDEP CAT/DEL supply is unfiltered 2

3 Motivation for Developing OST Robust analytical support to balance water supply, water quality, environmental objectives Compare performance of alternate operations Two contexts Current Operations: using ensemble inflow forecasts Long-term Planning: using historical or synthetic inflows One tool, one database, multiple scenarios Modify infrastructure capabilities to meet analytical needs Eliminate disconnect between actual rules and long-term planning assumptions 3

4 OST Components Data and Forecast System Simulation Models Visualization Tools 4

5 OST Data Sources Near real-time (15 minute) to daily automated acquisition from DEP, USGS, NWS AQUARIUS used for storage and semi-automated QA-QC Uses Model initialization Forecast conditioning Situational awareness One-stop data access for users # of sites # of signals Reservoir Operations USGS Streamgages Meteorological Stations Reservoir Buoy 2 15 Ops Precip Snow Core Snow Pillow Full Station Water Quality Sites Aqueduct Reservoir - Discrete Depth Reservoir - AutoProfiling Buoy 8 80 Reservoir - Manual Profile Stream - AutoSampling

6 OASIS Simulation Model NYC system + Delaware River Basin Integrated with W2 water quality models Simulates human operation of the system using operating rules and linear programming 6

7 How is OST used for Daily Operations? Initialize model with today s hydrologic conditions & system storage levels Generate future inflows based on NWS ensemble streamflow forecasts Simulate future system operations under forecasted inflows 7

8 How is OST used for Daily Operations? Evaluate system performance under baseline system operating rules Customize operations to address current system needs (e.g. water quality, balancing, spill mitigation, planned facility outages) 8

9 OST Usage for Outage Planning Rondout-West Branch Tunnel 900 mgd design capacity ~15-35 mgd loss at two key sections 9

10 Example: Planning a Short-term Tunnel Outage Schedule an outage and a reduced flow period for RWBT ROV/AUV investigation Execute simulation 10

11 Example: Planning a Short-term Tunnel Outage Examine impacts on system operations (reservoir storage levels, diversions, releases, spills) 11

12 Example: Planning an Extended Tunnel Outage Initial planning focused on 2 4 year outage, with and without additional augmentation supplies Severe drawdown of remaining supplies Successful outage completion heavily dependent on hydrology 240+ mgd of new supply would be required to sustain such a long outage Normal Operations Outage Operations 12

13 Refinements to Repair Design Focus shifted to decreasing the repair duration and examination of multi-year phased outages Explicit simulation of multiple different outage durations and phasing scenarios One continuous outage vs. multiple short-duration outages Assess likelihood of completion over a 1/2/3 year period 13

14 Refinements to Analytical Approach Explicit simulation of outage-related decision-making 1. Pre-outage operations Maximize storage in Catskill/Croton systems 2. Go/No-Go decision Are hydrologic conditions favorable for initiating an extended outage? 3. Demobilization triggers Forecast-based thresholds for demobilizing the repair if low inflows are projected Explicit simulation of demobilization / remobilization time depending on work progress 14

15 Explicit Simulation of Outage Decision-Making Do we start the outage? Are hydrologic conditions favorable for initiating an extended outage? Do we continue the outage? Can we continue the outage and reliably maintain supply? 15

16 Outcomes Construction of a bypass tunnel around the leaking Roseton section was ultimately identified as the preferred alternative Outage duration is limited to the time necessary to connect the bypass tunnel and repair the Wawarsing section (~8 months) Three additional alternatives also selected for development: Enhance existing water conservation program (~ -50 mgd) Increase transmission capacity of Catskill Aqueduct (~ +35 mgd) Increase In-City Groundwater capacity (~ +33 mgd) 16

17 RWBT Bypass Tunnel 17

18 Conclusions System model is instrumental in evaluating dynamic reservoir operations near-term operations long-term planning System model allows explicit simulation of: Hydrologic variability System constraints and potential improvement options Realistic operation decisions to ensure system reliability 18