Inquiry 8491317 Response.pdf
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- Solicitation number
- W912ES20B0014
About this file
This document contains a response to an inquiry regarding water quality standards for a federal contract opportunity to transfer dredge material from the McMillan Island placement site to the Buck Creek placement site in Iowa.
The response outlines the current applicable water quality standards for the Buck Creek discharge point as designated by the Iowa DNR, including thresholds for turbidity, dissolved oxygen, pH, and temperature. Background water quality data collection is required before, during, and after the project. Sampling reference points should be located upstream at least 50 feet above the mixing zone and downstream at least 50 feet below. The related federal contract opportunity is issued by the U.S. Army Corps of Engineers seeking bids to hydraulically transfer approximately 125,000 cubic yards of dredge material for the project. The solicitation is unrestricted and has an estimated value between $1-5 million.
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Response to Inquiry ID 8491317 – RE: Section 401 Water Quality
Attached area the current IA DNR state water quality standards. More information can be found on their state webpage here: https://www.iowadnr.gov/Environmental-Protection/Water-Quality/Water- Quality-Standards
The pdf (attached) is located here: https://www.legis.iowa.gov/docs/ACO/chapter/567.61.pdf
It is important to note that these could change at any time, so contractors should refer to the website and the current water quality standards included in Chapter 61 of the state's administrative code (Section 567) before starting the project. I've outlined the requested standards below as of today, but contractor's should verify these values closer to the project construction timeline to be certain.
As stated in the attached 401 Water Quality Certification document (effective June 25, 2014), this reach of Buck Creek is designated Class A2 (Secondary Contact Recreational Use); Class HH (Human Health);
and also Cold Water Aquatic Type - Type 1 Class B(CW1). Definitions for each of these classes are listed in the attached IA DNR State Water Quality Standards(Chapter 61, Section 567). To my knowledge, these designations and classifications are still current today. Cross-referencing these classifications with the existing standards would yield the following thresholds for the Buck Creek discharge point:
Turbidity:
61.3(2)
f. The turbidity of the receiving water shall not be increased by more than 25 Nephelometric turbidity units (NTUs) by any point source discharge.
Dissolved Oxygen (from Table 2):
Minimum value for at least 16 hours of every 24-hour period = 7.0 Minimum value at any time during every 24-hour period = 5.0
PH: 61.3(3)(b)(2) pH. The pH shall not be less than 6.5 nor greater than 9.0. The maximum change permitted as a result of a waste discharge shall not exceed 0.5 pH units.
Temperature: 61.3(3)(b)(2) Temperature.
2. No heat shall be added to streams designated as cold water fisheries that would cause an increase of more than 2°C. The rate of temperature change shall not exceed 1°C per hour. In no case shall heat be added in excess of that amount that would raise the stream temperature above 20°C.
Above are the current standards for the requested metrics as of today. Keep in mind that there are other water quality requirements listed in Chapter 61 that may apply such as for Ammonia, E. Coli, TSS, and other chemical constituents. See also paragraph 6, 7, and 8 in the attached Water Quality Certification for more information.
Background data is to be collected before the project, but closer to the project construction timeline. As we discussed previously, the contractor should minimally collect background data before the project starts, and tests should continue during and for a short time after the project concludes.
As far as reference points go for water quality sampling, the reference points should be upstream at least 50 feet above the mixing zone and the sampling point should be at least 50 feet below the mixing zone. Reference points could be slightly further away depending upon accessibility to Buck Creek so long as they are in a reasonable location to collect the intended information.
File details come from the government source that posted it. Updated .