Wells must be constructed in accordance with sealing standards under this chapter. In gravel-packed wells, the gravel mixture shall be placed around the screen so that bridging or size separation does not occur. The gravel pack must be clean, and chemically stable. All gravel and water used must be disinfected with at least fifty parts per million chlorine for a contact time of at least thirty minutes. Rinse water containing chlorine is a pollutant. Chlorine in the rinse water must be allowed to dissipate and the water must be discharged in a safe manner consistent with the intent of the Water Pollution Control Act, chapter 90.48 RCW.