comprehensive on-site wasterwater review seminar october 25, 2011 john h. shrader, rs 2307...

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• §366.012 Rules Concerning On-site

Sewage Disposal Systems

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.

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.

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:

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…

Design Basics

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


• 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)


• 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.


• 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;


• 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.


• 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.


• 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.


• §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


• 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;


• Make available general, operational information to the public.


• Variances

• 30TAC 285.3(h)Variances

• Requests for variances are considered on a case by case basis.

• Granted if


• (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.


• (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


• 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


• 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)


• 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 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


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 • 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


• 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


• 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)


• 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


• 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


• 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


• 285.33(b) Standard

– (1) Absorptive Drainfield


– (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


– (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


• (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 nonnon-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


• (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,


• (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


• (2) Surface Application Systems– (A) Flat terrain, slope less than 15%

• Or terraced• Vegetated• No food production• Disinfection required


• (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


• There is so much more, but it will have to wait…

comprehensive on-site wasterwater review seminar october 25, 2011 john h. shrader, rs 2307...

Documents

disposal options

disposal system slide

graywater standards

sewage collection

reuse of graywater

gallons of graywater

onsite wastewater treatment

domestic use