TECHNICAL MEMORANDUM
TO: Dennis Phinney, Project Manager
FROM: Brian Knoll and Justin Logan
DATE: Aug 11, 2021
SUBJECT: Preliminary Design Memorandum – Meeting Minutes July 28, 2021 PROJECT NO.: WRF1 Centrifuge Phase 2
A review meeting of the Preliminary Design Memorandum was held on July 28, 2021 at WRF1.
This memo includes the minutes from this review meeting, memorializing the decisions made during the meeting and including an updated opinion of overall project cost.
MEETING MINUTES
The following items were discussed during the July 28, 2021 meeting:
1. Existing polymer feed line connection is ¾” on the centrifuge. This limits the amount of water that can be diluted in with the polymer. Operations has found that the more water they add for dilution the better the centrifuge operates, resulting in dryer cake and clearer centrate. They would like to see if a 1” connection can be included on the new centrifuge and if the existing unit can be modified. The line feeding this connection is
1.5”. WEBB/AQUA will follow up with Alfa Laval (AL) to determine if a larger connection can be included.
2. Struvite is forming in the drain pump station. They are currently adding chemical to reduce this potential but precipitation of struvite can completely clog and blind off the pumps in the drain pump station. The City would like to re-pipe the centrate drain directly to the oxidation ditches in order to eliminate the struvite formation at the pump station and specifically in the drain pumps. A drain line will be added to go to both ditches. This will either go to the influent splitter box or the scum return lines at the effluent side of the ditches. The alignment will be determined and then WEBB/AQUA will work with the City to verify potential crossing conflicts. This will include potholing by the City or C Below.
3. Phasing will be structured so that the existing belt press remains operable until the new, 2nd centrifuge is online. Dewatering redundancy will be maintained during the project.
4. A single belt conveyor is preferred in lieu of the existing 3 screw conveyors that convey dewatered solids to the truck load out facility. Staff also desires that the conveyor be covered. WEBB/AQUA will verify the alignment with staff and add this to the project.
The opinion of cost has been updated, including this cost.
5. Solenoids provided with the existing centrifuge are difficult to source when they have to be replaced and have performed poorly. As such it is desired to specify and have AL provide Arco, slow acting, SS solenoid valves.
6. Water solenoids are difficult to maintain and access. They will be moved to the northeast side of the structure and placed in the vertical position to improve access for maintenance.
WRF1 Centrifuge Phase 2 – PDM Meeting Minutes
August 11, 2021
Innovative Engineering Solutions
7. Opinion of probable cost will be updated to include the longer belt conveyor and gravity drain line as part of the project. This is attached to these minutes.
8. This memo will be attached to the preliminary design report, thus finalizing the PDR.
ENGINEERS OPINION OF PROBABLE COST
The total probable cost has been updated as indicated above and is $2,237,000. This total includes 15% for design engineering and project administrations and 30% for contingency. The detailed estimate is shown on the following pages
Budgetary Estimate Probable Cost Opinion
WRF-1 Centrifuge Expansion
City of Corona
ENR: 12227 Los Angeles Construction Cost Jan-22
Section Size Description Unit Cost Quantity
00 00 00 PROCUREMENT AND CONTRACTING REQUIREMENTS
00 61 00 Bonds 1.55% 1 LS $23,900
00 73 16 Builders All Risk Insurance 0.87% 1 LS $13,400 00 89 01 Permits 0.00% 1 LS $0
01 00 00 GENERAL REQUIREMENTS
01 11 00 Summary of Work
01 32 13 Scheduling of Work 0.50% 1 LS $7,700
01 93 00 Facility Maintenance 0.50% 1 LS $7,700
01 21 00 Allowances
01 21 00 Allowance A3 Other Field Orders $0 1 ea $0
01 22 00 Unit Prices
01 29 73 Schedule of Values 0.40% 1 LS $6,200
01 31 19 Project Meetings 0.20% 1 LS $3,100
01 32 00 Construction Progress Documentation 0.20% 1 LS $3,100 01 32 33 Construction Photographic and Video Documentation $1,250 1 LS $1,250 01 33 00 Submittal Procedures 0.50% 1 LS $7,700
01 35 26 Governmental Safety Requirements 0.40% 1 LS $6,200 01 40 00 Quality Requirements
01 50 00 Temporary Facilities and Controls
01 61 00 Common Product Requirements 0.10% 1 LS $1,500
01 63 00 Product Substitution Procedures 0.05% 1 LS $800 01 64 00 Installation of Owner Furnished Items 30% $648,212 LS $194,464 01 64 50 System Integrators 1.00% 1 LS $15,400
01 65 00 Project Delivery Requirements 0.10% 1 LS $1,500 01 66 00 Project Storage and Handling Requirements 0.10% 1 LS $1,500 01 71 13 Mobilization and Demobilization 3.45% 1 LS $53,200 01 73 00 Execution 0.10% 1 LS $1,500
01 74 00 Cleaning and Waste Management 0.63% 1 LS $9,700 01 77 00 Closeout Procedures 1.99% 1 LS $30,700
01 78 23 Operation and Maintenance Data 0.13% 1 LS $2,000 01 78 36 Product Warranties 0.46% 1 LS $7,100
01 78 39 Project Record Documents 0.18% 1 LS $2,800
02 00 00 EXISTING CONDITIONS
02 41 13 Selective Site Demolition 1.87% 1 LS $28,800
02 41 16 Mechanical and Electrical Equipment Demolition - Belt Press $25,000 1 ea $25,000 02 41 16 Mechanical and Electrical Equipment Demolition - Conveyors $12,000 1 ea $12,000 05 50 00 METAL FABRICATIONS
05 50 00 Metal Fabrications $6,500 1 LS $6,500
05 53 00 Gratings $45 300 SF $13,500
09 00 00 FINISHES
09 80 00 Protective Coatings $10,000 1 LS $10,000
14 00 00 CONVEYING EQUIPMENT
14 40 00 Sludge Conveyance System $2,200 135 LF $297,000 23 00 00 HEATING, VENTILATION, AND AIR CONDITIONING
23 31 00 Fiberglass Ductwork and Accessories $5,000 1 LS $5,000 26 00 00 ELECTRICAL 16.00% 1 LS $246,800
33 00 00 UTILITIES
33 05 00 COMMON WORK RESULTS FOR UTILITIES
33 05 05 Pipeline Testing $2,500 1 LS $2,500
40 00 00 PROCESS INTEGRATION
40 05 00 Piping General $1,000 1 LS $1,000
40 05 07 Hangers and Support for Process Piping $10,000 1 LS $10,000 40 05 19 Ductile Iron Pipe $1,000 10 ea $10,000
40 05 31 Plastic Process Pipe $6,000 1 LS $6,000
40 05 31 Plastic Process Pipe (Drain Relocate) $200 400 LF $80,000 40 05 53 Identification for Piping and Equipment $500 1 LS $500 40 05 57 Actuators for Process Valves and Gates $900 2 ea $1,800 40 05 62 Plug Valves $1,000 1 ea $1,000
40 05 67 Ball Valves $200 3 ea $600
40 90 00 Instrumentation and Control for Process Systems 2.00% 1 LS $30,900 46 70 00 WATER AND WASTEWATER RESIDUALS HANDLING AND TREATMENT 46 76 00 Residuals Dewatering Equipment
46 76 33 75 hp Dewatering Centrifuge $351,212 1 ea $351,212 ENGINEER'S OPINION OF PROBABLE CONSTRUCTION COST $1,542,526 Right of Way and Land Acquisition not included
Offsite Utilities by Others (Offsite Cable, and Fiber Optic) not included Design Engineering and Project Administration 15% $231,379 Field Engineering not included
Contingency 30% $462,758
Financing not included
ENGINEER'S OPINION OF PROBABLE TOTAL COST $2,237,000
These figures have been prepared, at the request of a client, before finalizing Contract Documents. Figures are only an opinion and are provided solely as a guide. Estimator is not responsible for fluctuation in cost of material, labor or components or unforeseen contingencies.
OPTIONAL ITEMS