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APPENDIX A

Tables of Ratings and Ranges
for Geographic Targeting System Parameters

TABLE A-1. ASSIGNED WEIGHTS FOR DRASTIC PARAMETERS

Feature
"Generic"
DRASTIC Weights
"Pesticide"
DRASTIC Weights
Depth to Water
5
5
Net Recharge
4
4
Aquifer Media
3
3
Soil Media
2
5
Topography
1
3
Impact of the Vadose Zone Media
5
4
Hydraulic Conductivity
3
2

TABLE A-2. RANGES AND RATINGS FOR DEPTH TO WATER

DEPTH TO WATER (FEET)
Range
Rating
0 - 5
10
5 - 15
9
15 - 30
7
30 - 50
5
50 - 75
3
75 - 100
2
>= 100
1

TABLE A-3. RANGES AND RATINGS FOR NET RECHARGE

NET RECHARGE (INCHES/YEAR)
Range
Rating
0 - 2
1
2 - 4
3
4 - 7
6
7 - 10
8
>= 10
9
TABLE A-4. RANGES AND RATINGS FOR AQUIFER MEDIA

AQUIFER MEDIA
Range
Rating
Typical Rating
Massive Shale
1 - 3
2
Glacial Till
4 - 6
5
Bedded Sandstone and Shale Sequences
5 - 9
6
Massive Sandstone
4 - 9
6
Sand and Gravel
4 - 9
8

TABLE A-5. RANGES AND RATINGS FOR SOIL MEDIA

SOIL MEDIA
Range
Rating
Thin or Absent
10
Gravel
10
Sand
9
Peat
8
Shrinking and/or Aggregated Clay
7
Sandy Loam
6
Loam
5
Silty Loam
4
Clay Loam
3
Muck
2
Non-shrinking and Non-aggregated Clay
1

TABLE A-6. RANGES AND RATINGS FOR TOPOGRAPHY

TOPOGRAPHY (PERCENT SLOPE)
Range
Rating
0 - 2
10
2 - 6
9
6 - 12
5
12 - 18
3
>= 18
1

TABLE A-7. RANGES AND RATINGS FOR IMPACT OF THE VADOSE ZONE MEDIA

VADOSE ZONE MEDIA
Range
Rating
Typical Rating
Confining Layer
1
1
Silt/Clay
2 - 6
3
Shale
2 - 5
3
Bedded Sandstone and Shale
4 - 8
6
Sand and Gravel with significant Silt and Clay
4 - 8
6
Sand and Gravel
6 - 9
8

TABLE A-8. RANGES AND RATINGS FOR HYDRAULIC CONDUCTIVITY

HYDRAULIC CONDUCTIVITY (GPD/FT2)
Range
Rating
1 - 100
1
100 - 300
2
300 - 700
4
700 - 1000
6
1000 - 2000
8
>= 2000
10
TABLE A-9. RANGES AND RATINGS FOR VULNERABILITY FACTOR

PESTICIDE DRASTIC SCORE
Range
Rating
0 - <130
1 (Low)
130 - <160
2 (Moderate)
>= 160
3 (High)

TABLE A-10. RANGES AND RATINGS FOR SENSITIVITY FACTOR

MARKET VALUE OF PRODUCTION PER ACRE (BY COUNTY)
Range
Rating
$ 0 - <40
1 (Low)
40 - <60
2 (Moderate)
>= 60
3 (High)

TABLE A-11. RANGES AND RATINGS FOR RISK FACTOR

PERMITTED WATER VOLUME (AC_FT/YEAR)
Range
Rating
0 - <200
1 (Low)
200 - <1200
2 (Moderate)
>= 1200
3 (High)

TABLE A-12. RANGES AND RATINGS FOR MONITORING PRIORITY

TOTAL MONITORING SCORE
Range
Rating
3 - 4
Low
5 - 7
Moderate
8 - 9
High

Ground Water Home


DISCLAIMER
Last Updated: 01/06/2006
Scott Radig  - ND Dept. of Health