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Rural, Onsite & Small Community Wastewater & Waste Engineering Designing Soil Based Systems.

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Presentation on theme: "Rural, Onsite & Small Community Wastewater & Waste Engineering Designing Soil Based Systems."— Presentation transcript:

1 Rural, Onsite & Small Community Wastewater & Waste Engineering Designing Soil Based Systems

2 Site & Soil Assessment Results Mapping Unit Wea Soil type at site Wea Gravelly sand at 66 inches 0 - 3% slope At 18 inch depth - loam, moderate structure

3 Septic System

4 Leach Field

5 Wastewater Volume 120 gallons/bedroom 3 bedroom home 3 * 120 = 360 gpd

6 Linear Loading Rate Based on nature of limiting condition Gravelly loam (c) gpd/lf

7 Linear Loading Rate

8 Basal Loading Rate Based on characteristics at trench depth (18 inches) Loam, moderate structure (I) 0.6 gpd/ft2

9 Basal Loading Rate gpd/ft 2 A. Is the horizon gravelly coarse sand or coarser? 0.0 B. Is consistence stronger than firm or hard, or any cemented class?0.0 C. Is texture sandy clay, clay or silty clay of high clay content and structure massive or weak, or silt loam and structure massive? 0.0 D. Is texture sandy clay loam, clay loam or silty clay loam and structure massive?0.0 E. Is texture sandy clay, clay or silty clay of low clay content and structure moderate or strong? 0.2 F. Is texture sandy clay loam, clay loam or silty clay loam and structure weak? 0.2 G. Is texture sandy clay loam, clay loam or silty clay loam and structure moderate or strong? 0.4 H. Is texture sandy loam, loam, or silt loam and structure weak? 0.4 I. Is texture sandy loam, loam, or silt loam and structure moderate or strong?0.6 J. Is texture fine sand, very fine sand, loamy fine sand, or loamy very fine sand? 0.6 K. Is texture coarse sand with single grain structure? 0.8

10 Soil Absorption System Design Wastewater volume Linear loading rate Basal loading rate

11 System Width Long & thin along the contour of lot System width = linear loading rate / basal loading rate System Width = 10 gpd/ft / 0.6 gpd/ft2 System Width = 17 feet

12 System Length As long as possible System length = Wastewater volume / Linear loading rate System Length = 360 gpd / 10 gpd/ft System Length = 36 feet

13 Number of Trenches Backhoe bucket width - 2 ft No. of trenches = System width / Bucket width No. of trenches = 17 ft / 2 ft = 9 trenches

14 Soil Absorption System 9 trenches each 2 feet wide 36 feet long.

15 Site & Soil Assessment Results Mapping unit Kendallville Soil type at site Miamian Dense till at 28 inches 2-4% slope Surface horizon - silt loam, moderate structure

16 Mound System

17 Wastewater Volume 120 gallons/bedroom 3 bedroom home 3 * 120 = 360 gpd

18 Linear Loading Rate Based on nature of limiting condition Moderately dense till (b) gpd/lf

19 Linear Loading Rate

20 Basal Loading Rate Based on characteristic of surface horizon Silt loam, moderate structure (I) 0.6 gpd/ft2

21 Basal Loading Rate gpd/ft 2 A. Is the horizon gravelly coarse sand or coarser? 0.0 B. Is consistence stronger than firm or hard, or any cemented class?0.0 C. Is texture sandy clay, clay or silty clay of high clay content and structure massive or weak, or silt loam and structure massive? 0.0 D. Is texture sandy clay loam, clay loam or silty clay loam and structure massive?0.0 E. Is texture sandy clay, clay or silty clay of low clay content and structure moderate or strong? 0.2 F. Is texture sandy clay loam, clay loam or silty clay loam and structure weak? 0.2 G. Is texture sandy clay loam, clay loam or silty clay loam and structure moderate or strong? 0.4 H. Is texture sandy loam, loam, or silt loam and structure weak? 0.4 I. Is texture sandy loam, loam, or silt loam and structure moderate or strong?0.6 J. Is texture fine sand, very fine sand, loamy fine sand, or loamy very fine sand? 0.6 K. Is texture coarse sand with single grain structure? 0.8

22 Mound System Design Wastewater volume Linear loading rate Basal loading rate

23 Sand Width Long & thin along the contour of lot Abs. Area Width = linear loading rate / sand fill loading rate Abs. Area fill loading rate = 1 gpd/ft2 Abs. Area Width = 6 gpd/ft / 1 gpd/ft2 Abs. Area Width = 6 feet

24 Mound Size

25 Sand Length As long as possible Abs. Area Length = Wastewater volume / Linear loading rate Abs. Area Length = 360 gpd / 6 gpd/ft Abs. Area Length = 60 feet

26 Sand Height Sand + soil = 4 feet Sand height = 4 ft - soil depth Sand height = 4 ft - 28 inches Sand height = 48 inches - 28 inches Sand height = 20 inches

27 Sand Height down slope Sand height down slope = height upslope + slope * width Sand height down slope = 20 inches * 6 ft Sand height down slope = 20 in * 72 in Sand height down slope = 23 inches

28 Overall Mound Size Wastewater distribution system 9 inches on top of sand Aggregate or chambers

29 Cover with soil fill Insulate - protect from freezing 12 inches Shed water - crown top Additional 6 inches Cover soil to prevent breakout at mound toe Based on basal loading rate Slope sides for safety when mowing

30 Overall Mound Height Mound height = sand + aggregate + insulating soil fill + crown Mound height = 20 in + 9 in + 12 in + 6 in Mound height = 47 inches at top Mound height at downslope sand edge = 23 in + 9 in + 12 in Mound height at downslope sand edge = 44 inches

31 Width to avoid breakout at toe Basal width = Linear loading rate / basal loading rate Basal width = 6 gpd/ft / 0.6 gpd/ft2 Basal width = 10 feet

32 Safety for mowing 3:1 slope Slope drops 1 foot in 3 feet

33 3:1 slope 1 ft 3 ft

34 Overall Mound Width Mound width = Abs. Area width + upslope width + downslope width Upslope width = side slope * mound height * slope corr. Upslope width = 3 * 47 inches * 0.89 = 126 inches Downslope width = side slope * downslope height * slope corr. Downslope width = 3 * 44 inches * 1.14 = 151 in

35 Slope Correction Slope %Downslope Corr. factor Upslope Corr. factor

36 Overall Mound Width Mound width = Abs. Area width + upslope width + downslope width Mound width = 6 ft in in Mound width = 72 in in in Mound width = 352 inches = 29 feet

37 Overall Mound Length Mound length = Abs. Area length + 2 * endslope length Endslope length = 3 * mound height Endslope length = 3 * 47 in Endslope length = 141 inches = 12 feet Mound length = 60 feet + 2 * 12 feet Mound length = 84 feet

38 Overall Mound Size 84 feet long along the contour 29 feet wide covers basal width of 10 feet

39 Reading Crites & Tchobanoglous Burkes & Minnis Bull 813 Mound Systems for Onsite Wastewater Treatment AEX 743 Septic tank - Soil Absorption Systems AEX 744 Septic tank - Mound Systems


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