Laserfiche WebLink
1 <br />A copy of this record should be given to the client/contractor who should retain the <br />record for three years. <br />BMP C253: pH Control for High pH Water <br />Purpose <br />When pH levels in stormwater rise above 8.5 it is necessary to lower the pH levels to the <br />acceptable range of 6.5 to 8.5, this process is called pH neutralization. Stormwater with <br />pH levels exceeding water quality standards may be treated by infiltration, dispersion in <br />vegetation or compost, pumping to a sanitary sewer, disposal at a permitted concrete <br />batch plant with pH neutralization capabilities, or carbon dioxide sparging. BMP C252: <br />High pH Neutralization Using CO2 (p.409) gives guidelines for carbon dioxide sparging. <br />Reason for pH Neutralization: <br />A pH level range of 6.5 to 8.5 is typical for most natural watercourses, and this pH range <br />is required for the survival of aquatic organisms. Should the pH rise or drop out of this <br />range, fish and other aquatic organisms may become stressed and may die. <br />Conditions of Use <br />Causes of High pH: <br />High pH levels at construction sites are most commonly caused by the contact of storm - <br />water with poured or recycled concrete, cement, mortars, and other Portland cement or <br />lime containing construction materials. (See BMP C151: Concrete Handling (p.313) for <br />more information on concrete handling procedures). The principal caustic agent in <br />cement is calcium hydroxide (free lime). <br />Design and Installation Specifications <br />Disposal Methods: <br />Infiltration <br />. Infiltration is only allowed if soil type allows all water to infiltrate (no surface runoff) <br />without causing or contributing to a violation of surface or ground water quality <br />standards. <br />. Infiltration techniques should be consistent with Chapter V-7 -Infiltration and Biore- <br />tention Treatment Facilities (p.957) <br />Dispersion <br />Use BMP T5.30: Full Dispersion (p.939) <br />Sanitary Sewer Disposal <br />. Local sewer authority approval is required prior to disposal via the sanitary sewer. <br />2014 Stormwater Management Manual for Westem Washington <br />Volume 11 - Chapter 4 - Page 412 <br />