A qualified site evaluator must conduct a site and soil evaluation. This person prepares a report on the soil conditions and site survey, and locates structures on the property that have specified separation distances from on-site systems.

The choice of an OSSF system is based on the site and soil conditions found during the evaluation. Choosing the appropriate technology is critical to the system's success.

Each on-site sewage system consists of a treatment component, which initially treats the wastewater, and a land application component, which distributes the wastewater to the soil. To determine possible land application options, compare the key conditions of the site and soil to the requirements for the various systems.

The type of land application system you choose determines what kind of treatment system can be used. To obtain approval for the system you have chosen, you must contact a designated representative or TCEQ regional office. Examples of treatment options include septic tanks, aerobic treatment units, sand filters, trickling filters and constructed wetlands. The treatment system chosen depends on the water quality requirements of the land application system, which is chosen to accommodate the site and soil conditions. Final selection of the system components should be completed in cooperation with the professional designer.

The system must be planned by a person authorized by the permitting authority under current regulation. Installers can normally plan standard or conventional systems, including gravel-filled standard drain fields, unlined evaprotranspiration beds, gravel less pipe and leaching chambers.

In some instances, homeowners can design their systems with help from the local designated representatives. Systems that are more complex - including surface application, low-pressure dosing, mounds and non-standard systems - require professionally developed planning materials.

A professional designer is either a registered professional engineer (PE) or a registered sanitarian (RS) licensed to practice in Texas with experience in designing on-site wastewater systems. Several local jurisdictions in Texas require that the planning materials of all systems be submitted by a PE or RS.

A PE or RS is also required when submitting planning materials for:

• Lots smaller than 1 acre when served by an individual water system (well), those less than 1/2 acre when served by a public water supply (no individual wells) and those platted after January 1, 1988
• Non-standard and other more complex systems
• All systems in the Edwards Aquifer recharge zone
• Any on-site sewage system serving manufactured housing communities, recreational vehicle parks or multi-unit residential developments owned or controlled by a person who rents or leases such space
• Any OSSF for a structure not exempted by the Texas Engineering Practice Act. Such systems must have planning materials submitted only by a registered professional engineer
• Systems needing variances from the rules

A permit application and planning materials must be prepared and submitted in the property owner's name and on a form provided by the permitting authority.

The permitting authority reviews the application, site and soil evaluation, the type and size of the system selected, and other supporting documents required for a permit to be issued. The review ensures that rules in the jurisdiction are followed and that good engineering practices are used. An agency representative may visit the site to verify the application accuracy and completeness.

An authorization to construct must be granted by the permitting authority before building can begin. This authorization should include specific instructions on the number and schedule of inspections and at what stages of construction the inspections are required.

A Permit of Authorization to Construct may be withheld for, included, but not limited to, the following reasons:

• Information missing, omitted, or contradictory on the application as required in Chapter A 285.5 285.30 of TCEQ Rules for onsite sewage facilities
• A Flood Plain Development Permit not being issued
• Noncompliance with the Comal County Subdivision Regulations

Licensed installers or their apprentices can begin building the system only after receiving the authorization to construct. The system must be built according to the approved plans and permit application. Any changes to the system must be approved by the permitting authority before the changes are made.

In some cases, a new review will be needed, such as when site conditions are different from those submitted in the planning materials. The level of certification (Installer I or II) required for construction depends on the type of system.

The system must be inspected by the permitting authority at the appropriate stages of construction according to the type of system being installed. Inspections must be scheduled in advance and according to local policies. They should be comprehensive, covering all parts of the system.

Three inspections are required as the system is installed. This office must be notified as least one day (24 hours) before an inspection is needed. If the system fails or is not ready to be inspected when the designated representative arrives, the installer is responsible for a $150.00 reinspection fee. These requirements also apply to on-site sewage facilities in need of alteration or repair. After all the inspections and approval of the facility is completed, the applicant will be issued a Permit of License to Operate. The permit license to operate is required before a facility is put into use.

The inspection should be based on the approved application and plans, current regulations, and accepted engineering practices. There should be no surprises during the inspection if the approved application was detailed and complete, and the system was built according to the approved application.

A notice of approval or license to operate is issued by the permitting authority after the competed system has passed all inspections.