Wastewater Storage Pond Design Prepared by J E

Wastewater Storage Pond Design Prepared by J. E. Andrews, PE, NRCS - Lakewood, CO Section 8 - Wastewater Storage Pond Design Colorado CNMP Workshop

Workshop Objectives • Assemble some basic design data • Estimate pond size required • Develop a preliminary cost estimate Section 8 - Wastewater Storage Pond Design 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 Section 8 - Wastewater Storage Pond Design Colorado CNMP Workshop

Design Considerations Section 8 - Wastewater Storage Pond Design Colorado CNMP Workshop

Section 8 - Wastewater Storage Pond Design 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 8 a, 8 b & 8 c Section 8 - Wastewater Storage Pond Design 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 Section 8 - Wastewater Storage Pond Design 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 25 yr-24 hr Rainfall = 3. 4” Average Lake Evaporation = 48” Section 8 - Wastewater Storage Pond Design Colorado CNMP Workshop

Section 8 - Wastewater Storage Pond Design Colorado CNMP Workshop

Step 2 - Calculate Roof Runoff Volume Section 8 - Wastewater Storage Pond Design Colorado CNMP Workshop

Step 3 - Calculate Paved Area Runoff Volume * Annual Runoff = Annual Runoff % x Annual Rainfall 100 ** Find 25 yr-24 hr runoff from 3. 4” rain in Table 8 b. Section 8 - Wastewater Storage Pond Design Colorado CNMP Workshop

Finding runoff depth from a 3. 4” rain on a concrete feedlot using Table 8 b. Section 8 - Wastewater Storage Pond Design Colorado CNMP Workshop

Step 4 - Calculate Earthen Area Runoff Volume * Annual Runoff = Annual Runoff % x Annual Rainfall 100 ** Find 25 yr-24 hr runoff from 3. 4” rain in Table 8 b. Section 8 - Wastewater Storage Pond Design Colorado CNMP Workshop

Finding runoff depth from a 3. 4” rain on a earth surfaced feedlot using Table 8 b. (include areas outside the feedlot too) Section 8 - Wastewater Storage Pond Design Colorado CNMP Workshop

Step 5 - Total Runoff Volumes Section 8 - Wastewater Storage Pond Design Colorado CNMP Workshop

Step 6 - Calculate Design Volume * Process Wastewater Volume = 2, 000 gal/day x 365 days/year / 7. 5 gal/cu. ft. = 97, Section 8 - Wastewater Storage Pond Design 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 8 c, select a length & width, such that: • Fits available space • Selected volume is greater than design volume Section 8 - Wastewater Storage Pond Design Colorado CNMP Workshop

Use Table 8 c - 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 Section 8 - Wastewater Storage Pond Design Colorado CNMP Workshop

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 Section 8 - Wastewater Storage Pond Design Colorado CNMP Workshop

Worksheet 8 should now be complete for your operation. Section 8 - Wastewater Storage Pond Design Colorado CNMP Workshop

However, a complete engineer’s evaluation. . . results in a smaller pond, reducing cost ~ $4, 000 for Frank Section 8 - Wastewater Storage Pond Design Colorado CNMP Workshop

Section 8 - Wastewater Storage Pond Design Colorado CNMP Workshop