SPECIAL REQUIREMENTS FOR WASTEWA'PER DISPOSAL SYSTEMS KERR COUNTY, TEXAS The following are specifications for soil absorption waste disposal systems in Kerr County, Texas. I. Location Of Septic System. A. Once a permit is issued, a site inspection of the property should be made to determine the best location for the septic system. The installer should first locate the house waste line stub-outs and determine the depth of the pipe. In planning the location of the septic system, regulated setbacks should be considered. B. Minimum Safe Distance In Feet: From Private Water Wells Public Water Wells Public Water Supply Lines Streams, Ponds, Lakes To Septic Soil Absorption Tank System 50 100 50 150 5 10 50 125* Foundation Walls of Structures Property Lines 5 ]5 10 10 Sewer Pipe With Water Tight Joints 20 20 5 50 *Where average soil percolation rate is less than five (5) minutes per inch of fall, this distance is increased to 200 feet from the waters edge. IZ. Septic Tank Connection To House Waste Line. A. There shall be a minimum of 1/8 inch of fall per foot (1.25 inches in 10 feet) from the house to the inlet of the septic tank. B. Placement of the septic tank shall be in an area which will require a minimum of angle bends in the wasteline to the septic tank. 90° bends should be avoided. Page 2 Special Requirements For Wastewater Disposal Systems III C. All fittings shall be primed and glued. D. SDR 35 or Schedule 40 grade pipe shall be used in rock or where traffic will pass over the wasteline. E. Sewer pipe shall be backfilled carefully by hand to avoid swags and broken fittings. F. A sewer cleanout shall be placed between the house and septic tank as close to the house as possible. Drainfield And Absorption Bed Construction. A. Drainfield Construction. 1. The square footage requirements for drainfields is for the trench bottom. It does not take into account absorption through the sidewalls of the trench, evaporation, or transpiration (the uptake of water by rooted plants). 2. Trench bottoms shall be level in order to distribute the wastewater evenly. 3. The minimum requirement for washed gravel in trenches is 12 inches with at least 6 inches below the pipe. 4. Trench media may be clean graded gravel, washed rock or crushed stone and may range in size from 1.5 inches to 2.5 inches. River gravel is not allowable for trench media because cementitious properties of this type of material often result in early trench failure. 5. There shall be a minimum of 12 inches of fall between the septic tank outlet and the perforated distribution pipe. 6. A ten foot section of solid pipe shall be placed between the septic tank outlet and the perforated distribution pipe. 7. Trenches should be constructed as shallow as possible with a minimum depth of 18 inches and a maximum depth of 36 inches. 8. In areas where high ground water is a problem, additional gravel and a 10 inch sand layer over the gravel will be required (see trench construction graphic). 9. In areas where the soil is a clay type, trenches will be backfilled with sandy loam or sand to the finished grade. Page 3 Special Requirements For Wastewater Disposal Systems 10. When dynamite must be used to excavate trenches, 6 inches of sand will be required on the trench bottom to act as a filter in the prevention of ground water contamination. 11. Perforated pipe in trenches shall be laid on a level grade. 12. A leveling instrument is required in establishing grades for trenches, absorption beds, distribution pipe and for determining the necessary depth of the septic tank. The leveling instrument must be set up on the job site at the time of the final inspection. B. Absorption Bed Construction. 1. Absorption beds are required in soils where the average percolation rate is greater than 60 minutes per inch of fall. 2. Square footage requirements for beds are approximately 50~ greater than for trenches due to the lack of surface area for sidewall absorption. 3. A 10 inch layer of sand over the gravel is required on all absorption beds. 4. Where absorption beds are required, the soil is generally a clay type and is not suitable for backfill material. 5. All points in the bottom of an absorption bed must be the same elevation to insure equal distribution of waste- water. 6. Duel field dosing utilizing a valve is usually required with absorption beds. Using this construction method allows one bed to dry while the other is in use. It also provides for better distribution of wastewater with higher wastewater loads. 7. Two vent pipes are required in each absorption bed to en- hance evaporation and provide aerobic (in the presence of oxygen) treatment of wastewater in the beds. The vents also provide inspection access to determine when the beds need to be alternated. 8. The final fill material in an absorption bed shall be "turtle-backed" or shaped to prevent surface run off from ponding on the bed. C. Evapotranspiration Systems (E. T. Systems). Page 4 Special Requirements For Wastewater Disposal Systems 1. The E. T. system is required when: a, The soil depth to ground water is less than 18 inches and ground water is present throughout most of the year. b. Minimum safe distances from wells, streams, ponds, water lines, etc. can not be met with conventional absorption systems. 2. The beds should be constructed as shallow as possible with a depth ranging from 18 inches to 24 inches. This is ne- cessary to keep the beds aerobic and prevent clogging, The beds should not be excavated deeper than 24 inches because the object is not to store a large quantity of water, but to keep it close to the surface so that it will evaporate and be available for plant root absorption and transpiration. 3. E. T. systems will always have a minimum of two beds separated by an approved diversion valve. 4. Construction of E. T. beds will require a minimum of 12 inches of gravel, 10 inches of sand, backfill with sandy loam, 2 vent pipes in each bed and a water tight liner of polyethelene with a thickness of at least 10 mil. (see enclosed diagram). SEPTIC TANK SPECIFICIATIONS 1. GENERAL. All septic tank systems shall be designed and constructed in conformance with the latest edition of Construction Standards for Private Sewage Facilities as published by the Texas State Department of health Resources. 2. MATERIALS. Septic tanks should be watertight and constructed of materials not subject to excessive corrosion or decay. Precast concrete tanks should have a minimum wall thickness of 3 inches and should be adequately reinforced to facilitates handling. When precast concrete slabs are used as covers, they should be watertight, have a thickness of at least 3 inches, and be adequately reinforced. 3. MINIMUM TANK CAPACITY, ESTIMATED DAILY DISPOSAL REQUIREMENTS MINIMUM RESIDENCE SIZE (GALLONS PER DAY) TANK SIZE(GALLONS) Less than 1100 square feet 250 550 ** 1100 to 1300 square feet 300 750 1300 to 1500 square feet 350 750 1500 to 1800 square feet 400 1000 1800 to 2300 square feet 450 1000 2300 square feet & up 500 1000 * Use of garbage disposal will require 1000 gallon tank. ** Use of garbage disposal will require 750 gallon tank. TANKS IN SERIES: 1. Are recommended for 1500 to 2300 square foot homes without garbage disposals. 2. Are required for 1800 to 2300 square foot homes with garbage disposals. 3. Are required for all homes over 2500 square feet. 9. INLET AND OUTLET DEVICES. "T" branches or vented elbows are required for inlet and outlet devices because they provide a Weans for venting decomposition gases from the tank and absorption system. To prevent escape of scum and floating solids from the tank, the open spaces between the tops of the inlet and outlet devices and the underside of the tank lid should not be greater than approximately two inches. 5. BACKFILL. Backfill around septic tanks should be made in thin layers thoroughly tamped in a manner that will not produce undue strain on the tank. Settlement of backfill may be done with the use of water, provided the material is thoroughly wetted from the bottom upwards and the tank is first filled with water to prevent floating. 6. ACCESS. Adequate access must be provided to each compartment of the tank for inspec• lion and cleaning. Both the inlet and outlet devices should be accessible. Access must be provided to each compartment by a man}role having principal dimension of at toast 20 inches. Where the top of the tank is located more than 18 inches below the finished grade manholes and inspection holes should extend to approximately 8 inche below the finished grade, or can be extended to finished grade if a seal is provided to keep odors from escaping. NOTE: INSPECTION IS REQUIRED AFTER TANK AND PIPES ARE INSTALLED, BUT NOT COVERED. April 81 1)I~t11N h'LI~:IJJ til'bX'II'Il'l1'1'IVNS csET~RIIL. All drain fields shall 1x~ desi~ttx_r3 :vx] constnrcted in conforn>`rily Vastewater Discliaryc fie is tixx Allowable Sewage Application hate The Daily Wastewater Dischzrgc (n}, for dwelli.nys is determined as follows: Residen.x~ ~i zc l,~ss tha n 1700 s~; . ft. 1100 to 1300 sal. ft. 1300 to 1500 sy. ft. 1500 to 1800 sal. 1 t. 1800 to ?300 s~(. lt. Wer 230 0 s~{. 1 t . Intimated Dail Dis sal Inc iirements - - - - - ~'- -- L"'- -- --~---- - 250 (;allons per Ckry 300 " 350 " 400 " 450 " 500 " Tt1e Allowable Sew.ulr !1{~pl icat ion R.~t 'Phc Ita for Fxrcro.lation rates lx~twc'Ln a separate chart. Average ['cns~l.it uni I4~te Minutes Inch of l'a11 1- 10- 20- 30- 35- 45- 60- Greater thatr b0- (It<~) , is deternurx~cl as follows: t}ie valves yiv~n are interpolated on Sewage Application Rate (Ra) Gallons/Sc . F't. Ys -- -~~I ------y - 2.0 1.5 1.0 0.9 0.8* 0.7* 0.6* Absor}~tiun Decl I~r~quired b. Ttx trench hottaii .and drain pifx~ should tx~ at t}re same elevation through- out the field. c. The trench dept}r should not be less tlt'an 18 inches. d. T}x nururrnm :~ikicinN TN A VI{HY Tlt;t{m Self, (rl:It('ul.n'CIUN ftA'ft: i~lt F.A'I't: Ft '1'IInN 45 MIN/INt'lll U~~I'f.: Ii~::l~crt 1. nl ~ n ,~~i l,~~f .Il l,v t.uit: .~tnl I~il~o:: .uo iusl vl l,•~1 Lul I~"t ~~v, i~,l. ABSORPTION BED SYSTEM MINIMUM BED-BOTTOM SIZE Bed-Bottom Size (sq.ft.) = g Ra Q = Daily Wastewater Discharge Ra = Maximum Rate of Sewage Application Based on Percolation Test DAILY DISCHARGE FOR DWELLING (~) IS ~ DETERMINED AS FOLLOWS: ~ i ~'~ Residence Size Est.Daily Disposal Rqmts. _ Less than 1100 sq.ft. 250 gal/per/day 1100 to 1300 sq, ft. 300 ~~ ~~ ~~ ~' O 1 2300 to 1500 sq. ft. 350 ~~ " ~QdYa•' 1500 to 1800 sq. ft. 400 ~~ ~~ " is 1800 to 2300 sq, ft. 450 ~~ ~~ ~ Over 2300 sq. ft. 500 ~~ To find bottom size- EXAMPLE: (A)=20' i (H)=IS', thus 9nFrrlSfh : Inn ~n Fr 1 ~ .~•, ~ a , 1A '- ~~ P~ SQti ( ~~a°~4 ,/ .SO ~ '. i .: i ~0'~ '~ ~~ m ~% ze ,~. .% -' r ~~ `~Y ~' HED BOTTOM LEVEL ~~~ ~„ ~ 'See Crosa Section for bedding materials EXCAVATION FOR ABSORPTION BED ALLOWABLE SEWAGE APPLICATION (Ra) IS DETERMINED AS FOLLOWS: Percolation Rate of Application Rate (Ra) (Min./Inch) (Gal/Sg. Ft./Day 1-10 0.8 10-20 0.6 20-35 0.43 35-60 0.35 3ft.min.~ 4 ft.max. ( 4 ft.max. ` ~ 3ft.min. ~, , --~ )Distribution ~~~ (G) Pipe ~ (DP) i (F) .) j S j u ~ d s o (GB)~ •~~ o ~y • a a ~° o SOIL BOTTOM PERCOLATION TEST IS REQUIRED. INSPECTZON IS REQUIRED AFTER TANK AND PIPES ARE INSTALLED, BUT NOT COVERED. CROSS SECTION (Bedding Materials) LEGEND ~(G) Plant Perennial Grasses (F) 4-6" of earthfill of sand-loam, free of rocks and 'gumbo' clay, mounded to drain away from bed (S) 10 inch sand layer (GH) 12 inch layer of 1-y" to 2~" gravel bed (DP) 4" drainfield pipe placed at top of gravel bed APril 1981 EVAPOT}tAN.•',PIRATION SYSTt1.7 FOR 115E ll) where soil conditions (solid rock) are not suitable sue r.w , absorption systems (2) Restricted Area where soil ~L~~,.rptir.,. system not permitted MINIMUM BED-BOTTOM AREA Total Area Rey'd (sq.ft.l 3.875 (P) Q is the Daily waste water Discharge gaily Waste Water Discharge for dwellings is determined as follows: 300 gals. per day is the minimum discharoe rate used. This amount will accommodate 2 bedrooms. For rich additional bedroom, add 100 vallons.•• ••NOTE: The 200 gals. per day may De modified by: 1) number of persons residing in dwelling 2) intended use of dwelling 3) size of living area using: DIVIDED INTO DISTRIBUTION PIPE 1 or more z°B os~l I f DIVEitSIUN VALVE SEPTIC TANK tr _ _ _ _ EXCAVATION FOR BEDS DISTRIBUTION FIPE 2 or more UED UO'1'tY1M LL'V1:1. ~~ Less than 1500 sq. fi. - 2 bedrooms 1500-1900 sq. ft. - 3 bedrooms For each additional 900 sq.ft. - add 1 bedroom 3f t, min. ( 4 ft. max. I (spa~cing~_ spacing s r PLANT PERENNIAL GRASSES MOUNDED SANDY l.[lAM I ~. .°~~ • ~~• • e ° • a ° o • o SAND l GRAVEL (15" - 2rr") 'Cl}EH PAPEk G" Max. 10" 12" Min. 4" Drainfield Pipe Solid Rock bottom (no liner required) Approved Impervious Liner (required if in Restricted Area) TYPICAL CROSS SECTION :~L: Percolation Test not required. impervious liner fur sides and bottom of beds in Restricted A[e•.r can !•c m,du from reinforced concrete, concrete block with grouted surfaces, hot r•..}q~ed asphalt memb[ane or specially manufactured reservoir lines (p]„e.t is or rutd •er type). Irsrec[ion is rer)tiired after tank and pipes are installed but not cnverr•d. HOLOI Ni; 'TANK 1. Materi alS Holding tanks :;hall be watertight and constructed of sturdy ma 4:rials (cuncrvte, metal, fiberglass or tile) nut :subject to exce~asivr currosion,or decay. F'r seas[ cunrrete tanks should have a minimum wall th i~kne ss of tw~~ (2) inches and should be impervious to infiltration and exf i]tration and should be adeyuately rcinfur~ed. Concrete lids should be a minimum of three (3) inches thick, adequately reinforced and should be complete with a pump-out opening a minimiun of tun ilia) inches in diameter with a removable cover. The lid :should be sealed (air and watertight.) to the tank. All cuncre[e or metal surfaces, inside and out, should be coated with bitumastic or similar compound. 2. House Sewer The line from [he house plrtmbiny system Co the holding tack should be constructed of strut wzally suynd pipe such as cast iron, vitrzfiad clay or heavy duty P.V.C. It it recununended the pipe bu laid on a straight grade of not less than out-fourth of an inch fall per feet and have a minimum inside diameter of four (4) inches. The material used to seal the pipe joints should effectively prevent leakage and entry of roots into the joints. 3. Hold itiy _Tauk F'i ttinys "T" branches are required for the inlet to the tank so that gases from the tank can be vented through either the house plumbing or independently into the atmosphere. 4. Grease Tray (Optional Feature) An adequately sized grease trap can be installed in the house sewer line before it enters the holding tank thereby decreasing objectionable odors when properly cleaned. 5. House Sewage All household waste water of any kind must be emptied into the holding tank. 6. Anchorage Huldiuy tanks must be anchored to prevent floating when empty. 7. Minimum Size The holding tank must have a cepacity of at least 1000 gallons. fi. Ltspec[ion The holding tank system must be inspected by a representative of the Authority after the tank is installed and before the lid is installed and sealed. INDIVIDUAL HOME WASTE WATER DISPOSAL UNITS The installation and use of the individual aerobic wastewater disposal units other than septic systems is not opposed by the Texas Department of Health Resources, Texas Water Quality Board or the Upper Guadalupe River Authority. The effluent from an individual home aerobic wastewater disposal unit must be discharged into a properly designed and constructed soil absorption or evapotranspiration system. No discharges to the ground surface or into the waters of the State are authorized. As a practical matter, companies distributing aerobic individual home waste disposal systems should provide an inspection and repair service since the home- owner, in most instances, will not be in a position to judge whether the device is working as designed. The Upper Guadalupe River Authority will consider the ability of the distributor to service the installation in determining whether to approve an individual home waste disposal system. The principal structure or containing vessel of an individual home waste- water disposal unit should be designed to provide treatment to incoming sewage in the event of failure of mechanical and electrical devices. Since anaerobic conditions will prevail when aeration equipment is inoperable, the unit should be designed to function in a septic tank like manner during periods when the aerating device is not functioning. RECOMMENDATIONS FOR SEPTIC TANK CARE The purpose of a septic tank is to condition household wastes, including water from the laundry and the bath, discarded food scraps, and body waste so that it may be more readily percolated into the subsoil. The normal use of bleaches, detergents, soaps and drain cleaners does not harm or interfere with the operation of the system. The partially treated sewage effluent flowing from the tank still contains large numbers of harmful bacteria and organic matter in a finely divided state or solution. Foul odors, unsightly conditions and the health hazards will develop if this effluent is ponded on the surface of the ground or carried away in open ditches. Final disposal of the effluent in a subsurface soil absorption system is necessary. The bacteria present in a tank are able to thrive in the absence of oxygen. Such decomposition in the absence of air is called "septic" which led to the naming of the tank. Solids and scum are digested and reduced to a smaller volume by the bacteria during the interval between tank cleanings. The frequency of cleaning depends on the size of the septic tank and the number of people it serves. When a garbage grinder is used, more frequent cleaning will be required. With ordinary use and care, a septic tank may require cleaning every 2 or 3 years. In many cases septic tanks can be satisfactorily operated even longer. The homeowner can make measurements and decide for himself when his tank needs cleaning. An annual check is the best procedure. When the bottom of the scum is within 3" of the bottom of the outlet device the tank should be cleaned. The accumulated solids are ordinarily pumped out by commercial septic tank cleaner companies. A septic tank system should not be treated as if it were a city sewer. Economy in the use of water helps prevent overloading of a septic tank system that could shorten its life and necessitate expensive repairs. Leaky faucets and running commodes should be carefully guarded against and relatively little indigestible water or garbage should be placed in a septic tank system. Use of a garbage grinder can cause a rapid buildup of sludge or scum which means more frequent cleaning and possible system failure. A septic tank system can serve a home satisfactorily only if it is properly designed, installed and adequately maintained. When a septic tank system is improperly designed or maintained, liquid waste may overflow onto the ground surface or the plumbing in the home may become stopped up. These overflows not only create offensive odors but are also health hazards. Sewage may contain dysentery, infectious hepatitis, typhoid and paratyphoid or other infectious disease organisms. Ponded sewage creates breeding places for misquitoes and some other insects. There are no known chemicals, yeasts, bacteria, enzymes or other substances capable of eliminating or reducing the solids and scum in a septic tank. The addition of such products is not necessary for the proper functioning of a septic tank system. To facilitate cleaning and maintenance, the homeowner should have a diagram of his septic tank system showing the location of the house, the septic tank manholes, the piping and the soil absorption system. Septic tanks and drainfield systems frequently are damaged when heavy trucks or other equipment drive over them. An accurate diagram of the system enables the homeowner to keep heavy vehicles away from the critical area. A line of cast iron pipe instead of the shall be installed under crossings for heavy vehicles. Drainfield neglect of the septic tank is the most frequent cause of damage to systems. When the tank is not cleaned, solids build up until they are carried into the underground soil absorption system where they block the flow of the liquid into the soil. When this happens, the soil absorption system must be rebuilt. The precautions of periodic inspection and cleaning of the tank helps prevent this needless expense and work. Influv F1/~. 2 TWU 5}'.Y1'IC i'A4K5 IV tiI.Klllti ~~utf lalr w pipe l uYet flrsc t inflmi -14- First compartment should i,e 2 lu 3 limes lary;cr to:u, Liquid surfaco is second c.m~partment• s•unc la~vel iu inrt i~ ~ anks. REQiIIREMENTS FOR DESIGN AND APPROVAL OF DISPOSAL SYSTEPhS FOR NIIILTIPLE FAMILY DWELLINGS AND MOBILE IiC[~ PARKS I. DESIGN CRITERIA The general criteria used is that for each 3,000 square feet of living area, there is a r~1uirement £or 15,000 square feet of development property, provided it includes an area in size equal to 3.875 X the estimated daily wastewater flow (gallons per day), and that the area is suitable for wastewater disposal, and is exclusive of any structures, roads, parking areas, or other paved areas. II. APPF3~VAL PROCEDURES A. Owner or developer will provide UGRA with a ~noept plan that includes: Plat plan drawn to scale of the proposed develog~nt with location and description of property, lot sizes, proposed structural ing~rovements, roads, parking areas, driveways, drainage and utility easements, and designated areas for wastewater disposal. B. In planning the required area for wasts.~water disposal the following should be used: Designated Area =Daily Wastewater Load (gallons per day) X 3.875. ESTIMATED DAILY RESIDF~ICE SIZE WASTEWATER LOAD (GALLONS PER DAY) Less tha n 1100 square feet 250 1100 to 1300 square feet 300 1300 to 1500 square feet 350 1500 to 1800 square feet 400 1800 to 2300 square feet 450 2300 square feet & over 500 EXAMPLE: A four-plex residential structure with 1,000 square feet of living area per unit would require: Lot Size: 4,000 square feet living area total. 5,000 square feet developnent property for each 1,000 square feet living area = 5,000 X 4 = 20,000 square foot lot size. Wastewater Desig7~ated Area: 4 units X 200 gallons per day = 800 gallons per day. 800 gallons per day X 3.875 = 3,100 s mare feet wastewater disposal area. Multi Family Dwellings Page 2 C. UGRA Staff will make a survey of project site to determine suitability of waste disposal areas. Generally, areas will be suitable if soil slopes do not exceed 3~ and soil perwlation rates do not exceed 60 minutes/inch and there is no evidence of high ground water intrusion. If it is determined that an area is not suitable for waste disposal, additional or alternate areas will be required. D. Following UGRA approval of project wastewater disposal plan, waste disposal designated areas should be marked anti barriers erected around than so that the soil is left undisturbed during project construction. E. If the project is to be platted and approved by Kerr County Carmissioner's Court, o~rner is required to complete Waste Disposal Plan. Upper Guadalupe RiverAuthority 215 W. Water St. Ij _.-_ ~_._. iLdr~d P. O Box 1276 Kerrville, Texas 78028 512-896-5445 B.W. Bruns General Manager On 15 May 1984 the Commissioner's Court of Kerr County met and app- roved several amendments to the Rules of Kerr County for Private Sewage Facilities. I have enclosed a copy of the amended order for your reference. The most important changes to the Rules involve permit fees, a requirement for the licensing of septic tank installers and a requirement for a permit to repair a failing septic system. Permit fees have increased to $80.00 for standard residential and commercial systems - percolation test included if owner provides holes. Multi-family - commercial system permits for more than one dwelling on a common septic system are $200.00. The new fee schedule is in the appendix section of the enclosed "Rules". The permit fees were increased in order to offset the County's cost of operating this program. The requirement for the licensing of installers is found in Section XVIII of the "Rules". All contractors engaged in the installation of septic systems will be required to have an installers license beginning 14 May 1984. The General Manager of the Upper Guadalupe River Authority shall be the Licensing Authority. Licensing requirements will include: A. An initial license fee of $100.00 and a yearly renewal fee of $25.00. B. A passing test score on an Installer's Exam. Test questions will come from the enclosed "Rules", the Construction Standards for Private Sewage Facilities, and the Special Requirements for Waste Disposal Systems - Kerr County, Texas. The installer's exam will be available beginning 19 July 1984. The exam location will be at the offices of the Upper Guadalupe River Authority at 213 West Water Street, Kerrville, Texas. Page 2 June 1984 Regulation Amendments The exam may be taken anytime durin4 office hours, 8:30 a.m. - 5:00 p.m., Monday through Friday. (passing score = 708 correct answers) There is nocv a permit requirement for the repair of failing septic systems. The permit fee is $35.00. A site inspection with the installer will be made by a U. G.R.A. representative to determine the best approach to the repair of a failing system. If you have any questions about the regulation amendments or the licensing procedure, please give me a call. Sincerely, Lane Wolters, R. S. Water Quality and Environmental Health LW:kk Enclosures ( ) z~ r~i <:..,.,y ~d~. 4~