Addendum I to Request for Qualifications for Large Capital Projects Engineering Services

Transcription

1 Purchasing Department (O) (F) Mauldin Rd. Greenville, SC Addendum I to Request for Qualifications for Large Capital Projects Engineering Services Posting Date: July 7, 2016 In published Request for Qualifications for Large Capital Projects Engineering Services please note the following update(s): Add the following Section 3.6.c: c. For the appropriate category, provide a project approach and schedule for the hypothetical project described in the attached exhibits. Project approach should address all activities and project related aspects to be considered to complete the projects described. If you have any questions and/or concerns, please do not hesitate to contact Julie Dacus at JulieD@re-wa.org or Stephanie Selman at StephanieS@re-wa.org. Page 1 of 5

2 EXHIBIT A: PROJECT APPROACH CONVEYANCE Project Scope: Eliminate three existing pump stations that currently pump with a new 24-inch gravity sewer and a 3- MGD regional pump station approximately 5,000 feet downstream as shown in Figure 1. The pump stations to be eliminated are: Lakeside (1500 gpm current capacity) Powdersville 1 (750 gpm current capacity) Powdersville 2 (500 gpm current capacity). Currently, Powdersville 2 pumps to gravity sewer that goes to Powdersville 1, which pumps directly to Lakeside, which pumps to the collection system to the north along the Saluda River. The new regional pump station will accept flow from all three pump stations, including new service area created as a result of the project, and pump to the existing 18- inch force main, to which it will connect to for the remainder of the route. It will be located approximately one mile downstream, with a new capacity of 3 MGD. Provide a project approach and schedule that identifies all the activities and project related aspects to be considered for the design, bidding, and construction phases to complete the regional pump station, force main, and gravity sewer project detailed above. Page 2 of 5

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4 EXHIBIT B: PROJECT APPROACH - PROCESS Background The Mauldin Road WRRF is a 29 MGD facility with an average daily flow of 14 MGD. Improvements made during the upgrade completed in 2008 allow biological treatment of equalized wet weather flows up to 70 MGD. The NPDES permit includes a monthly average total phosphorus (TP) limit of 1.3 mg/l. Total nitrogen (TN) is included in the permit as monitor-and-report. The facility maintains compliance with its TP limitation primarily through an A2O process in Bioreactor 2 (BR2). BR2 is comprised of four basins, each divided into six cells (A, B, C, D, E, and F). All cells in BR2 are equipped with fine bubble diffusers for operating as aerobic zones. Normally, each basin s cells A, B, C, and D operate as anaerobic or anoxic zones by only operating their submersible mixers. Each basin is equipped with a NRCY submersible pump in Cell F to pump nitrified mixed liquor through a pre-anoxic channel to strip residual DO before return to Cells A, B, C, or back into F. Aeration to BR2 is provided by four (4) 500-HP Hoffman centrifugal blowers (model 67105A) installed as part of the facility improvements in These blowers also provide re-aeration air prior to effluent discharge. Scope Page 4 of 5

5 The existing blowers have reached the end of their useful life and are in need of rehabilitation or replacement. Provide a project approach for the evaluation, design, bidding, and construction phases of the BR2 blower system improvements project. The approach shall consider the following information: Air piping between the blower building and BR2 was replaced in 2009 after significant leaks were discovered in the system. Air continues to bubble up through the ground/asphalt despite the piping replacement. A reduction in the TP limit and inclusion of a total nitrogen limit may occur in the next permit cycle. Optimization of the existing BNR process is desired prior to planning for substantial capital improvements related to nutrient removal. To this end, limited denitrification is occurring in Cell D. Back-mixing is known to be occurring from Cell E to Cell D as confirmed by DO profiles. In addition, high DO concentrations (>4 mg/l) have been observed in Cell F. Provide a project approach and schedule that identifies all the activities and project related aspects to be considered to complete the Blower Improvement project identified above. Page 5 of 5