1. Wastewater Storage Pond Design
Prepared by J.E. Andrews, PE, NRCS - Lakewood, CO
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2. Workshop Objectives Assemble some basic design data
Estimate pond size required
Develop a preliminary cost estimate
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3. Consult with a knowledgeable Engineer to:
Consider other options and alternatives
Evaluate pond site location(s) & lining requirements
Analyze technical requirements for
storage period and pump needs
solids trap and snow removal
hydrologic & waste loading factors
need for treatment
Design inlet, outlet & other related facilities
Prepare construction drawings & specs
Perform construction inspection
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4. Design Considerations
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6. Information Needed for Estimating Pond Volume
Storage Period
Size of Runoff Producing Areas
Roofs, Paved Lots & Unpaved Lots
Areas for future expansion
Other Areas
Climate Data for site location (including evaporation)
Volume of manure, wastewater & other by products to be stored in the pond.
Worksheet #8 &Tables 8a, 8b & 8c
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7. Example - Frank’s Dairy
Located near Fort Morgan, Colorado
Pond effluent can be applied May through September
5 acres of earthen feedlot & solid manure stacking area
2,000 sq. ft. concrete surfaced holding area
1,000 sq. ft. of roofs that drain across the concrete lot
2,000 gal. wastewater per day from the milking center
Manure & other solids are kept out of the pond
No plans for expansion at this site
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8. Step 1 - Get Climate Data @ Fort Morgan Climate Station
Annual Rainfall = 12.7”
43% runs off paved areas
15% runs off earthen feedlots
25yr-24hr Rainfall = 3.4”
Average Lake Evaporation = 48”
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10. Step 2 - Calculate Roof Runoff Volume
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11. Step 3 - Calculate Paved Area Runoff Volume
* Annual Runoff = Annual Runoff % x Annual Rainfall 100
** Find 25yr-24hr runoff from 3.4” rain in Table 8b.
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12. Finding runoff depth from a 3
Finding runoff depth from a 3.4” rain on a concrete feedlot using Table 8b.
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13. Step 4 - Calculate Earthen Area Runoff Volume
* Annual Runoff = Annual Runoff % x Annual Rainfall 100
** Find 25yr-24hr runoff from 3.4” rain in Table 8b.
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14. Finding runoff depth from a 3
Finding runoff depth from a 3.4” rain on a earth surfaced feedlot using Table 8b. (include areas outside the feedlot too)
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15. Step 5 - Total Runoff Volumes
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16. Step 6 - Calculate Design Volume
* Process Wastewater Volume = 2,000 gal/day x 365 days/year / 7.5gal/cu. ft. = 97,333 cu. ft.
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17. Step 7 - Choose Pond Dimensions
Choose a depth between 6’ & 12’
As deep as possible within site limits
Pond bottom should be 4’ above the water table
From Table 8c, select a length & width, such that:
Fits available space
Selected volume is greater than design volume
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18. Use Table 8c - for a given depth choose a width & length that results in a volume greater than 177,453 cu ft.
Assume an 8 foot depth for Frank’s Dairy
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19. Estimated Cost ~ $18,000 Step 8 - Estimate Construction Cost
Volume Selected x $0.10 per cu. ft. ~ Cost
178,944 x $0.10 = $17,894 (round to nearest $1,000)
Estimated Cost ~ $18,000
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20. Worksheet 8 should now be complete for your operation.
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21. However, a complete engineer’s evaluation ...
results in a smaller pond, reducing cost ~ $4,000 for Frank
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