Design Basis Memorandum for Secondary Clarifier #3

Report:

Design Basis Memorandum for Secondary Clarifier #3

Project SC403 Secondary Clarifier Weir Structure

Removal and Replacement

(RMOW Wastewater Treatment Plant Upgrade)

Client:

Prepared by:

200 – 896 Cambie Street Vancouver, BC, V6B 2P6

Contact Person:

Ali Taleb P.Eng.

Email: [email protected] Tel: 604-681 0901

August 17, 2021

mailto:[email protected]

MidSea Engineering Ltd. 2

200-896 Cambie Street Vancouver, BC, V6B 2P6

PROJECT NO. 200135

DESIGN BASIS MEMORANDUM FOR SECONDARY

CLARIFIER #3

Contents 1. SCOPE OF WORK ........................................................................................................ 3

2. INTRODUCTION .......................................................................................................... 3

3. KWL CONDITION ASSESSMENT OF SECONDARY CLARIFIERS ........................................ 5

4. DESIGN CRITERIA ........................................................................................................ 5

4.1. Background information ..................................................................................................... 5

4.2. WASTEWATER CHARACTERIZATION PROGRAM ................................................................. 6

4.3. DESIGN LOADS .................................................................................................................... 6

4.4. EFFLUENT DISCHARGE PERMIT ........................................................................................... 7

5. SECONDARY CLARIFIER#3 ........................................................................................... 8

6. SITE SPECIFIC CONDITIONS ......................................................................................... 9

7. DESIGN STANDARDS ................................................................................................. 10

Steel Related Reference Standards: ................................................................................. 10

8. REFERENCES ............................................................................................................. 11

9. APPENDICES ............................................................................................................. 12

9.1. Technical Memorandum, KWL Consulting Engineers ....................................................... 13

9.2. Clarifier#3 Drawings .......................................................................................................... 14



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1. SCOPE OF WORK

MidSea Engineering is retained by Maven to prepare a Design Basis Memorandum for refurbishment of

the Secondary Clarifier#3 for Whistler Wastewater Treatment Plant (WWTP). The current memorandum

aims to present details regarding the current condition of the Secondary Clarifier#3 and the scope of

work and operations requirements for restoration, the design criteria including design loads and a brief

list of design codes and standards. At the end As-Constructed drawing will be enclosed.

2. INTRODUCTION

The Resort Municipality of Whistler (RMOW) operates a trickling filter/solid contact secondary

wastewater treatment plant (WWTP). The RMOW’s WWTP uses a sophisticated, enhanced biological

phosphorus removal (EBPR) process. This system builds on the carbon and nutrient loads entering the

plant to grow a specialized biomass able to withdraw phosphate from the water. The removal of

phosphate from the water relies on a food source “bugs” that comes from the system’s fermenter.

Currently the fermenter at the WWTP is offline and it has become necessary to introduce acetic acid into

the bioreactor as a food source. The fermenter is scheduled to come back online in 2023.

WWTP is located between the Sea to Sky Highway (Highway 99) and the north bank of the Cheakamus

River approximately 100m southwest of the intersection of Highway 99 and Cheakamus Lake Road at

the south entrance to Whistler.

The plant was last upgraded in 2007/2008. In 2006, Stantec was awarded an assignment to design the

upgrade of the Whistler WWTP and the project was completed on an accelerated schedule to enable

commissioning prior to the 2010 Olympics. The project upgraded the wastewater facility to meet the

projected community build out population of 62,125 bed units (as was expected to be reached in the year

2016). The design implemented biological phosphorus and nitrogen removal.

The following objectives were identified and followed in the design process for the upgrade of the

Whistler WWTP by Stantec:

• The RMOW developed and adopted a community vision on sustainability -Whistler 2030 Vision

(Currently RMOW adopts Whistler 2030 Vision) based on the principals of The Natural Step

Framework. Sustainable design is a key driver in this project. All aspects of the design from

initial process selection to detailed design decisions strive to meet the principles outlined in the

Whistler 2030 vision.



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• Odour control was a significant issue. Minimizing odours was an objective in design and

upgrade by Stantec. Odour is no longer an issue, the plant utilized a carbon filtration system to

treat the foul air.

• The plant is intended to meet the wastewater treatment needs of the RMOW. Hence, design

input from operations and engineering staff should be accommodated to the maximum extent

possible.

• Training of municipal staff should be provided throughout the project.

• The plant must continuously provide a favorable operational environment for plant operators.

• Operational issues and improvements to existing facilities will be addressed in this upgrade.

• Life cycle costs and provision of quality facilities must be considered in the overall project

assessment and operation.

• Where practical and feasible, consideration should be given to incorporating existing

equipment and facilities into the upgrade.

The upgrade plan performed by Stantec in 2007/2008 included following items:

• Septage receiving station improvement, DAF and biosolids dewatering building.

• Two train Modified Johannesburg Biological Nutrient Removal (BNR) bioreactor system.

• Primary Sludge Fermenter (currently out of service; this food source is currently supplemented

with acetic acid).

• New administration building.

• A new secondary clarifier (Clarifier#404).

• A new blower building with a room to house equipment for the District Energy System

• Construction of a UV disinfection building.

• Conversion of ATAD tanks to waste activated sludge and fermented primary sludge storage

tanks (currently the tanks are only being utilized for WAS storage).

• Soda Ash silo for alkalinity addition (currently this is out of service, and not required for the

operation at this time).

In the update project by Stantec, the Secondary Clarifiers # 1 and #2 were refitted, the Secondary

Clarifier#4 was newly added; however, the secondary clarifier# 3 was untouched. In April 2020, Kerr

Wood Leidal (KWL) performed a condition assessment of the four circular secondary clarifiers at the

Whistler Wastewater Treatment Plant (WWTP). The report identified critical action items for each



PROJECT NO. 200135


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clarifier. Need for major restoration has been identified for the Secondary Clarifier#3 which is reaching

end-of-life and shows significant corrosion and rust of steel works. The location of Secondary Clarifier#3

with respect to other clarifiers is presented in drawing number P403 of Stantec’s as-constructed

drawings. This memorandum intends to specify design basis criteria for the restoration of the

Secondary Clarifier#3.

3. KWL CONDITION ASSESSMENT OF SECONDARY CLARIFIERS

The Whistler Wastewater Treatment Plant (WWTP) operates two smaller clarifiers (#1 and #2), each 16m

in diameter, and two larger units (#3 and #4) each 22.5 m in diameter. Clarifiers #1 and #2 combined

have the same capacity as one larger clarifier.

In the Condition Assessment performed by KWL Consulting Engineers dated April 2020, the Secondary

Clarifiers were evaluated on a scale of one to five, where one is excellent and five represents failure, or

not working.

Clarifier #3 was given an overall Assessment Rating of four.

Critical Action Items:

1. The launders and weirs are close to end-of-life and require replacement, preferably within the next 12- 24 months. The submerged supports were not inspected but should be assessed structurally when the tank is empty.

2. The drive mechanism is 24 years old and considered near the end-of-life for this type of rotating equipment, although the supplier (WesTech) noted that some of their units have lasted 40 years with good maintenance. The motor was replaced in 2019, and it is reported that the electrical control panel is no longer working.

3. The submerged items were not inspected, but to guarantee continued performance and long-term operation, replacement of all internal equipment is recommended.

4. DESIGN CRITERIA

The design criteria presented in this chapter is from Stantec Pre-Design Report in March 2007 for a peak

of load in 2010 Olympics. RMOW is currently working on updating design criteria for 2040 build out. This

revised design criteria (Table 1, 2, & 3) will be available August 2021.

4.1. BACKGROUND INFORMATION

The design parameters outlined for the build out year (2016), based on 90% occupied Bed unit occupancy

projections are summarized in Table 1.



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Table 1 -Flow and Load Projections (Adopted from Table 4.1 Stantec Pre-Design Report, March 2007)

Flow Value Notes

2016 Annual Average Flow

(m3/d)

14,00

2016 Maximum Month Flow

(m3/d)

20,000 Based upon a maximum (m3/d)

month factor of 1.35 (reference

AE Technical Memorandum

2.2b)

2016 Peak Hour Flow (m3/d) 53,600

Total occupied bed units 55,935 Assumes 90% occupancy

TSS load (kg/d) 6,153 @0.11 kg/d per BU

BOD load (kg/d) 6,647 @0.10 kg/d per BU

Total P load (kg/d) 145 @ 0.0026 kg/d per BU

For process design purposes, a maximum monthly flow of 20,000 m3/d should be selected for the

refurbishment of Secondary Clarifier#3. Results from the waste characterization program shall be used

to adjust the design parameters for the detailed design.

4.2. WASTEWATER CHARACTERIZATION PROGRAM

Two sampling periods shall be employed, each one month in duration to characterize wastewater. In

absence of such sampling program, Appendix A of the Pre-Design Report by Stantec in March 2007 can

be used which includes sampling program data obtained from November 2006 to January 2007.

4.3. DESIGN LOADS

Secondary clarifiers shall be designed for the maximum monthly loads while maintained to be

hydraulically suitable for peak hour flows presented in Table 2. The data in this table was obtained from

sampling program data acquired by Stantec from November 2006 to January 2007.



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Table 2 -Maximum Month Design Loads Using Measured Concentrations November 2006 -January 2007

(Adopted from Table 4.3 Stantec Pre-Design Report, March 2007)

Parameter Design Concentration

(mg/L)

Avg day Load

(kg/d)

Max Month Load

(kg/d)

CBOD 250 3,675 5,000

TSS 250 3,675 5,000

TKN 40 588 800

NH3-N 25 368 500

TP 5 74 100

The design concentrations including safety factors because of the limited sampling period employed by

Stantec are presented in Table 3:

Table 3 -Selected Plant Design Loads (Adopted from Table 4.4 Stantec Pre-Design Report, March 2007)

Parameter Design Concentration

(mg/L)

Avg day Load

(kg/d)

Max Month Load

(kg/d)

CBOD 290 4,263 5,800

TSS 290 4,263 5,800

TKN 40 588 800

NH3-N 25 367 500

TP 7 103 140

Flow (m3/d) - 14,700 20,000

4.4. EFFLUENT DISCHARGE PERMIT

The RMOW’s effluent quality requirements are covered under Operational Certificate ME-01452. The

operational certificate parameters are summarized in Table 4.5 of Stantec Pre-Design Report and in



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Table 4 below. The certificate set limits on CBOD, TSS, soluble orthophosphorus and effluent toxicity.

All parameters shall never exceed values, except for orthophosphate loading which is monthly mass

loading from May 15th to September 15th.

Table 4 -Summary of Current Operational Certificates (never to exceed, except as noted) (Adopted from Table

4.5 Stantec Pre-Design Report, March 2007)

Parameter Concentration

CBOD 30 mg/L

Total Suspended Solids (TSS) 40 mg/L

96 hr LC50 (Fish bioassay) 100% effluent strength

Orthophosphate concentration (as phosphorus) 1.75 mg/L

Orthophosphate loading (as phosphorus) 36.6 kg/mth (May 15 to Sept 15)

5. SECONDARY CLARIFIER#3

Design criteria for Secondary Clarifier #3 are summarized in Table 6.2 of the Stantec Report, presented

in Table 5 as follows, assuming that all four clarifiers are in operation. Table 5 will be updated August

2021.

Table 5 - Secondary Clarifier Design Criteria (Adopted from Table 6.2 Stantec Pre-Design Report, March

2007)

Description Peak Hydraulic Flow Maximum Month Flow

Design Flow (Ml/d) 53.6 20

Design MLSS (mg/L) 3700 3700

RAZ Rate 0.7Q 0.7Q

Surface Overflow Rate (m3/m2/d) 44.8 16.7

Solids Loading Rate (kg/m2/d) 11.7 4.4

Total Clarifier Area (m2) 1197 1197

#of Units / Diameter (m) 2@16m, [email protected] 2@16m, [email protected]



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6. SITE SPECIFIC CONDITIONS

Table 6 - Climatic Design Data for the City of Whistler based on BC Building Code 2018

Feature Value

January 2.5% design dry bulb temperature °C -17

January 1% design dry bulb temperature °C -20

July 2.5% design dry bulb temperature °C 30

July 2.5% design wet bulb temperature °C 20

Annual total degree days below 18 °C 4180

Maximum 15-minute rainfall (mm) 10

One Day Rain, 1/50, (mm) 85

Annual rainfall (mm) 845

Moisture Index 0.99

Annual total precipitation (mm) 1215

Driving Rain wind pressure 1/5 years (Pa) 160

Ground snow load, snow component Ss (50 years) (kPa) 9.5

Ground snow load, rain component Sr (50 years) (kPa) 0.9

Hourly wind pressure 1/10 (kPa) 0.25

Hourly wind pressure 1/50 years (kPa) 0.32



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Table 7- Seismic Hazard 2% probability of exceedance in 50 years for City of Whistler

Sa (0.2) Sa (0.5) Sa (1.0) Sa (2.0) Sa (5.0) Sa (10.0) PGA (g) PGV (m/s)

0.438 0.357 0.233 0.152 0.058 0.02 0.203 0.296

7. DESIGN STANDARDS

Relevant analyses and design standards include but not limited to :

• British Columbia Building Code

• National Building Code of Canada

• ACI 350.3-06

STEEL RELATED REFERENCE STANDARDS:

CSA S16, Limit State Design of Steel Structures

CSA G40.21, Structural Quality Steel

ASTM A53, Standard Specification for Pipe

ASTM F3125 Grade A325, Standard Specification for Structural Steel Bolts

ASTM A563 GR DH, Standard Specification for NUTs

ASTM F436, Standard Specification for Washers

CISC Handbook of Steel Construction

ASTM 153, Standard Specification for Galvanization of hardware products

ASTM 123, Standard Specification for Zinc (Hot-Dip Galvanized) Coatings on Iron and Steel

Products

CSA W48 E49XX electrode classification for Arc Welding Electrodes

CSA W59M for welding

Steel Fabricators and operators approved by Canadian Welding Bureau to the requirements

of CSA W47.1.



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8. REFERENCES

[1] Associated Engineering Technical Memorandum (2006-2007)

[2] RMOW Wastewater Treatment Plant Upgrade- PRE-DESIGN REPORT, Stantec, March 2007.

[3] Technical Memorandum, KWL Consulting Engineers, April 2020.

[4] AS CONSTRUCTED DRAWINGS FOR RMOW Wastewater Treatment Plant, Knight LTD



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9. APPENDICES



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9.1. TECHNICAL MEMORANDUM, KWL CONSULTING ENGINEERS

Technical Memorandum

DATE: April 16, 2020

TO: Chelsey Roberts, AScT

Resort Municipality of Whistler FROM: Nigel Slater, P. Eng.

Don Nash, P.Eng. RE: SECONDARY CLARIFIER CONDITION ASSESSMENT

Resort Municipality of Whistler Our File 0029.326-300

1. Introduction KWL was retained to undertake a condition assessment of the four circular secondary clarifiers at the Whistler wastewater treatment plant (WWTP). There are two smaller clarifiers (#1 and #2) each 16 m in diameter, and two larger units (#3 and #4) each 22.5 m in diameter. Clarifiers #1 and #2 combined have the same capacity as one large clarifier.

2

TECHNICAL MEMORANDUMResort Municipality of Whistler

April 16, 2020

Clarifiers #1 and #2 were re-fitted around 2007/2008 with new mechanical/electrical equipment, along with construction of the new Clarifier #4, prior to the Olympics.

The inspection took place on Thursday, March 12, 2020. Items are rated on a scale of one to five, where one is excellent and five represents failed, or not working.

A visual inspection of all above grade and above water components to assess its condition and operational function was completed. Plant operational input and comments were collected from site staff. Each asset condition was scored, and recommendations were made for monitor, repair or replace.

Improvements and considerations are also noted.

2. Condition Assessment Overview A condition assessment of each clarifier is tabulated in Attachment A.

Photos of the inspection items of concern are provided in Attachment B.

The outcome of the condition assessment can be summarized as follows:

• In general, the clarifiers operate well with no major issues.

• There is heavy algae growth in the clarifiers which requires operations and maintenance attention in the summer months, including shut-downs for manual cleaning.

• The secondary release of Phosphorous can be an issue under low-flow seasons due to the long hydraulic retention time in the clarifiers, and the limitations of the RAS flowrate.

• Typically, one large clarifier is used in summer months, with an additional small clarifier brought into service on weekends to deal with the increased flow.

• The WWTP has an excess of capacity based on current flow and loadings (plant was designed for a peak during the 2010 Olympics).

• The mechanical equipment in Clarifier #3 is 24 years old and is reaching the end-of-life and requires refurbishment to guarantee continued performance for the long term. If a refurbishment is undertaken, there would be opportunities to update the design to modern standards and incorporate alternative equipment and components to increase the capacity and performance of the clarifier.

2.1 Clarifier #1

Overall Assessment Results

The overall rating is two.

Critical Action Items

Painted steelwork is corroding. Undertake remedial renovation work in the next 12 months to prevent further corrosion, and deterioration. Sandblasting, priming and epoxy painting will be required.

The building for Clarifier #1 and #2 requires repair and restoration work to the heating and ventilation system.

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April 16, 2020

Other Considerations

Consider covering the open-mesh grating to reduce moisture within the building.

2.2 Clarifier #2


The overall rating is two.


The painted steelwork is corroding. Undertake remedial renovation work in the next 12 months to prevent further corrosion, and deterioration. Sandblasting, priming and epoxy painting will be required.

The building for Clarifiers #1 and #2 requires repair and restoration work, heating and ventilation system.


Consider covering the open-mesh grating to reduce moisture within the building.

2.3 Clarifier #3


The overall rating is four.


The launders and weirs are close to end-of-life and require replacement, preferably within the next 12 – 24 months. The submerged supports were not inspected but should be assessed structurally when the tank is empty.

The drive mechanism is 24 years old and considered near the end-of-life for this type of rotating equipment, although the supplier (WesTech) noted that some of their units have lasted 40 years with good maintenance. The motor was replaced in 2019, and it is reported that the electrical control panel is no longer working.

The submerged items were not inspected, but to guarantee continued performance and long-term operation, replacement of all internal equipment is recommended. From photos supplied post-inspection, there is corrosion, but some of the internal steelwork appears to be in reasonable condition and it may be possible to repair or refurbish. However, any in-place cleaning and painting on-site for refurbishment work will need to be carefully monitored and supervised.


Algae cleaning is an ongoing maintenance issue especially during the summer, and it is recommended to add spray washing or covers to the clarifier.

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April 16, 2020

2.4 Clarifier #4


The overall rating is three.


The clarifier has problems with algae in the summer and consideration should be given to improving launder cleaning equipment, or to providing covers for launders.

Some maintenance is required on the launder V-notch weirs for levelling and equalizing the flow around the clarifier. Also, some general corrosion protection (sand blasting and painting) is required to prevent steelwork deterioration. It is recommended to complete this work during the next 12 months.


Inspect the submerged items when the tank is empty.

3. Main Items of Concern 1. Maintenance – Plant operation is generally “unplanned maintenance” with no specific maintenance

program at present. Typically, only the oil is changed. However, there should be other planned maintenance taking place including a weekly oil check, a yearly oil change, draining the condensate weekly, and lubrication per the O&M.

2. Algae – The growth of algae on the launder troughs and weirs is a constant maintenance and operational issue, especially during the summer when algae can be discharged into the discharge pipework and downstream UV system. Algae also increases TSS and BOD in the treated effluent. The brush cleaning system is not very effective on sectional weir segments, requires frequent adjustment, and does not keep up with the growth of algae and slime in the V-notches and launder troughs.

There are “touchless” alternatives including washer and jet sprays, which have demonstrated good performance and would provide a viable option for cleaning. Winter could be an issue with spray and freezing, but algae growth is lower in winter and less cleaning is required. Spray systems can operate continuously or intermittently, use wash-water (or potable water), at 20 US gpm and a pressure of 65 psi, and have a filter/strainer.

The most proven and effective long-term solution is to provide covers to prevent sunlight accessing the launders, which drastically reduces the growth of algae. There are several suppliers including Nefco and IEC Covers, and they can be made from HDPE, stainless steel or FRP. Covers are a passive system and require little maintenance. The main disadvantage of covers is that the treated effluent discharge over the weirs is no longer visible to the operator.

3. Instrumentation – Installation of sludge blanket detectors on each clarifier to provide real-time sludge blanket level monitoring should be considered. These units give an early warning of potential TSS carry-over from a high blanket or washout. The units would be linked to the WWTP SCADA for monitoring and alarms.

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April 16, 2020

4. Other Site Observations and Recommendations 1. Assuming Clarifier #3 will be completely re-fitted with new internal mechanical/electrical equipment,

consider the following recommendations:

a. Evaluate the option of installing the launders and weirs around the edge of the tank wall, having a single weir and scum baffle, and providing launder covers to prevent algae growth. In addition, having a single peripheral weir allows the entire surface of the tank to be skimmed, which is a definite improvement on the current design. In addition, Stamford baffles (or equivalent) could be installed inside the tank to reduce density currents and improve performance.

b. If double-sided weirs and launders are used, specify circular weirs and troughs without bracing, instead of the sectional lengths of straight weirs. Circular weirs are inherently easier to clean.

c. A larger diameter inlet dissipation well / stilling baffle to improve flocculation of the mixed liquor entering the clarifier.

d. A dipping scum box and beach and dual scraper arms to improve surface scum removal.

e. Investigate options for increasing return activated sludge (RAS) flowrate.

f. Specify stainless steel for items which are partially submerged in liquid to reduce steel corrosion at the liquid-air interface.

g. Alternative materials for construction, such as aluminum or fibre reinforced plastic (FRP) for stilling baffles.

2. Investigate options to increase the RAS flowrate for all clarifiers, and hydraulic modelling to optimize clarifier performance.

3. It is recommended to implement an asset management program with equipment and component numbering, maintenance requirements/servicing and a schedule of routine inspection and planned servicing.

5. Cost Opinion The following budgetary pricing is provided for estimating capital expenditure required to maintain the existing process equipment in the secondary clarifiers.

5.1 Clarifier #1 and #2

The Table 5-1 below summarizes the work required for Clarifiers #1 and #2, which could be undertaken by a local (Sea to Sky) contractor:

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April 16, 2020

Table 5-1: Estimated Costs

Clarifier #1 and #2 Items Clarifier #1 Clarifier #2 Building

Cleaning and painting $20,000 $20,000 $10,000

Heating and ventilation $0 $0 $15,000

Sludge blanket level detectors (optional) $10,000 $10,000 $0

Column totals $30,000 $30,000 $25,000

Sub total $85,000

Contingency (30%) $25,500

Engineering (15%) $12,750

Total $123,250

5.2 Clarifier #3

The following cost estimates were obtained from WesTech (Clarifier #3 original manufacturer), and Envirodyne (Manufacturer of equipment installed in clarifiers #1, #2 and #4).

There are several other suppliers of this equipment, typically in the USA.

Table 5-2 summarizes the quotes by WesTech and Envirodyne for the clarifier mechanical and electrical (M&E) replacements, and Table 5-3 summarizes the costs for optional items.


Clarifier #3 WesTech Envirodyne

Clarifier internals $182,000

Launder and baffles $171,000

Launder washer $69,000

Dive replacement $63,000

Shipping from USA $25,000 Included below

Lump sum price for total system Included above $441,000

Installation $102,000 $88,200

Total Supplier Costs $612,000 $529,200

Contingency (30%) $183,600 $158,760

Engineering (15%) $91,800 $79,380

Total $887,400 $767,340

Notes: Exchange rate 1 USD = 1.4 CAD. Installation 20% of capital, engineering 15%, and contingency 30%. Fabrication of equipment was stated at 16 – 24 weeks.

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April 16, 2020

Table 5-3: Optional Items

Items Cost

Covers $120,000

Sludge blanket level detectors $10,000

Total Supplier Costs $130,000



Total $188,500

Note: a spray system can be used instead of covers which would reduce the cost by $72,500 including engineering and contingency.

5.3 Clarifier #4

Table 5-4 summarizes the costs for Clarifier #4, which could be undertaken by a local (Sea to Sky) contractor and Table 5-5 summarizes the optional work items.


Items Cost

Cleaning and painting $20,000

Sub total $20,000



Total $29,000

Table 5-5: Optional Items

Items Cost

Covers $120,000

Sludge blanket level detectors $10,000

Total Supplier Costs $130,000



Total $188,500

Note: a spray system can be used instead of covers which would reduce the cost by $72,500 including engineering and contingency.

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April 16, 2020

5.4 Cost Summary

Table 5-6 summarizes the costs for each clarifier including optional items.

Table 5-6: Cost Summary

Cost Summary Including Optional Items

Cost

Clarifier #1, #2, and building $123,250

Clarifier #3 (Envirodyne price) $955,840

Clarifier #4 $217,500

Total $1,296,590

6. Closing We would like to thank the Resort Municipality of Whistler for the opportunity to support the condition assessment work. KWL would be pleased to provide additional support moving forward as needed for design, asset management planning, developing standard operating procedures, maintenance schedules, tendering, and construction support.

Attachment A

Assessment Sheets

Client: Regional Municipality of Whistler Comments Rating

Project Title Whistler Secondary Clarifier Condition Assessment

Description of Work Inspection of secondary clarifiers and associated equipment.

Date 12 March 2020

KWL Project No 0029.326

Item Clarifier # 1

Diameter, area etc. 16 m diameter, 201 m2, 4.75 m side-water depth, volume ~950 m3

Year built Year built unknown. Internals completely refurbished in 2008

Description

Concrete circular clarifier, center feed with stilling baffle and dissipation well, double-sided launder at 12 m

diameter with cross bracing, scum removal, two spiral sludge scrapers, center drive (Envirodyne, PA),

access bridge, 1:12 floor slope, 0.75m freeboard

Status Off-line (on standby)

Operational Issues and

comments

No major issues

No planned maintenance program, change oil as required. Not aware of other maintenance / O&M

No algae control, brushes etc., clean manually.

Issue with influent ML flow splitting between 1 and 2 due to pipework configuration, but controlled by

throttling #2. Flow is measured in a flowmeter before the flow split.

Check Envirodyne O&M and

maintenance program for the drive

system

2

Average Flows Rated for 5,000 m3/d (208 m3/h, 58 L/s)

Peak FlowExpected 10,000 m3/d (2 m/h up flow rate) but may have hydraulic or process restrictions from solids carry-

over or under-capacity of RAS

Flow would need to be shared between

clarifiers at this flowrate.

Weir Length 78m, weir overflow rate 0.75 L/m/s Normal Design

Capacity Surface Loading Rate (up flow rate) ~1m/h at 5,000 m3/d Normal Design

Solids loading Rate Calculated at 3.6kgMLSS/m2.h at 3,500mg/L MLSS Normal Design

Solids liquid separation Tank empty, no comment

Scum and scum box Moving surface scraper/collector, and beach. 2

Scum removal Discharge to sump/drain, collected by suction tanker

Scum sprayers None.

Weir trough Double-sided launders are ~900mm deep with cross bar bracing. V-notch weirs Access difficult 2

Algae None, tank empty

Cleaning Manual Labor intensive 2

Stilling Baffle Dissipation well and stilling baffle with scum outlets Standard design 2

Scrapers Two spiral sludge scrapers, across full width of tank, some rust/corrosion Repair/renovate 2

Bridge Fixed bridge access to drive, safe access 2

Bridge mechanism/drive Some oil leakage reported. Envirodyne drive mechanism from 2007/8, life expectancy 15-20 years Investigate maintenance 3

RAS flow RAS submersible pumps located inside the building in a wet well 2

Equipment5 HP / 3.7 kW 1,745rpm.

Flygt 3102.181 pumps.

Condition unknown, pumps are more

than 10 years old. 2

Flow measurement Yes

Control Variable speed

Standby capability Spare pump, one unit shared for Clarifiers #1 and #2.

WAS system Not applicable - Waste from Bioreactor based on sludge age

Flow splitting Issue with ML flow splitting between 1 and 2 but controlled by throttling #2 2

Outlet valves / gates 450 mm dia outlet pipework, then flowmeter and UV system

CorrosionSome corrosion starting on effluent launder and feed distribution baffle. Rusty fittings. Requires touch

up/painting maintenanceRepair/renovate 3

Safety Good, light, handrails, missing life float 2

Grating / handrails Generally good condition 2

Electrical Good condition 2

Valves and pipework Pipework in-tank in good condition. 2

BuildingsGenerally workable condition, steel framing shows corrosion. Requires heating and ventilation. Door needs

sealing. Cover open mesh wet wells to reduce moisture.Repair, building-mechanical work 4


Project Title: Whistler Secondary Clarifier Condition Assessment


Date 12 March 2020

KWL Project No: 0029.326

Item Clarifier # 2

Diameter, area etc. 16m diameter, 201 m2, 4.75 m side-water depth, volume ~950 m3

Year built Year built unknown. Internals completely refurbished in 2008

Description

Concrete circular clarifier, center feed with stilling baffle and dissipation well, double-sided launder at 12 m

diameter with cross bracing, scum removal, two spiral sludge scrapers, center drive (Envirodyne, PA),

access bridge, 1:12 floor slope, 0.75 m freeboard

Status Off-line (on standby)


comments

No major issues

No planned maintenance program, change oil as required. Not aware of other maintenance / O&M

Small crack in wall of #2 near building - needs review by structural/civil.

No algae control, brushes etc., clean manually.

Issue with influent ML flow splitting between 1 and 2 due to pipework configuration, but controlled by

throttling #2, Flow is measured by flowmeter before the flow split.

Civil inspection required

Check Envirodyne O&M and

maintenance program for the drive

system.

2

Average Flows Rated for 5,000m3/d (208m3/h, 58 L/s)

Peak FlowExpected 10,000 m3/d (2m/h up flow rate) but may have hydraulic or process restrictions from solids carry-

over or under-capacity of RAS

Operations would split flow between

clarifiers of this flowrate.

Weir Length 78 m, weir overflow rate 0.75 L/m/s Normal Design

Capacity Surface Loading Rate (up flow rate) ~1 m/h at 5,000 m3/d Normal Design

Solids loading Rate Calculated at 3.6kgMLSS/m2.h at 3,500mg/L MLSS Normal Design

Solids liquid separation Tank empty, no comment


Scum removal Discharge to sump/drain, collected by suction tanker

Scum sprayers None.

Weir trough Double sided launder ~900 mm deep trough without cross baffles. V-notch weirs. Access difficult 2

Algae None, tank empty

Cleaning Manual Labor intensive 2

Stilling Baffle Dissipation well and stilling baffle with scum outlets Standard design 2

Scrapers Two spiral sludge scrapers, across full width of tank, some rust/corrosion Repair/renovate 2

Bridge Fixed bridge access to drive, safe access

Bridge mechanism/drive No reported issues. Envirodyne drive mechanism from 2007/8, life expectancy 15-20 years 2

RAS flow RAS submersible pumps located inside the building in a wet well 2

Equipment5 HP / 3.7 kW 1,745rpm.





Control Variable speed

Standby capability Spare pump, one unit shared for Clarifiers #1 and #2


Flow splitting Issue with ML flow splitting between 1 and 2 but controlled by throttling #2 2

Outlet valves / gates 450 mm dia outlet pipework, then flowmeter and UV system

CorrosionSome corrosion starting on effluent launder and feed distribution baffle. Rusty fittings. Requires touch

up/painting maintenanceRepair/renovate 3




Valves and pipework Pipework in-tank in good condition. 2

Buildings Same comments as Clarifier #1 Repair, building-mechanical work 4




Date 12 March 2020


Item Clarifier # 3

Diameter, area etc. 22.5m diameter, 398 m2, 4.75m side-water depth, volume ~1,891m3

Year built Year built 1996/7

Description

Large concrete circular clarifier, center feed with stilling baffle and dissipation well, double-sided launder at

17m dia without cross bracing, scum removal, two spiral scrapers, center drive (Westech, UT), access

bridge, 1:12 floor slope, 0.75m freeboard

4

Status In-service, above liquid inspection only.


comments

Usually operate 1 large clarifier (#3 or #4) and bring on a small clarifier (#1 or #2) at weekends in summer.

No planned maintenance program, only change oil as required

Effluent launder channels have deteriorated and showing signs of leaking and are close to end-of-life.

Algae control, brushes etc. and not very effective and usually the tank is fully drained and manually cleaned

two or three times in the summer.

Concrete in good condition

Inspect wetted components when tank

is empty, especially structural elements.4

Average Flows Rated for 10,000m3/d (416m3/h, 116 L/s) - estimate.

Peak FlowExpected 20,000 m3/d (2m/h up flow rate) but may have hydraulic or process restrictions, solids carry-over

from blanket due to under-capacity of RAS.

Operate more tanks at this flowrate to

share the flow.


Capacity Surface Loading Rate (up flow rate) ~1m/h at 10,000m3/d Normal Design

Solids loading Rate Calculated at 3.6 kgMLSS/m2.h at 3,500mg/L MLSS Normal Design

TSS carry-over Minimal. Effluent quality excellent, and good clarity 1

Flow distributionGood, no apparent short-circuiting, weir overflow reasonably uniform around the launder, but some v-

notches blinded3


Scum removal Discharge to sump/drain adjacent to clarifier #3, collected by suction tanker

Scum sprayers None.

Floatables None. Minor floating scum (FOG) on the surface of the tank, but retained by weir baffle.

Weir trough

Double sided launder trough without cross baffles. V-notch weirs.

Lauders at end of life and show deterioration. Leaking in places, missing bolts, some bending etc.

Deposits of Ferric and/or corrosion of launder and supporting steelwork. Some V-notches are almost

blocked.

Replace 4

Algae Minimal on the surface

CleaningBrushes provided (Weir-Wolf, or similar system) around the weir and wall, but not very effective and require

maintenance and adjustment. Manual cleaning required, drain the tank and clean, 2 or 3 times in summer.

Remove and implement cleaning

program or covers3

Stilling Baffle Dissipation well and stilling baffle with scum outlets Structure 3

Scrapers Two spiral scrapers, across full width of tank Inspect when empty 3

Bridge Fixed bridge access to drive, safe access. 2

Bridge mechanism/drive

WesTech Mechanism, 72ft diameter (Dated December 1996, WesTech job 4870A). Westech supplied the

clarifier tank internals except the launder troughs. All equipment/baffles manufactured from mild steel,

painted.

The above water steel looks in reasonable condition, but with some evidence of surface corrosion/rusting

especially at the liquid-air interface.

No torque issues, scraper moves smoothly with no obvious jerkiness.

Generally unplanned maintenance – no specific maintenance program at present. Oil changes only.

(Westech nameplate states Check oil weekly, change yearly. Drain condensate weekly, lubricate per O&M)

Motor was replaced in 2019 with 1 HP, 1,750 rpm, TEFC premium motor.

The unit is variable speed and runs at 75%.

System is 24 years old, and considered

at the end-of-life. Dependent on how the

system has been maintained and what

(if anything) has been replaced etc. The

units were manufactured to a high

standard from cast iron (probably more

robust than modern equipment).

Westech states they have them in

operation over 40 years!

3

RAS flowRAS submersible pumps located in a wet well adjacent to clarifier #4.

Wet wells have covers and pump lifting hoist2

Equipment7.5 HP / 5.6 kW 1,740rpm.


Condition unknown. Shelf spare

required as pumps are more than 10

years old.

2


Control

Variable speed

Pump generally runs at 100% max RAS rate. RAS pipe is 250mm diameter, whereas clarifier #4 has

300mm diameter, so RAS maybe restricted from clarifier #3.

Standby capability Spare pump provided to share between Clarifier #3 and #4


Flow splitting No issues with ML flow split - 3-way inlet flow-splitter with motorized valves. All in good condition. 2

Outlet valves / gates 600 mm dia outlet pipework, then flowmeter and UV system. Below grade, no inspection

Corrosion

Corrosion on effluent launder and support steelwork. Rusty fittings.

When tank is drained, it is reported that there is rust in the tank from steelwork.

Corrosion/rusting around the drive mechanism and torque box requires painting/protection.

Corrosion of dissimilar metals in wet well for RAS pump hoist anchor bolts.

Replace launders and steelwork.

Inspect steelwork and underwater

components for corrosion/structural

issues, replace if necessary

4

Safety Good, light, handrails, life float 2


ElectricalGenerally good condition, some electrical cables from the local panel need to be tied up to cable trays.

Local control panel with stainless steel enclosure and alarm light reported as not working.Replace/refurbish 4

Valves and pipework Submerged or below-grade, no inspection. Inspect when empty.

Buildings No buildings




Date 12 March 2020


Item Clarifier # 4

Diameter, area etc. 22.5m diameter, 398 m2, 4.75m side-water depth, volume ~1,891m3

Year built Year built 2007

Description

Large concrete circular clarifier, center feed with stilling baffle and dissipation well, double-sided launder at

17m diameter with cross bracing, scum removal, two spiral sludge scrapers, center drive (Envirodyne, PA),

access bridge, 1:12 floor slope, 0.75m freeboard

2

Status In-service, above liquid inspection only.


comments

Large clarifier with Envirodyne equipment built around 2007 before the Olympics.

Usually operate 1 large clarifier (#3 or #4) and bring on a small clarifier (#1 or #2) at weekends in summer.

No planned maintenance program, only change oil as required.

Some algae control, brushes etc. on the outside but not very effective. Clarifier is drained 2 or 3 times in

summer for manual cleaning.

Concrete in good condition.

Recommend inspection when tank is drained.

Inspect wetted components when tank

is empty.3

Average Flows Rated for 10,000m3/d (416m3/h, 116 L/s).

Peak FlowExpected 20,000 m3/d (2m/h up flow rate) but may have hydraulic or process restrictions, solids carry-over

from blanket due to under-capacity of RAS.

Operate more tanks at this flowrate to

share the flow.


Capacity Surface Loading Rate (up flow rate) ~1m/h at 10,000m3/d Normal Design

Solids loading Rate Calculated at 3.6 kgMLSS/m2.h at 3,500mg/L MLSS Normal Design

TSS carry-over Minimal. Effluent quality excellent, and good clarity 1

Flow distributionGood, no apparent short-circuiting.

Weir overflow not uniform around the launder - requires levelling of v-notch weirsLevelling required. 3

Scum and scum box Moving surface scraper/collector, and beach.

Scum removal Discharge to sump/drain adjacent to clarifier #3, collected by suction tanker

Scum sprayers None.

Floatables Scum and floatables in the feed well and on the surface of the tank. Skim off to avoid build up 3

Weir troughDouble sided launder trough with cross baffles. V-notch weirs. Access difficult.

Launder v-notch weirs uneven and leaking - needs some maintenance.

Leveling and general maintenance

required.3

Algae Algae on the surface of the tank, walls and launders.

CleaningSome brushes provided around the weir and wall, but not very effective and require maintenance.

Manual cleaning required, drain the tank and clean, 2 or 3 times in summer.

Remove equipment and implement

cleaning program or covers3

Stilling Baffle Dissipation well and stilling baffle with scum outlets Inspect when empty 2

Scrapers Two spiral sludge scrapers, across full width of tank Inspect when empty 2

Bridge Fixed bridge access to drive, safe access. 2

Bridge mechanism/drive

Envirodyne Mechanism, All equipment/baffles mild steel painted.

Above water components in reasonable condition, some evidence of surface corrosion/rusting at liquid-air

interface..

No torque issues, scraper moves smoothly with no obvious jerkiness

Generally unplanned maintenance – no specific maintenance program at present. Oil changes only.

Motor was replaced with 0.5 HP, 1,725 rpm, Baldor/Reliance motor.

The unit is variable, but operates at a fixed speed.

Envirodyne drive mechanism from

2007/8, life expectancy 15-20 years

RAS flowRAS submersible pumps located in a wet well closer to clarifier #4 than #3.

Wet wells have covers and pump lifting hoist2

Equipment7.5 HP / 5.6 kW 1,740rpm.





ControlVariable speed

Pump generally runs at 100% max RAS rate. RAS pipe is 300mm diameter from #4 and 250mm from #3

Standby capability Spare pump provided to share between Clarifier #3 and #4.


Flow splitting No issues with ML flow split - 3-way inlet flow-splitter with motorized valves. All in good condition. 2

Outlet valves / gates 600 mm dia outlet pipework, then flowmeter and UV system. Below grade, no inspection

Corrosion Some corrosion starting on effluent launder supports at the water-air interface.

Paint and undertake general

maintenance during summer to prevent

further corrosion

3




Valves and pipework Submersed or below-grade, no inspection. Inspect when empty.

Buildings No buildings

Attachment B

Inspection Photos

RESORT MUNICIPALITY OF WHISTLER Secondary Clarifier Assessment

Technical Memorandum April 2020

PrefixClient

Photo 1: Clarifier 1&2 Corrosion Photo 2: Clarifier 1&2 Corrosion

Photo 3: Clarifier 1&2 Launder Trough Corrosion & Rusting

Photo 4: Clarifier 1&2 Envirodyne Drive Mechanism

Photo 5: Clarifier 1&2 Corrosion & Rusting

Photo 6: Clarifier 1&2 Building Frame Corrosion

Inspection Photos

2

0029.236-300



Prefix Client

Photo 7: Clarifier #2 Concrete

Photo 8: Clarifier 1&2 Steelwork Corrosion

Photo 9: Clarifier #3

Photo 10: Clarifier #3 Scum Scraper, Brushes & Launder

Photo 11: Clarifier #3 Brush Cleaning Photo 12: Clarifier #3 Launder Corrosion

Inspection Photos

3

0029.236-300



Prefix Client

Photo 13: Clarifier #3 Drive Mechanism Photo 14: Clarifier #3 Launder

Photo 15: Clarifier #3 Brush System

Photo 16: Clarifier #3 Drive & New Motor

Photo 17: Clarifier #4 Photo 18: Clarifier #4 Launder Corrosion

Inspection Photos

4

0029.236-300



Prefix Client

Photo 19: Clarifier #4 Uneven Overflow Photo 20: Clarifier #4 Wall Brush

Photo 21: Clarifier #4 Beach Photo 22: Clarifier 3&4 RAS

Photo 23: Clarifier #4 Algae/floatables



PROJECT NO. 200135


CLARIFIER #3

9.2. CLARIFIER#3 DRAWINGS

Param.Bhatti

Typewritten text

TO BE PROVIDED UPON REQUEST

Design Basis Memorandum for Secondary Clarifier #3

Documents

Transcript of Design Basis Memorandum for Secondary Clarifier #3