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Comprehensive On-site Wasterwater Review Seminar

Comprehensive On-site Wasterwater Review Seminar. October 25, 2011 John H. Shrader, RS 2307 Environmental Health Specialties. Design Basics and Disposal Options. Under what basis of authority can the Authorized Agent and its Designated Persons perform this duty to the public?

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Comprehensive On-site Wasterwater Review Seminar

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  1. Comprehensive On-site Wasterwater Review Seminar October 25, 2011 John H. Shrader, RS 2307 Environmental Health Specialties

  2. Design Basics and Disposal Options • Under what basis of authority can the Authorized Agent and its Designated Persons perform this duty to the public? • Health & Safety Code Chapter 366 • On-site Sewage Disposal Systems • §366.012 Rules Concerning On-site Sewage Disposal Systems

  3. Design Basics • Health & Safety Code Chapter 366 • On-site Sewage Disposal Systems • A little comfort for you: • §366.003 Immunity • The commission, an authorized agent, or a designated representative is not liable for damages resulting from the approval of the installation and operation of an on-site sewage disposal system.

  4. Design Basics • §366.004 Compliance Required • A person may not construct, alter, repair or extend, or cause to be constructed, altered, repaired or extended, an on-site sewage disposal system that does not comply with this chapter and applicable rules.

  5. Design Basics • §366.012 Rules Concerning On-site Sewage Disposal Systems • (a) The commission shall: • (1) adopt rules governing installation of in-site sewage disposal systems including rules concerning:

  6. Design Basics • Health & Safety Code Chapter 366.012 • (A) review and approval of on-site sewage disposal systems; and • (B) temporary waiver of a permit for an emergency repair; and • (2) adopt rules that: • (A) Encourage the use of economically feasible alternative techniques and technologies for on-site sewage disposal systems that can be used in soils not suitable for conventional on-site sewage disposal and…

  7. Design Basics • (B) address separation of graywater as defined by Section 341.039, in a residence served by an On-site sewage disposal system.

  8. Design Basics and Disposal Options • Sec. 341.039.  GRAYWATER STANDARDS. • (a) The commission by rule shall adopt and implement minimum standards for the use and reuse of graywater for: • (1)  irrigation and other agricultural purposes; • (2)  domestic use, to the extent consistent with Subsection (c); (foundation watering) • (3)  commercial purposes; and • (4)  industrial purposes (re-use)

  9. Design Basics and Disposal Options • Sec. 341.039.  GRAYWATER STANDARDS. • b)  The standards adopted by the commission under Subsection (a) must assure that the use of graywater is not a nuisance and does not damage the quality of surface water and groundwater in this state.

  10. Design Basics and Disposal Options • Sec. 341.039.  GRAYWATER STANDARDS. • (c)  The commission may not require a permit for the domestic use of less than 400 gallons of graywater each day if the graywater: • (1)  originates from a private residence; • (2)  is used by the occupants of that residence for gardening, composting, or landscaping at the residence; • (3)  is collected using a system that overflows into a sewage collection or on-site wastewater treatment and disposal system;

  11. Design Basics and Disposal Options • Sec. 341.039.  GRAYWATER STANDARDS. • (4)  is stored in tanks that: • (A)  are clearly labeled as nonpotable water; • (B)  restrict access, especially to children; and • (C)  eliminate habitat for mosquitoes and other vectors; • (5)  uses piping clearly identified as a nonpotable water conduit, including identification through the use of purple pipe, purple tape, or similar markings; • (6)  is generated without the formation of ponds or pools of graywater; • (7)  does not create runoff across the property lines or onto any paved surface; and • (8)  is distributed by a surface or subsurface system that does not spray into the air.

  12. Design Basics and Disposal Options • Sec. 341.039.  GRAYWATER STANDARDS. • d)  Each builder is encouraged to: • (1)  install plumbing in new housing in a manner that provides the capacity to collect graywater from all allowable sources; and • (2)  design and install a subsurface graywater system around the foundation of new housing in a way that minimizes foundation movement or cracking.

  13. Design Basics and Disposal Options • Sec. 341.039.  GRAYWATER STANDARDS. • (e)  In this section, "graywater" means wastewater from clothes-washing machines, showers, bathtubs, hand-washing lavatories, and sinks that are not used for disposal of hazardous or toxic ingredients. The term does not include wastewater: • (1)  that has come in contact with toilet waste; • (2)  from the washing of material, including diapers, soiled with human excreta; or • (3)  from sinks used for food preparation or disposal.

  14. Design Basics and Disposal Options • §366.012 • (b) include definitions and detailed descriptions of good management practices and procedures for the construction of on-site sewage disposal systems that: • (1) justify variation in field size or in other standard requirements; • (2) promote the use of good management practices or procedures in the construction of on-site sewage disposal systems

  15. Design Basics and Disposal Options • The point being: • (3) require the use of one or more specific management practices or procedures as a condition of approval of a standard on-site sewage disposal system if in the opinion of the commission or Authorized Agent, site conditions or other problems require use of additional management practices or procedures to insure proper operation of an on-site sewage disposal system;

  16. Design Basics and Disposal Options • Make available general, operational information to the public.

  17. Design Basics and Disposal Options • Variances • 30TAC 285.3(h)Variances • Requests for variances are considered on a case by case basis. • Granted if

  18. Design Basics and Disposal Options • (1) if owner, sanitarian or engineer demonstrates to the Authority that conditions are equivalent or greater protection of the public health and environment can be provided by alternate means. Separation distances shall not be granted unless provisions of this chapter cannot be met.

  19. Design Basics and Disposal Options • (2) request for variance must contain plans prepared by RS or PE w/seal date and signature.

  20. Standard Treatment and Disposal • General Requirements of disposal systems • Topography • Must be < 30% slope • If less than 2%, take steps to provide for surface drainage over, near and leading to drainfield • Parallel the slope contour

  21. Standard Treatment and Disposal • Flood Hazard • If within the 100-year flood plain • Location mitigates damage of system, which could result in damage to the environment. • Tank floatation precautions

  22. Design Basics and Disposal Options • PE must demonstrate that: • System will not increase flood height • All components with exception of risers, chlorinators, cleanouts, sprinklers, inspection ports shall be buried without adding fill • Non-buried components shall be elevated above flood level • Separation Requirements 285.91(10)

  23. Design Basics and Disposal Options • Best Practices • Rule allows burial of tanks to 12” • Risers must be installed to maximum of 6” above grade • Must be capped and sealed against infiltration • Inaccessible without excavation • Depicted on plans

  24. Standard Treatment and Disposal • Standard Disposal may be used if soil meets all criteria of 285.91(5) • If any of these characteristics of the property are not met, an alternative must be sought. • Proprietary or non-standard treatment and disposal

  25. Design Basics and Disposal OptionsStandard Treatment & Disposal • Pros: • Effective • Economically Feasible operation • Non Intrusive once installed • No Maintenance Contract

  26. CONS Not necessarily inexpensive to install Limitations 285.91(5) Table V Land Slope <30%, complex slopes Soil must be Ib, II, III to 2-feet below excavation Restrictive Horizon 2 feet below excavation Gravel Analysis < 30% gravel or 80% < 5.0mm Groundwater – No indication within 2-feet of excavation Flood potential – no increase in flood level, no contamination Land fill material Design Basics Standard Treatment & Disposal

  27. Design Basics and Disposal Options • Certain property conditions lead to failure of standard systems

  28. Design Basics and Treatment Options • Intermittent Sand Filters • Loading rate limitation 1.2g/day/sf • Surface Area = Q/1.2g • 300gpd/1.2g = 250SF • Minimum 24” sand media • Filter bed contained by impervious liner • Underdrains routed to drainfield or pump tank to alternate disposal system

  29. Design Basics and Treatment Options • Proprietary Treatment Systems • Approved by the Commission for use in State • Required Ongoing Maintenance • May be used as a component of a larger system for influent stronger than household wastes (300mg/L)

  30. Design Basics and Treatment Options • Non-standard Treatment • Activated sludge process • Rotating biological contactors • Recirculating sand filters • Trickling filters • Submerged rock biological filters • Other Sand filters • Case by Case Approval • Ongoing maintenance requirement determined by Authority

  31. Design Basics and Treatment Options • Other Design Considerations: • Waste Strength • Restaurant: • Minimum design strength 1200mg/L BOD after proper grease trap • Other high strength • Determined by professional designer • Best if actual waste strength can be determined • Flow Equalization – Control the flow to treatment

  32. Design Basics and Treatment Planning Waste Strength >300mg/L Residential Strength 300mg/L Subsurface Disposal Strength 140mg/L Disposal methods requiring Secondary Treatment

  33. Design Basics and Treatment Options • Secondary Treatment Disposal Systems Effluent Strength: • BOD • 30 day ave. 20mg/L • Seven day ave. 30mg/L • Daily Max. 45mg/L • Single Grab 65mg/L • pH 6.0 -9.0

  34. Design Basics and Disposal Options • 285.33(b) Standard • (1) Absorptive Drainfield

  35. Design Basics and Disposal Options

  36. Design Basics and Disposal Options • (2) Evaporative (ET) System • Only to be used in areas with evaporation in excess of rainfall. • (3) Pumped Effluent Drainfield • Use same design specifications as low pressure dosed drainfields • No Slopes greater than 2% • Only single family dwelllings • At least 1000LF of distribution pipe +400LF/bedroom over two • 70LF maximum Length

  37. Design Basics and Disposal Options • (3) Pumped effluent Drainfield • Like standard disposal systems • 18” – 36” in depth w/3foot separation between trenches • One feet beneath to restrictive horizon • Two feet beneath to groundwater • Pipe is 1.25-1.50” diameter, holes down in pea gravel to 2” media • Holes in distribution at 5’ spacing and 3/16-1/4” • Pump minimum 1/2HP • Back fill with Ib, II, or III

  38. Design Basics and Disposal Options • (c) Proprietary Disposal Systems • (1) Graveless Drainfield Piping • Only suitable in soils suitable for standard disposal • Corrugated, perforated polyethylene • Replaces need for distribution media • (2) Leaching Chambers • Bottomless Chambers w/ an open bottom • Linked together with non-perforated sewer pipe • May be used edge to edge to reduce drainfield size • Cannot be used in Ia, or IV soils • Replaces media for ET, Low Pressure Dosed Drainfields, or soil substitution drainfields

  39. Design Basics and Disposal Options • (3) Drip Irrigation • Matrix of small diameter lines buried 6” w/ pressure emitters spaced at max 30” • Post secondary treatment • Continuous, manual or intermittent flushing of disposal tubing. • May be used in all classes of soil. • Use loading rate of standard disposal • 1foot between tubing and groundwater,

  40. Design Basics and Disposal Options • (d) Nonstandard Disposal Systems • (1) Low-pressure dosed drainfield • Pumped under low pressure into solid wall force main, then perforated distribution pipe • (A) Equalized distribution without causing excessive blowout. • (B) Stop/Start switch with audible and visual alarm

  41. Design Basics and Disposal Options • (2) Surface Application Systems • (A) Flat terrain, slope less than 15% • Or terraced • Vegetated • No food production • Disinfection required

  42. Design Basics and Disposal Options • (3) Mound Drainfields • Mound drainfield constructed above the native soil. Height of mound is a function of the texture of the soil, depth of soil, basal area sizing, and sideslope • At least 1 foot of native soil • 1.5’ to restrictive horizon • 2’ to groundwater

  43. Design Basics and Disposal Options • There is so much more, but it will have to wait…

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