Wastewater Storage Pond Design Prepared by J.E. Andrews, PE, NRCS - Lakewood, CO Colorado CNMP Workshop

Workshop Objectives Assemble some basic design data Estimate pond size required Develop a preliminary cost estimate Colorado CNMP Workshop

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 Colorado CNMP Workshop

Design Considerations Colorado CNMP Workshop

Colorado CNMP Workshop

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 Colorado CNMP Workshop

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 Colorado CNMP Workshop

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” Colorado CNMP Workshop

Colorado CNMP Workshop

Step 2 - Calculate Roof Runoff Volume Colorado CNMP Workshop

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. Colorado CNMP Workshop

Finding runoff depth from a 3 Finding runoff depth from a 3.4” rain on a concrete feedlot using Table 8b. Colorado CNMP Workshop

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. Colorado CNMP Workshop

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) Colorado CNMP Workshop

Step 5 - Total Runoff Volumes Colorado CNMP Workshop

Step 6 - Calculate Design Volume * Process Wastewater Volume = 2,000 gal/day x 365 days/year / 7.5gal/cu. ft. = 97,333 cu. ft. Colorado CNMP Workshop

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 Colorado CNMP Workshop

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 Colorado CNMP Workshop

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 Colorado CNMP Workshop

Worksheet 8 should now be complete for your operation. Colorado CNMP Workshop

However, a complete engineer’s evaluation ... results in a smaller pond, reducing cost ~ $4,000 for Frank Colorado CNMP Workshop

Colorado CNMP Workshop