The URL can be used to link to this page

Home My WebLink AboutNC0026051_Request for Authorization Pkg_201801260 BLACK&VEATCH January 26, 2018 Black & Veatch International Corporation 11000 Regency Parkway, Suite 410, Cary, NC 27518 P +1919 462-7512 E ProffitKB@bv.com Mr. Ron Berry B&V Project 194729 North Carolina Department of Environment and Natural Resources B&V File 30.2000 Division of Water Resources/NPDES 512 N. Salisbury Street, 91h Floor Raleigh, North Carolina 27604 Attention: Mr. Ron Berry Subject: Request for Authorization to Construct Triangle WWTP Aeration System Improvements Project On behalf of Durham County, Black & Veatch is requesting an Authorization to Construct for the Triangle WWTP Aeration System Improvements Project. The project is categorized as plant facility modifications and is generally described as follows: Aeration system improvements within existing BNR Train No. 2 at the Triangle Wastewater Treatment Plant (WWTP) including addition of diffused aeration equipment and two aeration blowers; in-kind replacement of existing submersible mixing and pumping equipment; and basin cleanout to remove and dispose of all wastewater, solids, and debris. The construction timeline is as follows: Notice to Proceed to Substantial Completion 240 Calendar Days Notice to Proceed to Final Completion 270 Calendar Days We are hereby transmitting the following items for your review: • Application for Authorization to Construct • One set of Plans (22 x 34 size) • One set of Specifications • One copy of plant NPDES Permit NC0026051 • One copy of Basis of Design Report • One copy of Engineering Calculations notebook with supporting documentation • One electronic copy on CD of all above items Please contact me if you have any questions about the project or require additional information. can be reached at 919-462-7512 or e-mail at ProffitKBObv.com. Very truly yours, Black & Veatch International Company 1 i l Kurtis B. Proffit, P.E. Engineering Manager ZEK Enclosure(s) cc: Kyle Manning, DCo BUILDING A WORLD OF DIFFERENCE' K, Water Resources ENVIRONMENTAL QUALITY State of North Carolina Department of Environmental Quality Division of Water Resources APPLICATION FOR AUTHORIZATION TO CONSTRUCT PERMIT (FORM ATC -12-14) SECTION 1: INSTRUCTIONS AND INFORMATION A. The Division of Water Resources will accept this application package for review only if all of the items are provided and the application is complete. Failure to submit all of the required items will result in the application package being returned as incomplete per 15A NCAC 02T .0105(b). B. Plans and specifications must be prepared in accordance with 15 NCAC 02H. 0100, 15A NCAC 02T, North Carolina General Statute 133-3, North Carolina General Statute 143-215.1, and Division of Water Resources Minimum Design Criteria for NPDES Wastewater Treatment Facilities. C. The plans and specifications submitted must represent a completed final design that is ready to advertise for bid. D. Any content changes made to this Form ATC -12-14 shall result in the application package being returned. E. The Applicant shall submit ONE ORIGINAL and ONE DIGITAL COPY (CD) of the application, all supporting documentation and attachments. All information must be submitted bound or in a 3 -ring binder, with a Section tab for each Section, except the Engineering Plans. F. Check the boxes below to indicate that the information is provided and the requirements are met. G. If attachments are necessary for clarity or due to space limitations, such attachments are considered part of the application package and must be numbered to correspond to the item referenced. H. For any project that requires review under the State Environmental Policy Act (SEPA), an Authorization to Construct cannot be issued prior to the completion of a State Clearinghouse advertisement period for a FONSI, EIS, etc. unless the project qualifies for a Determination of Minor Construction Activity. I. For more information, visit the Division of Water Resources web site at: https://deg.nc.gov/about/divisions/water- resources/water-resources-permits/wastewater-branch/npdes-wastewater/authorization-to-construct. J. In addition to this Authorization to Construct, the Applicant should be aware that other permits may be required from other Sections of the Division of Water Resources (for example: reclaimed water facilities permits; Class A or B biosolids residuals permit). SECTION 2: APPLICANT INFORMATION AND PROJECT DESCRIPTION A. APPLICANT Applicant's name Durham County Signature authority's name per 15A NCAC 02T .0106(b) Stephanie Brixey Signature authority's title Interim Deputy Director/ POTW Director Complete mailing address 5926 Highway 55 East, Durham, NC 27713 Telephone number (919) 560-9034 Email address sbrixey@dconc.gov B. PROFESSIONAL ENGINEER Professional Engineer's name Kurtis B. Proffit Professional Engineer's title Engineering Manager North Carolina Professional Engineer's License No. 033729 Firm name Black & Veatch International Corporation Firm License number F-0794 Complete mailing address 11000 Regency Parkway, Suite 410, Cary, NC 27518 Application for Authorization to Construct Permit (FORM ATC -12-14) Page 1 Water Resources ENVIRONMENTAL QUALITY State of North Carolina Department of Environmental Quality Division of Water Resources APPLICATION FOR AUTHORIZATION TO CONSTRUCT PERMIT (FORM ATC -12-14) Telephone number (919) 462-7512 Email address ProffitKB@bv.com C. NPDES PERMIT NPDES Permit number I NCO026051 I Current Permitted flow (MGD) — include permit flow phases if applicable 12.0 MGD D. PROJECT DESCRIPTION Provide a brief description of the project: Aeration system improvements within existing BNR Train No. 2 at the Triangle Wastewater Treatment Plant (WWTP) including addition of diffused aeration eauiament and two aeration blowers: in-kind replacement of existing submersible mixing and oumpine eauioment: and basin cleanout to remove and dispose of all wastewater, solids, and debris. SECTION 3: APPLICATION ITEMS REQUIRED FOR SUBMITTAL FOR ALL PROJECTS A. Cover Letter ® The letter must include a request for the Authorization to Construct; the facility NPDES Number; a brief project description that indicates whether the project is a new facility, facility modification, treatment process modification, or facility expansion; the construction timeline; and a list of all items and attachments included in the application package. ® If any of the requirements of 15 NCAC 02H. 0100, 15A NCAC 02T, North Carolina General Statute 133-3. North Carolina General Statute 143-215.1, and Division of Water Resources Minimum Design Criteria for NPDES Wastewater Treatment Facilities are not met by the proposed design, the letter must include an itemized list of the requirements that are not met. B. NPDES Permit ® Submit Part I of the Final NPDES permit for this facility that includes Part A (Effluent Limitations and Monitoring Requirements) for the monthly average flow limit that corresponds to the work that is requested for this project. C. Special Order by Consent ❑ If the facility is subject to any Special Orders by Consent (SOC), submit the applicable SOC. ® Not Applicable. D. Finding of No Significant Impact or Record of Decision ❑ Submit a copy of the Finding of No Significant Impact or Record of Decision for this project. ❑ Provide a brief description of any of the mitigating factors or activities included in the approved Environmental Document that impact any aspect of design of this project, if not specified in the Finding of No Significant Impact or Record of Decision. ® Not Applicable. Application for Authorization to Construct Permit (FORM ATC -12-14) Page 2 State of North Carolina j ' Department of Environmental Quality Division of Water Resources Water Resources ENVIRONMENTAL QUALITY APPLICATION FOR AUTHORIZATION TO CONSTRUCT PERMIT (FORM ATC -12-14) E. Engineering Plans ® Per 15A NCAC 02T .0504(c)(1), submit one set of detailed plans that have been signed, sealed and dated by a North Carolina Licensed Professional Engineer. ® Per 21 NCAC 56.1103(a)(6), the name, address and License number of the Licensee's firm shall be included on each sheet of the engineering drawings. ® Plans must be labeled as follows: FINAL DRAWING — FOR REVIEW PURPOSES ONLY— NOT RELEASED FOR CONSTRUCTION. ® 15A NCAC 02H .0124 requires multiple (dual at a minimum) components such as pumps, chemical feed systems, aeration equipment and disinfection equipment. Is this requirement met by the design? ® Yes or ❑ No. If no, provide an explanation: Plans shall include: ® Plans for all applicable disciplines needed for bidding and construction of the proposed project (check as appropriate): ® Civil ❑ Not Applicable ® Process Mechanical ❑ Not Applicable ® Structural ❑ Not Applicable ® Electrical ❑ Not Applicable ® Instrumentation/Controls ❑ Not Applicable ❑ Architectural ® Not Applicable ❑ Building Mechanical ® Not Applicable ❑ Building Plumbing ® Not Applicable ® Plan and profile views and associated details of all modified treatment units including piping, valves, and equipment (pumps, blowers, mixers, diffusers, etc.) ® Are any modifications proposed that impact the hydraulic profile of the treatment facility? ❑ Yes or ® No. If yes, provide a hydraulic profile drawing on one sheet that includes all impacted upstream and downstream units. The profile shall include the top of wall elevations of each impacted treatment unit and the water surface elevations within each impacted treatment unit for two flow conditions: (1) the NPDES permitted flow with all trains in service and (2) the peak hourly flow with one treatment train removed from service. ® Are any modifications proposed that impact the process flow diagram or process flow schematic of the treatment facility? ❑ Yes or ® No. If yes, provide the process flow diagram or process flow schematic showing all modified flow paths including aeration, recycle/return, wasting, and chemical feed, with the location of all monitoring and control instruments noted. F. ® Engineering Specifications ® Per 15A NCAC 02T .0504(c)(2), submit one set of specifications that have been signed, sealed and dated by a North Carolina Licensed Professional Engineer. ® Specifications must be labeled as follows: FINAL SPECIFICATIONS — FOR REVIEW PURPOSES ONLY — NOT RELEASED FOR CONSTRUCTION. Specifications shall include: ® Specifications for all applicable disciplines needed for bidding and construction of the proposed project (check as appropriate): ® Civil ❑ Not Applicable ® Process Mechanical ❑ Not Applicable Application for Authorization to Construct Permit (FORM ATC -12-14) Page 3 State of North Carolina Department of Environmental Quality Division of Water Resources Water Resources ENVIRONMENTAL QUALITY APPLICATION FOR AUTHORIZATION TO CONSTRUCT PERMIT (FORM ATC -12-14) ® Structural ❑ Not Applicable ® Electrical ® Instrumentation/Controls ❑ Architectural ❑ Building Mechanical ❑ Building Plumbing ❑ Not Applicable ❑ Not Applicable ® Not Applicable ® Not Applicable ® Not Applicable ® Detailed specifications for all treatment units and processes including piping, valves, equipment (pumps, blowers, mixers, diffusers, etc.), and instrumentation. ® Means of ensuring quality and integrity of the finished product including leakage testing requirements for structures and pipelines, and performance testing requirements for equipment. ® Bid Form for publicly bid projects. G. Construction Sequence Plan ® Construction Sequence Plan such that construction activities will not result in overflows or bypasses to waters of the State. The Plan must not imply that the Contractor is responsible for operation of treatment facilities. List the location of the Construction Sequence Plan as in the Engineering Plans or in the Engineering Specifications or in both: Specification Section 01310 — Construction Scheduling H. Engineering Calculations ® Per 15A NCAC 02T .0504(c)(3), submit one set of engineering calculations that have been signed, sealed and dated by a North Carolina Licensed Professional Engineer; the seal, signature and date shall be placed on the cover sheet of the calculations. For new or expanding facilities and for treatment process modifications that are included in Section 4.C, the calculations shall include at a minimum: ❑ Demonstration of how peak hour design flow was determined with a justification of the selected peaking factor. ❑ Influent pollutant loading demonstrating how the design influent characteristics in Section 4.6.2 of this form were determined. ❑ Pollutant loading for each treatment unit demonstrating how the design effluent concentrations in Section 4.13.2 of this form were determined. ❑ Hydraulic loading for each treatment unit. ® Sizing criteria for each treatment unit and associated equipment (blowers, mixers, pumps, etc.) ❑ Total dynamic head (TDH) calculations and system curve analysis for each pump specified that is included in Section 4.C.6. ❑ Buoyancy calculations for all below grade structures. ® Supporting documentation that the specified auxiliary power source is capable of powering all essential treatment units. Application for Authorization to Construct Permit (FORM ATC -12-14) Page 4 Water Resources ENVIRONMENTAL QUALITY I. Permits J. State of North Carolina Department of Environmental Quality Division of Water Resources APPLICATION FOR AUTHORIZATION TO CONSTRUCT PERMIT (FORM ATC -12-14) ® Provide the following information for each permit and/or certification required for this project: Permit/Certification Not Applicable Date Submitted Date Approved Permit/ Certification Number If Not Issued Provide Status and Expected Issuance Date Dam Safety X Soil Erosion and Sediment Control X LISCOE / Section 404 Permit X Water Quality Certification (401) X LISCOE /Section 10 X Stormwater Management Plan X CAMA X NCDOT Encroachment Agreement X Railroad Encroachment Agreement X Other: Durham Level 1 Site Plan Review To Be Submitted in February 2018 Residuals Management Plan ❑ For all new facilities, expanding facilities, or modifications that result in a change to sludge production and/or sludge processes, provide a Residuals Management Plan meeting the requirements of 15A NCAC 02T .0504(1) and 15A NCAC 02T .0508: the Plan must include: ❑ A detailed explanation as to how the generated residuals (including trash, sediment and grit) will be collected, handled, processed, stored, treated, and disposed. ❑ An evaluation of the treatment facility's residuals storage requirements based upon the maximum anticipated residuals production rate and ability to remove residuals. ❑ A permit for residuals utilization or a written commitment to the Applicant from a Permittee of a Department approved residuals disposal/utilization program that has adequate permitted capacity to accept the residuals or has submitted a residuals/utilization program application. ❑ If oil, grease, grit or screenings removal and collection is a designated unit process, a detailed explanation as to how the oil/grease will be collected, handled, processed, stored and disposed. ® Not Applicable. Application for Authorization to Construct Permit (FORM ATC -12-14) Page 5 K, Water Resources State of North Carolina Department of Environmental Quality Division of Water Resources ENVIRONMENTAL QUALITY APPLICATION FOR AUTHORIZATION TO CONSTRUCT PERMIT (FORM ATC -12-14) SECTION 4: PROJECT INFORMATION A. WASTEWATER TREATMENT PLANT FLOW INFORMATION —COMPLETE FOR NEW OR EXPANDING FACILITIES 1. Provide the following flow information: Plant Flows Existing Plant Design For Past 12 Months: Start Date: month/yr End Date: month/yr MGD MGD MGD For Past 24 Months: Start Date: month/yr End Date: month/yr Current NPDES Permit Limit Current Annual Average (past 12 months) Maximum Month MGD MGD Maximum Day MGD MGD Peak Hour MGD MGD Application for Authorization to Construct Permit (FORM ATC -12-14) Page 6 7 -r- TA I A I - Water Resources ENVIRONMENTAL QUALITY State of North Carolina Department of Environmental Quality Division of Water Resources APPLICATION FOR AUTHORIZATION TO CONSTRUCT PERMIT (FORM ATC -12-14) B. WASTEWATER TREATMENT FACILITY DESIGN INFORMATION —COMPLETE FOR NEW OR EXPANDING FACILITIES AND FOR TREATMENT PROCESS MODIFICATIONS 1. Have all of the requirements of 15 NCAC 02H. 0100, 15A NCAC 02T, North Carolina General Statute 133-3, North Carolina General Statute 143-215.1, and Division of Water Resources Minimum Design Criteria for NPDES Wastewater Treatment Facilities been met by the proposed design and specifications? ® Yes or ❑ No. If no, provide justification as to why the requirements are not met, consistent with 15A NCAC 02T .0105(n): Provide the design influent and effluent characteristics that are used as the basis for the project design, and the NPDES permit limits for the following parameters: No change to influent and effluent characteristics. The new diffused aeration system provided under this project in BNR Train No. 2 replaces existing brush aerator equipment as a more cost-effective long-term solution, when considering the energy savings of the diffused aeration system and remaining useful design life of the brush aerators. Refer to AOR calculation within the set of blower calculations which documents the basis of sizing of the diffused aeration system to be equivalent to the four existing brush aerators. �^ Project Basis of Design Design Influent Design Influent Influent Concentration Load Concentration - (Must be (Must be Current Annual supported by supported by Design Effluent Average (past Engineering Engineering Concentration and/or NPDES Permit Limits 12 months) if Calculations Calculations Load (monthly average) Parameter Available [Section 3.H]) [Section 3.H]) 1 Ammonia Nitrogen mg/L Summer 1.0 mg/L Summer (NH3-N) mg/L mg/L Ib/day mg/L Winter 1.8 mg/L Winter Biochemical mg/L Summer 5.0 mg/L Summer Oxygen Demand mg/L mg/L Ib/day (BODS) mg/L Winter 10.0 mg/L Winter Fecal Coliform per 100 mL 200 per 100 mL Nitrate + Nitrite Nitrogen (NO3-N + mg/L mg/L NO2-N) Total Kjeldahl mg/L Nitrogen mg/L mg/L Total Nitrogen Ib/year 111,207 lb/year mg/L mg/L Total Phosphorus mg/L mg/L Ib/day i Ib/year 8,432 lb/year Total Suspended mg/L mg/L Ib/day mg/L 30.0 mg/L Solids (TSS) Application for Authorization to Construct Permit (FORM ATC -12-14) Page 7 State of North Carolina ` Department of Environmental Quality Division of Water Resources Water Resources ENVIRONMENTAL QUALITY APPLICATION FOR AUTHORIZATION TO CONSTRUCT PERMIT (FORM ATC -12-14) 3. Based on the "Project Basis of Design" parameters listed above, will the proposed design allow the treatment facility to meet the NPDES Permit Limits listed above? ® Yes or ❑ No. If no, describe how and why the Permit Limits will not be met: 4. Per 15A NCAC 02T .0505(1). by-pass and overflow lines are prohibited. Is this condition met by the design? ® Yes or ❑ No If no, describe the treatment units bypassed, why this is necessary, and where the bypass discharges: 5. Per 15A NCAC 02T .0505(k), multiple pumps shall be provided wherever pumps are used. Is this condition met by the design? ® Yes or ❑ No. If no, provide an explanation: 6. Per 15A NCAC 02T.05050) power reliability shall be provided consisting of automatically activated standby power supply onsite capable of powering all essential treatment units under design conditions, or dual power supply shall be provided per 15A NCAC 02H. 0124(2)(a). Is this condition met by the design? ® Yes or ❑ No. If no, provide (as an attachment to this Application) written approval from the Director that the facility: ➢ Has a private water supply that automatically shuts off during power failures and does not contain elevated water storage tanks, and ➢ Has sufficient storage capacity that no potential for overflow exists, and ➢ Can tolerate septic wastewater due to prolonged detention. 7. Per 15A NCAC 02T .0505(o), a minimum of 30 days of residual storage shall be provided. Is this condition met by the design? ❑ Yes or ❑ No. If no, explain the alternative design criteria proposed for this project in accordance 15A NCAC 02T .105(n): Not Applicable, design does not chance existing sludge production and/or sludge processes. 8. Per 15A NCAC 02T .0505(a). the public shall be prohibited from access to the wastewater treatment facilities. Explain how the design complies with this requirement: Plant has an existing full perimeter security fence and plant entrance gate which is always closed and opens only by security code or calling into the Control Buildine reauestine the Bate be opened. The project does not impact the existing security fencing. 9. Is the treatment facility located within the 100 -year flood plain? ® Yes or ❑ No. If yes, describe how the facility is protected from the 100 -year flood: A berm surrounding the facility is raised approximately 1.4 feet above the 100 year flood elevation. C. WASTEWATER TREATMENT UNIT AND MECHANICAL EQUIPMENT INFORMATION —COMPLETE FOR NEW OR EXPANDING FACILITIES AND FOR MODIFIED TREATMENT UNITS 1. PRELIMINARY AND PRIMARY TREATMENT (i.e., physical removal operations and flow equalization): NOT APPLICABLE 2. SECONDARY TREATMENT (BIOLOGICAL REACTORS AND CLARIFIERS) (i.e., biological and chemical processes to remove organics and nutrients) Application for Authorization to Construct Permit (FORM ATC -12-14) Page 8 No. of Plan Sheet Specification TCalculations Treatment Unit Units Type Size per Unit Reference Provided? Reference (Yes or No) Aerobic Zones/ gallons Tanks Anoxic Zones/ _ gallons Tanks Anaerobic gallons Zones/Tanks Sequencing Batch 0 -- gallons Reactor (SBR) Application for Authorization to Construct Permit (FORM ATC -12-14) Page 8 Water Resources ENVIRONMENTAL OUAL•TY State of North Carolina Department of Environmental Quality Division of Water Resources APPLICATION FOR AUTHORIZATION TO CONSTRUCT PERMIT (FORM ATC -12-14) Membrane 0 -- gallons Capacity of Requirement met by the Setback Parameter Bioreactor (MBR) Design? If "No", identify plan Sheet Specification Location Secondary Clarifier Type Circular ft diameter; ft side ownership or not to be maintained as part of the project site Blowers Any private or public water supply source Reference Reference water depth Surface waters (streams — intermittent and perennial, perennial 50 ft ❑ Yes Secondary Clarifier waterbodies, and wetlands) Rectangular square feet; ft side Diffused Aeration Rotary Lobe PD 1,500 M-1 11615 ❑ No Any property line water depth ❑ Yes ❑ No Other: Diffused 2 Membrane 50'x 36' M-1 / M-2 11570 Yes Aeration Disc 3. TERTIARY TREATMENT —NOT APPLICABLE 4. DISINFECTION —NOT APPLICABLE 5. RESIDUALS TREATMENT —.NOT APPLICABLE 6. PUMP SYSTEMS (include influent, intermediate, effluent, major recycles, waste sludge, thickened waste sludge and plant drain pumps) — NOT APPLICABLE, IN-KIND WALL PUMP REPLACEMENT ONLY 7. MIXERS —NOT APPLICABLE, IN-KIND MIXER REPLACEMENT ONLY 8. BLOWERS 9. ODOR CONTROL —NOT APPLICABLE D. SETBACKS —COMPLETE FOR NEW WASTEWATER TREATMENT STRUCTURES — NOT APPLICABLE 1. The minimum distance for each setback parameter to the wastewater treatment/storage units per 15A NCAC 02T .0506(b) are as follows: Minimum Distance Is Minimum Distance Capacity of Requirement met by the Setback Parameter No. of Design? If "No", identify plan Sheet Specification Location purpose Type each Blower ❑ Yes ❑ No ownership or not to be maintained as part of the project site Blowers Any private or public water supply source Reference Reference ❑ No Surface waters (streams — intermittent and perennial, perennial 50 ft ❑ Yes (CFM) waterbodies, and wetlands) BNR Train No. 2 2 Diffused Aeration Rotary Lobe PD 1,500 M-1 11615 9. ODOR CONTROL —NOT APPLICABLE D. SETBACKS —COMPLETE FOR NEW WASTEWATER TREATMENT STRUCTURES — NOT APPLICABLE 1. The minimum distance for each setback parameter to the wastewater treatment/storage units per 15A NCAC 02T .0506(b) are as follows: 2. Have any setback waivers been obtained per 15A NCAC 02T .0506(d)? ❑ Yes or No. If yes, have these waivers been written, notarized and signed by all parties involved and recorded with the County Register of Deeds? ❑ Yes or ❑ No. If no, provide an explanation: Application for Authorization to Construct Permit (FORM ATC -12-14) Page 9 Minimum Distance Is Minimum Distance Required from Nearest Requirement met by the Setback Parameter Treatment/Storage Design? If "No", identify Unit Setback Waivers in Item D.2 Below Any habitable residence or place of assembly under separate 100 ft ❑ Yes ❑ No ownership or not to be maintained as part of the project site Any private or public water supply source 100 ft ❑ Yes ❑ No Surface waters (streams — intermittent and perennial, perennial 50 ft ❑ Yes ❑ No waterbodies, and wetlands) Any well with exception of monitoring wells 100 ft ❑ Yes ❑ No Any property line 50 ft ❑ Yes ❑ No 2. Have any setback waivers been obtained per 15A NCAC 02T .0506(d)? ❑ Yes or No. If yes, have these waivers been written, notarized and signed by all parties involved and recorded with the County Register of Deeds? ❑ Yes or ❑ No. If no, provide an explanation: Application for Authorization to Construct Permit (FORM ATC -12-14) Page 9 State of North Carolina Department of Environmental Quality Division of Water Resources Water Resources ENVIRONMENTAL QUALITY APPLICATION FOR AUTHORIZATION TO CONSTRUCT PERMIT (FORM ATC -12-14) SECTION 5: APPLICATION CERTIFICATION BY PROFESSIONAL ENGINEER Professional Engineer's Certification per 15A NCAC 02T.0105: I, Kurtis B. Proffit , attest that this application package for an Authorization to Construct (Typed Name of Professional Engineer) for the Triangle WWTP Aeration System Improvements project (Facility and Project Name) was prepared under my direct supervisory control and to the best of my knowledge is accurate, complete and consistent with the information supplied in the engineering plans, specifications, calculations, and all other supporting documentation for this project. I further attest that to the best of my knowledge the proposed design has been prepared in accordance with all applicable regulations and statutes, 15 NCAC 02H. 0100, 15A NCAC 02T, North Carolina General Statute 133-3, North Carolina General Statute 143-215.1, and Division of Water Resources Minimum Design Criteria for NPDES Wastewater Treatment Facilities, and this Authorization to Construct Permit Application, except as provided for and explained in Section 4.6.1 of this Application. I understand that the Division of Water Resources' issuance of the Authorization to Construct Permit may be based solely upon this Certification and that the Division may waive the technical review of the plans, specifications, calculations and other supporting documentation provided in this application package. I further understand that the application package may be subject to a future audit by the Division. Although certain portions of this submittal package may have been prepared, signed and sealed by other professionals licensed in North Carolina, inclusion of these materials under my signature and seal signifies that I have reviewed the materials and have determined that the materials are consistent with the project design. I understand that in accordance with General Statutes 143-215.6A and 143-215.68, any person who knowingly makes any false statement, representation, or certification in any application package shall be guilty of a Class 2 misdemeanor, which may include a fine not to exceed $10,000, as well as civil penalties up to $25,000 per violation. North Carolina Professional Engineer's seal with written signature placed over or adjacent to the seal and dated: .• N CARO `033729 :� o. ••000000000 O \ , B.P�,••%% of/,7(p/7D/g Application for Authorization to Construct Permit (FORM ATC -12-14) Page 10 State of North Carolina Department of Environmental Quality Division of Water Resources Water Resources ENVIRONMENTAL DUALITY APPLICATION FOR AUTHORIZATION TO CONSTRUCT PERMIT (FORM ATC -12-14) SECTION 6: APPLICATION CERTIFICATION BY APPLICANT Applicant's Certification per 15A NCAC 02T .0106(b): I, Stephanie Brixey, Interim POTW Director, attest that this application package for an Authorization to Construct (Typed Name of Signature Authority and Title) for the Triangle WWTP Aeration System Improvements Proiect (Facility and Project Name) has been reviewed by me and is accurate and complete to the best of my knowledge. I also understand that if all required parts of this application package are not completed and that if all required supporting information and attachments are not included, this application package will be returned to me as incomplete. I further certify that in accordance with 15A NCAC 02T .0120(b), the Applicant or any affiliate has not been convicted of environmental crimes, has not abandoned a wastewater facility without proper closure, does not have an outstanding civil penalty where all appeals have been abandoned or exhausted, are compliant with any active compliance schedule, and does not have any overdue annual fees. I understand that the Division of Water Resources' issuance of the Authorization to Construct Permit may be based solely upon acceptance of the Licensed Professional Engineer's Certification contained in Section 5, and that the Division may waive the technical review of the plans, specifications, calculations and other supporting documentation provided in this application package. I further understand that the application package may be subject to a future audit. I understand that in accordance with General Statutes 143-215.6A and 143-215.613 any person who knowingly makes any false statement, representation, or certification in any application package shall be guilty of a Class 2 misdemeanor, which may include a fine not to exceed $10,000, as well as civil penalties up to $25,000 per violation. Signature: lQ Date: 1,Q ct I a OI y THE COMPLETED APPLICATION AND SUPPORTING INFORMATION SHALL BE SUBMITTED TO: NORTH CAROLINA DEPARTMENT OF ENVIRONMENT AND NATURAL RESOURCES DIVISION OF WATER RESOURCES/NPDES By U.S. Postal Service By Courier/Special Delivery: 1617 MAIL SERVICE CENTER 512 N. SALISBURY STREET, 9TH FLOOR RALEIGH, NORTH CAROLINA 27699-1617 RALEIGH, NORTH CAROLINA 27604 TELEPHONE NUMBER: (919) 807-6351 Application for Authorization to Construct Permit (FORM ATC -12-14) Page 12 .4 CCDENR North Carolina Department of Environment and Natural Resources Division of Water Resources Water Quality Programs Pat McCrory Thomas A. Reeder John E. Skvarla, III Governor Director Secretary Mr. Joseph Pearce Utility Division Manager/POTW Director County of Durham Engineering Department/Utility Division 5926 NC Highway 55 East Durham, North Carolina 27713 Dear Mr. Pearce: August 30, 2013 Subject: Minor Modification NPDES Permit No. NCO026051 Durham County Triangle W WTP Durham County Facility Class rV 9 The Division received your request for a Minor Modification to remove condition A.(8)(c.) from the permit. The Division grants you request based on the de minimis nature of the atmospheric blowoffs of reuse water. Please insert the enclosed modified permit sheet and discard the old sheet. This permit modification becomes effective on the effective date of the permit. All other terms and conditions in the original permit remain unchanged and in full effect. These modifications are issued pursuant to the requirements of North Carolina General Statute 143-215.1 and the Memorandum of Agreement between North Carolina and the U.S. Environmental Protection Agency dated December 6, 1983. If you have any questions about the NPDES permit process, please contact me at the following e- mail address: sereei.chermkov(cr�.ncdenr.gov, or telephone. number: 919-807-6393. 1617 Mail Service Center, Raleigh, North Carolina 27699-1617 Location: 512 N. Salisbury St. Raleigh, North Carolina 27604 Phone: 919-807-63001 FAX: 919807-6492 Internet: w .ncwateroualiN.orc An Equal Opportunity 1 Affirmative Action Employer None Carolina turallbl Respectfully, Jeffrey Poupart Point Source Branch Supervisor cc: Central Files NPDES Files Raleigh Regional Office / Surface Water Protection Section EPA Region IV (e -copy) Aquatic Toxicology Unit (e -copy) Basin Coalition Coordinator (Carrie.Ruhltnan@ncdenr.gov) Permit No. NC0026051 (i.) Monthly TN (or TP) Load (lb/mo) = TN (or TP) x TMF x 8.34 where: TN or TP = the average Total Nitrogen or Total Phosphorus concentration (mg/L) of the composite samples collected during the month TMF = the Total Monthly Flow of wastewater discharged during the month (MG/mo) 8.34 = conversion factor, from (mg/L x MG) to pounds (ii.) Annual TN (or TP) Load (lb/yr) = Sum of the 12 Monthly TN (or TP) Loads for the calendar year (b.) The Permittee shall report monthly Total Nitrogen and Total Phosphorus results (mg/ L and lb/mo) in the appropriate discharge monitoring report for each month and shall report each calendar year's results (lb/yr) with the December report for that year. A.(9.) NUTRIENT MONITORING REOPENER Pursuant to N.C. General Statute Section 143-215.1 and the implementing rules found in Title 15A of the North Carolina Administrative Code, Subchapter 2H, specifically, 15A NCAC 2H.0112(b) (1) and 21-1.0114(a), and Part II, Sections B-12 and B-13 of this permit, the Director of DWQ may reopen this permit to require supplemental nutrient monitoring of the discharge. The additional monitoring will be to support water quality modeling efforts within the Cape Fear River Basin, and shall be consistent with a monitoring plan developed jointly by the Division and affected stakeholders. A.(10.) STANDARD CONDITIONS FOR NPDES PERMITS The Division will provide an updated version of the Standard Conditions for NPDES Permits to the permittee upon approval of the version by the EPA. Then, the old version shall be replaced with an updated version. North Carolina Beverly Eaves Perdue Governor NCDENR Department of Environment and Natural Resources Division of Water Quality Charles Wakild, P.E. Director January 4, 2013 Mr. Joseph Pearce, P.E. Utility Division Manager County of Durham Engineering Department/Utility Division 5926 NC Highway 55 East Durham, North Carolina 27713 Subject: NPDES Permit Modification Permit Number NCO026051 Durham County Triangle WWTP Durham County Dear Mr. Pearce: Dee Freeman Secretary Division personnel have reviewed and approved your application for minor modification of the subject permit. Accordingly we are forwarding the attached modified permit page. Please remove the existing "Effluent Limitations and Monitoring Requirements" page and replace it with the one attached to this letter. This modification reduces the effluent monitoring frequencies for Biochemical Oxygen Demand (BODS), Total Suspended Solids (TSS), Ammonia Nitrogen (NH3-N) and Fecal Coliform from daily (5/week) to 2/week monitoring. The modification was based upon an evaluation of three years of facility effluent monitoring data. The facility's performance satisfies the criteria established in the "DWQ Guidance Regarding the Reduction of Monitoring Frequencies in NPDES Permits for Exceptionally Performing Facilities" as approved by the Director of the Division of Water Quality on October 22, 2012, and justifies reduced monitoring for these parameters. The modified monitoring frequencies will become effective on February 1, 2013. This modification is issued pursuant to the requirements of North Carolina General Statute 143-215.1 and the Memorandum of Agreement between North Carolina and the U.S. Environmental Protection Agency dated October 15, 2007 (or as subsequently amended). Please note that this permit is not transferable except after notice to the Division. The Division may require modification or revocation and reissuance of the permit. This permit does not affect the legal requirements to obtain other permits which may be required by the Division of Water Quality or permits required by the Division of Land Resources, the Coastal Area Management Act or any other Federal or Local governmental permit that may be required. 1617 Mail Service Center, Raleigh, North Carolina 27699-1617 One Location: 512 N. Salisbury St. Raleigh, North Carolina 27664 NorthCarolina Phone: 919.807-63601 FAX: 919$07-6492 �/1 %aturalll, Internet: www.ncwaterquality.org An Equal Opportunity 1 ARrmalive Action Employer Mr. Joseph Pearce, P.E. NC0026051 Modification 01042013 p. 2 If you have any questions concerning this permit, please contact Bob Sledge at telephone number (919) 807-6398 or via e-mail at bob.sledge@ncdenr.gov. �kfnce ly, Charles Wakild, P.E. cc: Central Files Raleigh Regional Office/Surface Water Protection Section NPDES Permit File cc: Aquatic Toxicology Unit EPA Region 4 — Ben Ghost Permit No. NCO026051 A.(-.) EFFLUENT LIMITATIONS AND MONITORING REQUIREMENTS Beginning February 1, 2013 and lasting until expiration, the Permittee is authorized to discharge treated wastewater from Outfall 001. Such discharges shall be limited and monitored by the Permittee as specified below: EFFLUENT CHARACTERISTICS EFFLUENT LIMITATIONS MONITORING REQUIREMENTS Monthly Weekly Average Average Daily Maximum Measurement Frequency Sample Type Sample Location' Flow 12.0 MGD Continuous Recording Influent or Effluent Total Monthly Flow (MG) Monitor & Report Monthly Recorded or Calculated Influent or Effluent BOD,day, = (April it 1 — Octobedobe r 31) 5.0 mg/L 7.5 mg/L 2/Week Composite Influent & Effluent (20°C)' BOD, (November (November 1—March 31) 10.0 mg/L 15.0 mg/L 2/Week Composite Influent & Effluent Total Suspended Solids' 30.0 mg/L 45.0 mg/L 2/Week Composite Influent & Effluent NH3 as N (April 1 -October 31) 1.0 mg/L 3.0 mg/L 2/Week Composite Effluent NH3 as N (November 1 -March 31) 1.8 mg/L 5.4 mg/L 2/Week Composite Effluent Fecal Coliform (geometric mean) 200/100ml- 400/100ml- 2/Week Grab Effluent Dissolved Oxygen Daily Grab Effluent Temperature (°C) Daily Grab Effluent pH" Daily Grab Effluent Total Residual Chlorines 17 pg/L Daily Grab Effluent Chloroforms 2/Month Grab Effluent Bromodichloromethanes 1.8 pg/L Weekly Grab Effluent Dibromochloromethanes 1.3 pg/L Weekly Grab Effluent TKN Monitor & Report (mg/L) Weekly Composite Effluent NO3-N + NO2-N Monitor & Report (mg/L) Weekly Composite Effluent Total Nitrogen, TN Monitor & Report (mg/L) Weekly Composite Effluent TN Load 6•' Monitor & Report (Ib/mo) 111,207 lb/yr Monthly Annually Calculated Effluent Total Phosphorus, TP Monitor & Report Weekly Composite Effluent TP Load 6•' Monitor & Report (Ib/mo) 8,432 lb/yr Monthly Annually Calculated Effluent Total Mercury, 12 ng/L 36 ng/L Quarterly Grab Effluent Fluoride 1800 pg/L 1800 pg/L Weekly Composite Effluent Total Copper Quarterly Composite Effluent Total Zinc Quarterly Composite Effluent Chloride Quarterly Composite Effluent Effluent Pollutant Scan , See fo9otnote Composite/ rab Effluent Chronic Toxicity 10 Quarterly Composite Effluent All footnotes are listed on the following page. AGPIAV- KOWA North Carolina Department of Environment and Natural Resources Beverly Eaves Perdue Governor Mr. Joseph Pearce Utility Division Manager/POTW Director County of Durham Engineering Department/Utility Division 5926 NC Highway 55 East Durham, North Carolina 27713 Dear Mr. Pearce: Division of Water Quality Coleen H. Sullins Director October 21, 2011 i� i a Dee Freeman Secretary Subject: Issuance of NPDES Pemut NCO026051 Durham County Triangle WWTP Durham County Facility Class rV Division personnel have reviewed and approved your application for renewal of the subject permit. Accordingly, we are forwarding the attached NPDES discharge permit. This permit is issued pursuant to the requirements of North Carolina General Statute 143-215.1 and the Memorandum of Agreement between North Carolina and the U.S. Environmental Protection Agency dated October 15, 2007 (or as subsequently amended). The Final Permit contains following significant changes from the Draft Permit: • Monitoring frequency for Cu and Zn were reduced to Quarterly based on the review of the effluent data and in response to your request. • Instream monitoring for nutrients was removed from the permit to eliminate redundancy and in response to your request. • A special condition entitled Standard Conditions for NPDES Permits was added to the permit in response to your request. This Final Permit maintains the following changes contained in the Draft Permit: A weekly average limit for Hg has been removed from the permit based on a statistical analysis of the effluent data. A monitoring frequency for Hg has been reduced to quarterly due to the removal of the limit. 1617 Mail Service Center, Raleigh, North Carolina 27699-1617 Location: 512 N. Salisbury St. Raleigh, North Carolina 27604 One Phone. 919-807-63001 FAX: 919-807-64921 Customer Service: 1-877823.6748 NorthCarolina Internet: w-Dcvvaterquahly.org // An Equal Opportunity t Affirmative Action Employer )WA(rally • Instream monitoring at the downstream location D2 has been deleted based on the review of the effluent data and in response to your request. • Instream monitoring frequency at the downstream location D1 has been reduced to weekly during slimmer period for the following parameters: dissolved oxygen, temperature, conductivity, fecal Coliform, pH. The decision is based on the review of the monitoring data and in response to your request. • Monitoring frequency for annual pollutant scan has been reduced to 3 times during 5 years in response to your request. • Monitoring frequency for chlorides has been reduced to quarterly based on the review of the effluent data and in response to your request. • A monthly average limit for fluoride has been added to the permit to meet the new EPA requirement. If any parts, measurement frequencies or sampling requirements contained in this permit are unacceptable to you, you have the right to an adjudicatory hearing upon written request within thirty (30) days following receipt of this letter. This request must be in the form of a written petition, conforming to Chapter 150B of the North Carolina General Statutes, and filed with the Office of Administrative Hearings (6714 Mail Service Center, Raleigh, North Carolina 27699-6714). Unless such demand is made, this decision shall be final and binding. Please note that this permit is not transferable except after notice to the Division. The Division may require modification or revocation and reissuance of the permit. This permit does not affect the legal requirements to obtain other permits which may be required by the Division of Water Quality or permits required by the Division of Land Resources, the Coastal Area Management Act or any other Federal or Local governmental permit that may be required. If you have any questions concerning this permit, please contact Sergei Chemikov at telephone number (919) 807-6393. Sincerely, oleen H. Sullins cc: Central Files NPDES Files Raleigh Regional Office / Surface Water Protection Section EPA Region IV (e -copy) Aquatic Toxicology Unit (e -copy) Basin Coalition Coordinator Qennie.Atkins@ncdenngov) 1617 Mail Service Center, Raleigh, North Carolina 27699-1617 Location: 512 N, Salisbury St. Raleigh, North Carolina 27604 One Phone: 919-807-63001 FAX: 919.807-64921 Customer Service: 1-877.623-6748 NorthCarolina Internet: www.ncwaterquality.org Naturally //� An Equal Opportunity l Affirmative Action Employer ss Permit No. NCO026051 STATE OF NORTH CAROLINA DEPARTMENT OF ENVIRONMENT AND NATURAL RESOURCES DIVISION OF WATER QUALITY PERMIT TO DISCHARGE WASTEWATER UNDER THE NATIONAL POLLUTANT DISCHARGE ELIMINATION SYSTEM In compliance with the provisions of North Carolina General Statute 143-215.1, other lawful standards and regulations promulgated and adopted by the North Carolina Environmental Management Commission, and the Federal Water Pollution Control Act, as amended, Durham County is hereby authorized to discharge wastewater from a facility located at the Durham County Triangle WWTP 5926 NC Highway 55 Durham County to receiving waters designated as Northeast Creek in the Cape Fear River Basin in accordance with effluent limitations, monitoring requirements, and other conditions set forth in Parts I, TI, III, and N hereof. This permit shall become effective......................................................... This permit and authorization to discharge shall expire at midnight on .......... Signedthis day......................................................................... ...................................... ...........December 1, 2011. ...... April 30, 2016. October 21, 2011. VLoleen H. Sullins, Director Division of Water Quality By Authority of the Environmental Management Commission Permit No. NC0026U51 SUPPLEMENT TO PERMIT COVER SHEET All previous NPDES Permits issued to this facility, whether for operation or discharge are hereby revoked. As of this permit issuance, any previously issued permit bearing this number is no longer effective. Therefore, the exclusive authority to operate and discharge from this facility arises under the permit conditions, requirements, terms, and provisions included herein. Durham County is hereby authorized to: Continue to operate an existing 12.0 MGD wastewater treatment facility located south of Durham at the Durham County Triangle WWTP off NC Highway 55 in Durham County. The facility includes the following treatment components: • Mechanical fine screens • Mechanical grit removal • Parshall flume • Influent pump station • Three 5 -stage BNR trains • Four secondary clarifiers • Five tertiary sand filters • Ultraviolet disinfection • Post aeration • Sludge lagoon • Waste and return activated sludge pumping system • Methanol, potassium hydroxide, and sodium hypochlorite storage and feed systems • Liquid waste activated sludge storage (projected service date is the end of 2012) • Dewatering facility (projected service date is the end of 2012) • Truck loading for contract composting operation (projected service date is the end of 2012) 2. Discharge from said treatment works (via Outfall 001) into Northeast Creek, a Class WS -IV NSW water in the Cape Fear River Basin, at the location specified on the attached map. A .1 Permit No. NCO026051 A.(1.) EFFLUENT LIMITATIONS AND MONITORING REQUIREMENTS Beginning upon the effective date of this permit and lasting until expiration, the Permittee is authorized to discharge treated wastewater from Outfall 001. Such discharges shall be limited and monitored by the Permittee as specified below: EFFLUENT CHARACTERISTICS EFFLUENT LIMITATIONS MONITORING REQUIREMENTS Monthly Average Weekly Average Daily Maximum Measurement Frequency Sample Type Sample Location' Flow 12.0 MGD Continuous Recording Influent or Effluent Total Monthly Flow (MG) Monitor & Report Monthly Recorded or Calculated Influent or Effluent BOD,day, ' (April it 1—Octobedober 31) 5.0 mg/L 7.5 mg/L Daily Composite Influent & Effluent BOD, (200C)' (November 1 —March 31) 10.0 mg/L 15.0 mg/L Dail y Composite Po Influent & Effluent Total Suspended Solids' 30.0 mg/L 45.0 mg/L Daily Composite Influent & Effluent NH3 as N (April 1 -October 31) 1.0 mg/L 3.0 mg/L Daily Composite Effluent NH3 as N (November 1 -March 31) 1.8 mg/L 5.4 mg/L Dail y Composite W Effluent Fecal Coliform (geometric mean) 200/100ml 400/100mL Dail Y Grab Effluent Dissolved Oxygen' Daily Grab Effluent Temperature (°C) Daily Grab Effluent PH a Daily Grab Effluent Total Residual Chlorines 17 pg/L Daily Grab Effluent Chloroforms 2/Month Grab Effluent Bromodichloromethanes 1.8 pg/L Weekly Grab Effluent _ Dibromochloromethanes 1.3 pg/L Weekly Grab Effluent TKN Monitor & Report (mg/L) Weekly Composite Effluent NO3-N + NO2-N Monitor & Report (mg/L) Weekly Composite Effluent Total Nitrogen, TN Monitor & Report (mg/L) Weekly Composite Effluent TN Load 6,7 - Monitor & Report (Ib/mo) 111,207 lb/yr Monthly Annually Calculated Effluent Total Phosphorus, TP Monitor & Report Weekly Composite Effluent TP Load 6,' Monitor & Report (Ib/mo) 8,432 lb/yr Monthly Annually Calculated Effluent Total Mercuryb 12 ng/L3 36 ng[L,' Quarterly Grab Effluent Fluoride 1800 pg/L 1800 pg/L Weekly Composite Effluent Total Copper Quarterly Composite Effluent Total Zinc Quarterly Composite Effluent Chloride Quarterly Composite Effluent Effluent Pollutant Scans See footnote 9 Composite/ Grab Effluent Chronic Toxicity 1p Quarterly Composite Effluent All footnotes are listed on the following page. Permit No. NCO026051 Footnotes: 1. See Condition A. (2.), for Instream Monitoring Requirements. 2. The monthly average effluent BOD5 and TSS concentrations shall not exceed 15% of the respective influent value (85%. removal). 3. The daily effluent dissolved oxygen concentration shall not be less than 6.0 mg/ L. 4. The pH shall not be less than 6.0 standard units nor greater than 9.0 standard units. 5. Limit and/or monitoring applies only when chlorine is added to treatment system. The Division shall consider all effluent TRC values reported below 50 pg/L to be in compliance with the permit. However, the Permittee shall continue to record and submit all values reported by a North Carolina certified laboratory (including field certified), even if these values fall below 50 pg/L. 6. Refer to Special Condition A.(8.), Calculation of Total Nitrogen or Total Phosphorus Loads. 7. Compliance with mass limits shall be determined in accordance with Special Condition A.(7.), Annual Limits for Total Nitrogen or Total Phosphorus. 8. Mercury samples shall be analyzed using EPA Method 1631E. 9. Sampling should be conducted 3 times during the 5 year permit term. See Special Condition A. (4.), Effluent Pollutant Scan. 10. Chronic Toxicity (Ceriodaphnia) at 90%; February, May, August, and November; refer to Special Condition A.(3.). There shall be no discharge of floating solids or visible foam in other than trace amounts. A.(2.) INSTREAM MONITORING REQUIREMENTS Beginning upon the permit effective date and lasting until expiration, the Permittee shall monitor instream conditions as specified below': INSTREAM CHARACTERISTICS MONITORING REQUIREMENTS MEASUREMENT FREQUENCY SAMPLE TYPE SAMPLE LOCATION Dissolved Oxygen Weekly Grab Upstream, Dl Temperature Weekly Grab Upstream, DI Conductivity Weekly Grab Upstream, D3 Fecal Coliform Weekly Grab Upstream, D1 pry Weekly Grab xe Upstream, Dl Footnotes: 1. As a participant in the Upper Cape Fear River Basin Association, the instream monitoring requirements as stated above are waived. Should your membership in the association be terminated, you shall notify the Division immediately and the instream monitoring requirements specified in your permit shall be reinstated. 2. Upstream = at NCSR 1102. D1 = Downstream at NCSR 1100. Permit No. NCO026051 A.(3.) CHRONIC TOXICITY PASS/FAIL PERMIT LIMIT The effluent discharge shall at no time exhibit observable inhibition of reproduction or significant mortality to Cenodaphnia dubia at an effluent concentration of 90%. The permit holder shall perform at a minimum, quarterly monitoring using test procedures outlined in the "North Carolina Ceriodaphnia Chronic Effluent Bioassay Procedure," Revised February 1998, or subsequent versions or "North Carolina Phase II Chronic Whole Effluent Toxicity Test Procedure" (Revised -February 1998) or subsequent versions. The tests will be performed during the months of February, May, August, and November. Effluent sampling for this testing shall be performed at the NPDES permitted final effluent discharge below all treatment processes. If the test procedure performed as the first test of any single quarter results in a failure or ChV below the permit limit, then multiple -concentration testing shall be performed at a minimum, in each of the two following months as described in "North Carolina Phase II Chronic Whole Effluent Toxicity Test Procedure" (Revised -February 1998) or subsequent versions. The chronic value for multiple concentration tests will be determined using the geometric mean of the highest concentration having no detectable impairment of reproduction or survival and the lowest concentration that does have a detectable impairment of reproduction or survival. The definition of "detectable impairment," collection methods, exposure regimes, and further statistical methods are specified in the "North Carolina Phase II Chronic Whole Effluent Toxicity Test Procedure" (Revised - February 1998) or subsequent versions. All toxicity testing results required as part of this permit condition will be entered on the Effluent Discharge Monitoring Form (MR -1) for the months in which tests were performed, using the parameter code TGP3B for the pass/fail results and THP313 for the Chronic Value. Additionally, DWQ Form AT -3 (original) is to be sent to the following address: NCDENR/ DWQ/Environmental Sciences Section 1621 Mail Service Center Raleigh, North Carolina 27699-1621 Completed Aquatic Toxicity Test Forms shall be filed with the Environmental Sciences Section no later than 30 days after the end of the reporting period for which the report is made. Test data shall be complete, accurate, include all supporting chemical/physical measurements and all concentration/ response data, and be certified by laboratory supervisor and ORC or approved designate signature. Total residual chlorine of the effluent toxicity sample must be measured and reported if chlorine is employed for disinfection of the waste stream. Should there be no discharge of flow from the facility during a month in which toxicity monitoring is required, the permittee will complete the information located at the top of the aquatic toxicity (AT) test form indicating the facility name, permit number, pipe number, county, and the month/year of the report with the notation of "No Flow' in the comment area of the form. The report shall be submitted to the Environmental Sciences Section at the address cited above. Should the permittee fail to monitor during a month in which toxicity monitoring is required, monitoring will be required during the following month. Should any test data from this monitoring requirement or tests performed by the North Carolina Division of Water Quality indicate potential impacts to the receiving stream, this permit may be re -opened and modified to include alternate monitoring requirements or limits. NOTE: Failure to achieve test conditions as specified in the cited document, such as minimum control organism survival, minimum control organism reproduction, and appropriate environmental controls, shall constitute an invalid test and will require immediate follow-up testing to be completed no later than the last day of the month following the month of the initial monitoring. The facility shall conduct the second species toxicity test four times during the term of the permit and submit the testing results with the renewal package. Testing shall reflect the seasonal variability. Permit No. NCO026051 A.(4.) EFFLUENT POLLUTANT SCAN The Permittee shall perform an Effluent Pollutant Scan for all parameters listed in the attached table 3 times during the upcoming permit term. The analytical methods shall be in accordance with 40 CFR Part 136 and shall be sufficiently sensitive to determine whether parameters are present in concentrations greater than applicable standards and criteria. Samples shall represent seasonal variations. Unless otherwise indicated, metals shall be analyzed as "total recoverable." Ammonia (as N) Chlorine (total residual, TRC) Dissolved oxygen Nitrate/Nitrite Kjeldahl nitrogen Oil and grease Phosphorus Total dissolved solids Hardness Antimony Arsenic Beryllium Cadmium Chromium Copper Lead Mercury' Nickel Selenium Silver Thallium Zinc Cyanide Total phenolic compounds Volatile organic compounds: Acrolein Trans-1,2-dichloroethylene 1,1-dichloroethylene 1,2-dichloropropane 1,3-dichloropropylene Ethylbenzene Methyl bromide Methyl chloride Methylene chloride 1,1,2,2 -tetrachloroethane Tetrachloroethylene Toluene 1,1,1 -trichloroethane 1,1,2 -trichloroethane Trichloroethylene Vinyl chloride Acid -extractable compounds: P -chloro -m -cresol 2 -chlorophenol 2,4-dichlorophenol 2,4 -dimethylphenol 4,6-dinitro-o-cresol 2,4-dinitrophenol 2-nitrophenol 4-nitrophenol Pentachlorophenol Phenol Acrylonitrile 2,4,6 -trichlorophenol Benzene Base -neutral compounds: Bromoform Acenaphthene Carbon tetrachloride Chlorobenzene Chlorodibromomethane Chloroethane 2-chloroethylvinyl ether Chloroform Dichlorobromomethane 1,1-dichloroethane 1,2-dichloroethane Acenaphthylene ' Anthracene Benzidine Benzo(a)anthracene Benzo(a)pyrene 3,4 benzofluoranthene Benzo(ghi)perylene Benzo(k)fluoranthene Bis (2-chloroethoxy) methane Bis (2-chloroethyl) ether Bis (2-chloroisopropyl) ether Bis (2-ethylhexyl) phthalate 4-bromophenyl phenyl ether Butyl benzyl phthalate 2-chloronaphthalene 4-chlorophenyl phenyl ether Chrysene Di -n -butyl phthalate Di-n-octyl phthalate Dibenzo(a,h)anthracene 1,2 -dichlorobenzene 1,3 -dichlorobenzene 1,4 -dichlorobenzene 3,3-dichlorobenzidine Diethyl phthalate Dimethyl phthalate 2,4-dinitrotoluene 2,6-dinitrotoluene 1,2-diphenylhydrazine Fluoranthene Fluorene Hexachlorobenzene Hexachlorobutadiene Hexachlorocyclo-pentadiene Hexachloroethane Indeno(1,2,3-cd)pyrene Isophorone Naphthalene Nitrobenzene N-nitrosodi-n-propylamine N-nitrosodimethylamine N-nitrosodiphenylamine Phenanthrene Pyrene 1,2,4-trichlorobenzene Test results shall be reported to the Division in DWQ Form- DMR-PPA1 or in a form approved by the Director within 90 days of sampling. The report shall be submitted to the following address: NC DENR/ DWQ/ Central Files 1617 Mail Service Center Raleigh, North Carolina 27699-1617. 'Mercury samples shall be analyzed using EPA Method 1631E. Permit No. NCO026051 A.(5.) REUSE OF TREATMENT PLANT EFFLUENT The effluent from the Durham County Triangle W WTP is authorized for onsite reuse subject to the following conditions: • The reuse water will be used onsite, within the fenced perimeter of the wastewater treatment plant with controlled public access, and for very specific internal uses (i.e., restrooms, HVAC system, and vehicle washdown). • The reuse water will be used by plant personnel who are trained and knowledgeable about reuse water. • An RPZ device will be required onsite to protect the potable water supply. • A water meter will be installed on the reuse line to monitor usage. • No runoff shall occur from the vehicle washdown area. • Reuse piping valves will be properly labeled and locking. A.(6.) NUTRIENT ALLOCATIONS (a.) The following table lists the Total Nitrogen (TN) and Total Phosphorus (TP) allocations assigned to, acquired by, or transferred to the Permittee in accordance with the Jordan Lake nutrient management rule (T15A NCAC 02B.0270) and the status of each as of permit issuance. For compliance purposes, this table does not supersede any TN or TP limit established elsewhere in this permit or in the NPDES permit of a compliance association of which the Permittee is a Co - Permittee Member. Total Nitrogen Allocation ALLOCATION ALLOCATION AMOUNT nt TYPE SOURCE DATE STATUS Delivered (Ib/yr) Discharge (Ib/yr) Base Assigned by Rule 8/11/09 106,759 111,207 Active (T15A NCAC 02B .0270) TOTAL 106,759 111,207 Active Footnote: (1) Nitrogen Transport Factor = 96% Total Phosphorus Allocation ALLOCATION ALLOCATION AMOUNT t't TYPE SOURCE DATE STATUS Delivered (Ibfyr) Discharge (Iblyr) Base Assigned by Rule 8/11/09 8,179 8,432 Active (T15A NCAC 026.0270) TOTAL 8,179 8,432 Active Fuumute. (1) Phosphorus Transport Factor = 97°% (b.) Any addition, deletion, or modification of the listed allocation(s) (other than to correct typographical errors) or any change in status of any of the listed allocations shall be considered a major modification of this permit and shall be subject to the public review process afforded such modifications under state and federal rules. Permit No. NC0026051 A.(7.) ANNUAL LIMITS FOR TOTAL NITROGEN OR TOTAL PHOSPHORUS (a.) Total Nitrogen (TN) and Total Phosphorus (TP) allocations and load limits for NPDES dischargers in the Jordan Lake watershed are annual limits and apply on a calendar year basis. (b.) For any given calendar year, the Permittee shall be in compliance with the annual TN (or TP) Load limit in this Permit if: (i.) the Permittee's annual TN (or TP) Load is less than or equal to the effective limit, or (ii.) the Permittee is a Co -Permittee Member of a compliance association. (c.) The TN (or TP) Load limit in this Permit may be modified as the result of allowable changes in the Permittee's allocations. (i.) Allowable changes include those resulting from purchase of TN (or TP) allocation from an authorized mitigation banker, the Ecosystem Enhancement Program, or other source allowed under applicable regulations; purchase, sale, trade, or lease of allocation between the Permittee and other dischargers; regionalization; and other transactions approved by the Division. (ii.) The Permittee may request a modification of the TN (or TP) Load limit in this Permit to reflect allowable changes in its allocation(s). (A) Upon receipt of timely and proper application, the Division will modify the permit as appropriate and in accordance with state and federal program requirements. (B) Changes in TN (or TP) limits become effective on January 1 of the year following permit modification. The Division must receive application no later than August 31 for changes proposed for the following calendar year. (iii.) Any requests for modification should be sent to: NCDENR/ DWQ/ NPDES Programs Attn: Jordan Lake Watershed Coordinator 1617 Mail Service Center Raleigh, NC 27699-1617 (d.) If the Permittee is a member and co -permittee of an approved compliance association on January 1 of a given year, its TN and TP discharges during that year are governed by that association's group NPDES permit and the limits therein. (i.) The Permittee shall be considered a Co -Permittee Member for any given calendar year in which it is identified as such in Appendix A of the association's group NPDES permit. (ii.) Association roster(s) and members' TN and TP allocations will be updated annually and in accordance with state and federal program requirements. (iii.) If the Permittee intends to join or leave a compliance association, the Division must be notified of the proposed action in accordance with the procedures defined in the association's NPDES permit. (A) Upon receipt of timely and proper notification, the Division will modify the permit as appropriate and in accordance with state and federal program requirements. (B) Membership changes in a compliance association become effective on January 1 of the year following modification of the association's permit. (e.) The TN and TP monitoring and reporting requirements in this Permit remain in effect throughout the term of the Permit and are not affected by the Permittee's membership in a compliance association. A.(S.) CALCULATION OF TOTAL NITROGEN OR TOTAL PHOSPHORUS LOADS (a.) The Permittee shall calculate monthly and annual TN Loads as follows: Permit No. NC0026051 (i.) Monthly TN (or TP) Load (lb/mo) = TN (or TP) x TMF x 8.34 where: TN or TP = the average Total Nitrogen or Total Phosphorus concentration (mg/L) of the composite samples collected during the month TMF = the Total Monthly Flow of wastewater discharged during the month (MG/mo) 8.34 = conversion factor, from (mg/L x MG) to pounds (ii.) Annual TN (or TP) Load (lb/yr) = Sum of the 12 Monthly TN (or TP) Loads for the calendar year (b.) The Permittee shall report monthly Total Nitrogen and Total Phosphorus results (mg/L and lb/mo) in the appropriate discharge monitoring report for each month and shall report each calendar year's results (lb/yr) with the December report for that year. (c.) The Permittee shall report monthly volume of water discharged from the blow -off valves and Total Nitrogen and Total Phosphorus content of the discharge (mg/L and lb/month). A.(9.) NUTRIENT MONITORING REOPENER Pursuant to N.C. General Statute Section 143-215.1 and the implementing rules found in Title 15A of the North Carolina Administrative Code, Subchapter 2H, specifically, 15A NCAC 2H.0112(b) (1) and 2H.0114(a), and Part II, Sections B-12 and B-13 of this permit, the Director of DWQ may reopen this permit to require supplemental nutrient monitoring of the discharge. The additional monitoring will be to support water quality modeling efforts within the Cape Fear River Basin, and shall be consistent with a monitoring plan developed jointly by the Division and affected stakeholders. A.(10.) STANDARD CONDITIONS FOR NPDES PERMITS The Division will provide an updated version of the Standard Conditions for NPDES Permits to the permittee upon approval of the version by the EPA. Then, the old version shall be replaced with an updated version. TECHNICAL MEMORANDUM Triangle WWTP Aeration System Improvements B&V PROJECT NO. 194729 PREPARED FOR Durham County 2 MAY 2017 CA 66 0 'S.�N�'1PiE��/�� kv BLACK & VEATCH Building a World of difference® Durham County ' Technical Memorandum Table of Contents Section1. Background................................................................................................................... 5 Section2. Objective......................................................................................................................... 6 Section 3. Aeration System Alternatives Evaluation........................................................... 7 3.1 Background............................................................................................................................................7 3.2 Aeration Requirements.....................................................................................................................7 3.3 Fine Bubble Diffused Aeration System Alternatives............................................................. 8 3.4 Alternative Blower Technologies..............................................................................................10 3.4.1 Rotary Lobe Positive Displacement Blowers..............................................................11 3.4.2 Dry Rotary Screw Positive Displacement Blowers...................................................11 3.4.3 Multi -stage Centrifugal Blowers.......................................................................................12 3.4.4 Qualitative Comparison of Blower Technologies......................................................12 3.4.5 Blower Selections...................................................................................................................14 3.5 Life Cycle Cost Evaluation.............................................................................................................15 3.5.1 Assumptions.............................................................................................................................15 3.5.2 Recommendation....................................................................................................................17 Section 4. Electrical Considerations........................................................................................19 Section 5. Structural Considerations......................................................................................21 5.1 Existing Conditions.......................................................................................................................... 21 5.2 Structural Observations And Repair Action Items............................................................. 21 5.3 Structural Review For BLower Installation........................................................................... 23 Section 6. General Requirements............................................................................................24 6.1 Maintenance of Plant Operations(MOPO)............................................................................. 24 6.2 Permits................................................................................................................................................. 24 6.3 Schedule...............................................................................................................................................25 Section 7. Summary of Recommendations...........................................................................26 BLACK & VEATCH I Background 3 Technical Memorandum I Durham County LIST OF TABLES Table 3-1: Fine Bubble Diffuser System Summary.......................................................................................9 Table 3-2: Qualitative Comparison of Blower Technologies.................................................................13 Table 3-3: Aeration Blower Design Criteria.................................................................................................14 Table 3-4: Life Cycle Cost Evaluation Results..............................................................................................17 Table4-1: Motor FLA Requirements.............................................................................................................. 20 Table6-1: List of Permits..................................................................................................................................... 24 Table6-2: Project Schedule................................................................................................................................. 25 Table 7-1: Estimate of Probable Construction Cost.................................................................................. 27 LIST OF FIGURES Figure 1-1: TWWTP B N R Treatment Trains...................................................................................................5 Figure 3-1: SOTR for 9 Meter Rotor Brush Aerator (figure provided by Veolia)...................................................................................................................................................... 8 Figure 3-2: Membrane Disc Diffusers................................................................................................................8 Figure3-3: Tube Diffusers......................................................................................................................................8 Figure 3-4: Example Installation of a Retrievable Diffuser System....................................................10 Figure 3-5: Proposed Blower Location on Oxidation Ditch Operating Walkway..............................................................................................................................................10 Figure 3-6: Typical Lobe PD Blower with and without sound enclosure.........................................11 Figure 3-7: Typical Dry Screw PD Blower.....................................................................................................12 Figure 3-8: Typical Multi -stage Centrifugal Blower..................................................................................12 Figure 3-9: Life Cycle Cost Evaluation Results............................................................................................16 Figure 3-10: Recommended Aeration System Improvements.............................................................18 Figure 4-1: Electrical Site Plan...........................................................................................................................19 Figure 5-1: Existing Cracking in Walkway.................................................................................................... 21 Figure 5-2: Efflorescence at Expansion Joint............................................................................................... 22 Figure 5-3: Hypalon Strip and Seal System (Batten Bars Not Shown) (Photo Courtesy of Sika Corporation, USA).......................................................................................... 23 APPENDICES Appendix A Engineer's Estimate of Probable Construction Cost Appendix B Diffuser & Blower Information for Recommended Alternative Appendix C Hypalon Strip & Seal System 4 MAY 2017 Durham County ' Technical Memorandum Section 1. Background Durham County owns and operates the 12 million gallon per day (MGD) Triangle Wastewater Treatment Plant (TWWTP), which was constructed in 2001. The plant site is located in the 100 - year floodplain. The plant site elevation varies between 2 to 3.5 feet below the 100 -year flood elevation, resulting in predominantly above grade construction as shown in Figure 1-1. Figure 1-1: TWWTP BNR Treatment Trains The biological treatment system includes three five -stage oxidation ditch biological nutrient removal (BNR) treatment trains featuring common wall construction, each designed for an average daily flow of 4.0 mgd. Each oxidation ditch includes four 75 horsepower (hp) Kruger brush aerators (rotors) for maintaining aerobic conditions. The operation and number of brush aerators placed into service are controlled by a programmable logic control (PLC) based control panel that uses an operator adjustable dissolved oxygen (DO) set -point, which is measured by two DO probes located in the ditch. The brush aerator standard oxygen transfer rate (SOTR) is dictated by the rotor blade submergence, which is controlled by an electric actuated effluent weir in each oxidation ditch. The side water depth in the oxidation ditch is approximately 18 feet, thereby requiring the continuous operation of two 7.4 hp submersible mixers for maintaining the solids in suspension. The average daily influent flow to the plant is approximately 6.0 mgd, thereby requiring only two treatment trains. Over the past several years, plant staff observed the brush aerators overloading and tripping out at increased rotor blade submergence depths to address peak oxygen demands. Plant staff has noted an increase in maintenance associated with the brush aerators. In 2015, the rotor shaft of one of the brush aerators that serves the middle treatment train (Train No. 2) sheared. Currently, the plant is operating two (Train Nos. 1 and 3) of three treatment trains. The depth of the oxidation ditches, increased maintenance and useful design life (-20 years) of the brush aerators, and Durham County's utilities division desire to improve the efficiency and resiliency of the TWWTP have resulted in the County investigating more efficient alternative aeration systems. BLACK & VEATCH I Background 5 Technical Memorandum Durham County Section 2. Objective This technical memorandum (TM) investigates alternative diffused aeration and blower type configurations and provides a recommended diffused aeration system, based on the application, site constraints, and life cycle costs of the capital expenditure. In addition, this memorandum provides a recommendation for repairing the cracking and subsequent leaking expansion joint observed by plant staff that spans the length of the treatment train. This TM provides the design basis for developing the contract documents and provides an engineer's estimate of probable construction cost, permit requirements, and schedule for implementing the proposed recommendation. 6 MAY 2017 Durham County ' Technical Memorandum Section 3. Aeration System Alternatives Evaluation 3.1 BACKGROUND The aeration system evaluation considers different blower technologies and types of fine bubble diffused aeration (tube versus membrane disc) to determine the most efficient overall system for addressing the brush aerator failure in treatment train No. 2. Diffused aeration was considered in lieu of other types of aeration systems when considering the depth of the oxidation ditch, initial capital costs, aeration efficiency, and site constraints. A key consideration of the alternatives evaluation is determining the most cost-effective long-term solution, when considering the energy savings of the diffused aeration system and remaining useful design life of the brush aerators. The ability to regulate the airflow delivered by the blower(s) and subsequent DO concentration maintained in the oxidation ditch, as well as the location of the diffused aeration grids is critical to avoid upsets in the anoxic zones of the process. Therefore, the blower(s) will be equipped with a manually operated adjustable frequency drive (AFD) to allow adjustment of the airflow delivered by the blower to reduce energy consumption, while reducing the capital cost of the investment by not integrating the improvements into the existing PLC -based control system. The existing brush aerators would remain in service and be controlled by the existing PLC -based control panel, based on the operator adjustable DO set -point and augments the oxygen supplied by the blower(s). The aeration system alternatives evaluated in this TM include different combinations of blowers and fine bubble diffuser grids to augment the existing brush aerators. Four brush aerators are required in each oxidation ditch to satisfy the oxygen demand required by the process biology. Therefore, the option to "Do Nothing" was not considered a viable alternative since this would compromise the treatment performance and capacity of the plant. 3.2 AERATION REQUIREMENTS The equivalent actual oxygen requirement (AOR) provided by one of the existing 75 hp brush aerators was calculated, according to the standard oxygen requirement (SOTR) for one brush aerator, as shown in Figure 3-1 based on the maximum rotor blade immersion of 11.5 inches. Adjusting the SOTR for above field conditions, based on a residual DO concentration of 2.0 mg/L and a summer wastewater temperature of 30oC, resulted in an a AOR of 122 pounds of oxygen per hour (lb Oz/hr). This calculated AOR served as the basis used by the diffused aeration system suppliers to determine SOTR, air flowrate (SCFM) and discharge pressure that would serve to size the blower(s) for replacing the brush aerator(s). Alternative 1: Equivalent airflow rate required for one blower to provide the oxygen capacity supplied by one brush aerator Alternative 2: Airflow rate that would be required by one blower to provide the oxygen capacity supplied by two brush aerators Alternative 3: Airflow rate that would be required by two blowers to provide the oxygen capacity supplied by four brush aerators, assuming no stand-by blower units Alternative 4: Airflow rate that would be required one blower to provide the installed oxygen capacity of four brush aerators. This option considered a stand-by blower would be furnished in BLACK & VEATCH I Aeration System Alternatives Evaluation 7 Technical Memorandum Durham County addition to a duty blower and represents the most conservative and expensive of the alternatives. Alternative 5: This option considered the maximum airflow rate that could be furnished by one 75 horsepower blower to determine the number of brush aerators offset by the blower and the corresponding energy savings. GLIA Meter Rotor --4--transfer Rate -45—PdWer 1WA1r Maximum Optimum Maximum Immersion mmers�or� ��-60 HP a 94.4 X0.0 74.4 = X 64.4 54.4 CL 44.4 MA 24.4 4-05_M 9A 7_u 9.6 9.0 14A11-11 12.0 fr hbffl rlilnlrtleri Immersion lin) Figure 3-1: SOTR for 9 Meter Rotor Brush Aerator (figure provided by Veolia) 3.3 FINE BUBBLE DIFFUSED AERATION SYSTEM ALTERNATIVES Two types of fine bubble diffused aeration systems were evaluated for this project; membrane disc and tube diffusers. Figures 3-2 and 3-3 provide a photo of membrane disc and tube diffusers, respectively. Figure 3-2: Membrane Disc Diffusers Figure 3-3: Tube Diffusers 8 MAY 2017 Durham County Technical Memorandum Both the membrane disc and tube diffuser suppliers recommended a single diffuser grid arrangement for Alternative Nos. 1, 2, and 5 which are represented as Option No. 1 in Table 3-1. Two diffuser grids were recommended by both suppliers for Alternative Nos. 3 and 4, which is represented as Option No. 2 in the table below. Common to both types of diffuser arrangements was a 304 stainless steel dropleg pipe transitioning to Schedule 40 PVC to serve a fixed floor diffuser grid anchored to the channel floor of the oxidation ditch. Table 3-1 provides a summary of the membrane disc and tube diffusers systems for each option. Number of grids Number of diffusers per grid Footprint per grid Dropleg pipe diameter, inches Air flowrate per grid, scfm Total air flowrate, scfm Air flowrate per diffuser, scfm Transfer efficiency Table 3-1: Fine Bubble Diffuser System Summary 1 1 2 2 372 72 720 108 25'x36' 40'x36' 50'x36' 55'x36' 6 6 8 8 713 709 1,440 1,470 713 709 2,888 2,940 1.92 9.85 2.0 13.6 34.4% 35.2% 34.0% 34.0% Cost proposals were received for both membrane disc diffusers and the tube diffusers. The costs for tube diffusers were found to be substantial higher than membrane disc diffusers. Therefore, membrane disc diffusers are recommended and used as the basis for the fine bubble diffused aeration grids included the life cycle cost evaluation. Although fine bubble diffused aeration systems are typically fixed to basin floor, retrievable systems are available, as shown in Figure 3-4. Retrievable systems were investigated, as part of this evaluation and found to be twice the cost of a fixed floor system and is therefore not recommended. BLACK & VEATCH I Aeration System Alternatives Evaluation 9 Technical Memorandum I Durham County Figure 3-4: Example Installation of a Retrievable Diffuser System Overtime the manufacturer recommends the diffusers be cleaned. To alleviate the need to drain a basin, the membrane disc manufacturers offera portable liquid cleaning system, which can be used for in-situ cleaning of the diffusers, thereby not requiring the oxidation ditch (basin) to be drained. According to diffuser manufracturer, the estimated cost of the in-situcleaning system is approximately $20,000. 3.4 ALTERNATIVE BLOWER TECHNOLOGIES A number of blower types and technologies could be considered for diffused aeration systems including positive displacement, single or multi -stage centrifugal, and gearless turbo type blowers. Single stage centrifugal blowers are more cost-effective for larger airflow capacity requirements and were therefore were not considered for this application. Each of the blower types evaluated considers locating the blower(s) outside on the operating walkway of oxidation ditch for Treatment Train No. 2, as shown in Figure 3-5, to reduce the costs of the aeration piping, minimize construction costs, and simplify the installation when considering the height and location of the treatment train above existing grade in conjunction with the 100 -year flood plan elevation. High speed gearless turbo blowers are not recommended for outdoor installations due to the Figure 3-5: Proposed Blower Location on potential maintenance implications of exposing the oxidation Ditch Operating Walkway electronic components within the blower housing to humidity and temperature fluctuations. The option of housing the gearless turbo blower(s) inside a new building on an elevated slab outside the oxidation ditches would not be cost-effective in comparison to alternative blower technologies. In addition, there is not adequate space for a pre- engineered enclosure on the operating walkway of the oxidation ditch. Therefore, high speed gearless turbo blowers were not further considered, as part of the evaluation. 10 MAY 2017 Durham County Technical Memorandum Three types of blower technologies which were considered for the evaluation included the following: ■ Rotary Lobe Positive Displacement (LPD) ■ Dry Rotary Screw Positive Displacement (SPD) ■ Multi -stage Centrifugal (MS) For the purpose of this TM, the rotary lobe positive displacement blowers are referred to as 'Lobe PD blowers'; the dry rotary screw positive displacement blowers as 'Dry Screw PD blowers'; and the multi -stage centrifugal blowers are referred to as 'Multistage Blowers'. The following sections provide a description of each of the three blower technology. 3.4.1 Rotary Lobe Positive Displacement Blowers Rotary lobe PD blowers are variable pressure, constant capacity machines which use two parallel rotary lobes rotating in opposite directions to compress the air to meet the discharge pressure requirements for the application. They are provided with inlet and discharge silencers to reduce pulsations, and can either be operated as constant speed machines or provided with adjustable frequency drives (AFDs) where capacity control and turndown is required. Sound attenuating enclosures are typically recommended for lobe PD blowers in outdoor locations where noise attenuation is warranted. Figure 3-6: Typical Lobe PD Blower with and without sound enclosure 3.4.2 Dry Rotary Screw Positive Displacement Blowers Dry screw PD blowers are a newer type of positive displacement blower technology relative to rotary lobe blowers. Unlike the rotary lobe blower, dry screw PD blowers compress the air internally, resulting in lower power requirements and reduced pulsations from the blower. Sound attenuating enclosures are standard for dry screw PD blowers, as illustrated in Figure 3-7. BLACK & VEATCH I Aeration System Alternatives Evaluation 11 Technical Memorandum I Durham County Figure 3-7: Typical Dry Screw PD Blower 3.4.3 Multi -stage Centrifugal Blowers Multi -stage centrifugal blowers are constant pressure, variable capacity machines that consist of a series of impellers used to compress the air to the final discharge pressure. Either an inlet throttling valve or AFD is used for applications with varying airflow requirements. AFDs are generally used to improve efficiency. Typically multi -stage blowers have a higher capital cost and are more efficient when compared to positive displacement blowers. Figure 3-8: Typical Multi -stage Centrifugal Blower 3.4.4 Qualitative Comparison of Blower Technologies The following non -economic factors were considered in evaluating the blower technologies: Power consumption Space requirements ■ Packaging ■ Typical noise levels ■ Turndown capability ■ Maintenance requirements F Operating speeds F Number of operating installations 12 MAY 2017 Durham County Technical Memorandum The following table presents a qualitative comparison of the three blower technologies. Table 3-2: Qualitative Comparison of Blower Technologies Efficiency Low Low -Medium Low -Medium [11 Noise Medium -High [�1 Medium [�1 Medium [21 Pulsations Medium Low None Footprint Moving Parts Voltage Requirement (V) Capacity Control Maximum speed (RPM) Capacity Turndown Metal to Metal Contact Lubrication Municipal Operating History Small -Medium Medium 460 AFD 3,600 -20% of rated Yes (bearings only and timing gears) Yes High Medium Medium 460 AFD 3,600 -20% of rated Yes (bearings only and timing gears) Yes Low Medium (long and narrow) Few 460 Combination [3] 3,600 -60% of rated N Yes (bearings only) Yes High Maintenance Low -Medium Low -Medium Low Notes: I�1 Efficiency level indicated for multistage blowers is based on blower sizes within the capacity range required for this application. [�1 Noise level indicated is based on lobe PD and multistage blowers being furnished with sound attenuating enclosures. Dry screw PD blowers are furnished standard with sound attenuating enclosures. [31 Capacity control and turndown for multistage blowers is based on the use of an inlet throttling inlet valve or an AFD. All three blower technologies are suitable for the application. However, dry screw PD blowers are a relatively newer technology that has been used in the municipal market with fewer applications. A key consideration of the qualitative assessment was the blower footprint and space required around the unit for servicing, when considering the desire to locate the blower on the oxidation ditch walkway to avoid the construction of an elevated equipment pad at grade, minimize air piping, and simplify construction to reduce the capital cost. BLACK & VEATCH I Aeration System Alternatives Evaluation 13 Technical Memorandum Durham County 3.4.5 Blower Selections Proposals from blower manufacturers for each of the three blower technologies were requested based on the airflow requirements of the membrane disc diffuser option summarized in Section 3.3. Blower discharge pressure requirements accounted for the diffuser submergence depth, estimated headloss across the membrane diffusers and distribution piping, as well as the potential for fouling. A blower discharge pressure of 9.2 psig was used in conjunction with the airflow requirements summarized in Section 3.3. Rated blower capacities, pressure requirements, and site conditions were provided to the blower manufacturers in order for them to provide selections. The following table provides a matrix summary of the design criteria and resulting blower selection information for each alternative and blower technology considered. Table 3-3: Aeration Blower Design Criteria Number of diffuser grids 1 1 2 2 1 Air flowrate per grid 713 scfm 1,440 scfm 1,440 scfm 1,440 scfm Varies b/t blower type Number of blowers 1 1 2 2 1 No. of duty/standby 1 Duty 1 Duty 2 Duty 1 Duty 1 Duty Rated blower capacity, 750 scfm 1,500 scfm 1,500 scfm 3,000 scfm Varies b/t summer conditions, each blower type [1] Winter turndown 150 scfm 225 scfm 225 scfm 450 scfm Varies b/t capacity blower type [2] Blower discharge 9.2 psig pressure Min rise -to -surge at 0.3 psi turndown [3] Blower Motor Rating 60 hp 125 hp 125 hp 250 hp 75 hp Lobe PD Blower 5'-8" x 4'-0" T-2" x 5'-2" T-2" x T-2" 10'-6" x 8'-4" T-2" x 4'-6" footprint Dry Screw PD Blower 8'-8" x 4'-8" 9'-6" x 5'-6" 9'-6" x T-6" 13'-0" x 6'-10" 8'-8" x 4'-8" footprint (with VFD) Multistage Blower 7'-0" x 3'-0" 9'-6" x 3'-6" 9'-6" x 3'-6" 10'-6" x 4'-0" 9'-6" x T-6" footprint Notes: [i] Alternative 5 rated blower capacity in summer conditions is 1,200 scfm for lobe PD blower; 1,190 scfm for dry screw PD blower; and 1,150 scfm for multistage blower. 121 Alternative 5 winter turndown capacity is 400 scfm for lobe PD blower, 225 scfm for dry screw PD blower, and 750 scfm for multistage blower. 131 Rise -to -surge applies to multistage centrifugal blowers. 14 MAY 2017 Durham County ' Technical Memorandum The blower selections were first evaluated based on their required footprint relative to the available space on the operating walkway of the oxidation ditch. The footprint requirements for each of the 3,000 scfm Alternative 4 blower selections were found to be too large to fit within the available space. Therefore, Alternative 4 was eliminated from further evaluation. Alternatives 1, 2, 3, and 5 were evaluated further based on a life cycle cost comparison discussed in the following section. 3.5 LIFE CYCLE COST EVALUATION A life cycle cost analysis was performed for Alternatives 1, 2, 3, and 5 as summarized in Section 3.2 to determine the most cost-effective solution. The life cycle cost for each alternative includes the capital cost of the equipment, as well as the annual energy costs. Capital costs for each alternative include the costs of the blower(s), fine bubble diffusers, aeration piping, associated electrical, mobilization, contractor's overhead and profit, engineering, and installation. The capital costs do not include contingency. In addition, the life cycle cost evaluation includes a baseline alternative to replace the brush aerator that failed with an identical brush aerator, as a basis of comparison for the life cycle costs associated with the aeration system improvement alternatives. This alternative is identified as "Brush Aerator" in the subsequent life cycle cost results. 3.5.1 Assumptions The life cycle cost evaluation was based on the following assumptions: Life cycle cost based on 20 -year net present worth Discount rate of 4.625% (EPA, 2015) Power cost of $0.05618/kWh based on TWWTP power bill for February 2017 Operational cost based on average design conditions with additional brush aerators not augmented by the blower(s) for each alternative operating continuously The results of the life cycle cost evaluation are presented graphically in the following Figure 3-9 and in tabular form in Table 3-4. Each alternative and blower technology is listed with the associated capital cost, annual operating cost and a calculated life cycle cost as described above. The blower technology for each alternative is identified as "LPD" for lobe positive displacement blowers, "SPD" for rotary screw positive displacement blowers, and "MS" for multi -stage centrifugal blowers. In Table 3-4, each alternative is also presented with a percent difference for comparison purposes. The percent difference is based on each alternative's life cycle cost compared to the alternative with the lowest life cycle cost. BLACK & VEATCH I Aeration System Alternatives Evaluation is $1,600,000 h $1,400,000 a� U U $1,200,000 w a $1,000,000 0 � $800,000 0 a� N $600,000 a t W Z $400,000 a� c $200,000 N $0 Technical Memorandum Durham County y46 a`°� y46 c40 y46 c40 y4p Aeration Improvement Alternative & Associated Blower Technology ■ 20 -Year Net Present Worth ■ Capital Cost ■ Annual Operating Cost Figure 3-9: Life Cycle Cost Evaluation Results 16 MAY 2017 Durham County ' Technical Memorandum Table 3-4: Life Cycle Cost Evaluation Results Alt 3 - LPD 2 (125 hp 4 $465,000 $61,000 $1,253,000 0% each) Brush Aerator N/A N/A $162,000 $89,000 $1,266,000 0% Alt 2 - LPD 1 (125 hp) 2 $304,000 $75,000 $1,268,000 0% Alt 2 - SPD 1 (125 hp) 2 $365,000 $73,000 $1,308,000 1% Alt 1 - LPD 1 (60 hp) 1 $250,000 $84,000 $1,327,000 1% Alt 3 - SPD 2 (125 hp 4 $588,000 $58,000 $1,334,000 2% each) Alt 5 - LPD 1 (75 hp) 2 $285,000 $82,000 $1,336,000 2% Alt 1 - SPD 1 (60 hp) 1 $307,000 $81,000 $1,355,000 2% Alt 5 - MS 1 (75 hp) 2 $424,000 $74,000 $1,374,000 2% Alt 5 - SPD 1 (75 hp) 2 $335,000 $81,000 $1,382,000 2% Alt 2 - MS 1 (125 hp) 2 $428,000 $80,000 $1,451,000 4% Alt 1 - MS 1 (60 hp) 1 $363,000 $86,000 $1,465,000 4% Alt 3 - MS 2 (125 hp 4 $713,000 $70,000 $1,619,000 6% each) 3.5.2 Recommendation The life cycle cost analysis indicates Alternative No. 3 as the most favorable. Alternative No. 3 includes the installation of two 125 hp rotary lobe positive displacement blowers, each with a capacity of 1,500 scfm, in conjunction with two membrane disc diffuser grids to provide the equivalent installed oxygen capacity of four brush aerators. Alternative No. 2 and the Brush Aerator alternative are essentially equal in terms of life cycle cost due to the lower capital cost associated with in kind replacement of the failed brush aerator. However, long-term use of brush aerator technology does not address the current reliability concerns or provide the operational flexibility for potential future capacity re -rating. Alternative No. 2 consists of one 125 hp rotary lobe positive displacement blower with a capacity of 1,500 scfm and one membrane disc diffused aeration grid. This is the preferred alternative when considering that it provides a return on investment comparable to Alternative 3 with substantially less initial capital, and takes advantage of the useful design life of the existing brush aerators. Refer to the following Figure 3-10 for an illustration of the recommended Alternative 2. The location of the diffuser grid on the east side of the oxidation ditch was selected to maximize the BLACK & VEATCH I Aeration System Alternatives Evaluation 17 Technical Memorandum Durham County distance upstream of the nitrate recycle pump while also minimizing the length of piping from the blower. Figure 3-10: Recommended Aeration System Improvements 18 MAY 2017 3.0-] AI m - p m II11 m -- �... BNR Train No.1 � ------- - ------------— ----------- I II � ------------- O I a 3C -Il ` a — — I m II cif II u I eF (D Existing Brush „ " --, Aerator and i Submersible Mixer i Future Blower \ _ a BNR Train No. 2 1 Blower i�c Alternative 2 1! C Lobed PD Type',, I 9 Oxidation Ditch , �'»z , 'stn D I Q eg ii ®i Diffuser Grid Future Diffuser �� I J u R Grid BNR Train No. 3 Oxidation Ditch Broken ` Brush AA _\ ,f I \ ` Aerator - Figure 3-10: Recommended Aeration System Improvements 18 MAY 2017 Durham County Technical Memorandum Section 4. Electrical Considerations The new blower(s) will be equipped with a manually operated adjustable frequency drive (AFD) to allow adjustment of the airflow delivered by the blower. A local on/off disconnect will be provided on the operating walkway of the oxidation ditch adjacent to the new blower. Power supply to the existing brush aerators is fed out of Electrical Building No. 2 just north of the BNR Trains. The available spare bucket for the motor control center (MCC) in Electrical Building No. 2 does not provide ample room to accommodate the AFD size required for the blower for any of the alternatives investigated. Furthermore, there is not adequate space required to accommodate a free-standing AFD enclosure while adhering to the space requirements dictated by the National Electrical Code. Therefore, the new AFD should located in the Main Electrical Building. Figure 4-1 below shows the electrical buildings relative to the proposed blower location. Figure 4-1: Electrical Site Plan The new AFD will be provided with AFD rated cable, which has a larger outside diameter than standard cable. According to the as -built drawings, the existing conduit used to feed the brush aerator that failed is a 1-1/2 inch diameter conduit fed from Electrical Building No. 2. The existing conduit diameter is not large enough even for the 60 HP AFD blower considered for Alternative 1. Additionally, spare conduits large enough to accommodate the AFD rated cable do not exist. Therefore, new conduit will be required for the recommended alternative. BLACK & VEATCH I Electrical Considerations 19 Technical Memorandum I Durham County Cable sizes were determined for each of the blower alternatives. These cable sizes are listed in Table 4-1. The cable sizes were based on values for XHHN cables. Black & Veatch recommends that a cable designed to limit voltage spikes be used for AFDs applications. The motor for the recommended alternative will include a short-circuit protective device with maximum rating/setting not more than 800% FLA, unless not adequate to allow motor start. Table 4-1: Motor FLA Requirements 60 77 96.3 #2 125 156 195.0 #4/0 250 302 377.5 #500mcm (2#4/0) The following are assumptions associated with the cable sizes indicated in the Table 4-1: Motor FLA is based on NEC Table 430.250. Cables were sized based on the FLA of the proposed motors, this size will need to be verified and possibly adjusted based on voltage drop, applicable derating factors, manufacture's specifications, and selected AFD input requirements per NEC 300, and 430 Section X. RHO of 90 was assumed. Correction factor of 0.9 applied when selecting cable size. Cables were assumed to be installed in PVC conduit in concrete encased duct bank. Conduit sizing below is based on sample AFD rated cable outside diameter measurements (with allowance for motor unit heater conductors). 20 MAY 2017 Durham County ' Technical Memorandum Section 5. Structural Considerations 5.1 EXISTING CONDITIONS On February 8th, 2017, B&V visited the TWWTP. A walkthrough of the BNR basin perimeter and walkways was conducted with the County staff to assess the expansion joint associated with BNR Treatment Train No. 2. Observations noted during the site visit along with repair recommendations, where applicable, are discussed below in the following subsections. 5.2 STRUCTURAL OBSERVATIONS AND REPAIR ACTION ITEMS There was notable cracking in the walls and walkways observed at the oxidation ditches during the walkthrough. Representative photos of the cracks are illustrated in Figure 5-1. The type of cracking noted is typical for environmental structures of this age and exposure. At this time the cracks do not affect the structural integrity of the tanks. However, the condition of the tanks should be monitored periodically in order to take repair action if necessary in the future. Figure 5-1: Existing Cracking in Walkway There were numerous expansion joints throughout the structure. These joints were not actively leaking on the day of the site visit. However, there was significant efflorescence around the joints and some moisture present at the base of one joint at BNR Treatment Train No. 2, as shown in Figure 5-2. The efflorescence is indicative of leakage in the past. The plant staff also indicated that historically these joints have been a significant source of leakage. Long term leakage at the joints could lead to future erosion of the supporting ground at the base of the walls. While the tanks are out of service for the work of this project we recommend these joints be sealed. BLACK & VEATCH I Structural Considerations 21 Technical Memorandum Durham County Figure 5-2: Efflorescence at Expansion Joint. We recommend sealing the joints using a surface applied hypalon strip. Below is a sample sketch of the hypalon strip and seal system. The hypalon is a flexible material that is epoxied to the adjacent sides of the joint. The material is allowed to flex over the expansion joint and is adhered on each side of the movement joint to create a watertight bond. This will create a watertight seal and still allow movement during seasonal moisture variations. Batten bars are used when the joints are installed in negative pressure situations such as an adjacent tank being in service. Batten bars are stainless steel plate 2" wide installed on each side of the joint over the length of the joint. The bars provide an active connection to resist negative pressure (water pressure towards the interior of the tank). 22 MAY 2017 Durham County ' Technical Memorandum Sikadur-Combiflex® SG System SEE SPECIFICATIONS 1- DIA. SMOOTH STEEL (A36)�� SLEEVE --A 12' BAR O O.C., 20' LONG 3/4- EXP. JT. MATERIAL — 3/4' EXP. JT. 3/4' CLEAR 1' EXP. JT. MATERIAL — 1' EXP. JT. FILTER FABRIC (12- NAPE) (FLOOR SLAB ONLY) Red masking tape Sikadur` adhesive Sikadur-Combiflex` SG tape Sikadur" adhesive Prepared concrete surface Joint filler PART POLYUERTHANE SEALANT BACKER ROD — 3/4' EXP. JT. DAM BACKER ROD — 1' UP. JT. EXPANSION JOINT DETAIL (NTS.) Figure 5-3: Hypalon Strip and Seal System (Batten Bars Not Shown) (Photo Courtesy of Sika Corporation, USA). 5.3 STRUCTURAL REVIEW FOR BLOWER INSTALLATION Preliminary review of the existing walkway slab and beam system was conducted for the potential blower system installation. Although there is sufficient structural capacity in the slab and beam system there is potential resonant vibration of the slab. We recommend the blowers be located directly above the support beam at the center of the subject walkway. If that location is not possible due to access and space requirements then we recommend installing a stiffening element to the slab. An equipment pad can be used to elevate the equipment and double as a structural stiffening element. This will increase the natural frequency of the slab such that it meets the recommended range of avoidance with the equipment. BLACK & VEATCH I Structural Considerations 23 NOTE: FOR WALL SECTIONS CONTRACTOR SHALL INSTALL ELASTOMERIC SEALANT AND FOAM BACKER ROOS ON BOTH �N SIDES OF CONCRETE SECTION 6, # NOTE: WATERSTOPS IN WALL SECTIONS �a SHALL TERMINATE PRIOR TO REACHING o THE TOP OF WALL EXPANSION JOINT DETAIL (NTS.) Figure 5-3: Hypalon Strip and Seal System (Batten Bars Not Shown) (Photo Courtesy of Sika Corporation, USA). 5.3 STRUCTURAL REVIEW FOR BLOWER INSTALLATION Preliminary review of the existing walkway slab and beam system was conducted for the potential blower system installation. Although there is sufficient structural capacity in the slab and beam system there is potential resonant vibration of the slab. We recommend the blowers be located directly above the support beam at the center of the subject walkway. If that location is not possible due to access and space requirements then we recommend installing a stiffening element to the slab. An equipment pad can be used to elevate the equipment and double as a structural stiffening element. This will increase the natural frequency of the slab such that it meets the recommended range of avoidance with the equipment. BLACK & VEATCH I Structural Considerations 23 Technical Memorandum I Durham County Section 6. General Requirements 6.1 MAINTENANCE OF PLANT OPERATIONS (MOPO) The existing BNR Train No. 2 has been out of service since the brush aerator failure and will remain out of service until the aeration improvements are complete. Therefore, the BNR Train No. 2 cleanout, installation of the blower, diffused aeration grid, and piping will have no impact to plant operations. There will also be no impact to plant operations for the concrete expansion joint repair, including the exterior BNR Train No. 2 walls which are common to Trains 1 and 2. Those repairs can be completed with adjacent Trains 1 and 3 in service and full of water. Electrical and controls integration and connections will likely require brief shutdowns of certain electrical and controls systems. It is recommended that the following requirements be included in the Contract Documents as a means to balance plant operations with construction activities: Permission to interrupt or shutdown any equipment, utility service, or systems shall be requested in writing a minimum of 14 calendar days prior to the desired date of interruption. One localized electrical and SCADA system shutdown may be required in order to perform modifications necessary to incorporate wiring and communications required for the new work. Duration for shutdown of electrical and SCADA service to any equipment or systems to remain in service shall not exceed three (3) hours. 6.2 PERMITS The following table provides a summary of permitting requirements anticipated for the recommended aeration improvements. Table 6-1: List of Permits Authorization to NCDENR, Required for Ron Berry 90 days Construct (ATC) Division of modification of (919) 807-6396 Water equipment which has ron.berry@ncdenr.gov Resources the potential to affect the treatment process Level 1 Site Plan Durham Required for projects Lee Davis 10 days Review City -County with no increase in (919) 560-4137 x28216 Planning impervious surfaces, Lee.Davis@DurhamNC.gov Department new land disturbance or building area, or any changes that would require review by any agency except Planning 24 MAY 2017 Durham County Technical Memorandum Building Permit City -County To be obtained by William Bradham TBD Inspections Contractor but gene.bradham@durhamnc.gov Division recommend 919-560-4144 submitting 90% plans and specs for cursory review prior to bidding Erosion and NCDENR, Not required due to N/A N/A sediment control Land Quality limits of disturbance Section less than 1 acre Stormwater Durham Not required due to no N/A N/A County change in impervious area 6.3 SCHEDULE The following table provides a summary of the anticipated schedule through design and construction for the recommended aeration improvements. The construction schedule is based on typical lead times provided by the diffused aeration system and blower manufacturers. Table 6-2: Project Schedule Preliminary Engineering 2 months Detailed Design 4 months Permitting 3 months Bidding & Award 2 months Construction 9 months Submittal Prep 1.5 months Submittal Review 1.5 months Fab & Delivery 4 months Installation & Startup 1 month Completion 1 month BLACK & VEATCH I General Requirements 25 Technical Memorandum I Durham County Section 7. Summary of Recommendations The list below summarizes the aeration improvement recommendations included in this TM. Install one (1) 1,500 scfm, 125 hp rotary lobe positive displacement blower with sound attenuating enclosure on the existing deck of BNR Train No. 2 adjacent to the broken brush aerator. Install one (1) membrane disc diffused aeration grid with total footprint of 50'x36'and 720 diffusers. Install aeration piping from blower to diffuser drop leg including 12" discharge header with tees and blind flange connections for future blower integration, 8" air supply to new diffuser dropleg, and 8" isolation butterfly valve. All piping to be Schedule 10S 304 Stainless Steel. Install one (1) 125 hp AFD inside the Main Electrical Building. Install concrete encased duct bank with PVC conduit for cable routing from Main Electrical Building to new aeration blower. Repair and seal concrete expansion joint using a surface applied hypalon strip. BNR Train No. 2 cleanout including existing solids removal and disposal. The estimated quantity of solids to be removed and hauled to a landfill for disposal is 1,500 cubic yards. It is anticipated that the solids removal will require the use of a crane and bobcat for twelve days, and a crew of four working for two weeks. An estimate of probable construction cost was developed for the aeration improvement recommendations listed above. The estimate includes markups for mobilization, contractor's overhead and profit, contingency, and engineering. Contractor's overhead and profit was set at 10% and 15%, respectively based on typical values observed for this size project. Contingency was set at 30% to account for the current level of design, uncertainties in the bidding environment, and potential changes in material cost. The following table summarizes our estimate of probable construction cost for the project. The complete breakdown of the estimate is included in Appendix A. 26 MAY 2017 Durham County ' Technical Memorandum Table 7-1: Estimate of Probable Construction Cost Train No. 2 Basin Cleanout $94,000 Concrete Expansion Joint Repair $34,000 Fine Bubble Diffused Aeration System $44,000 Aeration Blower $45,000 Mechanical Piping & Valves $12,000 Adjustable Frequency Drive $17,000 Electrical Conduit and Wiring $21,000 Subtotal $267,000 Mobilization (3%) $9,000 Contractor Profit (15%) $42,000 Contractor Overhead (10%) $28,000 Contingency (30%) $104,000 Subtotal $450,000 Engineering $125,000 Total Project Cost $575,000 BLACK & VEATCH I Summary of Recommendations 27 Black & Veatch Appendix A Engineer's Estimate of Probable Construction Cost Triangle WWTP Aeration System Improvements Black & Veatch 5/2/2017 TRIANGLE WWTP AERATION SYSTEM IMPROVEMENTS ENGINEER'S ESTIMATE OF PROBABLE CONSTRUCTION COST Project: Triangle WWTP Aeration System Improvements Computed By: KBP Location: Durham, North Carolina Checked By: JWB Owner: Durham County Design Status of Estimate: Preliminary Description: Aeration System Improvements Project Number: 194729 Quanti Material Eq ui ment Labor No. Basis Per Total Per Total Man $/Man Total Description Total Units Unit Unit Hours Hour Cost Train No. 2 Basin Cleanout Solids Removal & Disposal 1500 CY $25 $37,500 $0 $0 320.0 $45 $14,400 $52,000 Crane Rental 12 day $0 $0 $3,100 $37,200 0.0 $45 $0 $37,000 Bob Cat Rental 12 days $0 $0 $400 $4,800 0.0 $45 $0 $5,000 91 Subtotal $94,000 Concrete Expansion Joint Repair Hypalon Strip 1415 LF $15 $21,225 $0 $0 0.1$45 $6,368 $28,000 Hypalon Strip with Batten Bars 165 LF $30 $4,950 $0 $0 0.1 $45 $743 $6,000 Subtotal $34,000 Aeration Equipment Fine Bubble Diffusered Aeration System 720 LS $35 $25,000 $0 $0 0.6 $45 $19,440 $44,000 Aeration Blower 1 LS $40,000 $40,000 $1,200 $1,200 80.0 $45 $3,600 $45,000 Subtotal $89,000 Mechanical Piping & Valves 12" 304SS Sched IOS Aeration Piping 10 LF $60 $600 $3 $30 0.6 $45 $270 $1,000 8" 304SS Sched 10S Aeration Piping 30 LF $35 $1,050 $3 $90 0.8 $45 $1,080 $2,000 12"x8" Reducer 2 EA $150 $300 $60 $120 8.0 $45 $720 $1,000 12" Blind Flange 2 EA $100 $200 $60 $120 8.0 $45 $720 $1,000 12"x8" Tee 2 EA $1,135 $2,270 $86 $172 18.0 $45 $1,620 $4,000 8"90°Elbow 2 EA $153 $306 $38 $76 8.0 $45 $720 $1,000 Pipe Supports 1 LS $1,000 $1,000 $0 $0 0.0 $45 $0 $1,000 8" Butterfly Valve 1 EA $700 $700 $60 $60 12.0 $45 $540 $1,000 $12,000 Electrical: Adjustable Frequency Drive 1 EA $6,200.00 $6,200 $0 $0 240.0 $45 $10,800 $17,000 Electrical Conduit and Wiring1 LS $10,090.00 $10,090 $0 $0 240.0 $45 $10,800 $21,000 Subtotal $38,000 Subtotal $267,000 Mobilization 3% $9,000 Subtotal $276,000 Contractor Profit 15% $42,000 Contractor Overhead 10% $28,000 Subtotal $346,000 Contingency 30% $104,000 Subtotal $450,000 Engineering $125,000 Total Estimate of Probable Construction Cost $5759000 Black & Veatch Appendix B Diffuser & Blower Information for Recommended Alternative Triangle WWTP Aeration System Improvements Black & Veatch 5/2/2017 J SANITAIRE a xylem brand Diffused Aeration Equipment for Durham, NC - Triangle WWTP Grid to replace 4 Aerators Sanitaire #27689-17s March 2, 2017 jb KAOD27689-17\2017-2-17 4 Aertor Design 2scfm-diff.aer Charlotte, NC www.sanitaire.com Sanitaire Aeration Design Inputs for: Durham, NC - Triangle WWTP, Sanitaire #27689-17s Tank Geometry 2 Trains each Consisting of: Parameter Units Pass 1 Parallel Reactors Pass Process 1 Aerobic SW D ft 18.2 Submergence ft 17.1 Volume ft3 32,706.0 Reactor Geometry: FASL Rect Length ft 36.0 Width ft 50.0 Oxygen/Air Distribution Zone 1 Pass 1 Default 1 100.0% Oxygenation Parameter Units I AOR 4 Aerators No. Trains Operating 2 Oxygen Requirement Ib/day 11,712.0-A Standard Oxygen Correction Factor Parameters Parameter Units I AOR 4 Aerators Alpha 0.6 Beta 0.98 Theta 1.024 Dissolved Oxygen mg/I 2 Site Elevation FASL 250 Ambient Pressure PSIA 14.58 Water Temperature °C 30 Notes: Bold, Italicized text indicate assumptions made by Sanitaire A - Indicates Actual (AOR) Requirement. S - Indicates Standard Condition (SOR) Oxygen requirement. If the AOR/SOR parameter is not given, then its value will be evaluated later if suitable alpha, beta, D.O., theta, pressure, and temperature data is supplied. Round tanks are evaluated as rectangular tanks diameter equal to length and equal surface area. Annular tanks are evaluated as rectangular tanks of width equal to the annular width and equal surface area. Sanitaire, A Xylem Brand Page 2 of 6 Sanitaire Project Name: Durham, NC - Triangle WWTP Sanitaire Project #27689-17s Design Summary Notes: (1) Design air is the maximum of process air or mixing air (2) Delivered oxygen based on design air (3) Brake Horsepower based on adiabatic compression, 70% mechanical efficiency and 0.30 psi lineloss (4) Performance based on diffuser density (At/Ad), submergence, and diffuser unit air flow. (5) Diffuser Air Flow based on Active Valve Modulation (6) Blower Pressure Capability also requires consideration of: A. The Air Main headloss (piping, fittings, valves, instrumentation, etc.) between the blower and the aeration assembly dropleg connections. B. Potential for increased headloss resulting from diffuser fouling and/or aging. Please refer to the US EPA Fine Pore Design Manual (EPA/625/1-89/023), WEF Manual of Practice FD -13, and other technical publications for a detailed discussion on this subject. Note that this headloss consideration relates to all Fine Pore systems regardless of supplier or type of diffuser element. C. Increased diffuser submergence during Peak Flow conditions. (7) Air Flow defined at 30°C (8) Fine Mixing air based on 0.12 scfm/ft2 Sanitaire, A Xylem Brand Page 3 of 6 Aerators Units Default No. Trains in Operation 2 No. Grids in Operation 2 No. Operating Diffusers 1,440 SOR Ib/day 24,612 SOTE % 34.0 Total Air Rate scfm 2,888 Min.Diffuser Air Rate scfm/diff. 2.01 Max. Diffuser Air Rate scfm/diff. 2.01 Static Pressure psig 7.41 Diffuser DWP @ Min Air psig 0.56 Diffuser DWP @ Max Air psig 0.56 Pressure @ Top of Dropleg psig 8.2 Est. Blower Efficiency 70% Est. Motor Efficiency 90% Shaft Power Bhp 129.4 Est. Motor Electrical Load kW 107.3 Est. Standard Aeration Efficiency #SOR/BHP-hr 7.93 Notes: (1) Design air is the maximum of process air or mixing air (2) Delivered oxygen based on design air (3) Brake Horsepower based on adiabatic compression, 70% mechanical efficiency and 0.30 psi lineloss (4) Performance based on diffuser density (At/Ad), submergence, and diffuser unit air flow. (5) Diffuser Air Flow based on Active Valve Modulation (6) Blower Pressure Capability also requires consideration of: A. The Air Main headloss (piping, fittings, valves, instrumentation, etc.) between the blower and the aeration assembly dropleg connections. B. Potential for increased headloss resulting from diffuser fouling and/or aging. Please refer to the US EPA Fine Pore Design Manual (EPA/625/1-89/023), WEF Manual of Practice FD -13, and other technical publications for a detailed discussion on this subject. Note that this headloss consideration relates to all Fine Pore systems regardless of supplier or type of diffuser element. C. Increased diffuser submergence during Peak Flow conditions. (7) Air Flow defined at 30°C (8) Fine Mixing air based on 0.12 scfm/ft2 Sanitaire, A Xylem Brand Page 3 of 6 Sanitaire Project Name: Durham, NC - Triangle WWTP Sanitaire Project #27689-17s Consulting Engineer: Operating Condition: AOR 4 Aerators Oxygen Distribution: Default Aeration System Design Parameter Units Zone 1 Totals/Overall Pass 1 SWD ft 18.17 Subm ft 17.12 Volume ft3 32,706.0 65,412.0 No. Parallel Tanks 1 No. Trains in Operation 2 Grid Count 1 2 Dropleg Diameter inches 8 At/Ad 6.09756 Diffuser Density % Floor 16.40% Diffusers/Grid 720 1,440 Oxygen Transfer Diffuser Type SSII-9 Alpha 0.6 Beta 0.98 Theta 1.024 D.O. mg/I 2 Water Temp °C 30 AOR/SOR 0.4759 0.4759 Oxygen Distribution %/Zone 100.0% 100.0% AOR Ib/day 11,712.0 11,712.0 SOR Ib/day 24,611.8 24,611.8 Air Rate (7) scfm Performance Mixing Criteria scfm/ft2 0.12 Safety Factor % Mixing Air (8) scfm 432.0 Process Air (for SOR) scfm 2,887.7 Design Air (1,7) scfm 2,887.7 2,887.7 Diffuser Air Rate scfm/Diff. 2.01 2.01 Delivered SOR Ib/day 24,611.8 24,611.8 Delivered SOTE % 34.0% 34.0% Pressure @ Top of Dropleg psig 8.20 8.20 Shaft Power Bhp 129.4 129.4 Notes: (1) Design air is the maximum of process air or mixing air (2) Delivered oxygen based on design air (3) Brake Horsepower based on adiabatic compression, 70% mechanical efficiency and 0.30 psi lineloss (4) Performance based on diffuser density (At/Ad), submergence, and diffuser unit air flow. (5) Diffuser Air Flow based on Active Valve Modulation (6) Blower Pressure Capability also requires consideration of: A. The Air Main headloss (piping, fittings, valves, instrumentation, etc.) between the blower and the aeration assembly dropleg connections. B. Potential for increased headloss resulting from diffuser fouling and/or aging. Please refer to the US EPA Fine Pore Design Manual (EPA/625/1-89/023), WEF Manual of Practice FD -13, and other technical publications for a detailed discussion on this subject. Note that this headloss consideration relates to all Fine Pore systems regardless of supplier or type of diffuser element. C. Increased diffuser submergence during Peak Flow conditions. (7) Air Flow defined at 30°C (8) Fine Mixing air based on 0.12 scfm/ft2 Sanitaire, A Xylem Brand Page 4 of 6 Sanitaire Project Name: Durham, NC - Triangle WWTP Sanitaire Project #27689-17s Headloss Summary by System Operating Point Consulting Engineer: Operating Condition: AOR 4 Aerators Oxygen Distribution: Default Grid Design Grid Pressure Grid Air Flow Units Grid 1 Diffuser Count scfm 720 Dropleg Diameter inches 8 Line Count inches 16 Line Spacing ft 2.08 Manifold Diameter inches 8 Manifold Length ft 31.25 Header Length ft 47.25 Manifold Location End Manifold Elevation PSI Inline Dropleg Location psi End Header Orientation psi Width Grid Pressure Grid Air Flow scfm 1,443.8 Diffuser Air Flow scfm 2.01 Submergence ft 17.12 Orifice Diameter inches 13/64 Static Header Pressure Differential in Assembly psig 2.66E-02 Average Header Pressure in Assembly PSI 8.14 A: Average Headloss from Top of Dropleg To Headers PSI 5.64E-02 B: Diffuser Orifice Headloss psi 1.70E-01 C: Diffuser Dynamic Wet Pressure psi 5.61 E-01 D: Static Pressure psig 7.41 Total Pressure Required at Top of Dropleg (A+B+C+D) psig 8.20 Friction Headloss (A+B) PSI 2.26E-01 Sanitaire, A Xylem Brand Page 5 of 6 0 I 0 U) LLu 36' - 0 Ingle Train Information Grid Grid Drop Header Header Header Discs/ At/ Discs/ No Count Le 0" Count S c ft. Len ft. Grid Ad Train 1 1 8 18 2.08 47.25 720 8.10 720 Total Discs/Train 720 PRELIMINARYe7HISVUWaR&4FROTVTbD96FOC�ONT&TY DOCUMENTS, SUBMITTALS, OR CONSTRUCTION Sanitaire OUST p'p��q°p nartyv 1° �a -"WN B� 8A ■aYnmNmla�loert DUMe4 NO — TrimWe wm er ogre Y7e8�T/a a IQIIBIa �W owe Na�� WWTP sgr .n,Mat�Yaoaanao ar 9• Dlao Aantlon BYstam � By onre Excelsior Blower Systems P.O. Box 15126 - 331 June Avenue Blandon, PA 1 951 0-51 26 Phone: 800-921-0002 Fax: 610-921-9727 Black & Veatch Engineers 201 South Orange Avenue, Suite 500 Orlando, FL 32801 Attn: Steven Scott Re: Durham County, WWTP March 19, 2017 Quote# 35306 1 Gardner Denver 616 "Heliflow" Series Positive Displacement Blower 1500 SCFM / 1691 ICFM 9.8 PSIG 270' Elevation 105°F 2890 RPM 92.9 BHP 1 Elevated Steel Base 1 V -Belt Drive 1 Enclosed OSHA Style Drive Guard 1 PL -3" Weight Type Relief Valve 1 Universal CCS -8" Inlet Air Filter with Paper Element 1 Universal RISY-8" Inlet Silencer with Saddles 1 Universal SDY-8" Discharge Silencers with Saddles 1 125 HP — 1800 RPM - TEFC - 444T — 460/3/60 - 1.15 S.F. - Electric Motor Premium Efficient — Certified for VFD Service 1 Motor Slide Base 1 Layout & Mount Blower, Motor & Drive 2 Spool Type Flexible Connector 1 Protective Crating 1 Wika 2.5" Pressure Gauge 1 Dwyer Inlet Vacuum Gauge 1 Flexi-Hinge 518-8" Check Valve 1 Deltech Model 52-8" Butterfly Valve 1 Fully Assemble & Finish Paint All Components 1 Aluminum Sound Enclosure 1 Spare V -Belt Set 1 Spare Filter Element 1 AEON Synthetic Blower Oil for Initial Start up 8 Submittals, Shop Drawings & O/M Manuals 1 Freight to Job Site 1 Start Up Service Total Price for One (1) Blower Package Approximate Weight is 5800 lbs. $ 39,750.00 If you have any questions, please contact Gene Franckowiak at 800-921-0002. Gardner Denver Blowers come off an assembly line in Sedalia, Missouri - Not a BOAT Gardner Denver - Keeping Americans Workin_g 8" 150# FLG,- 8" 150# FLG, 8° 150# FLG. 72 62 5 2 DOORS T O O 00 , 00 , 2 DOORS 86 3/4"0 (TYP 4) E, F X X -FAN / \ J 1 � 1 rCW A DOOR r i i I D 1 4 T 10 A BLOWER: G.D. HELIFLOW 616 B MOTOR: C MOTOR SLIDE BASE: D ELEVATED STEEL BASE E V -BELT DRIVE: BLOWER SHV: MOTOR SHV: BELT: F DRIVE GUARD G INLET FILTER / SILENCER: UNIVERSAL CCS -8" H INLET SILENCER: UNIVERSAL RISY-8" I DISCHARGE SILENCER: UNIVERSAL SDY-8" J FLEXIBLE PIPE CONNECTOR: FLEX -FAB TYPE 1-8" K PRESSURE RELIEF VALVE: L CHECK VALVE: F.E. 518-8" M BUTTERFLY VALVE: 8" N DIFFERENTIAL PRESSURE GAUGE: DWYER 2020, 0-20" WC P PRESSURE GAUGE: 0-15 PSI X NOISE ENCLOSURE: ALUMINUM WITH ACOUSTIC FOAM, PERFORATED GALVANIZED STEEL INNER LINER, 6 LATCHING DOORS, LOUVERS AND EXHAUST FAN (1/15 HP, 115/1/60) WITH THERMOSTAT ESTIMATED BLOWER PACKAGE WT: 3,650 # ESTIMATED NOISE ENCLOSURE WT: 800 # NOISE ENCLOSURE SHIPS KNOCKED DOWN EXCELSIOR Blower Systems Inc. READING, PENNSYLVANIA DATE: 8/17/11 SCALE: NONE HE616-A-8x8-E Black & Veatch Appendix C Hypalon S& Seal System Triangle WWTP Aeration System Improvements Black & Veatch 5/2/2017 Sikadur-Combiflex° SG System High Performance Joint and Crack Waterproofing System Ow Now W=IIIIIII am* NOW 0,0- Sikadur-Combiflex® SG System The SikadurLCombiflex' SG system is the second generation development of the globally proven Sikadur-Combiflex® with even improved performance such as advanced adhesion properties and drinking water approval. The unique system consists of the Sikadur- Combiflex® SG tape and the Sikadue adhesives. It is widely used as joint waterproofing in watertight concrete structures. Main Advantages ■ Waterproofing of joints with extreme movements ■ Easy to install and adjust to complicated construction details ■ Excellent adhesion to different substrates ■ Resistant to high water pressure ■ Crack sealing system ■ Easy to control and repair Function: ■ Blocking the path of water penetration ■ Increased length of water penetration ■ Fully bonded to the concrete preventing underflow e = water penetration (EN 206) s = increassed length for water penetration Typical Applications Basements ■ High water tightness and durability ■ Easy to control/ repair ■ Independent of concreting steps ■ High joint movement capacity Infrastructure Bridges ■ De-icing salt resistance ■ UV resistant Tunnel Ventilation Ducts ■ Airtight ■ Flexible to joint tolerances Drinking Water ■ Approved in contact with drinking water ■ Long-term water resistance ■ Easy to control/repair Swimming Pools ■ Resistance to ozone, chlorine and UV ■ Good cleaning ability ■ Non abrasive to skin Refurbishment ■ Crack sealing ■ Resistance to negative water pressure Sewage Treatment Plants ■ Resistance to sewage water ■ Good abrasion resistance ■ Independent of concreting steps ■ High joint movement capacity Ground Water Protection ■ Chemical resistant ■ High safety of environment ■ Impermeable Facade Joints ■ High joint movements ■ Overpaintable (adhesive) ■ Weather resistant Sikadur-Combifiex° SG System Where to use? Expansion Joints ■ Temperature dilatation ■ Construction settlements ■ Material connection ■ Building connection �&O Red masking tape Sikadur" adhesive Sikadur-Combiflex® SG tape Sikadur® adhesive Prepared concrete surface Joint filler Construction Joints ■ Connection between concrete steps ■ Floor -to -wall Connection ■ Different material connection ■ Inside -outside application logo,! . Cracks Repair ■ Construction settlements ■ Shrinkage ■ Thermal influences ■ Structural overload Sikadur° Adhesives To achieve a watertight, durable connection between Sikadur-Combiflex° SG tape and the substrate Sikadur adhe- sives are used. Main Advantages ■ Excellent adhesion to many substrates ■ Available with normal and rapid hardening grades of adhesive Sikadur-Combiflex® CF Adhesive ■ Optimum workability and finish ■ Provides smooth surface Sikadur°-31 CF ■ Higher layer thickness is required Sikadur®-31 DW ■ Drinking water approval Sikadur°-33 ■ Mechanical mixing and dosage with Sika® CoMix-101 ■ Very suitable for high volumes Sikadur-Combiflex® SG Tape Sikadur-Combiflex' SG is a flexible prefabricated waterproofing tapes based on modified flexible Polyolefin (FPO) with advanced adhesion. Main Advantages ■ Advanced adhesion, no activation on site required ■ Can be used in contact with potable/ drinking water ■ High water pressure resistance ■ High durability and chemical resistance ■ UV- and weather resistant ■ Root resistance ■ Plasticizer free Sikadur-Combiflex®SG type P Sikadur-Combiflex SG -10 P Sikadur-Combiflex SG -20 P Tape width [mm] 100, 150, 200, 250, 300 150, 200, 250, 300 400, 500, 1000, 2000 400, 500, 1000, 2000 Tape length [m] 25 25 Sikadur-Combiflex® SG type M (with red masking tape for easier application in expansion joints) Sikadur-CombiflexoI M Sikadur-Combiflex'I Tape thickness [mm] 1.0 2.0 Tape width [mm] 100, 150, 200, 250, 300 150, 200, 250, 300 Tape length [m] 25 25 Sikadur°-Combiflex° SG System - Application Substrate preparation by means of sandblasting, grinding etc., followed by vacuuming. In case of dirt clean the surface of the Sikadur-Combiflex' SG tape with a dry or wet cloth. Use water and no solvent for cleaning. 5. .ti I+ Y ' Use masking strips to cover the joint. Mix Sikadur®-Combiflex®CF adhesive Apply the Sikadur'-Combiflex' CF Press the Sikadur�Combiflex® SG tape components A and B for a minimum of adhesive on the left-hand and the right-hand without trapping air into the adhesive by using 3 minutes until the mix is homogeneous. side of the joint. Then remove masking strip. a suitable roller. The adhesive should be squeezed out on both sides by — 5 mm. 1J Apply the Sikadurl-Combliflex® CF Adhesive on the tape. Remove the red middle strip and the masking strips on both sides to ensure a neat and precise detail. Connect tape ends by hot air welding. Prepare the welding area by roughing the surface by scotch brite or sand paper. Overlap 40 - 50 mm. Sikadur-Combiflex° SG System - Case Studies Sihlcity-Shopping, Business, Fun and Fitness Centre Zurich, Switzerland Project Description: Building complex containing shopping, cinema, office accommodation etc. Waterproofing of expansion and construction joints in the basement construction Project Requirements: Watertight concrete construction Waterproofing of joints in areas of ground- water pressure i'ipm I IF, Tunnel du Mont Blanc, France Project Description: Extensions of the fraco-italien Tunnel such as technical gallery etc Project Requirements: Watertight joint sealing system Flexibility to joint tolerances Water Tank, Riyadh, Saudi Arabia Project Description: Waterproof construction for collection of extra water for emergency purpose Project Requirements: Long-term water resistant High joint movement capacity Sika Solution: Sika Solution: Sika Solution: Sealing of the expansion and construction Sealing of the joints with the Sikadur- Sealing of the 25 km joints with the joints with the Sikadur-Combiflex° Combiflex° system, protection of technical Sikadur-Combiflex° system system against groundwater pressure installations from water Sika Full Range Solutions for Construction Concrete Production Waterproofing Flooring LF L Sika' ViscoCrete' Sikaplan",Sikalastic" Sikafloor' Sika® Retarder® Sika® & Tricosal" Water -stops SikaBond' Sika" SikaAer® Sika® Injection Systems Corrosion and Fire Protection SikaCor" Sika® Unitherm® Joint Sealing Sikaflex' Sikasil° Concrete Repair and Protection Structural Strengthening 4.4i_" Sika MonoTop' Sikagard' Sikadur" Grouting Sika' CarboDur® SikaWrap" Sikadur" Roofing Also available from Sika Sikadur SikaGrout'' Sika AnchorFix' s rorp11omi9 of uaaomem Stmotums with Sikaplan" J Sarnafil® Sikaplan° SikaRoof' MTC® ILL Z—Aiiiii— Flexible Waterproofing of Tunnels I a` antl Tricosal° Water Stops Sika"Injection Systems for with Sikaplan"Membranes erproofing of Expansion and Concrete Structures struction Joints Our most current General Sales Conditions shall apply. Please consult the Product Data Sheet prior to any use and processing. S ancel9aa Q bh a since 1991 Innovation & since Consistency 1 1 91 0 DURHAM COUNTY UF DURHAM COUNTY DURHAM, NORTH CAROLINA TRIANGLE WWTP AERATION SYSTEM IMPROVEMENTS ENGINEERING CALCULATIONS January 2018 Project No. 194729 BLACK & VEATCH International Company Business License F-0794 11000 Regency Parkway, Suite 410 Cary, North Carolina 27518 Black & Client Name: Durham County Veatch Project Name: Triangle WWTP Aeration system Improvements Project No.: 194729.1300 Rev No. Calculation Title: AOR Calculation Calculation No./File No.: C-001 I— W H Version 3.0 Purpose: Calculate Actual Oxygen Requirement (AOR) from existing brush aerators References: Wastewater Engineering Treatment, Disposal, and Reuse Veolia 9 Meter Rotor Brush Aerator Figure (see below) Q VEQ L 1A :1a In 9 Meter Rotor Transfer Rale � va.er Draw Mazlmum Maoumum immersion optimum mmer on �, 60 HP Prepared By: Kurtis Proffit Date: Feb 17, 2017 Verified By: B. Sabherwal Date: Feb 22, 2017 Page: 2 of 2 woo 90.0 tm� 7a.0 sp.0 sa.0 a 00.0 w.o m.o L.0&0 eA '7-0 r.0 a -e 1" 11-0 12.0 u„rnunwnwan Immersion {int Procedure: AOR - SOR x ('8 caw - coo x 07-20 x a Cs Where: SOR = 190 Ib 02/hr, Standard Oxygen Requirement or design capacity of 9.0 meter 75 hp Rotor Aerator at standard conditions, SOTR in above figure at max immersion 0.95 Ratio of oxygen saturation value of wastewater to that of clean water Csw = 7.49 Oxygen saturation value of clean water for the site conditions temperature of 30°C and actual barometric pressure at the site EL 250 ft above MSL of 14.59 psia (755 mm Hg, Ref Metcalf & Eddy Table E-2) Co = 2 mg/L, Residual concentration of dissolved oxygen desired during normal operation = 2.0 mg/L = 1.024 Temperature correction factor = 1.024 a = 0.9 Ratio of oxygen transfer in wastewater to that of clean water at same temperature provided by Kruger T = 30 Design wastewater temperature in °C Cs = 9.092 Oxygen saturation value of clean water at standard conditions AOR = 122.0 Actual Oxygen Requirement or capacity of 9.0 meter 75 hp Maxi Rotor Aerator at field conditions, Ib 02/hr Number of brush aerators per basin = 4 Equivalent AOR for all brush aerators = 487.8 Ib 02/hr REVISED, SUPERSEDED, AND VOID CALCULATIONS MUST BE CLEARLY IDENTIFIED, INITIALED, AND DATED BY THE RESPONSIBLE INDIVIDUAL. Water Proprietary and Confidential CONTROLLED when read online WTR-FM-EN-0014, dtd 1/302017 Page 1 of 1 Printed copy m UNCONTROLLED Owner: Durham County Computed : HRT Plant: Triangle WWTP Date: 1/15/2018 PN: 194729 Checked by:JVG Title: Blower Discharge Pressure Date: 1/10/2018 Rev. Date: 1/15/2018 PURPOSE To determine the discharge pressure required by the blowers for delivery of air to the aeration basins. REFERENCES 1 Email from Bickram Sabherwal, Subject: RRRWWTP Blower Evaluationon Monday 8.29.2016. 2 Sanitarie Diffuser Pre -Selection, Tech Memo 3 Basis of Design and Flow Memo ASSUMPTIONS 1 Calculations apply to air only General Side Water Depth Diffuser Submergance Diffuser Distance from Floor Pressure at Diffuser Diffuser Losses 9" Tube Fine Bubble Diffuser Pressure at top of dropleg Aging & Fouling System Losses Pipping Losses Saftey Factor Inlet Losses Blower Discharge Pressure Discharge Pressure Differential Pressure Maximum Intitial Top of Dropleg Maximum Aged Diff Top of Dropleg = 18.20 ft Reference 1 & 2 = 17.10 ft Reference 2 = 1.10 ft = 7.42 psi = 0.75 psi Assumed 8.17 Reference 1 & 2 = 0.50 psi Assumed = 0.43 psi Assumed = 0.10 psi Assumed = 0.40 psi Assumed = 9.20 psig = 9.60 psig = 8.17 psig = 8.67 psig Owner: Durham County Computed : HRT Plant: Triangle WWTP Date: 1/15/2018 PN: 194729 Checked by:JVG Title: Blower Air Requirements - Alternative 2 Date: 1/10/2018 Revision Date: 1/15/2018 PURPOSE To determine the blower configuration to adequately meet the aeartion demands. REFERENCES 1 Site Drawings 2 Weatherbase.com - Durham, NC 3 2005 ASHRAE Handbook 4 EDI & Sanitaire Proposals dated 2/28/2017 and 3/2/2017, respectively. 5 Basis of Design and Flow Memo 6 ICFM = SCFM (P — (2H . Vap,))(T + 460)(Ph ) (nh -(aH, x vap))(7� +460)(P) ASSUMPTIONS 1 Calculations apply to air only Standard Air Conditions Pressure = 14.70 Temperature = 68.0 Vapor Pressure = 0.34 Relative Humidity = 36% Site Conditions Elevation = 270 Reference 1 Barometric Pressure = 14.6 Inlet Air Conditions Summer Winter Inlet Pressure = 14.20 14.20 psia Inlet Temperature (Ref 2) = 105.0 0.0 °F Inlet Temperature (Ref3) 100.0 16.0 °F Inlet Vapor Pressure = 0.95 0.00 psig Inlet Relative Humidity = 54% 10% % Annual Percentage = 75% 25% % Process Aeration Requirements (Ref 4) Max Flow Min Mixing Flow II Replace 2 Brush Aerators (*) = 1,500 225 SCFM Ref 5 *Assume aeration demands for replacing 2 brush aerators is half of the replacing four alternatives. II System Aeration Requirements (ICFM) Summer Winter Replace 2 Brush Aerators (*) = 1,708 1,342 ICFM *Assume aeration demands for replacing 2 brush aerators is half of the replacing four alternatives. Blowers Number of Duty Blowers Number of Standy Blowers Capacity per Blower Approx Turndown per Blower Total Capacity (Duty Blowers) Total Capacity (All Blowers) Option 1 (2+1) = 2 = 1,500 SCFM 750 SCFM 3,000 SCFM = 3,000 Design Points Capacity per Blower = 1,708 ICFM Turndown per Blower = 854 ICFM Assumed Owner: Durham County Computed : HRT Plant: Triangle WWTP Date: 1/15/2018 PN: 194729 Checked by:JVG Title: Blower Air Requirments & Pipe Sizing Date: 1/10/2018 Revision Date: 1/15/2018 PURPOSE To confirm the aeration header size and to determine the basin drop leg pipe sizes. REFERENCES & CALCULATIONS 1 Current Drawing set 2 2005 ASHRAE Handbook - Fundamentals - Springfield, MO 3 Weatherbase.com - Springfield, MO 4 ICF, = SCFM (F� — (RH, x Vap,))(T, + 460)(Pb ) (Pn —(nx, xVap,))(T +460)(P) 5 ACFM = ICFM P. x (T, + 460) Pd x (T. + 460 ) 6 Maximum design air velocity criteria through 30 inch and larger pipe is 5,000 fpm. Maximum design air velocity criteria through pipe smaller than 30 inch is 3,500 fpm. ASSUMPTIONS 1 Calculations apply to air only Standard Air Conditions Pressure = 14.70 psia Temperature = 68.0 °F Vapor Pressure = 0.34 psig Relative Humiditiy = 36% Site Conditions Elevation = 270 ft Reference 1 Barometric Pressure = 14.6 psia Inle Summer Air Conditions Inlet Pressure = 14.2 psia Inlet Temperature = 100 °F Reference 2 Inlet Vapor Pressure = 0.95 psig Inlet Relative Humiditiy = 54% Reference Discharge Air Conditions Discharge Pressure = 9.20 psig Discharge Pressure = 23.8 psia Discharge Temperature = 275.0 °F Assumed Flow Breakdown: Each basin has three droplegs Each metering line meters for two basins. Total of 5 metering lines for the 10 basins. Basin Flow = Max 1,150 to Min 680 SCFM Dropleg 1 (65% of Basin Flow, as determined by the process group) Dropleg 2 (22% of Basin Fow, as determined by the process group) Dropleg 3 (13% of Basin Flow, as determined by the process group) Aeration Requirements (MMS)** Disch 1 Blower = ** MMS - Max Month Pipe Sizing Indv Blwr Inlet Design Airflow (MMS) Maximum Allowable Velocity Minimum Pipe Diameter Nominal Pipe Diameter Actual Pipe I.D. Actual Inlet Velocity Pipe Sizing Indv Blwr Disch Design Airflow (MMS) Maximum Allowable Velocity Minimum Pipe Diameter Nominal Pipe Diameter Actual Pipe I.D. Actual Inlet Velocity SUM (Ref. s) ICFM (Calc. 4) ACFM (Calc. s) 1,500 1,693 1,326 1,693 ICFM = 3,500 fpm = 9.42 in in = 10.42 in = 2,858 fpm = 1,326 ACFM = 3,500 fpm = 8.33 in = 8.0 in = 8.33 in = 3,504 fpm Reference 6 Reference 6 Owner: Durham County Computed : HRT Plant: Triangle WWTP Date: 1/15/2018 PN: 194729 Checked by:JVG Title: PRESSURE LOSS CALCS Date: 1/10/2018 The purpose of this program is to determine the pressure loss through an air pipe SCFM 1500 system. The Fritzsche Formula, which is valid for air line pressures from 3 to 15 psig, ICFM 1708 is used to calculate pressure losses. ACFM 1326 The following are required inputs: Inlet Press 14.6 psia Q, Air Flow Rate, icfm Disch Press 9.2 psig d, Line Size I.D., in. L/D, from Mach. Eng. Dept. Proc. M-0004 LL, Line Length, ft Water depth, ft Outputs are calculated based upon the following formulas: L = UD (d/12), or LL where L = Equivalent Length, ft V = Q / [(pi/4) cIA21 where V = Velocity, fpm and pi = 3.146 LP=AP - SL where LP = Line Press., psia, AP = Atmos. Press., psia, and SL = System Loss, psia, is defined below IL = (L QA1.857)/(1480 LP cIA5) where IL = Item Loss, psi SL = SIL where SIL = The sum of IL Item losses, such as water head, which are not calculated using the Fritzche Formula can be directly enter into the Item Loss column. A direct entry will erase the Item Loss formula. Care should taken that after modifications the appropriate formula or direct entry is in applicable cells. Atmospheric Pressure should be entered in the Line Pressure column for Item 1. Also, the pressure increase produced by the blower should be added to the Line Pressure entry for the blower. Blower pressure increase should be decreased or increased until the discharge line pressure equals the atmospheric pressure. Normally maximum velocities should be limited to 3,500 fpm. However in large capacity systems, or systems with long pipe lengths, it may be necessary to exceed 3,500 fpm. LONGEST PIPE RUN 0.13 PSI LONGEST PIPE RUN FLOW LINE LINE EQUIV. LINE ITEM SYSTEM ITEM RATE SIZE L/D LENGTH LENGTH VEL. PRESS. LOSS LOSS COMMENTS NO. DESCRIPTION icfm-> acfm I. D., in. ft. ft. fpm psia psi psi 1 BLOWER DISCHARGE 1,326 8.33 0.0 3,499 23.80 0.0000 0.0000 Downstream of check valve 2 ELBOW (90) Long R 1,326 8.33 14 9.7 3,499 23.80 0.0043 0.0043 3 INCREASER (6x8) 1,326 8.33 15.7 10.9 3,499 23.79 0.0049 0.0092 4 PIPE 1,326 8.33 0.5 0.5 3,499 23.79 0.0002 0.0094 5 EXPANSION JOINT 1,326 8.33 1 1.0 3,499 23.79 0.0004 0.0098 6 PIPE 1,326 8.33 1.33 1.3 3,499 23.79 0.0006 0.0104 7 ELBOW (90) Long R 1,326 8.33 14 9.7 3,499 23.78 0.0043 0.0148 8 PIPE 1,326 8.33 21.75 21.8 3,499 23.78 0.0097 0.0245 9 ELBOW (90) Long R 1,326 8.33 14 9.7 3,499 23.77 0.0043 0.0288 PIPE 1,326 8.33 0.166666667 0.2 3,499 23.77 0.0001 0.0289 BUTTERFLY VALVE 1,326 8.33 45 31.2 3,499 23.77 0.0139 0.0428 PIPE 1,326 8.33 0.166666667 0.2 3,499 23.75 0.0001 0.0429 10 TEE BRANCH 1,326 8.33 41.7 28.9 3,499 23.75 0.0129 0.0558 11 PIPE 1,326 8.33 0.0 3,499 23.74 0.0000 0.0558 12 BUTTERFLY VALVE 1,326 8.33 45 31.2 3,499 23.74 0.0139 0.0697 13 PIPE 1,326 8.33 0.0 3,499 23.73 0.0000 0.0697 14 TEE BRANCH 1,326 8.33 0.0 3,499 23.73 0.0000 0.0697 15 BUTTERFLYVALVE 1,326 8.33 45 31.2 3,499 23.73 0.0140 0.0837 16 PIPE 1,326 8.33 0.33 0.3 3,499 23.71 0.0001 0.0838 17 ELBOW (90) Long R 1,326 8.33 14 9.7 3,499 23.71 0.0043 0.0882 18 PIPE 1,326 8.33 0.33 0.3 3,499 23.71 0.0001 0.0883 19 ELBOW (90) Long R 1,326 8.33 14 9.7 3,499 23.71 0.0043 0.0927 20 PIPE 1,326 8.33 6.75 6.8 3,499 23.70 0.0030 0.0957 21 ELBOW (45) LR 1,326 8.33 9.9 6.9 3,499 23.70 0.0031 0.0988 22 ELBOW (45) LR 1,326 8.33 9.9 6.9 3,499 23.70 0.0031 0.1018 23 PIPE 1,326 8.33 1 1.0 3,499 23.69 0.0004 0.1023 24 ELBOW (90) Long R 1,326 8.33 14 9.7 3,499 23.69 0.0043 0.1066 25 PIPE 1,326 8.33 29 29.0 3,499 23.69 0.0130 0.1196 26 EXPANSION JOINT 1,326 8.33 1 1.0 3,499 23.68 0.0004 0.1200 27 PIPE 1,326 8.33 6.5 6.5 3,499 23.68 0.0029 0.1229 28 ELBOW (90) Long R 1,326 8.33 14 9.7 3,499 23.67 0.0044 0.1273 29 CONT/DIFF TRANSITION 1,326 8.33 0.0 3,499 23.67 0.0000 0.1273 0.1273 MMILHOUSEgM ENGINEERING & CONSTRUCTION Project No: Calculation Title: Calculation Status: Prepared By: Reviewed By: Purpose 194729 MSB4 Load Stud Brad Holland Joe Zurad Calculation Cover Sheet Project Name: Triangle WWTP Aeration System Improvements Calc No. Rev No: Date: 1/23/18 Date: 1/25/18 The purpose of the calculation is to: 1. Verify the Emergency backup generator can supply the buss MSB4 with the addition of new blower loads. Acceptance Criteria Results of the load calculations are accepted when the following conditions are met: 1. Rating of backup generator is greater than 110% of the calculated running FLA of MSB4. Rcfcrcnrcc 1. References are contained in the owner supplied As -built drawings dated June 2009, and Sealed 08/30/2013. Calculation Inputs Inputs to the calculation were obtained from the project construction documents dated 08/30/2013 and the related project files with the exception of the following assumptions: 1. Rating of existing generator, as well as existing loads shown on As -built drawings are correct 2. Demand Factor of .8 is adequate and conservative for the Dewatering Facility, MCC9, and Panel P9 Calculation Methodology Load calculations were prepared using the approved software program: Excel. Calculation Output and Recommendations The calculation outputs are modified as follows for incorporation into the construction documents: 1. Validation of sufficient bus sizing. Calculation Results The results of the Load calculations are incorporated in the construction documents as follows: 1. The maximum output of 1500A of the existing 1000KW Backup generator is sufficient to power the running FLA of MSB4. Attachments 0 Calculation results report from software. Client Name Durham County Page 1 of 2 Project Name Triangle WWTP Aeration System Improvements Prepared By Bradley Holland Title Load Study Calculation Date 1/23/2018 Project Number 194729 Verified By Joe Zurad Bus Name MSB4 Date 1/25/2018 BLUE HIGHLIGHTED AREA FOR INPUT DATA EQUIPMENT NAME LOAD TYPE LOAD PF DEM FACT CONNECTED RUNNING FEEDER SIZING KW -C KVAR-C I KVA-C AMPS -C KW -R KVAR-R KVA-R JAMPS CB ISTARTER CABLE Dewatering Facility KVA 818.67 0.80 0.80 654.94 491.2 818.7 1027.52 523.9 393.0 654.9 822.02 1600 15-500KCMIL,5#4/0G,(5)3" OD2 Blower 1 AFD 125.00 0.95 1.00 122.08 40.1 128.5 161.29 122.1 40.1 128.5 161.29 225 3-350KCMIL,#4G,2-1/2" OD2Blower 2 AFD 125.00 0.95 1.00 122.08 40.1 128.5 161.29 122.1 40.1 128.5 161.29 225 3-350KCMIL,#4G,2-1/2" MCC 9 KVA 112.07 0.80 0.80 89.66 67.2 112.1 140.66 71.7 53.8 89.7 112.53 200 3#4/0,#6G,2" Panel Board P9 KVA 34.89 0.80 1.00 27.91 20.9 34.9 43.79 27.9 20.9 34.9 43.79 60 3#2,#10G,1-1/4" 1.00 0.0 0.0 0.00 0.0 0.0 0.0 0.00 1.00 0.0 0.0 0.00 0.0 0.0 0.0 0.00 1.00 0.0 0.0 0.00 0.0 0.0 0.0 0.00 1.00 0.0 0.0 0.00 0.0 0.0 0.0 0.00 1.00 0.0 0.0 0.00 0.0 0.0 0.0 0.00 1.00 0.0 0.0 0.00 0.0 0.0 0.0 0.00 TOTAL BUS LOADS 1016.7 659.6 1211.9 867.8 547.9 1026.3 CONNECTED FLA 1521.1 P.F 0.839 RUNNING FLA 1288.1 P.F. 0.846 MAX CB 1600 LOAD TYPES NOTES MAIN SERVICE CABLE 15-500KCMIL,5#4/0N,(5)3" MOTOR (hp) 1. Calculations are based on 460 volts, 3 phase. MAIN FEEDER CABLE 15-500KCMIL,5#4/OG,(5)3" KVA 2. Lookup data valid through 500 hp. Manual inputs KW are required above 500 hp. AFD (hp) 3. Motor FLA based on NEC, not calculated values. Water Proprietary and Confidential CONTROLLED when read online WTR-FM-EN-0700, old 41412017 Page 1 of 1 Printed copy is UNCONTROLLED