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? Health & Safety Code Chapter 366 On-site Sewage Disposal Systems § Rules Concerning On-site Sewage Disposal Systems

Design Basics Health & Safety Code Chapter 366 On-site Sewage Disposal Systems A little comfort for you: § 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.

Design Basics § 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.

Design Basics § 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:

Design Basics Health & Safety Code Chapter –(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…

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

Design Basics and Disposal Options Sec 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)

Design Basics and Disposal Options Sec 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.

Design Basics and Disposal Options Sec 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;

Design Basics and Disposal Options Sec 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.

Design Basics and Disposal Options Sec 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.

Design Basics and Disposal Options Sec 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.

Design Basics and Disposal Options § (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

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;

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

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

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.

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

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

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

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 (10)

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

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

Design Basics and Disposal Options Standard Treatment & Disposal Pros: Effective Economically Feasible operation Non Intrusive once installed No Maintenance Contract

Design Basics Standard Treatment & Disposal CONS Not necessarily inexpensive to install Limitations (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 and Disposal Options Certain property conditions lead to failure of standard systems

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

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)

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

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

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

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 Grab65mg/L pH

Design Basics and Disposal Options (b) Standard –(1) Absorptive Drainfield

Design Basics and Disposal Options

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

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 ” 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

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,

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

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

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

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