FACILITY SITE DRAINAGE: FACILITY SITE DRAINAGE D. Jones


Objectives: Objectives Understand the importance of drainage factors in farmstead layout Be able to recognize and evaluate drainage patterns. Be able to design appropriate surface and subsurface drainages


Factors to consider : Factors to consider Farmstead site should be well drained. Usually brown or red soil gray or black soils indicate poor drainage Soil should be deep enough for foundations (at least 4 or 5 feet to rock) Ideal" slope is 2-6%. Steeper slopes can be modified to create acceptable site but $$


Factors to consider : Factors to consider Avoid soils susceptible to frost heaving, or soils that expand when wet and shrink when dry (swelling clays) Construction possible on such sites but soil under foundation and floors must be replaced with more suitable material


Slide5: Soil permeability map


Surface drainage: Surface drainage Use surface drainage to remove surface water Use subsurface drainage for remaining areas. (Surface drainage removes water much faster than subsurface.) Don’t fight natural drainage patterns. Don’t put a building in a natural swale


Buildings: Buildings Soil around poorly drained foundation area can be saturated so more frost heaving & settlement Elevate floor >= 6" above surrounding soil to protect wooden sill plate at bottom of stud wall Provide at least 6" (preferably 9") drop in first 25'. (The slope of the first 25-50' from a building is the most critical slope)


Slide8: Use drain to keep area under footer dry Foundation drainage may be necessary to prevent frost heaving 6” min. ¼”/ft for 25’ Wood Flooring Siding (2%)


Slide9: Wet Basement Crushed Stone Water Table Drain Tile Wrong Way to Protect Basement Floor Wall Footing Backfill


Slide10: Mostly Dry Basement Crushed Stone Water Table Drain Tile Floor Wall Footing Backfill Water Table Better Way to Protect Basement


Slide11: Dry Basement Washed Sand Water Table Drain Tile Floor Wall Footing Water Table Best Way to Protect Basement Porous Sandy Backfill Original Soil


Vegetated diversions: Vegetated diversions If at base of hill, use diversion terrace to divert water around farmstead Slope diversion be at least 1% to prevent ponding and sedimentation If slope exceeds 4%, bottom width should be at least 6’ For slopes over 6%, consult your local NRCS


Vegetated diversions: Vegetated diversions Bottom channel width should be 3' - 10'. As channel gets wider, more problems with ponding and sedimentation 1’ depth should handle runoff from areas less than 15 acres. If larger area, call NRCS Top width should be at least 3'


Slide14: Drainage & field slope 3’ min 10’ max 5 – 6’ 3’ min 1’ 3’ min 5 – 6’ 3’ min 1’ 12” deep 1’ fall or rise in 6’ distance is written as 6:1 slope Grass Waterways


Slide15: Grain feed center Livestock Center Shop and Machinery Tree windbreak Diversion terrace for field runoff Farm court Home Main Road Diversion terrace For snow melt and Farmstead runoff


General Drainage Guidelines: General Drainage Guidelines Don't isolate areas by requiring water to flow over roads Use at least 12" dia. culverts under roads Cattle guards or formed drainageways with grated covers better than culverts Consider a drive-through crossing (ford) rather than bridge to cross small streams Ford – Remove at least 12” of stream bottom material and replace with coarse aggregate to build a solid base at crossing


Small Stream Crossings - Fords: Small Stream Crossings - Fords Use for crossing shallow streams Excavate 12” soil and replace with coarse gravel Original stream surface


Drainage Swales: Drainage Swales Slope at 6"/100' (roughly 1/16"/foot) 3"/100' slope (0.2-0.3%) is minimum Very gentle sideslopes to allow crossing and easy mowing


Slide19: Make enclosed area saucer-shaped & drain to culvert 12” min dia. Culvert, or 12” min. wide formed channel with cover grate or cattle guard


Concrete surfaces: Concrete surfaces See S & E Handbook for specific slope recommendations for livestock facilities


Runoff from earthen feedlots: Runoff from earthen feedlots Surface should slope at 4% (~ 1/2"/ft) to prevent ponding and mudholes (4-6% is best) Slopes over 10% can erode, requiring frequent earth moving to maintain lot surface around paved areas Keep slopes short Orient lot so short direction of lot is on steeper slope and longer direction on flatter slope to minimize erosion


Approximating Slopes: Approximating Slopes 1/8”/foot 1% = 1’/100’ ¼”/ft = 2/8”/ft 2% = 2’/100’ 3/8”/foot 3% = 3’/100’ ½”/ft = 4/8”/ft 4% = 4’/100’ 5/8”/foot 5% = 5’/100’ ¾”/ft = 6/8”/ft 6% = 6’/100’ 1/8” = 0.125” & 0.125”/12” = 0.01042 or 1.042% 8/8” = 1” & 1”/12” = 0.0833 or 8.33%


General guidelines - Subsurface Drainage: General guidelines - Subsurface Drainage Subsurface drainage may be needed to protect roads, manure storages pits, grain pits and building floors & foundations Construction can damage existing drains and cause seep areas Obtain map of existing drainage lines in area If new lines are added, update map Install interceptor around top of farmstead to divert tile flow from upslope areas


General guidelines - Subsurface Drainage: General guidelines - Subsurface Drainage Subsurface drains on farmstead should be a minimum of 4" dia. and at least 0.1% slope (2" in 100'). See drainage contractor for proper sizing of pipe for lines longer than 500 feet. If subsurface drain crosses under a road, use heavier culvert pipe or bed properly to prevent collapsing from heavy loads


All Weather Gravel Farm Road: All Weather Gravel Farm Road Major roads need ditches and may need subsurface drains to lower water content of the base & provide firm, all-weather road


Road Drainage: Road Drainage Bed well or reinforce pipe if it passes under road or other area with heavy traffic ½ pipe dia fill on all sides of pipe Load


Slide27: 100’ 99’ 98’ 97’ Topographic Map - Valley Cross section A-A A A 99’ 98’ 99’ Plan (top) view Cross Section


Slide28: 97’ 98’ 99’ 100 Topographic Map - Ridge Cross section A-A Plan (top) view Cross Section


Slide31: 100’ 99’ 98’ 97’ 96’ 95’ 94’ Show drainage paths for each Plot the cross section for A-A and tell if is a ridge or valley Name: ______________ Gutter Downspouts Shop/Mach. Storage Homework