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Kittson County, CSAH 38 – Lateral Effect Calculations
Aug-09
Lateral Effect Calc Steps• Define Project
• Wetland Areas
• Ditch/drainage characterization
• Soils
• Calculation
Project Overview
• 4 miles road improvement
• Ditch upgrade
Aug-09
Identify Wetland Areas
Aug-09
Characterize DitchExisting ditch 2 ft deep
Proposed, 4 ft deep
Aug-09
Soils
• StrathconaI94A – Fine Sandy Loam
Aug-09
Soils for LE values
• Use Rosetta to generate K and f
Aug-09
Parameter SummaryDepth of ditch – d = 3 ft
Depth to impermeable layer – D = 10 ft
Drainable Porosity – f = 0.02720
Surface Storage – s = 0.1 in
Initial water surface height – m0 = 3 ft
Final water surface height – m = 2 ft
Time to for drawdown – t = 16 days
Saturated conductivity – Ks =
0.050252
7.424311
0.53957
0.702210
Ks (in/hr)Layer thickness (in)
Aug-09
Plug and Chug Depth of ditch – d = 2 ft
Depth to impermeable layer – D = 10 ft
Drainable Porosity – f = 0.02720
Surface Storage – s = 0.1 in
Initial water surface height – m0 = 2 ft
Final water surface height – m = 1 ft
Time to for drawdown – t = 16 days
Saturated conductivity – Ks = 1.88
0.050252
7.424311
0.53957
0.702210
Ks (in/hr)Layer thickness (in)
0.050252
7.424311
0.53957
0.702210
Ks (in/hr)Layer thickness (in)
Aug-09
Now repeat for ditch improveDepth of ditch – d = 3 ft
Depth to impermeable layer – D = 10 ft
Drainable Porosity – f = 0.02720
Surface Storage – s = 0.1 in
Initial water surface height – m0 = 3 ft
Final water surface height – m = 2 ft
Time to for drawdown – t = 16 days
Saturated conductivity – Ks = 1.88
0.050252
7.424311
0.53957
0.702210
Ks (in/hr)Layer thickness (in)
0.050252
7.424311
0.53957
0.702210
Ks (in/hr)Layer thickness (in)
Aug-09
Kittson County CSAH 38
Wetland Impact Determination
Wetland
(reach)
Dominant
Soil
Average Ditch
Depth
(Improvement)
Lateral Effect (based on
Representative
Value)
Wetland
Impact
Wetland A (54+00 to 56+00)
191A
Rosewood
1.0’ (R ditch) Pre: 326’
Post: 416’
Net: 90’
Wetland B 69+00 to 72+00)
194A
Strathcona
1.0’ (R ditch) Pre: 105’
Post: 135’
Net: 30’
Wetland C (78+00 to 125+00)
194A
Strathcona
2.0’ (R ditch)
2.0’ (L ditch)
Pre: 105’
Post: 157’
Net: 52’
Wetland D (133+00 to 155+00)
194A
Strathcona
1.0’ (R ditch)
1.0’ (L ditch)
Pre: 105’
Post: 135’
Net: 30’
Wetland E (162+00 to 179+00)
194A
Strathcona
1.0’ (R ditch)
1.0’ (L ditch)
Pre: 105’
Post: 135’
Net: 30’
Wetland F (195+00 to 196+00)
1106A
Enstrom
2.0’ (R ditch) Pre: 125’
Post: 186’
Net: 61’
Totals
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Aug-09
Summary• Define Project
• Wetland Areas
• Ditch/drainage characterization
• Soils
• Calculation
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