Spreadsheet: 067b3149-298f-42cc-88d6-4d695e23b318
Sheet: Sheet1

Unnamed: 0 | Cumulative Nitrate Loading Analysis - Wehrmann Model | Unnamed: 2 | Unnamed: 3 | Unnamed: 4 | Unnamed: 5 | Unnamed: 6 | Unnamed: 7 | Unnamed: 8 | Unnamed: 9 | Unnamed: 10 | Unnamed: 11 | Unnamed: 12
 | Colorado Water Quality Control Division, Feb. 2012
 | Step 1: Calculate Vb (Volume of groundwater entering the leach field from up gradient area)
 | K (ft/day) | i (ft/ft) | A (ft^2) |  |  |  |  |  |  |  | Vb (gpd)
 | 5 | 0.001 | 100000 |  |  |  |  |  |  |  | 3740
 | K is the hydraulic conductivity of the aquifer
 | i is the hydraulic gradient
 | A is the area of the upgradient area in square feet
 | Step 2:  Enter Cb (ambient concentration of nitrate-nitrogen) |  |  |  |  |  |  |  |  |  | Cb (mg/l)
 | What is the ambient concentration of NO3- as N contained in the groundwater entering the leach field? |  |  |  |  |  |  |  |  |  | 0.5
 | Step 3: Calculate Vi (volume of precipitation infiltrating beneath the leach field)
 | Length (ft) | [NAME] (ft) | Infiltration (ft/day) |  |  |  |  |  |  |  | Vi (gpd)
 | 100 | 50 | 0.00032 |  |  |  |  |  |  |  | 11.968
 | Step 4: Enter Ci (concentration of nitrate-nitrogen contained in the infiltrating precipitation) |  |  |  |  |  |  |  |  |  | Ci (mg/l)
 | What is the concentration of nitrate-nitrogen contained in the infiltrating precipitation? |  |  |  |  |  |  |  |  |  | 0.05
 | [use 0.05 mg/l as default]
 | Step 5: Calculate Vs (volume of septic effluent introduced beneath the leach field)
 | # Bedrooms or Residents per lot |  | gpd/lot | # Lots |  |  |  |  |  |  | Vs (gpd)
 | 5 |  | 500 | 1 |  |  |  |  |  |  | 500
 | Step 6: [NAME] (concentration of nitrate-nitrogen contained in the septic effluent) |  |  |  |  |  |  |  |  |  | Cs (mg/l)
 | What is the concentration of NO3- as N contained in the septic effluent? |  |  |  |  |  |  |  |  |  | 40
 | [use 40.0 mg/l as default, unless other information is available]
 | Step 7: Calculate Vp (volume of groundwater pumped by wells beneath the leach field)
 | gpd/Lot | # Lots | [NAME]. (acres) | Same Aquifer? Y=1; N=0 |  |  |  |  |  |  | Vp (gpd)
 | 0 | 1 | 0.5 | 0 |  |  |  |  |  |  | 0
 | Note: Vp > 0 only if pumping from same aquifer zone as Vs receptor aquifer zone; otherwise Vp = 0
 | Lawn irrigation assumes net 18 gallons/ft^2/year for bluegrass (Source: NRCS)
 | Step 8: Enter Cp (concentration of nitrate-nitrogen contained in the pumped groundwater) |  |  |  |  |  |  |  |  |  | Cp (mg/l)
 | What is the concentration of nitrate-nitrogen contained in the pumped groundwater? |  |  |  |  |  |  |  |  |  | 0.5
 | [use Cb as default]
 | [NAME]
 | Vb | Volume of groundwater entering the leach field from up gradient area |  |  |  |  |  |  |  |  | 3740 | gpd
 | Cb | Ambient concentration of nitrate-nitrogen contained in the groundwater entering the leach field |  |  |  |  |  |  |  |  | 0.5 | mg/l
 | Vi | Volume of precipitation infiltrating beneath the leach field |  |  |  |  |  |  |  |  | 11.968 | gpd
 | Ci | Concentration of nitrate-nitrogen contained in the infiltrating precipitation |  |  |  |  |  |  |  |  | 0.05 | mg/l
 | Vs | Volume of septic effluent introduced beneath the leach field |  |  |  |  |  |  |  |  | 500 | gpd
 | Cs | Concentration of nitrae-nitrogen contained in the septic effluent |  |  |  |  |  |  |  |  | 40 | mg/l
 | Vp | Volume of groundwater pumped by wells beneath the leach field |  |  |  |  |  |  |  |  | 0 | gpd
 | Cp | Concentration of nitrate-nitrogen contained in the pumped groundwater |  |  |  |  |  |  |  |  | 0.5 | mg/l
 | Co | Diluted concentration of nitrate-nitrogen leaving the leach field. |  |  |  |  |  |  |  |  | 5.143641344431567 | mg/l
 |  | Co = VbCb + ViCi + VsCs  - VpCp / (Vb + Vi + Vs – Vp )
 | Version 1.0, [NAME] and [NAME], 2/2/2012