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4.2.2 pH Sampling 1 pH monitoring is required for"Significant concrete work" (i.e., greater than 1000 cubic yards poured concrete over the life of the project). The use of recycled concrete or engineered soils (soil amendments including but not limited to Portland cement-treated base [CTB], cement kiln dust[CKD] or fly ash)also requires pH monitoring. I For significant concrete work, pH sampling will start the first day concrete is poured and continue until it is cured, typically three (3)weeks after the last pour. For engineered soils and recycled concrete, pH sampling begins when engineered soils or recycled concrete are first exposed to precipitation and continues until the area is fully Istabilized. If the measured pH is 8.5 or greater, the following measures will be taken: I1. Prevent high pH water from entering storm sewer systems or surface water. 2. Adjust or neutralize the high pH water to the range of 6.5 to 8.5 su using appropriate I technology such as carbon dioxide (CO2) sparging (liquid or dry ice). 3. Written approval will be obtained from Ecology prior to the use of chemical treatment other than CO2 sparging or dry ice. IMethod for sampling pH: Table 9—pH Sampling Method I ❑ pH meter ❑ pH test kit ❑ Wide range pH indicator paper I ® To be determined I I I I I I IPage 128