GALVESTON COUNTY DESIGN & CONSTRUCTION REQUIREMENTS FOR 
ON - SITE SEWAGE FACILITIES
 
 
Every owner of any building or part thereof occupied by people for any purpose, any part of the day or night, including any business or place of business, shall provide sanitary toilet accommodations in such building and said accommodations which utilize private wastewater facilities and which is located inside the boundaries of the Galveston County Health District must have a valid wastewater permit issued by the Galveston County Health District.
  1. Any developer, contractor, builder or other interested person or persons desiring to construct OSSF in Galveston County, Texas must obtain approval from the Galveston County Health District of the plan for wastewater disposal before any construction of any kind is begun. To obtain approval he/she must also fulfill the following requirements:
    1. Submit two (2) copies of the form entitled "Galveston County Health District On-Site Wastewater Facility Application and Inspection Report". The plot on the above mentioned form must include:
      1. Size and shape of lot or property.
      2. All structures on lot such as buildings, barns, pens, etc.
      3. Size and location of treatment tank(s).
      4. Size and location of wastewater disposal area.
      5. Distance of treatment tank(s) from house, property line, well and wastewater disposal area.
      6. Distance of wastewater disposal area from house, property line, well and septic tank.
      7. Distance and direction to closest neighboring well from treatment tank(s) and wastewater disposal area.
      8. Distance and direction to closest open water such as ponds, lakes, streams, etc.
    2. All private wastewater facilities shall be constructed on minimum size lots of one (1) acre and/or lots of sufficient size and shape that any water well is at least fifty (50) feet from any septic tank and at least one-hundred (100) feet from any wastewater disposal area with an area dedicated for wastewater disposal equal to two (2) times the design area. The On-Site Sewage Facility shall be the size specified by the Health District, unless a site evaluation indicates the On-Site Sewage Facility should by larger or smaller. The lot, in any event, must be of sufficient size and shape to meet all the terms and conditions of the permit requirements.
    3. The private wastewater treatment facility must be designed and constructed in a manner so as to meet all of the terms and requirements prescribed by the "Construction Standards For On-Site Sewage Facilities" published by the Texas Natural Resources Conservation Commission, the "Construction Standards for On-Site Sewage Facilities: of the Galveston County Health District, and must further meet all special design and construction requirements of the Galveston County Health District. Any person desiring to build or create a subdivision, business establishment, recreational park, multiple dwelling or any similar place or building using private wastewater facilities shall have a site-specific design by a registered sanitarian or registered professional engineer.
  2. On-Site Sewage Facility Design & Construction
    The design and construction of all On-Site Sewage Facilities (OSSF's) shall conform to specifications of Title 30 Texas Administrative Code (TAC) Chapter 285, unless otherwise approved by the Health District.
    1. Plumbing to OSSF
      1. The outside plumbing of every building utilizing on - site sewage facilities shall meet all terms and conditions of these requirements.
    2. Wastewater Treatment Tanks
      1. All lines must be constructed so that all wastewater goes through the treatment tank(s).
      2. Wastewater Treatment tank design and construction shall conform to specifications prescribed by the "OSSF Rule" published by the Texas Natural Resource Conservation Commission or shall otherwise be approved by the Health District. In order to provide a good watertight treatment tank, the inlet and outlet lines should be installed in a permanent manner at the time the treatment tank is constructed. If more than one tank or compartment is used, the subsequent tanks or compartments should have inlet and outlet devices designed the same as for a single-compartment tank, except that the elevation, or flow line of both inlet and outlet devices in the subsequent units should be the same as the outlet device in the first unit. A port, with an opening of not less than 12 inches, shall be provided to each compartment for inspection, cleaning and maintaining; and shall not be located directly over the inlet and outlet devices.
      3. The design, construction and location of any grease traps shall be approved by the Galveston County Health District.
      4. Any place of business which dispose of cooking grease, cooking oils, motor oils, lubricating grease, gasoline, or where a significant amount of soap residue and/or lint is experienced will be required to have a grease trap the size, design, construction and location of which shall be approved by the Galveston County Health District. This shall include, but not limited to cafes, restaurants, cafeterias, service stations, mechanical repair shops and washaterias. All drains which are used primarily for the disposal of the above mentioned oils, greases and soaps shall be discharged through a grease trap before entering a septic tank system.
    3. Wastewater Disposal Area
      1. A wastewater from the wastewater treatment tanks must be routed to a wastewater disposal area.
      2. A wastewater disposal area is an area of property that is reserved and used for the disposal of wastewater effluent discharged from an approved treatment process requiring further handling to render if safe from a public health standpoint. Acceptable standard disposal methods shall consist of a drainfield to disperse the effluent into adjacent soil (absorptive) or into the surrounding air through evapotranspiration (evaporation and transpiration).
    4. On-Site Sewage Facility (OSSF)
      1. An On-Site sewage disposal system, consisting of wastewater treatment tank(s) and a wastewater disposal area used for the disposal of sewage produced on the site where the system is located.
      2. The three most commonly installed OSSF in Galveston County consists of an anaerobic (septic) wastewater treatment tank followed by one of three wastewater disposal areas, an absorptive drainfield, a leaching chamber or graveless pipe.
        1. Absorptive drainfield. An absorptive drainfield is an excavation constructed

          2. In suitable soil. A porous media (crushed rock, stone, etc.) is then placed in the excavation and perforated pipe (drain line) placed in the media and connected to the outlet of the treatment system. The media is covered with a permeable geotextile fabric and the remainder of the excavation backfilled with previously removed soil. The top of the excavation area is seeded with plants or grasses, where vegetation is sustainable, to aid in water elimination. The following considerations must be met for approval of an absorptive drainfield:
        2. Excavation. The excavation must be constructed in suitable soils. The excavation shall not exceed a depth of three feet. Multiple excavations must be separated horizontally by at least three feet of undisturbed soil. After excavation surfaces (sidewalls and bottom) must be scarified as needed. The bottom of the excavation shall be not less than 18 inches in width and level to within one inch over each 25 feet of excavation. The size of the excavation shall be calculated using data from Table I. The formula A = Q/Ra shall be used to determine drainfield area where:
              3. A = absorptive area
              Q = average daily sewage flow in gallons per day
              Ra = soil application rate in gallons per square foot per day
            The usable surface area shall be calculated by adding the excavation bottom area to the total excavated perimeter ( in feet) multiplied by one foot (bottom area + perimeter x 1.0).
               
              Absorptive Area  = (L x W) + 2(L + W)
              Where: L = Drainfield Length
              W  = Drainfield Width
               
          1. The length of the excavation may be determined as follows when the area and width are known:
              2. L = (A-2W)/(W+2)
          2. For excavations three feet wide or less use the following formula to determine L:
              3. L = A/(W + 2)
          3. Porous Media. The porous media shall consist of clean, washed and graded gravel, broken concrete, rock, crushed stone, chipped tires or similar aggregate that is generally one uniform size ranging from 0.75 - 2.0 inches along the greatest dimension.
              1. The permitting authority may consider and approve on a case-by-case basis the use of chipped tire sizes greater than 0.75 - 2.0 inches along the greatest dimension.
              2. When chipped tires are used in conjunction with geotextile fabric, a heavier duty geotextile fabric must be utilized to minimize fabric

                3. punctures and eliminate fabric tears due to protruding steel belt remnants.

              3. Soft media such as oyster shell and soft limestone will not be approved.
          4. Drain line. The drain line shall be constructed of perforated distribution pipe and fittings in compliance with the following specifications:
            1. Three or four inch diameter polyvinyl chloride pipe with a standard diameter polyvinyl chloride pipe with a standard dimension ratio-(SDR) of 35 or less.
            2. Four inch diameter corrugated polyethylene, ASTM F405 in rigid ten foot joints only.
            3. Three or four inch diameter polyethylene smoothwall, ASTM F810.
            4. Any other pipe approved by the executive director.
          5. Installation Requirements. The drain line shall be placed in the porous media with at least six inches of media between the bottom of the excavation and the bottom of the drain line. The drain line shall be completely covered by the porous media and the drain line perforations shall be below the horizontal center line of the pipe. Single drain lines shall not exceed 150 feet. The drain lines shall be placed parallel to each other and parallel to the longest horizontal dimension of the excavation. For excavations greater than three feet in width, the maximum separation distance between parallel drain lines shall be four feet (center to center). Multiple drain lines shall be manifolded together with solid or perforated pipe. The opposite ends of multiple drain lines shall be manifolded together with solid line or looped together using perforated line and bedding. If drainfield is not to be looped, end caps must be used.
          6. Permeable soil barrier. A permeable soil barrier shall be placed between the top of the porous media and the excavation backfill. Geotextile fabric shall be used for the permeable soil barrier.
          7. Backfilling. Backfilling is the process of replacing the soil removed during excavating back into the drainfield and on top of the geotextile fabric. Only Class Ib or II soils shall be used for backfill. The backfill material shall be mounded over the excavated area so that the center of the excavation slopes down to the outer perimeter to allow for settling.
          8. Gravel-less drainfield piping. Gravel-less pipe may be used only on sites suitable for standard subsurface sewage disposal methods. Gravel-less pipe is available in eight-inch or ten-inch diameter corrugated perforated polyethylene pipe. The pipe is enclosed in a layer of unwoven spun-bonded polypropylene, polyester or nylon filter wrap. Gravel-less pipe shall meet American Society for Testing and Materials, ASTM F-667 Standard Specifications for large diameter corrugated high density polyethylene (ASTM D 1248) tubing.
          9. Planning parameters. Gravel-less drainfield pipe may be substituted for pipe in absorptive drainfields. When gravel-less pipe is substituted, the porous media around conventional pipe will not be required. All other planning parameters for absorptive drainfields apply to gravel-less pipe.
          10. Installation. The proper installation of adequate construction materials is virtually important to the success of gravel-less drainfield systems. Materials include gravel-less pipe, backfill, end caps, offset connectors and filter cloth. The connection from the septic tank to the gravel-less line shall be made by using an eight or ten-inch offset connector. It is important that the gravel-less line be laid level with the continuous stripe up, and joined with couplings. The filter cloth must be pulled over the joint to eliminate soil infiltration. The gravel-less pipe must be held in place during initial backfilling to prevent movement of the pipe in the excavation. The end of each gravel-less line shall have an end cap and inspection port installed.
          11. Drainfield Sizing. Eight inch diameter gravel-less pipe shall use W = 2.0 feet and 10 inch gravel-less pipe shall use W = 2.5 feet for absorptive drainfield sizing.
          12. Leaching Chambers. Leaching chambers are bottomless chambers which are planned for installation in a drainfield excavation with the open bottom of the chamber in direct contact with the excavation. The chambers are linked together with sewer pipe (no perforations) in such a manner as to completely cover the excavation with adjacent chambers in contact with each other. Other special conditions for leaching chambers are as follows:
            1. The excavation may be educed by 40% from the value calculated using Table I. The following formula may be used for excavations utilizing leaching chambers:
                2.  
                L = 0.6A/(W + 2)
                Where: A = minimum absorptive area; and
                W = leaching chamber panel width
                 
            2. These chambers shall not be used for absorptive drainfields in Class Ia or IV soils.
            3. Backfill covering leaching chambers should be Class Ib, or II soil.
          13. On-Site Sewage Facilities utilizing aerobic wastewater treatment tanks or other mechanical apparatus must be designed by a Registered Sanitarian or a Registered Professional Engineer.

            14. The Galveston County Health District encourages the development of feasible innovative septic tank system designs which are not specifically covered in the County or State construction standards. Any alternate system must, however, be approved by the Director of the Health District before installation. The Health District Director may require that sufficient evidence or proof be submitted to substantiate any claim that may be made regarding material, method of construction and/or effectiveness of the system.