Engineering presentation.pptx for Wastewater

Arkansas Onsite Wastewater Program

1. Arkansas Onsite Wastewater Program

2. Onsite Wastewater Rules

3. Act 402 of 1977 “Safe and adequate sewage disposal promotes the health and welfare of the citizens of this state by minimizing the exposure of the citizens, farm animals, domestic animals, fish and wildlife of this state to human excreta and domestic wastes, by minimizing the contamination of drinking water supplies and the hazards to recreational areas of this state, and by minimizing the pollution of other ground and surface waters of this state.” “Individual sewage disposal systems, when properly designed and constructed in suitable soils, provide renovation of wastewater and inject the renovated wastewater back into the hydrologic cycle.” Bulletin #9 prior to 1977

4. Why do we have a wastewater rule?

5. Why do we have a wastewater rule?

6. Number of onsite wastewater systems in Arkansas

7. 2023 Septic Permit Breakdown

8. 2023 Septic Permit Breakdown By Dispersal Method: Standard: 6165 Surface Discharge: 112 Capping Fill: 99 Drip Dispersal: 47 Holding Tank: 42 Serial: 62 LPD: 7 Other: 1 By Region: Northwest: 3638 Central: 1460 Northeast: 735 Southwest: 504 Southeast: 198

9. Subsurface dispersal Septic tank, distribution box Subsurface dispersal via pipe and gravel or gravel substitute Treated effluent with subsurface disposal drip tubing Treated effluent and surface discharge Treated wastewater via home treatment plant with disinfection and surface discharge with setbacks to property lines. ADEQ NPDES permits. Requires 3 acres Types of onsite wastewater systems

10. Septic Tanks

11. Standard systems

12. Absorption trenches - Gravel

13. EZ Flow Chambers Several types of trench media available https://www.healthy.arkansas.gov/images/uploads/pdf/Onsite_Wastewater_Approved_Product_List.pdf

14. Absorption trenches – Substitutes

15. Drip Dispersal Systems

16. Surface Discharging systems

17. Soil pits

18. Shallow seasonal water tables are identified using redoximorphic features. Brief SWT: iron or manganese concentrations, iron depletions less color chroma > 3 Moderate SWT: chroma ≤ 2 less than 50% Long SWT: chroma ≤ 2 greater than 50% Soil factors and system design

19. Soil conditions for onsite wastewater design

20. Soil conditions for onsite wastewater design

21. Bedrock Bottom of proposed trench depth must be 18” above the depth to bedrock for most soils. 36” depth to bedrock required for standard 18’ trenches. Texture High clay content prohibits water movement due to soil swelling Clay percentage must be below 60% to be suitable for subsurface disposal. Clay percentages above 40% use low Hydraulic Conductivity loading rates. Max loading rate .30 gal/ sqft /day Bedrock and Texture

22. Field Texturing

23. Texture Triangle

24. Soil suitability changes rapidly throughout the landscape

25. Unsaturated soil and clay percentage less than 60% clay. Loading rates range from 0.00 to 0.75 depending on soil conditions Soil conditions include depth to seasonal water table, depth to bedrock, and clay percentage. How do we determine soil suitability? Dig in the dirt. What is required for standard subsurface system?

26. Licensed with the Department to submit septic system designs to the department on behalf of property owner. EHP-19 Individual Onsite Wastewater Application EHP-19N Non-Individual Onsite Wastewater Application Designated Representatives

27. Licensed Installer

28. Common problems found with permit submittals. Soil not suitable No flags for system components Field lines not flagged on contour Flowline elevations not designed for maximum storage Not sufficient absorption available for GPD and soil criteria Permits can be submitted online or in person at local health unit

29. Site destruction after permit approval before installation.

30. Subdivision Review

31. Subdivision Review

32. Systems with multiple homes connected to one absorption area. Absorption area not owned by homeowner and effluent pumped to one or more absorption areas through one common force main. STEP Systems

33. Inside Dimensions: (in inches) Length: 108” Width: 50” Depth of water: 44” Total Volume = L x W x D 231 108” x 50” x 44” = 237,600 in 3 ÷ 231 in 3 per gallon = Basic Calculations 237,600 in 3 1028.6 gallons