SWAP Technical Advisory Committee

Transcription

1 SWAP Technical Advisory Committee July 26, 2016 Department of Environmental Quality Jay Frick

2 Today s Objectives Presentation Outline: Brief History of SWAP What is SWAP and how did it come about? NC s approach to SWAP How did NC satisfy the EPA requirements? SWAP data and its uses What are the resulting SWAP products and how are they used? 2

3 Brief History of SWAP 1996 SDWA Amendments Section 1453 required that all states create a Source Water Assessment Program (SWAP) Delineate source water assessment areas Inventory potential contaminant sources Determine the susceptibility of each public water system to contamination Provide SWAP information to the public 3

4 Brief History of SWAP Some concerns regarding drinking water 4

5 Brief History of SWAP Some concerns regarding drinking water 5

6 6 Brief History of SWAP

7 7 Brief History of SWAP

8 8 Brief History of SWAP

9 Brief History of SWAP A proactive message... Pollution prevention is recognized as the most effective approach to ensuring a safe, long-term source of drinking water. 9

10 Brief History of SWAP A proactive message... Pollution prevention is recognized as the most effective approach to ensuring a safe, long-term source of drinking water. With an economic appeal... An EPA study estimates it is 20 to 400 times more expensive to treat contamination than to prevent it. 10

11 NC s Approach to SWAP Shaping NC s design for SWAP General strategy: build on existing state programs with an approach that is non-regulatory and incentives driven Calculate and report SWAP results using GIS Consider SWAP results as a lens to assess priorities in other programs Solicit input via a TAC, public meetings and a public comment period 11

12 NC s Approach to SWAP October 1999: NC Completes its SWAP blueprint and seeks EPA approval The Yellow Book is available online and documents technical details 12

13 NC s Approach to SWAP Delineate of the source water assessment areas (SWAA) For Ground Water: Fixed radius method, which uses the contributing area Where: A C = Q W Q is max pumping rate, and W is the average recharge rate 13

14 NC s Approach to SWAP Delineate of the source water assessment areas (SWAA) For Ground Water: Complicated by differences in transmissivity A 2:1 ratio of transmissivity was assumed Results in an elliptical shaped area, and Orientation of the ellipse is unknown Simplified by using circle with r = semimajor axis A SWAP = 2A C = 2Q W r SWAP = 2Q πw 14

15 15 NC s Approach to SWAP

16 NC s Approach to SWAP Delineate of the source water assessment areas For Surface Water: WS-I: entire watershed is considered the critical area WS-II and III: critical area plus watershed area. Extra emphasis on 1000 stream zones in the WA. WS-IV and V: critical area plus protected area. Extra emphasis on 1000 stream zones in the PA. Plus up to 25 mile distance of 1000 stream zones past the PA. 16

17 NC s Approach to SWAP Stream Zone with 1000 buffers Example: Assessment area for Lumberton s WS-IV Protected Area Critical Area 17

18 NC s Approach to SWAP NC Source Water Assessment Areas... cover approximately xx% of the state 18

19 NC s Approach to SWAP NC Source Water Assessment Areas... cover approximately 34% of the state 19

20 NC s Approach to SWAP Develop database of potential contaminant sources 20

21 NC s Approach to SWAP Develop database of potential contaminant sources Includes nearly 44,000 PCSs from 16 agencies and programs 21

22 22 NC s Approach to SWAP

23 NC s Approach to SWAP Assessment area for Lumberton 23

24 NC s Approach to SWAP Determine susceptibility to contamination Susceptibility rating is an indicator of relative risk. Ratings used to identify priorities. Ratings are not an indicator of contaminated water Ratings are categorically defined: higher, moderate or lower Ratings based on: contaminant rating # of PCS and proximity to an intake inherent vulnerability potential for PCSs to reach an intake 24

25 NC s Approach to SWAP Susceptibility Ratings Contaminant Rating Inherent Vulnerability Rating 25

26 NC s Approach to SWAP Inherent Vulnerability for ground water Inherent Vulnerability Rating Aquifer Rating Unsaturated Zone Rating Well Construction & Integrity Land Slope Land Use Land Cover Vertical Conductivity 26

27 NC s Approach to SWAP Inherent Vulnerability for surface water Inherent Vulnerability Rating Watershed Classification Intake Location Watershed Characteristic Raw Water Quality Annual Precipitation Land Slope Land Use Land Cover GW Contribution 27

28 28 NC s Approach to SWAP

29 NC s Approach to SWAP USGS developed a GIS based, overlay-and-index method 29

30 NC s Approach to SWAP Watershed Characteristics Annual Precipitation Land Slope Land Use Land Cover GW Contribution w=3 w=2 w=1 w=3 w=1 Grid cell rating: Average grid cell calculation: 30

31 Detailed technical reports for all public water systems NC s Approach to SWAP Approx systems and 8400 sources 31

32 32 NC s Approach to SWAP

33 GIS-based information delivery NC s Approach to SWAP 33

34 Uses of SWAP data SWAP results are used in a variety of ways Other agencies use SWAP data to set priorities for environmental protection activities Used to initiate local source water protection planning efforts Online mapping tool used to make site-specific decisions (siting new wells, environmental assessments, etc.) 34

35 Uses of SWAP data NC Source Water Assessment Areas... used to identify priority areas 35

36 NRCS EQIP Program Ranking Tool NC s Approach to SWAP Description of Priority: Does this application include conservation practices within: (A) DWQ targeted basins (B) 303d listed watersheds impaired by agricultural activities (C) boundaries of a drinking water assessment area as delineated by the PWS Section of NC DEQ? Will this application increase the SCI? Yes (Y) or No (N) Points Will this application implement any practices that increase the extent of native early successional habitat, other declining habitats, or reduce grassland nesting bird disruption? 20 Will this application implement any practices that enhance, protect and restore water quality within the watershed of a Special Aquatic Habitat? 20 Will this application implement any practices that enhance, protect and restore water quality as part of a multi-land user planning effort or community project? 20 36

37 37 NC s Approach to SWAP

38 38 NC s Approach to SWAP

39 39 NC s Approach to SWAP

40 40 NC s Approach to SWAP

41 Uses of SWAP data In Conclusion: SWAP has been an asset to NC s drinking water protection strategy for nearly 18 years. We hope you will help us find ways to update and improve it! Prioritize the PCSs (to be sure they re not all high ) Improve the data delivery and the SWAP reports Identify ways to expand the uses for SWAP information 41