IN-NETWORK CHLORINE RESIDUAL MANAGEMENT Using GIS to assess flush point efficacy Ian Toohey, P.E. Systems Planning Austin Water
TABLE OF CONTENTS 1. Background 3. Surface Creation 2. Residual Sampling Analysis 4. Analysis and Recommendations
1. BACKGROUND SYSTEM OVERVIEW, PRE-WTP4
1. BACKGROUND FLUSH POINTS Generally focused on outer edges of the system Reduce water age & improve disinfection residuals Dedicated crews flush & record samples
1. BACKGROUND 2013 RESIDUAL SAMPLING ANALYSIS Plot before & after chlorine residual samples from flush events Analyze residual recovery relative to water loss & flush frequency Evaluate candidate sites for increased frequency, reduced frequency, or removal
1. BACKGROUND SYSTEM OVERVIEW, POST-WTP4
2. RESIDUAL SAMPLING ANALYSIS - UPDATE Capture time frame around the introduction of WTP4 Assess impact of changing flows on residuals in different parts of the system Revisit scheduling of existing flush points
2. RESIDUAL SAMPLING ANALYSIS - UPDATE
3. SURFACE CREATION PURPOSE New Flush Points Needed? Hypothesis: 1) The need for flushing is related to maintaining chlorine residuals; 2) We collect chlorine residual samples from all over the City on a monthly basis; 3) Let s make some surfaces and find out where a new flush point should go!
3. SURFACE CREATION - PROCEDURE Raster Creation from Points Kernel Interpolation w/ Barriers Month-on- Month Percent Difference Raster Calculator Cumulative Difference Raster Calculator
3. RASTER CREATION FROM POINTS Tool: Geostatistical Analyst -> Interpolation -> Kernel Interpolation w/ Barriers Inputs: 1) Point features (chlorine residual sample readings) 2) Barrier features (pressure zone boundaries) 3) Kernel function (Epanechnikov first order polynomial) Challenges: 1) RUNTIME! (7 hours/surface x 22 surfaces) 2) Geostatistical Wizard bogged down 3) Bounding box (no extrapolation)
3. MONTH-ON-MONTH PERCENT DIFFERENCE Tool: Spatial Analyst -> Map Algebra -> Raster Calculator APR 2014 APR 2015
3. MONTH-ON-MONTH PERCENT DIFFERENCE Tool: Spatial Analyst -> Map Algebra -> Raster Calculator AAAAAAAAAA AAAAAAAAAA AAAAAAAAAA 2014 January February March April May June July August September October November December 2015 January February March April May June July August September October November December
3. MONTH-ON-MONTH PERCENT DIFFERENCE Tool: Spatial Analyst -> Map Algebra -> Raster Calculator JAN-FEB Concept: small % differences will accumulate over time SSSSSSSSSSSSSSSSSS (PPPPPPPPPPPPPP DDDDDDDDDDDDDDDDDDDD RRRRRRRRRRRRRR) JJaaaaaaaaaaaa Areas of change will emerge over time as more layers are added
3. MONTH-ON-MONTH PERCENT DIFFERENCE Tool: Spatial Analyst -> Map Algebra -> Raster Calculator JAN-MAR Concept: small % differences will accumulate over time SSSSSSSSSSSSSSSSSS (PPPPPPPPPPPPPP DDDDDDDDDDDDDDDDDDDD RRRRRRRRRRRRRR) JJaaaaaaaaaaaa Areas of change will emerge over time as more layers are added
3. MONTH-ON-MONTH PERCENT DIFFERENCE Tool: Spatial Analyst -> Map Algebra -> Raster Calculator JAN-APR Concept: small % differences will accumulate over time SSSSSSSSSSSSSSSSSS (PPPPPPPPPPPPPP DDDDDDDDDDDDDDDDDDDD RRRRRRRRRRRRRR) JJaaaaaaaaaaaa Areas of change will emerge over time as more layers are added
3. MONTH-ON-MONTH PERCENT DIFFERENCE Tool: Spatial Analyst -> Map Algebra -> Raster Calculator JAN-MAY Concept: small % differences will accumulate over time SSSSSSSSSSSSSSSSSS (PPPPPPPPPPPPPP DDDDDDDDDDDDDDDDDDDD RRRRRRRRRRRRRR) JJaaaaaaaaaaaa Areas of change will emerge over time as more layers are added
3. MONTH-ON-MONTH PERCENT DIFFERENCE Tool: Spatial Analyst -> Map Algebra -> Raster Calculator JAN-JUNE Concept: small % differences will accumulate over time SSSSSSSSSSSSSSSSSS (PPPPPPPPPPPPPP DDDDDDDDDDDDDDDDDDDD RRRRRRRRRRRRRR) JJaaaaaaaaaaaa Areas of change will emerge over time as more layers are added
3. MONTH-ON-MONTH PERCENT DIFFERENCE Tool: Spatial Analyst -> Map Algebra -> Raster Calculator JAN-JULY Concept: small % differences will accumulate over time SSSSSSSSSSSSSSSSSS (PPPPPPPPPPPPPP DDDDDDDDDDDDDDDDDDDD RRRRRRRRRRRRRR) JJaaaaaaaaaaaa Areas of change will emerge over time as more layers are added
3. MONTH-ON-MONTH PERCENT DIFFERENCE Tool: Spatial Analyst -> Map Algebra -> Raster Calculator JAN-AUG Concept: small % differences will accumulate over time SSSSSSSSSSSSSSSSSS (PPPPPPPPPPPPPP DDDDDDDDDDDDDDDDDDDD RRRRRRRRRRRRRR) JJaaaaaaaaaaaa Areas of change will emerge over time as more layers are added
3. MONTH-ON-MONTH PERCENT DIFFERENCE Tool: Spatial Analyst -> Map Algebra -> Raster Calculator JAN-SEPT Concept: small % differences will accumulate over time SSSSSSSSSSSSSSSSSS (PPPPPPPPPPPPPP DDDDDDDDDDDDDDDDDDDD RRRRRRRRRRRRRR) JJaaaaaaaaaaaa Areas of change will emerge over time as more layers are added
4. ANALYSIS AND RECOMMENDATIONS JAN-SEPT Study areas of relative residual increase/decrease NOTE: East Austin 66 TM maintenance Compare to flush point analysis results as validation
4. ANALYSIS AND RECOMMENDATIONS JAN-SEPT Study areas of relative residual increase/decrease NOTE: East Austin 66 TM maintenance Compare to flush point analysis results as validation
4. ANALYSIS AND RECOMMENDATIONS JAN-SEPT Shifting locations of removed sites, locating new ones Perform similar analysis to monitor effect of major infrastructure maintenance outages Temporary flush points during rehab work
THANK YOU! Ian Toohey, P.E. Systems Planning Austin Water Ian.toohey@austintexas.gov