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You are here: Home / Drinking Water / Chemicals / Radionuclides / Radionuclide Testing for Interim Approval of Well Completion

Radionuclide Testing for Interim Approval of Well Completion

Required testing, required checklists, and other information for completing a well interim approval.

Well Completion Checklist for Plan Review

In order for you to receive interim approval, you must complete each item on the Plans Review: Well Completion Checklist Adobe Acrobat PDF Document, including specified chemical testing. For certain counties, you must also conduct radionuclide testing.

Counties for which Radionuclide Testing is Required for Well Completion

Several areas of Texas have elevated radionuclide levels. If you are drilling a well in one of the counties listed in Table 1, you must conduct radionuclide testing for interim approval. This list was prepared from compliance data for existing water systems. Counties listed here have had samples exceeding the maximum contaminant levels for gross alpha and/or combined radium 226 and radium 228.

Counties where Radionuclide Testing is Required

County Name State Code *
Atascosa 007
Bexar 015
Bosque 018
Brazoria 020
Brewster 022
Burnet 027
Concho 048
Dallam 056
Erath 072
Fort Bend 079
Frio 082
Gillespie 086
Gray 090
Grayson 091
Harris 101
Irion 118
Kendall 130
Kerr 133
Liberty 146
Llano 150
Lubbock 152
McCulloch 154
Mason 160
Matagorda 161
Medina 163
Montgomery 170
Moore 171
Parker 184
Pecos 186
Polk 187
Refugio 196
San Jacinto 204
San Saba 206
Tarrant 220
Tyler 229
Upton 231
Val Verde 233
Victoria 235
Walker 236
Washington 239
Williamson 246
Zavala 254

* The state county code is the first three digits of the PWS ID number

Compliance-Related Information to Consider

Before you consider methods and laboratories you must consider the information listed in Table 2. The laboratory you use must be able to conduct analyses for gross alpha, gross beta and radium-228. For gross alpha and radium-228, if the levels of these contaminants exceed the "trigger" conditions below, the laboratory must be able to perform the additional testing listed for radium-226, combined uranium and the uranium isotopes 234, 235, 238. For gross beta, if the levels exceed the "trigger" conditions below (not common), the laboratory must perform tritium, radioactive strontium and gamma emitters. In other words, when you review your radiological data and the report has gross alpha over 15 pCi/L and uraniums are not reported, you will have to resample or reanalyze and resubmit complete results. If you see gross alpha plus radium-228 over 5 pCi/L, and don't have radium-226, you will have to resample or reanalyze and resubmit complete results.

Contaminant (pCi/Liter except *) Trigger
Gross Alpha Performed on all samples
Gross Beta Performed on all samples
Radium-228 Performed on all samples
Radium-226 If gross alpha + Ra-228 >5.0 pCi/Liter
Combined Uranium* If gross alpha >15 pCi/Liter; reported in ( g/Liter)
Uranium-234 If gross alpha >15 pCi/Liter
Uranium-235
If gross alpha >15 pCi/Liter
Uranium-238 If gross alpha >15 pCi/Liter
Tritium If gross beta >50 and the system is designated by TCEQ as vulnerable.
Radioactive Strontium If gross beta >50 and the system is designated by TCEQ as vulnerable.
Gamma-Emitting Radionuclides If gross beta >50 and the system is designated by TCEQ as vulnerable.

You must calculate radionuclide compliance for gross alpha and Combined radium-226 and radium-228 from analytical results if the laboratory does not. Non-detections are calculated as a zero ("<" sign in front of a result). See below:

Compliance Calculations from Radionuclide Analytical Results

  • Gross alpha (pCi/L): gross alpha result - uranium-234 result - uranium-238 result - uranium-235 result = compliance level (Maximum Contaminant Level is 15 pCi/L)
  • Combined radium (pCi/L): radium-226 result + radium-228 result = compliance level (MCL is 5 pCi/L)
  • Combined Uranium (MCL is 30 µg/L): no calculation

Acceptable Methods for Radionuclide Testing

Our Compliance Support Division maintains a list of acceptable methods for analyzing for radionuclides in public drinking water. Also be aware that radionuclide analyses take longer to complete, so plan ahead.

Laboratory Information for Radionuclides Only

At this time, public water systems are not required to use a laboratory certified by the TCEQ for public drinking water for the well completion interim approval. This is subject to change. Before using any lab, you must verify that the laboratory can conduct the analyses as required above.