16 Del. Admin. Code § 4462-11.0

Current through Register Vol. 28, No. 7, January 1, 2025

Section 4462-11.0 - Corrosivity

11.1 Corrosivity Sampling, Reporting and Analytical Methodology: Suppliers of water for community public water systems shall collect samples from a representative entry point to the water distribution system for the purpose of analyses to determine the corrosivity characteristics of the water.

11.1.1 Sampling Requirements: For water suppliers utilizing surface water wholly or in part, two (2) samples per plant are required, one (1) during mid-winter and one (1) during mid-summer. For water suppliers utilizing wholly ground water sources, one (1) sample per plant per year shall be required.

11.1.1.1 The minimum number of samples required to be taken by the system shall be based on the number of treatment plants used by the system, except that multiple wells drawing raw water from a single aquifer may be considered one (1) treatment plant for determining the minimum number of samples.

11.1.1.2 Determination of the corrosivity characteristics of the water shall include measurement of pH, calcium hardness, alkalinity, temperature, total dissolved solids (total filterable residue) and the calculation of the Langelier Index (LI) in accordance with subsection 11.1.3.1. The determination of corrosivity characteristics shall only include one (1) round of sampling (two (2) samples per plant for surface water and one sample per plant for ground water sources). However, the Division may require addition or more frequent monitoring as appropriate. In addition, the Division has the discretion to require monitoring for additional parameters which may indicate corrosivity characteristics such as sulfates and chlorides. In certain cases, the Aggressive Index (AI) as described in subsection 11.1.3.2 can be used instead of the LI. The Division will make this determination. Waters exhibiting a LI of less than -2.0 or an AI of less than 10.0 shall be considered highly corrosive/aggressive.

11.1.2 Reporting to the Division: The supplier of water shall report to the Division the results of the analyses for corrosivity characteristics pursuant to subsection 4.1.1.

11.1.3 Analytical Methodology: Analyses conducted to determine the corrosivity of the water shall be made in accordance with the following methods:

11.1.3.1 Langelier Index -- "Standard Methods for the Examination of Water and Wastewater," 19th Edition, Method 203.

11.1.3.2 Aggressive Index -- "AWWA Standard for Asbestos-Cement Pipe, 4 in. through 24 in. for Water Other Liquids," AWWA C400-77, Revision of C400-75, AWWA, Denver, Colorado.

11.1.3.3 Total Filterable Residue -- "Standard Methods for the Examination of Water and Wastewater," 19th Edition, Method 208B, or "Methods of Chemical Analysis of Water and Wastes," Method 160.1.

11.1.3.4 Temperature, Calcium, Alkalinity, and pH -- in accordance with 40 CFR 141.23(k)(1). Copies may be obtained from the Office of Drinking Water.

11.1.3.5 Chloride and Sulfate - in accordance with 40 CFR 143.4. Copies may be obtained from the Office of Drinking Water.

11.1.3.6 Any alternate analytical technique approved by the Division.

11.1.4 Reporting of Construction Materials: PWSs shall identify whether the following construction materials are present in their distribution system and report to the Division:

11.1.4.1 Lead from piping, solder, caulking, interior lining of distribution mains, alloys and home plumbing.

11.1.4.2 Copper from piping and alloys, service lines and home plumbing.

11.1.4.3 Galvanized piping, service lines and home plumbing.

11.1.4.4 Ferrous piping materials such as cast iron and steel.

11.1.4.5 Asbestos cement pipe.

11.1.4.6 Vinyl lined asbestos cement pipe.

11.1.4.7 Coal tar lined pipes and tanks.

11.1.4.8 In addition, the Division may require identification and reporting of other materials of construction present in distribution systems that may contribute contaminants to the drinking water.

16 Del. Admin. Code § 4462-11.0

19 DE Reg. 517( 12/1/2015) (Final)