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4.2.2 pH Sampling <br /> pH monitoring is required for"Significant concrete work" (i.e., greater than 1000 cubic yards <br /> poured concrete over the life of the project).The use of recycled concrete or engineered soils <br /> (soil amendments including but not limited to Portland cement-treated base [CTB], cement kiln <br /> dust [CKD] or fly ash) also requires pH monitoring. <br /> For significant concrete work, pH sampling will start the first day concrete is poured and <br /> continue until it is cured, typically three (3)weeks after the last pour. <br /> For engineered soils and recycled concrete, pH sampling begins when engineered soils or <br /> recycled concrete are first exposed to precipitation and continues until the area is fully <br /> stabilized. <br /> If the measured pH is 8.5 or greater, the following measures will be taken: <br /> 1. Prevent high pH water from entering storm sewer systems or surface water. <br /> 2. Adjust or neutralize the high pH water to the range of 6.5 to 8.5 su using appropriate <br /> technology such as carbon dioxide (CO2) sparging (liquid or dry ice). <br /> 3. Written approval will be obtained from Ecology prior to the use of chemical treatment <br /> other than CO2 sparging or dry ice. <br /> Method for sampling pH: TBD <br /> Table 9— pH Sampling Method <br /> ❑ pH meter <br /> ® pH test kit <br /> [❑ Wide range pH indicator paper <br /> Page 125 <br />