Raymond Beckford OSSF Plan Reviewer HARRIS COUNTY’S MISSION STATEMENT Our mission is to serve the constituents of Harris County by ensuring developments in the unincorporated areas will not pose a threat to the safety and welfare of the public as prescribed by Commissioners Court. We will accomplish this by providing expedient and professional service while enforcing all applicable Harris County regulations. THE APPLICATION FOR AN OSSF PERMIT OSSF Permits Costs: Residential - $260.00 Commercial - $410.00 Must be signed by the property owner Affidavit to the Public Harris County will file the affidavit for the property owner with the County Clerk’s Office. Filing Fee $16.00 (Cash or Money Order made payable to Harris County) Acknowledgment of Testing Requirements for an OSSF Must be signed by the property owner In Brief TEXAS LOCAL GOVERNMENT CODE SUBCHAPTER A. SUBDIVISION PLATTING REQUIREMENTS IN GENERAL § 232.001 Plat Required (a) The owner of a tract of land located outside the limits of a municipality who divides the tract into two or more parts to lay out a subdivision of the tract, ….,must have a plat of the subdivision prepared. WHEN PLATTING IS REQUIRED SUMMARY Tracts less than 10 acres but larger than 5 acres – if created after September 1, 1999 Tracts less than 5 acres – if created after September 1, 1989 RESIDENTIAL LOT SIZING 30 TAC 285.4 (a) (1) A. Subdivisions of single family dwellings platted or created after the effective date…, served by a public water supply and using individual OSSFs for sewage disposal, shall have lots of at least ½ acre. B. Subdivisions of single family dwellings platted or created after the effective date…, not served by a public water supply and using individual OSSFs, shall have lots at least one acre. THIS PROPERTY MUST PLAT Legal Description: TR 21A, Block 1, Plaza 290 U/R The HCAD tax map Shows the property owner’s tract with the legal description and the dimensions of the property. Tax Assessor Block Book Map Shows the tract in its original configuration. To access block book maps: www.tax.co.harris.tx.us The recorded plat SITE EVALUATION Soil Seasonal groundwater elevation Topography Flood hazard Separation requirements (setbacks) THE STANDARD SOIL/SITE EVALUATION FORM Required per §285.30 Prepared by: Registered Site Evaluator Professional Engineer The site/soil evaluation can be presented in any format. Must have the same information as on the standard site/soil evaluation. SOIL EVALUATION •A minimum of two soil bores required •Show the soil bores on the site drawing. Use the texture by feel test to verify the class of soil Show the depth of indications of the “seasonal” water table, not ground water Remember to sign and seal the report Development in the 100-year Flood plain & Floodway Subject: §285.31 (c ) (2) Flood Hazards • In the100-year flood plain how will tank floatation be eliminated. • In the floodway - P.E. only a. System shall not increase the height of the flood b. Components completely buried without adding fill c. Alarms, junction boxes, compressors must be elevated above 100-year flood plain Date: Certification for a proposed spray irrigation system installed in the regulated flood-way located at __________________________________________ Per the requirements of 30 TAC 285; specifically §285.31(c)(2), a professional engineer must demonstrate that the proposed system will not increase the height of the flood. Per the Rule, the proposed system is a surface application system and the proposed components that will be above the existing surface grade (e.g.: access risers and control panel(s)) are exempted by the Rule. The installer must perform a competent installation in accordance with the Rule and ; after settling around the tank battery and spray area piping installation, have no fill above the existing grade. The pertinent Rule follows: §285.31(c) Surface drainage criteria. (2) Flood hazard. Any potential OSSF site within a 100-year floodplain is subject to special planning requirements. The OSSF shall be located so that a flood will not damage the OSSF during a flood event, resulting in contamination of the environment. Planning materials shall indicate how tank flotation is eliminated. Additionally, if the site is within the regulated floodway, a professional engineer shall demonstrate that: (A) the system shall not increase the height of the flood; (B) all components, with the exception of risers, chlorinators, cleanouts, sprinklers, and inspection ports, shall be completely buried without adding fill; and (C) non-buried components (e.g. alarms, junction boxes, and compressors) shall be elevated above the 100-year flood elevation. If there are any questions, please contact me immediately. Signature and seal of Professional Engineer PLANNING MATERIAL REVIEW THE OSSF SITE PLAN Must be drawn to standard engineering scale, i.e. 1” = 10’, 20’, …60’ NOT 1” = 70’ , 1” = 150’ and NOT architecture scale Show both existing and proposed development Show the easements & setback requirements Show existing & proposed water wells Show existing & proposed water lines System Flow Diagram 750 Gallons 500 Gallons 500 Gallons chlorinator 10/10 Requirements In watersheds impaired for bacteria on the EPA 303(d) list, all OSSFs must use secondary treatment meeting a 30-day avg. CBOD of 10 mg/L & TSS of 10mg/L Most ATUs installed in Harris County must be listed on our approved list of ATUs meeting the 10/10 requirement Septic tanks installed in Harris County must be listed on our approved septic tank list Surface Spray Irrigation 0.041 gal/sf/day isotherm goes through Hwy 6/Telge Rd. Nothing within 10 feet of a sprinkler nozzle Specify the sprinkler nozzle criteria- max. inlet pressure of 40 psi, gpm, low angle 15° or less in trajectory Provide a landscape plan- what type of grass or other vegetation will be planted Provide the spray schedule Reduced spray area if designed by report prepared by Clifford Fedler, Ph.D., PE, Evaluation of Surface Application Rates for Texas OSSF Systems Drip Irrigation Correct application rate, length of drip tube needed Size the pump, supply and return lines Provide dosing calculations – how many doses per day Specify the filtering device – must filter down to 100 microns State or show how deep the drip tube is to be installed Show detailed diagram for mound i.e. how high & wide is the mound, how deep are the emitters into mound. Specify class of soil & cubic yards of fill needed. Fill permit is required for mounds. Hydraulic Detention Time (HDT) The amount of time it takes wastewater to travel through a component in the treatment system HDT = Tank Volume ÷ avg. flow Longer HDT allows for cleaner effluent Significant in the pretreatment tank 500 gallon Pretreatment Tank (min.) Source: Analyzing Wastewater Treatment Systems, B. Lesikar, Ph.D., PE et.al ATU sized by the number of bedrooms (150 gallons per bedroom) A four bedroom house would need a 600 gallon ATU Our Requirement for Pump Tanks Pump tanks shall be equipped such that when pumping a portion of the effluent is returned below the static water level to insure scour of the pump tank bottom RESIDENTIAL DESIGN PARAMETERS Hydraulic Loading Average flows Correct calculations Component sizing Proper setting of components & controls Dose volume Pump rates COMMERCIAL DESIGN PARAMETERS Hydraulic Loading Organic Loading Peak & Average Flows Number of People Days of Operation Hours of Operation Correct Calculations Component Sizing Proper setting of components & controls FLOW EQUALIZATION (SURGE) TANKS Compensates for peak flows Should be a part of the OSSF for: restaurants, schools, churches, office/warehouses Often undersized Control panel should be able to track: high water alarm events, dosing events, pump operation time Grease Trap Sizing Use both EPA and Uniform Plumbing Code methods. Use the larger of the two sizes. PROVIDE REFERENCES Texas Commission on Environmental Quality Chapter 285 Table III Goldstein, S. and W. Moberg, 1973. Wastewater Treatment Systems for Rural Communities US Environmental Protection Agency (EPA) Design Manual Onsite Wastewater Treatment, 1980 B. Lesikar, W. Stuth, Sr., et al., 2008. Texas AgriLife Extension Service. Analyzing Wastewater Treatment Systems-Serving Residential and Commercial Facilities for High Strength and Hydraulic Loading. COMMON DESIGN DEFICIENCES Surveys not submitted Site plan not to scale Site plan dimensions don’t match property dimensions Buoyancy calculations Undersized components & disposal fields BOD calculations Reference source for hydraulic and organic loading A Few Things To Consider Consider flow equalization for two or more homes on one system Consider expansion during the design phase Include flow monitoring devices - water meters, elapse time meters, cycle counters Commercial effluent filters will help lower BOD QUESTIONS Ray Beckford 713-956-3047 raymond.beckford@hcpid.org