(a) Required samples and measurements shall be taken of the effluent from the sampling point described in the permit. Should the permit not specify a sampling point, samples shall be collected immediately following the last treatment unit. These procedures shall be followed unless an alternative sampling and/or measuring point is approved in advance in writing by the executive director.
(b) Samples shall be taken and measurements shall be made at the minimum frequencies specified in the permit for each parameter. If a permit does not specify a sampling frequency, the permittee shall follow the frequencies set forth in §319.9 of this title (relating to Self-Monitoring Frequency). If a parameter included in a permit is not listed in the applicable table, the permittee will be instructed by the executive director in writing as to what frequency of analysis shall be followed.
(c) The permit may specify different sampling and/or measurement frequencies than specified in §319.9 of this title on a case-by-case basis, and in such cases the permit controls.
(d) For land application or evaporation facilities, the monitoring requirements shall be specified in the permit. The permittee shall monitor flow to a land application site on a daily basis and an evaporation system on a weekly basis when utilized. The specific plot or site used for land application shall be specified in the permit by name or description.
(e) The monitoring requirements set out in this subchapter are minimum requirements unless the permit specifies a lesser frequency. The executive director may establish a more frequent measurement schedule, if necessary, to protect human health or the environment. Additional measurements, samples, analyses, and recordation are encouraged in order to facilitate more effective management and control of facility operations. If the permittee monitors any pollutant at the sampling point described in the permit more frequently than required by this subchapter or the permit using approved analytical methods as specified in §319.11 of this title (relating to Sampling and Laboratory Testing Methods), the results of such monitoring shall be included in the calculation and reporting of the value submitted on the required discharge monitoring report or monthly effluent report. Increased frequency of sampling shall be indicated on the report.
(f) Calculations for all limitations which require averaging of measurements shall utilize an arithmetic mean unless otherwise specified in the permit.

Source Note: The provisions of this §319.5 adopted to be effective July 27, 1988, 13 TexReg 3514; amended to be effective October 8, 1990, 15 TexReg 5501; amended to be effective November 12, 2020, 45 TexReg 8000