Loading...
HomeMy WebLinkAboutNC0024201_Meeting Notes_19941018NPDES DOCUMENT SCANNING COVER SHEET NC0024201 Roanoke River WWTP NPDES Permit: Document Type: Permit Issuance Wasteload Allocation Authorization to Construct (AtC) Permit Modification Complete File - Historical Engineering Alternatives (EAA) Correspondence Owner Name Change 4f Meeting Notes Instream Assessment (67b) Speculative Limits Environmental Assessment (EA) Document Date: October 18, 1994 This document is printed on reuse paper - ignore any content on the reirerse side North Carolina Division of Environmental Management Water Quality Section Environmental Sciences Branch October 18,1994 MEMORANDUM To: Don Safrit Through: Jay Saube From: Harold Quidley Subject: Site evaluation of the Roanoke Rapids WWTP discharge On September 13, 1994, a site evaluation of the Roanoke Rapids WWTP outfall (NC0024201) was conducted by Juan Mangles, Jim Fisher and Harold Quidley. The facility discharges treated wastewater (8.3 MGD) into Chockoyotte Creek approximately 100 feet upstream from the confluence with the Roanoke River. DEM previously requested that the discharge outfall be relocated from Chockoyotte Creek to the Roanoke River prior to NPDES permit reissuance. Juan Mangles (DEM) has been evaluating available data and will be making recommendations regarding the discharge relocation issue. At the time of the site evaluation, flow in the Roanoke River was being regulated at 2000 cfs (release from the Roanoke River Dam, VEPCO) to accommodate a time -of -travel study being conducted by DEM from Roanoke Rapids, 74.2 miles downstream to Hamilton. During our visit, Chockoyotte Creek appeared to be at low flow. Approximately 400 feet upstream from the outfall, Chockoyotte Creek exhibited a rocky streambed with a depth of only several inches. The effluent was bright red in color and a considerable amount of surface foaming was evident in the creek. The surface foam was evident about 75 feet upstream from the outfall in Chockoyotte Creek. Accompanying this memo are slides of Chockoyotte Creek, the effluent outfall and the Roanoke River that were taken during the September 13 site evaluation. Please return the slides to us at your convenience so we can keep them in our files. SLIDES: #1. Roanoke Rapids WWTP effluent outfall/Chockoyotte Creek. Slide taken from the right bank, looking down at outfall, right is Chockoyotte Creek upstream, left is downstream. #2. Close up view of Slide #1 (outfall), showing foaming and effluent moving upstream about 75 feet. #3. Roanoke Rapids WWTP effluent outfall pipe. Red textile dye in effluent. #4. Chockoyotte Creek at effluent outfall, slide taken from walkway at effluent pipe, looking north at the Roanoke River/Chockoyotte Creek confluence. #5. Slide taken at Chockoyotte Creek/Roanoke River confluence looking south. White pipe in background marks the effluent outfall. Note red dye in Creek. #6. Slide taken at Chockoyotte Creek/Roanoke River confluence looking east (downstream Roanoke River). Showing surface foaming from effluent dispersing in Roanoke River. #7. Same as #6, but taken from the top of the bank looking down at the confluence. #8. Same as #6 and #7, showing more of the Roanoke River. #9. Pipes crossing Chockoyotte Creek about 400 feet upstream from the Roanoke Rapids outfall. #10. Slide taken while standing on the pipe in #9. Chockoyotte Creek, about 400 feet upstream from outfall, looking downstream (north) toward the outfall. #11. Slide taken while standing on the pipe in #9. Chockoyotte Creek, about 400 feet upstream from outfall, looking upstream (south) showing low flow conditions and rocky streambed. Roanoke Rapids Sanitary District DEM's Internal Meeting AGENDA October 13,1994 1. Issue Briefing a. Facility permitted to discharge to Roanoke River mainstem b. Outfall always located approx. 200 ft upstream of mouth of Chockoyottee Creek c. Existing permit limits (25 CBOD5, no DO, no ammonia, no disinfection) based on minimum release flows of 1,000 cfs and 2,000 cfs for toxics and oxygen consuming wastes, respectively d. USGS 7Q10 flow estimate is 0.6 cfs at current discharge site e. NPDES permit re -issued in 1993 requires facility to relocate from Chockoyottee Creek to the mainstem upon expansion or prior to permit expiration in 1997 f. Facility has requested 4.6 million dollars from bonds money to upgrade existing treatment works. Upgrade will consist primarily of additional extended aeration capabilities, along with a new clarifier and disinfection facilities. Also, improvements to existing lab facilities will be included. The upgrade is not expected to improve effluent quality, according to their engineer. The upgrade is intended to bring facility into more up to date treatment works g. Existing permit NPDES requirement to relocate the outfall was linked to this upgrade in an attempt to relocate the discharge at the same time that the upgrade would have been done h. 201 Facility Plan raised some questions on the relevance of relocating the discharge. No definite answer , solution, cost analysis, or comparison of cost vs. benefits was provided. On April 21, 1994, Instream Assessment indicated that the 201 Plan should not be approved without a definite resolution to the discharge relocation. No additional information was provided to Instream Assessment i. On July 1, 1994, the Raleigh Regional Office, requests that DEM should reconsider this relocation request since "the area for construction and relocation would be very difficult, expensive, and perhaps dangerous", and "the high costs projected to relocate the discharge compared to possible limited environmental advantages (and some possible disadvantages)". Furthermore, the region requests that Technical Support and Environmental Sciences Branch conduct a study to determine if the discharge should be relocated to the center of the river with a diffuser, relocated on a river bank, or should remain at existing location. j. Shortly after, the Sanitary District conducted a study to determine DO concentration at different sites in Chockoyottee Creek, around the outfall. The data suggests that certain dilution exists in the receiving stream which results in fairly good mixing of the wastewater in the receiving stream. It is speculated that water from the river enters the mouth of the creek, creating a higher dilution that otherwise would exist in a 0.6 cfs flow stream. The extent of this upstream flux into Chockoyottee Creek has not been assessed. k. Since this small study was conducted by the District in July, ESB did not consider it was necessary for DEM to conduct any additional investigations. This decision was made without consultations with Technical Support 1. Constructions Grants had prioritized this project due to the relocation requirement. Therefore, Construction Grants requested the relocation issue to be resolved now and speculative permit limits for the existing point of discharge be provided if the discharge were to remain at the existing location upon permit renewal m. Technical Support believes that the relocation may not be warranted. Some valid points of concern exist which may not justify this relocation n. Construction Grants wanted a prompt answer on the relocation issue, so that funds could be released o. Technical Support developed limits with the best available information and agreed to allow the discharge to remain at existing site. Memo did not go out. p. On September 26, 1994, Don Safrit notified Construction Grants that relocation of the discharge was not necessary with this upgrade. He indicated that the relocation issue needed to be studied further q. Current limits apply until expiration in 1997 2. Difficulty in developing effluent limitations in that site a. Level b is not appropriate. Existing BOD5 and new DO limit may be OK b. Estimation of dilution for toxic limits (including ammonia) & whole effluent Toxicity test c. Standard operational procedures are not appropriate 3. Should Construction Grants funds be withheld until limits are developed? Upgrade and design may be different. $ could be saved! 4. Open Discussion of Options a.Effluent limits b.Effluent Channel c. EMC variance 5. Wrap-up. Next step.