NATIONAL POLLUTANT DISCHARGE ELIMINATION SYSTEM (NPDES) PERMIT Permit Evaluation Review Report Oregon Department of Environmental Quality 2020 SW Fourth Avenue, Suite 400 Portland, Oregon 97201 503-229-5263 FAX 503-229-6945 Final Permittee: City of Portland Facility Location: Bureau of Water Works 16400 NE Airport Way, Portland Oregon. 2010 N Interstate Ave. Portland OR 97227 Sources Covered: Numerous Receiving Stream: Columbia River, Johnson Creek, Columbia Slough, Bull Run River, Sandy River, and various other streams and creeks Source Category: Minor industrial Proposed Action: Permit modification File Information: Source Contact: WQ-Multnomah County Curt Ireland, PE File No. 70730 503/823-7598 EPA Reference No.: OR-003113-5 Application Date: 26 July 2005 Application No. 980672 Permit No. 101617 Preparer: Date Prepared: Elliot Zais, PhD, PE 15 October 2007 Water Quality Source Control Section Preparer, Signature: Northwest Region 503/229-5292 / - Portland Water Bureau Evaluation Report Page 2 of 23 Fact sheets are required by EPA regulations to include the following items when applicable. A brief description of the type of facility or activity which is the subject of the draft permit; The type and quantity of wastes, fluids, or pollutants which are proposed to be or are being treated, stored, disposed of, injected, emitted, or discharged. A brief summary ofthe basis for the draft permit conditions including references to applicable statutory or regulatory provisions and appropriate supporting references to the administrative record required by §124.9 (for EPA-issued permits); Reasons why any requested variances or alternatives to required standards do or do not appear justified; A description of the procedures for reaching a final decision on the draft permit including: (i)The beginning and ending dates of the comment period under §124.10 and the address where comments will be received; (ii) Procedures for requesting a hearing and the nature of that hearing; and (iii) Any other procedures by which the public may participate in the final decision. Name and telephone number of a person to contact for additional information. Justification for waiver of any application requirements under §122.21 (j) or (q) of this chapter. Any calculations or other necessary explanation of the derivation of specific effluent limitations and conditions or standards for sewage sludge use or disposal, including a citation to the applicable effluent limitation guideline, performance standard, or standard for sewage sludge use or disposal as required by §122.44 and reasons why they are applicable or an explanation of how the alternate effluent limitations were developed. When the draft permit contains any of the following conditions, an explanation of the reasons that such conditions are applicable: (i) Limitations to control toxic pollutants under §122.44(e) of this chapter; (ii) Limitations on internal waste streams under §122.45(1) of this chapter; (iii) Limitations on indicator pollutants under §125.3(g) of this chapter; (iv) Limitations set on a case-by-case basis under §125.3 (c)(2) or (c)(3) of this chapter, or pursuant to Section 405(d)(4) of the CWA; (v) Limitations to meet the criteria for permit issuance under §122.4(i) of this chapter, or (vi) Waivers from monitoring requirements granted under §122.44(a) of this chapter. INTRODUCTION The City of Portland owns and operates a ground water pump station located at 16400 NE Airport Way, Portland Oregon. The City's NPDES permit was renewed in 2004. It expires on 31 December 2007. FACILITY DESCRIPTION AND UPDATE The facility was completed in 1984. The primary purpose ofthe station is to receive ground water from 27 existing wells in the area and pump it to the Powell Butte Reservoir for Portland Water Bureau Evaluation Report Page 3 of 23 distribution to the City's water supply system. Pumping is accomplished with six 14 000 gpm turbine pumps. Total pumping capacity is 120 MGD. The City also occasionally drains water supply conduits for scheduled maintenance. These discharges are included under this permit with appropriate monitoring and reporting requirements. The City normally drains conduits into dry wash areas where discharge will not affect stream water quality. In areas where this is not practical, the City reduces the discharge chlorine concentration by either flushing the conduit with non-chlorinated water or by dechlorinating the water with ascorbic acid (vitamin C). The following discussion is taken from the City's 2004 renewal application. It is still relevant. The Water Bureau originally applied for this permit in 1982 solely for the discharge of potable water to the Columbia River that would result from proposed electrical power generation activities. Other than an initial test run, no hydroelectric operations have been conducted since. The conduit blowoffs were added during the permit renewal in 1987. More groundwater collection system outfalls were added during the last permit renewal and the 1998-1999 permit modification process. This permit has slowly evolved over time to cover most of the outfalls associated with the Bureau's water supply system. Over this same period, we have developed a better understanding of NPDES permitting requirements. Given this, it makes sense at this time to include the remaining outfalls in this permit renewal application. This will result in the final permit applying to all established points of discharge for the water supply system. These outfalls are associated with Powell Butte Reservoir and the blowoffs on the inlet and outlet transmission lines connecting the Ground Water Pump Station, the three Bull Run conduits and the Powell Butte Reservoir. By including these sites in this permit renewal, it is our intent to rectify any prior omissions. Attached are a site map and a written description of the discharges occurring at Powell Butte Reservoir (Attachment 005). Drawings ofthe conduit inter-ties with blowoff locations are included in Attachment (005 A-L). A GIS map ofthe blowoffs on the Groundwater Transmission Main and Powell Butte Inlet and outlet Lines are also included in this attachment. As we have discussed previously, the Bureau is planning to build a pump to waste line to the Columbia River for the Blue Lake Aquifer wells. At this writing, construction is approximately two years out. It will almost certainly occur within this upcoming permit cycle so we are going to include this new outfall with this permit renewal application. This future outfall will be designated as 001-F. Attached is a map showing the approximate location of the proposed outfall and a preliminary drawing showing its construction (Attachment 001-F) During this last permit cycle there have been a number of changes with regard to the groundwater system. Three new Aquifer Storage and Recovery (ASR) wells Portland Water Bureau Evaluation Report Page 4 of 23 have been drilled and one existing well has been modified for ASR. In compliance with DHS rules, all four of these wells have dedicated pump to waste lines. Well 35 was drilled at the same location as Wells 26 and 32 and discharges from the pump to waste line also go to Outfall 001-C. Well 36 is located on the Ground Water Pump Station site and its pump-to-waste line discharges to Outfall 001-A as described in our letter of May 15, 2002. Well 37 was drilled at the old Well 23 site on Holman Street. The pump to waste line discharges into a Multnomah County Drainage District (MCDD) ditch adjacent to the site. Water travels westward going under I-205 and enters the Port of Portland storm sewer system. Eventually it enters the Slough just west of Glass Plant Road via a MCDD outfall. We propose to designate the outfall for the discharges from this well as Outfall 001-G. Attached is a map ofthe site, outfall construction details, and a map showing the path taken by water discharged from the pump to waste line (Attachment 001-G). Well 8 was modified to become an ASR well. A new pump to waste line was constructed at the site. This line discharges into a ditch that is part of the City of Gresham storm sewer system and eventually enters the Columbia Slough just east of 185th Avenue. We propose to designate the outfall for the discharges from this well as Outfall 001-H. Attached is a map ofthe site and a map showing the path taken by water discharged from the pump to waste line (Attachment 001-H). Also included with this attachment are details ofthe outfall structure. While preparing this renewal application package, it became apparent that there was a need for better identifying each outfall specifically. Previously, the groundwater collection system outfalls were identified as Outfalls 001-A through 001-E and the conduit blowoffs as 002 (various) with each one identified by its conduit station number listed in a table. There were slightly over one hundred conduit blowoffs listed. In order to simplify things and assign each outfall a unique identifier, we propose to modify the outfall numbering system as follows: Outfall 001 series - Ground Water Pump Station and groundwater collection system Outfall 002 series - Conduit 2 blowoffs Outfall 003 series - Conduit 3 blowoffs Outfall 004 series - Conduit 4 blowoffs Outfall 005 series - Powell Butte Reservoir and inlet/outlet line blowoffs In addition to the attachments mentioned above, we have provided the following information as attachments to Form 2C: Attachment 1 is a table listing all the discharge points (outfalls) for the water supply system. Table I - Outfall Locations provides information pertaining to location, flow rates and volumes, and receiving system for each outfall. This table is intended to fulfill the requirements of Part I of Form 2C. Portland Water Bureau Evaluation Report Page 5 of 23 Attachment 2 shows schematic drawings of the water supply system and the entire supply and distribution system.