Page 1 of 3 Addendum 4 Digester Gas Treatment System Project CITY OF MODESTO Addendum No. 4 Digester Gas Treatment System Project City of Modesto Project No. 2009/25 In the City of Modesto Bid Opening January 12, 2010 at 11:00 a.m. THIS ADDENDUM FORMS A PART OF THE CONTRACT DOCUMENTS AND MODIFIES THE ORIGINAL DRAWINGS AND SPECIFICATIONS AS NOTED HEREIN. BY SUBMISSION OF A PROPOSAL FOR THIS PROJECT, THE BIDDER IS ACKNOWLEDGING CONFIRMATION OF THE RECEIPT OF ALL ADDENDA ISSUED FOR THE PROJECT AND HAS INCLUDED COSTS FOR SUCH IN THE PROPOSAL SUBMITTED. PROJECT SPECIFICATIONS: DIVISION 01 – GENERAL REQUIREMENTS, 1. Section 01140, WORK RESTRICTIONS, Page 01140-5, Add: “1.12 TEMPORARY DIGESTER GAS PIPING SYSTEM A. Digester No. 2 must remain in service during construction of the Project. B. Contractor shall provide temporary piping for Digester No. 2 digester gas line to allow temporary bypass of digester gas from Digester No. 2. See Sheets M- 1A, M-4A, and M-5A. C. Connections to existing piping shall be provided with isolation valves as indicated on the Drawings to facilitate construction of the temporary piping system within the shutdown constraints defined in Article 1.07. D. Temporary digester gas piping shall be Schedule 80 PVC and shall be supported at 5 foot intervals and as specified in Section 15061. E. Upon completion of construction and testing of new permanent stainless steel piping system, contractor shall demolish the temporary piping system up to the isolation valves and shall cap temporary piping isolation valves with blind flanges.” PROJECT SPECIFICATIONS: DIVISION 11 – EQUIPMENT, 1. Section 11371, DIGESTER GAS ROTARY-LOBE BLOWERS, Page 11371-4, Part 1.12, Paragraph E.4.a is amended to read: “a. Low suction pressure (provide adjustable time delay set at 10 seconds initially for blower startup.”
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Page 1 of 3 Addendum 4 Digester Gas Treatment System Project
CITY OF MODESTO
Addendum No. 4
Digester Gas Treatment System Project
City of Modesto Project No. 2009/25 In the City of Modesto
Bid Opening January 12, 2010 at 11:00 a.m.
THIS ADDENDUM FORMS A PART OF THE CONTRACT DOCUMENTS AND MODIFIES THE ORIGINAL DRAWINGS AND SPECIFICATIONS AS NOTED HEREIN. BY SUBMISSION OF A PROPOSAL FOR THIS PROJECT, THE BIDDER IS ACKNOWLEDGING CONFIRMATION OF THE RECEIPT OF ALL ADDENDA ISSUED FOR THE PROJECT AND HAS INCLUDED COSTS FOR SUCH IN THE PROPOSAL SUBMITTED. PROJECT SPECIFICATIONS: DIVISION 01 – GENERAL REQUIREMENTS, 1. Section 01140, WORK RESTRICTIONS, Page 01140-5, Add:
“1.12 TEMPORARY DIGESTER GAS PIPING SYSTEM A. Digester No. 2 must remain in service during construction of the Project.
B. Contractor shall provide temporary piping for Digester No. 2 digester gas line
to allow temporary bypass of digester gas from Digester No. 2. See Sheets M-1A, M-4A, and M-5A.
C. Connections to existing piping shall be provided with isolation valves as
indicated on the Drawings to facilitate construction of the temporary piping system within the shutdown constraints defined in Article 1.07.
D. Temporary digester gas piping shall be Schedule 80 PVC and shall be
supported at 5 foot intervals and as specified in Section 15061.
E. Upon completion of construction and testing of new permanent stainless steel piping system, contractor shall demolish the temporary piping system up to the isolation valves and shall cap temporary piping isolation valves with blind flanges.”
PROJECT SPECIFICATIONS: DIVISION 11 – EQUIPMENT, 1. Section 11371, DIGESTER GAS ROTARY-LOBE BLOWERS, Page 11371-4, Part
1.12, Paragraph E.4.a is amended to read:
“a. Low suction pressure (provide adjustable time delay set at 10 seconds initially for blower startup.”
Page 2 of 3 Addendum 4 Digester Gas Treatment System Project
2. Section 11381, DIGESTER ACCESSORIES, Page 11381-1, Part 2.02, Add:
“B. Self-contained backpressure regulator for high pressure service:
1. Manufacturers: a. Fisher, 98 Series.
2. Materials: a. Body: Stainless steel. b. Internal: Stainless steel. c. Packing: PTFE.
3. Self-contained pressure regulator. 4. Flanged ends. 5. Pass 7,200 standard cubic feet per hour gas at 0.8 specific gravity. 6. Minimum 1 inch size. 7. Adjustable set point from 2 to 7 pounds per square inch gauge.”
3. Section 11382, DIGESTER GAS SCRUBBER, Page 11382-1, Part 1.01, Paragraph C is
amended to read: “C. Equipment Tag Numbers: TNK-101A, BLO-101.”
4. Section 11382, DIGESTER GAS SCRUBBER, Page 11382-4, Part 2.03, Paragraph J is amended to read: “J. The tank shall be tested pneumatically or hydrostatically (to an internal pressure of 1 psig) by the manufacturer prior to coating.”
5. Section 11382, DIGESTER GAS SCRUBBER, Page 11382-5, Part 2.06, Paragraph D is
amended to read: “D. At flow rates specified the media bed shall be designed to limit media replacement to a maximum of once per year. Supporting calculations shall be submitted with the Shop Drawing.”
6. Section 11382, DIGESTER GAS SCRUBBER, Page 11382-6, Part 3.01, Paragraph B is amended to read: “B. Each completed unit, having the iron sponge media installed, shall be isolated by gas piping valves and tested through one of the regeneration connections with air at 1 psig for 1 hour without detectable air loss. Correction for thermal variation will be allowed.”
DESIGN DRAWINGS: 1. Sheet S-1, BOILER FUEL TREATMENT SYSTEM PLAN AND SECTION,
Replace with the attached Sheet S-1A. Changes on this drawing are clouded.
Page 3 of 3 Addendum 4 Digester Gas Treatment System Project
2. Sheet M-1, EXISTING SLUDGE HANDLING BUILDING PLAN, Replace with the attached Sheet M-1A. Changes on this drawing are clouded.
3. Sheet M-2, EXISTING SLUDGE HANDLING BUILDING PHOTOS AND
SECTION, Replace with the attached Sheet M-2A. Changes on this drawing are clouded.
4. Sheet M-3, BOILER FUEL TREATMENT SYSTEM PLAN, Replace with the
attached Sheet M-3A. Changes on this drawing are clouded. 5. Sheet M-4, DIGESTER NO. 2 PLAN, Replace with the attached Sheet M-4A. Changes
on this drawing are clouded. 6. Sheet M-5, DIGESTER GAS SYSTEM SCHEMATIC, Replace with the attached
Sheet M-5A. Changes on this drawing are clouded. 7. Sheet TP-2, TYPICAL DETAILS PIPING, Replace with the attached Sheet TP-2A.
Changes on this drawing are clouded.
__________________________ Jason Pretzlaf Carollo Engineers, P.C. PE No. M33959 Dated January 5, 2010
