Laserfiche WebLink
c) The Permittee has demonstrated compliance with the water quality <br /> limit for turbidity: <br /> 1) No more than 5 NTUs over background turbidity, if background <br /> is less than 50 NTUs,or <br /> 2) No more than 10%over background turbidity, if background is <br /> 50 NTUs or greater; or <br /> d) The discharge stops or is eliminated. <br /> D. pH Sampling Requirements—Significant Concrete Work or Engineered Soils <br /> If construction activity results in the disturbance of 1 acre or more, and involves <br /> significant concrete work(significant concrete work means greater than 1000 cubic <br /> yards poured concrete used over the life of a project)or the use of recycled concrete or <br /> engineered soils(soil amendments including but not limited to Portland cement-treated <br /> base [CTB],cement kiln dust[CKD]„or fly ash),and stormwater from the affected area <br /> drains to surface waters of the State or to a storm sewer system that drains to surface <br /> waters of the State,the Permittee must conduct pH sampling as set forth below.Note: In <br /> addition, discharges to segments of water bodies on Washington State's 303(d) list <br /> (Category 5) for high pH are subject to a numeric effluent limit for pH;refer to Special <br /> Condition S8. <br /> 1. For sites with significant concrete work,the Permittee must begin the pH sampling <br /> period when the concrete is first poured and exposed to precipitation, and continue <br /> weekly throughout and after the concrete pour and curing period,until stormwater <br /> pH is in the range of 6.5 to 8.5 (su). <br /> 2. For sites with recycled concrete,the Permittee must begin the weekly pH sampling <br /> period when the recycled concrete is first exposed to precipitation and must <br /> continue until the recycled concrete is fully stabilized and stormwater pH is in the <br /> range of 6.5 to 8.5 (su). <br /> 3. For sites with engineered soils,the Permittee must begin the pH sampling period <br /> when the soil amendments are first exposed to precipitation and must continue <br /> until the area of engineered soils is fully stabilized. <br /> 4. During the applicable pH monitoring period defined above,the Permittee must <br /> obtain a representative sample of stormwater and conduct pH analysis at least once <br /> per week. <br /> 5. The Permittee must sample pH in the sediment trap/pond(s) or other locations that <br /> receive stormwater runoff from the area of significant concrete work or engineered <br /> soils before the stormwater discharges to surface waters. <br /> 6. The benchmark value for pH is 8.5 standard units. Anytime sampling indicates that <br /> pH is 8.5 or greater,the Permittee must either: <br /> Construction Stormwater General Permit <br /> Page 19 <br />