San Antonio Water System: Edwards Aquifer Recharge Zone

Edwards Aquifer Recharge Zone
Collection System Evaluation and Maintenance Program
RJN Group, Inc.

COMPLIANCE REQUIREMENTS UNDER CHAPTER 213
See Texas Commission on Environmental Quality (TCEQ)

EDWARDS AQUIFER ADMINISTRATIVE GUIDANCE

The RJN team is working with the San Antonio Water System (SAWS) to eliminate exfiltration (or leakage) of wastewater flow into the Edwards Aquifer. Legislation requiring specific measures required is included in Title 30 Texas Administrative Code (30 TAC) Chapter 213 - Edwards Aquifer Rule

Implementation on the Edwards Aquifer Rule

The Rule was promulgated to protect the drinking water provided from the Edwards Aquifer to many municipalities. The Rules essentially address activities that could pose a threat to water quality in the Aquifer and the surface streams that feed it. The Edwards Aquifer is divided into three zones:

The City of San Antonio covers each of the three zones; therefore, different areas of the City will have different requirements.

The Contributing Zone
The Recharge Zone
The Transition Zone

Each zone has separate and distinct requirements based on the effects of surface activity on the Aquifer. The City of San Antonio covers each of the three zones; therefore, different areas of the City will have different requirements.

A wastewater collection system located in the recharge zone is regulated under the Rule. One of the requirements of collection systems located in the recharge zone is to perform testing of the system every five years. Testing must be performed on every line that is at least 6-inches in diameter to find out whether there are any defects such as:

Offsets
Open joints
Cracks
Crushed lines
Other damage and defects that would allow sewage to leak

Private service laterals, manholes, connections, and lift station wet wells must be included in these tests. A Texas-licensed professional engineer must certify test results.

Test Methods

The Edwards Aquifer Rule provides for several acceptable methods of testing that include:

In-place deflection testing to ensure that piping has not exceeded a deflection rate of 5 percent
Close circuit television (color) to verify that the lines are free of defects
Smoke testing for private service laterals to indicate leaks

Other test methods may be used if approved by the Texas Commission on Environmental Quality (TCEQ). Records of testing must be retained for five years.

Repair of the Defects

If the tests reveal defects, measures must be taken immediately to contain the leakage and prevent the discharge of sewage into the Edwards Aquifer or any surface water. The repairs must be completed as soon as possible, but at least within one year. Any new lines that may be required as a result of the testing shall follow standards and meet the design criteria in 30 TAC: Chapter 213 - "Edwards Aquifer Rule" and Chapter 317 - "Design Criteria for Sewer Systems." A geological assessment will be performed along the corridor of the sewer lines to be rehabilitated. Stormwater runoff will be controlled using best management practices (BMP) both during and after construction. All required permits and approvals will be completed before construction begins.

If the tests reveal defects, measures must be taken immediately to contain the leakage and prevent the discharge of sewage into the Edwards Aquifer or any surface water.

Before installing or upgrading any sewer collection system (SCS) an SCS plan application must be filed. If the design includes lift stations and/or force mains, a lift station/force main system application must also be filed.

All plans, specifications and contract documents must be prepared by or under the direct super-
vision of a licensed professional engineer and must include the required general construction notes. A completed application, "Wastewater Permits Section Submittal Application" must be submitted to comply with statewide rules for SCS. In addition to statewide standards, the Edwards Aquifer rules call for additional design and construction guidelines. Notable items to include:

All manhole covers and rings that are installed, rehabilitated, or replaced must be watertight
Gravity sewer lines must be made of PVC pipe with a SDR of 35 or less
Material used to backfill and embed completed sewer lines must meet the standards applicable statewide
New sewer lines must be constructed with stubouts to accommodate anticipated extensions
Sewer lines that bridge caverns or sensitive features must be built to maintain their structural integrity across that span
Sewer lines may not be constructed in the five-year flood plain unless an exception is received from the TNRCC regional office
Construction testing of installed pipe includes infiltration, exfiltration or low pressure air testing
Construction testing of manholes includes testing independently of the sewer lines using hydrostatic exfiltration testing, vacuum testing or other approved method

Design requirements for rehabilitation of sewer lines must comply with Chapter 317 for new pipe and manholes. The use of trenchless technology is considered non-conforming technology (Chapter 217.57 - proposed new) and will be subject to review and approval by the reviewing authority prior to construction.

Completed Repairs

Thirty (30) days after the repairs are completed (allowing for backfill to settle), one of the test methods mentioned previously must be used to test the lines again. This testing must be done within fifteen (15) days with the test results being submitted to the TNRCC within thirty (30) days of completing the tests. These test records must also be maintained for five (5) years.

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