sewage treatment and disposal feasibility study · treatment plant site and treatment process has...

163.11

SEWAGE TREATMENT AND DISPOSAL FEASIBILITY STUDY

DECEMBER 2010

OPUS DAYTONKNIGHT CONSULTANTS LTD.

163.11

THIRD PARTY DISCLAIMER AND COPYRIGHT

This document has been prepared by Dayton & Knight Ltd. for the benefit of the client to whom it is addressed. The information contained in this document represents Dayton & Knight Ltd.’s best professional judgment in light of the knowledge and information available to Dayton & Knight Ltd. at the time of its preparation. Except as required by law, this document is to be treated as confidential and may be used and relied upon only by the client, its officers and employees. Dayton & Knight Ltd. denies any liability whatsoever to other parties who may obtain access to this document for any injury, loss or damage suffered by such parties arising from their use of, or reliance upon, the document or any of its contents without the express written consent of Dayton & Knight Ltd. and the client. This document is for the sole use of the addressee and Dayton & Knight Ltd. This document contains proprietary and confidential information that shall not be reproduced in any manner or disclosed to or discussed with any other parties without the express written permission of Dayton & Knight Ltd. Information in this document is to be considered the intellectual property of Dayton & Knight Ltd. in accordance with Canadian Copyright Law.

163.11 ©2010 Page i

SEWAGE TREATMENT AND DISPOSAL – FEASIBILITY STUDY

TABLE OF CONTENTS

1.0 INTRODUCTION............................................................................................................ 1-1

1.1 Background .......................................................................................................... 1-1 1.2 Scope of Work ..................................................................................................... 1-3 1.3 Conduct of Study ................................................................................................. 1-3

2.0 EXISTING SEWAGE SYSTEM ..................................................................................... 2-1

2.1 Sewage System .................................................................................................... 2-1 2.1.1 Collection System .................................................................................... 2-1 2.1.2 Pumping Stations ..................................................................................... 2-2 2.1.3 Outfall ...................................................................................................... 2-5

2.2 Treatment and Disposal Requirements ................................................................ 2-6 2.3 Sewage Flows ...................................................................................................... 2-7

3.0 VILLAGE GROWTH AND DEVELOPMENT .............................................................. 3-1

3.1 Historical Population ........................................................................................... 3-1 3.2 Future Growth and Development ......................................................................... 3-1

4.0 DESIGN CONSIDERATIONS AND CRITERIA ........................................................... 4-1

4.1 Water Supply and Consumption .......................................................................... 4-1 4.2 Treatment and Disposal Standards/Guidelines .................................................... 4-2 4.3 Wastewater Flow Projections .............................................................................. 4-4 4.4 Wastewater Quality .............................................................................................. 4-5 4.5 Treatment Options ............................................................................................... 4-5 4.6 Effluent Disposal ............................................................................................... 4-12 4.7 Treatment Plant Siting Criteria .......................................................................... 4-14 4.8 Treatment Plant Site Options ............................................................................. 4-15

5.0 TREATMENT AND DISPOSAL OPTIONS .................................................................. 5-1

5.1 Treatment Plant Concept Design ......................................................................... 5-2 5.2 Option 1 – Smith Point Area ................................................................................ 5-3

TABLE OF CONTENTS (cont’d.)

163.11 ©2010 Page ii

5.3 Option 2 – Central Area ....................................................................................... 5-4 5.4 Option 3 – Skidegate Landing West .................................................................... 5-5 5.5 Option 4 – Skidegate Landing East ...................................................................... 5-6 5.6 Option 5 - Joint Treatment with Skidegate Band ................................................. 5-7 5.7 Evaluation .......................................................................................................... 5-10

6.0 SUMMARY, CONCLUSIONS AND RECOMMENDATIONS .................................... 6-1

6.1 Summary and Conclusions................................................................................... 6-1 6.2 Recommendations ................................................................................................ 6-2

APPENDICES 1 References 2 Environment Canada Inspectors Direction 3 Cost Estimates LIST OF TABLES 2-1 Pump Station Nos. 4 and 5 Recorded Flows .................................................................... 2-7 2-2 Pump Station No. 4 Unit Flows ....................................................................................... 2-8 3-1 Projected Population Growth ........................................................................................... 3-2 4-1 Standards tor Effluent Discharges to Marine Waters ....................................................... 4-3 5-1 Treatment and Disposal Cost Comparison .................................................................... 5-10 5-2 Cost to Provide Conveyance System from Skidegate Landing To Site

Options 1, 2 and 3 .......................................................................................................... 5-11 LIST OF FIGURES 2-1 Sheets 1 and 2 – Existing Sewer System 5-1 Sewage Treatment and Disposal, Options 1, 2, 3 and 4 5-2 Sewage Treatment and Disposal, Option 5

163.11 ©2010 Page 1-1

SEWAGE TREATMENT AND DISPOSAL – FEASIBILITY STUDY 1.0 INTRODUCTION

The Village of Queen Charlotte (Village) currently discharges untreated sewage into the marine

waters of Bearskin Bay. This feasibility study develops and evaluates several sewage treatment

and disposal options. The objective is to provide information to allow the Village to make an

informed decision on the best treatment and disposal option for its long term needs.

Sections that follow describe the existing sewage system, discuss community growth and

development, outline regulatory requirements and design criteria, and develop and evaluate

treatment and disposal options.

The study report concludes with recommendations for advancement of the preferred option to the

design stage.

1.1 Background

The Village, including Skidegate Landing, currently houses about 960 people. A sewage

collection system services most of the residents (about 870 people) and commercial

development in the Village core The unserviced area between Smith Point (existing

outfall) and Skidegate Landing, housing about 80 people, is serviced with septic tanks.

The ferry terminal in Skidegate Landing utilizes a holding tank.

163.11 ©2010 Page 1-2

Within the Village core, a series of four pumping stations convey the sewage to a fifth

pump station near Smith Point where the sewage is discharged into Bearskin Bay. No

treatment is provided. The discharge is authorized under Ministry of Environment

permit.

In 2000, a Long Term Water and Sewerage Plan (D&K 2000) was prepared for the

Village. It provided for a projected population of 1530 in 2021, developed four treatment

and disposal options and made three recommendations:

• Install standby generators at pumping stations to address the overflow issue on loss of

Hydro power.

• Video inspect the outfall to determine its condition.

• Initiate a public consultation process to assist Council in selecting a treatment plant

site and a treatment process; based on the four options developed in the report.

The generators have been installed at each pumping station. The outfall has not been

inspected (but is budgeted for inspection in 2010). The process for selection of a

treatment plant site and treatment process has not been initiated.

In 2009 Environment Canada issued an Inspector’s Direction under the Fisheries Act.

The Direction required the Village of submit a report outlining a strategy for development

of a plan to provide sewage treatment. The plan is to be finalized by December 31, 2010.

Council, in response to the Inspector’s Direction, authorized an update of the sewage plan

to include a Village owned and operated treatment plant and the option of joint treatment

using the neighbouring community treatment plant owned by the Skidegate Band.

163.11 ©2010 Page 1-3

1.2 Scope of Work

In a letter dated May 5, 2009, Dayton & Knight set out a terms of reference for this

feasibility study.

In summary, the study scope includes:

• Compile and review existing data.

• Meet with Council to review scope and agree on the service area, population

projections and potential treatment plant sites. Brief Council on treatment

technologies.

• Develop treatment and disposal options. Anticipated options are:

o Site near Smith Point (existing outfall)

o Site near Ferry Terminal (new outfall)

o Joint treatment with Skidegate Band (existing Band plant and outfall)

• Evaluate options and summarize findings in report.

• Present draft report to Council and finalize.

By letter dated February 16, 2010, the Village authorized the study to proceed.

1.3 Conduct of Study

Data were compiled and analyzed in preparation for the initial meeting with Council held

on March 15, 2010. At the meeting, Council members and staff were briefed on

treatment technologies and the Provincial standards for effluent disposal. Council and

staff also identified potential sites for a treatment plant.

Draft No. 1 of the report was submitted for staff review on July 29, 2010. Comments

were received and Draft No. 2 was submitted for review by Council on August 17, 2010.

Council then held a meeting with the Skidegate Band Council to discuss the joint

163.11 ©2010 Page 1-4

treatment option. A copy of the section of the report on the joint treatment option was

left with the Band Council for their review and response.

At a Council meeting on December 1, 2010 review comments on Draft No.2 were

received and report finalization was authorized in order to comply with the December 31,

2010 completion date established by Environment Canada.

The review comments awaited from the Skidegate Band Council will be addressed as a

follow up action to this report.

163.11 ©2010 Page 2-1

SEWAGE TREATMENT AND DISPOSAL – FEASIBILITY STUDY 2.0 EXISTING SEWAGE SYSTEM

A brief description of the sewage system, discharge Permit requirements and the analysis of

sewage flows are set out in this section.

2.1 Sewage System

Since their construction in 1984 only minor extensions to the sewer collectors have been

constructed to accommodate new development. In spring 2010, a forcemain was

constructed from the new Honna River water treatment plant to the existing sewer at 10th

Street to allow discharge of backwash residuals.

Figure 2-1, Sheets 1 and 2, illustrate the sewage system within the Village core.

2.1.1

Collection System

The collection system comprises 150, 200 and 250 mm PVC pipe. Forcemains range in

size from 100 mm to 200 mm and are PVC pipe. Service connections are 100 mm diameter

PVC to residential connections and 150 mm PVC to larger commercial connections.

Where homes/businesses are too low to be serviced by gravity, individual pumps were

provided to allow the property to be pumped into the sewage collection system. Property

owners are responsible for the ongoing operation and maintenance of the pumps. There

are approximately 20 pumped serviced connections.

School

0 50 100 200 metres

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ay

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Plan 15372

Plan 8612

Plan 1415 Plan 6873

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BeattiePoint

Bearskin Bay

SmithPoint

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P:\PRODWGS\QUEEN-CHARLOTTE\163-11\163.11 FIGURE 2-1 10-07-27

Asphalt Road Surface

Gravel Road Surface

Force Main (size in mm)

Manhole

Lift Station

Sewer Lines (size in mm)

LEGEND

30

200

200

LS4

VILLAGE OF QUEEN CHARLOTTE

EXISTING SEWAGE SYSTEM

SHEET 1 OF 2

FIGURE 2-1

Note:

Sewers are 150mm diameterunless shown otherwise.

HaidaPoint

SkidegateLanding

Outfall extends 500mbeyond this point

Outfall PumpingStation

200

Outfa

ll

N

DL 16 School

0 50 100 200 metres

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6th

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8th

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9th

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3rd Ave

Highway 33

2nd Ave

10th

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5th Ave

6th Ave

7th

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Highway 33

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Queen Charlotte Mainline

4th

St

Bay

5th

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Plan14055

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EXISTING SEWAGE SYSTEM

SHEET 2 OF 2

FIGURE 2-1

Residuals Forcemain FromWater Treatment Plant

N

100

Note:

Sewers are 150mm diameterunless shown otherwise.


163.11 ©2010 Page 2-2

There are 402 service connections serving residential and commercial properties in the

Village core. Most residences and businesses are connected to the sewer system.

As noted previously, the unserviced area between Smith Point and Skidegate Landing is

serviced with septic tanks and the Ferry Terminal with a holding tank.

2.1.2

Pumping Stations

All pumping stations are duplex submersible fibreglass reinforced plastic (FRP) stations

with emergency overflows and kiosks to house electrical equipment and controls. The

stations contain Flygt pumps, initially installed in 1984. In 2000, Flygt provided the

following data (which differs significantly from the pump data shown on the as

constructed drawings). Since 2000, the pumps are reported to have undergone annual

servicing with some pump replacement, but no model changes.

1. Pumping Station No. 1, located at Highway 33 and 8th

Street.

• 2 Pumps – Flygt Model CP 3085 MT

3 in. inlet/outlet

6.52 inch impeller #434

3.0 HP, 208/3/60

225 USgpm (180 gpm) at 26 ft TDH

• 6 ft. diameter wet well

• 4 inch forcemain

• 8 inch overflow

163.11 ©2010 Page 2-3

2.

Pumping Station No. 2, located at 3rd Avenue and 5th Street.

• 2 Pumps – Flygt Model CP 3127 HT

4 inch inlet/outlet


10 HP, 208/3/60

400 USgpm (320 gpm) @ 56 ft TDH

• 6 ft diameter wet well


• 8 inch overflow

3.

Pumping Station No. 3, located on Bay Street.


4 inch inlet/outlet


10 HP, 208/3/60




• 10 inch overflow

4.

Pumping Station No. 4, located on Wharf Street.


4 inch inlet/outlet


10 HP, 208/3/60


• 8 ft. diameter wet well

163.11 ©2010 Page 2-4



5.

The Outfall Pumping Station No. 5, located near Smith Point on Highway 33.

• Comminutor


4 inch inlet/outlet

9.12 inch Impeller #483

10 HP, 208/3/60

580 USgpm (460 gpm) at 42.6 ft TDH

Average = 490 gpm

650 USgpm (520 gpm) at 36.1 ft TDH


• 8 inch outfall


Staff advise the pumping stations have adequate capacity for present day connections and

that annual servicing remains in effect. The stations appear to be in good condition.

In 2003, standby diesel generator sets were installed at each of the pumping stations to limit

overflow during power outage. Each generator (supplied by Simson Maxwell) is identical

as follows:

Model: 25PS-U2G-63

Standby Service: 25kW, 31.25 kVA, 3Ph., 120/208 V, 60 Hz., 1800 RPM

Engine Model: CM51029

Gen. Model: UC1224C

ATC Model: TS853MS3-100A-208

Control Panel: EGC-PV-ES52-M

163.11 ©2010 Page 2-5

Battery Charger: CH12V3AE

Battery: Group 27C, 850 CA, 700CCA, 135R/C

Since the installation of the gensets, there have been no reported overflows of sewage from

the pumping stations.

An odour control unit (supplied by Sanitherm Engineering) was also added to Pump Station

No. 4 in 2003. It is a Calgon Centaur HSV granular activated carbon unit as follows:

VentSorb Model: HF400, 120 USgal, 170 lbs activated carbon

Regeneration Time: 24 hours (1200 US gallons at 1-USgpm)

Fabco Blower Model: HFR 160-17D, 1/2 HP, 200 cfm @ 4” w.c., 230/3/60.

Ongoing maintenance of the odour control unit includes the requirement to regenerate the

activated carbon on an annual or bi-annual basis.

2.1.3

Outfall

The outfall Pumping Station No. 5 discharges sewage through an approximately 1200 m

long 200 mm HDPE Series 45 outfall. The pipe is reported to be buried in a trench to just

below the low tide mark and it then continues on the sea bottom to terminate at a depth of

20 m below low water. The outfall terminus reduces to 100 mm HDPE Series 60 pipe in

the form of a single port angled upward diffuser that discharges at the 17.2 m depth below

low water. Concrete anchor blocks are spaced along the outfall to weight the pipe and

prevent its movement.

163.11 ©2010 Page 2-6

2.2 Treatment and Disposal Requirements

There is no treatment of sewage prior to its discharge into Bearskin Bay.

The discharge is authorized by Ministry of Environment Permit No. 6427, issued March 15,

1989. The Permit includes the following important requirements:

• Maximum Day Flow = 2295 m3

• Effluent quality = comminuted raw domestic sewage.

/d

• Sufficient land to be acquired for future treatment plant.

• Outfall to be 1200 m seaward of low water and at 20 m depth below low water.

In a letter dated August 6/09 (Appendix 2) Environment Canada issued an Inspector’s

Direction under the Fisheries Act to the Village. The Direction noted the Village discharges

untreated sewage to Bearskin Bay in violation of the Fisheries Act. The Inspector directed

the Village as follows:

1. Submit written report by October 31/09 that outlines strategy for development of a Plan.

2. Beginning January 30, 2010, submit quarterly reports to the Inspector outlining

measures taken in previous quarter to meet the Inspector’s Direction.

3. By June 1, 2010 finalize the Plan to provide sewage treatment for the Village.

The Direction was amended May 31, 2010 to extend the date to finalize the Plan to

December 31, 2010.

163.11 ©2010 Page 2-7

2.3 Sewage Flows

Village staff records the pump hour readings at each of the five pumping stations Monday

through Friday. The design flow rate for each pump is then multiplied by the pump run

hours to estimate the daily, weekly, or monthly flow from each pump station. Pump

Station No. 5 discharges the total Village flow into the outfall.

Flow records for 2008 and 2009 for Pump Station Nos. 4 and 5 were analyzed and along

with precipitation data and are summarized in Table 2-1.

TABLE 2-1 PUMP STATION NOS. 4 AND 5 RECORDED FLOWS

Month

2008 2009

Flow (m3Precipitation

(mm) /mo) Flow (m3

Precipitation (mm)

/mo)

P.Stn. 4 P.Stn. 5 P.Stn. 4 P.Stn. 5

Jan 19,120 17,514 116.4 12,290 23,946 96.2

Feb 11,750 23,162 112.8 10,730 25,973 76.6

Mar 16,770 55,257 103.4 1 10,010 21,608 88.1

Apr 13,830 12,959 73.0 9,500 18,432 19.4

May 12,820 19,851 58.5 8,100 13,460 41.4

June 10,900 9,770 56.8 8,470 14,189 26.0

July 11,450 17,757 71.0 8,900 15,014 5.6

Aug 9,360 18,230 33.0 9,460 16,865 61.0

Sept 9,740 19,973 80.0 10,090 12,717 103.6

Oct 13,590 30,500 109.0 9,230 22,162 86.8

Nov 11,790 24,014 197.8 16,720 53,419 114.8 2

Dec 13,900 22,176 58.4 9,820 11,878 56.4

TOTALS 155,020 271,163 - 123,320 249,663 3

1 Monthly flow not valid as pump controls malfunctioned from March 5 to 20. 2 Monthly recorded flow not valid. 3 Excludes November 2009.

163.11 ©2010 Page 2-8

Tributary to Pump Station No. 4 is about 95% of the Village sewer connections. Flow from

Pump Station No. 5 should be about 5% higher than the flow from Pump Station No. 4. As can

be seen in Table 2-1, flow from Pump Station No. 5 is generally two times the flow from Pump

Station No. 4. We conclude the flow records at Pump Station No. 5 are not reliable; possibly due

to the pumps not producing the pump rated flow.

The flow records for Pump Station No. 4 have been used to calculate the unit flows; summarized

in Table 2-2.

TABLE 2-2 PUMP STATION NO. 4 UNIT FLOWS

Flow 2008 2009

m3 lpcd /d m3 lpcd /d

Average Annual (AAF) 425 524 338 417

Maximum Month (MMF)

617 (Jan.) 761 557 (Nov.) 688

Maximum Day (MDF) 1160 (Oct 22) 1432 710 (Oct. 29) 877

Unit flows were calculated using an estimated 810 people tributary to Pump Station No. 4 (950

people less 100 in Skidegate Landing times 95%).

163.11 ©2010 Page 3-1

SEWAGE TREATMENT AND DISPOSAL – FEASIBILITY STUDY 3.0 VILLAGE GROWTH AND DEVELOPMENT

Historical population data and the Village’s outlook for future development are highlighted in

this section.

3.1 Historical Population

Census data for the Village (including Skidegate Landing) shows a decrease in population

in recent years.

1986 1996 2001 2006

1090 1222 1045 948

Discussion with Village staff indicates the 2010 population is about 960, including

approximately 80 residents between Smith Point and Skidegate Landing and 20 or so

residents in Skidegate Landing.

3.2 Future Growth and Development

The Official Community Plan (OCP) is dated 1993. The Village is presently in the

process of updating the OCP. The update is scheduled to be completed by end of 2010 or

early 2011.

163.11 ©2010 Page 3-2

Populations projections in the draft OCP include a low, medium and high growth rate

over 25 years as follows:

TABLE 3-1 PROJECTED POPULATION GROWTH

Year Population Growth

Low Medium High

2008 1000 1000 1000

2033 1250 1500 2000

Based on discussions with Village staff, it is apparent there is considerable uncertainty on

the rate of future growth, and there is even the possibility of further decline in population

in the near future.

For the purpose of developing concept designs for this feasibility study, the 2010

population is estimated at 960 people, and the 2030 population is predicted to increase to

1250 people.

163.11 ©2010 Page 4-1

SEWAGE TREATMENT AND DISPOSAL – FEASIBILITY STUDY 4.0 DESIGN CONSIDERATIONS AND CRITERIA

In this section water supply protection is discussed, treatment and effluent disposal

standards/guidelines are summarized, wastewater flow projections are made, and wastewater

quality criteria are selected. Also included in this section is a description of the treatment plant

site options.

4.1 Water Supply and Consumption

It is important that wastewater facilities are sited in a location that will prevent

contamination of the community water supply. The Village water sources are two wells

at Tarundl Creek and the Honna River. Both these sources are treated.

Both sources are to the west of existing and proposed OCP development. No sewage

treatment plant sites are proposed near the water sources (Section 4.5).

The proposed sewage treatment plant and disposal facilities will not adversely affect the

water supply sources.

Water consumption records provide a check on sewage flow estimates. Water used

within a home or business forms the dry weather base sewage flow. In wet weather,

sewage flows increase due to inflow and infiltration (I&I) into the sewage collection

system.

163.11 ©2010 Page 4-2

Water meter flow records for 2008 and 2009 show average annual consumption of 512

lpcd for 2008 and 526 lpcd for 2009. These unit flows are normal relative to other British

Columbia coastal communities. The average annual sewage flows (Table 2-2) in 2008

were 524 lpcd and in 2009 were 417 lpcd. The relationship between water consumption

and sewage flows is reasonable.

4.2 Treatment and Disposal Standards/Guidelines

The Municipal Sewage Regulation (MSR) issued in 1999 under the Province’s then

Waste Management Act (now Environmental Management Act) establishes Province

wide standards for effluent quality, for design and construction of wastewater facilities

and for effluent and environmental monitoring.

The Organic Matter Recycling Regulation (OMRR) issued in 2002 under the Waste

Management Act establishes Province wide standards for biosolids reuse.

Effluent quality standards for use of reclaimed water, for discharge to receiving waters

and for discharge to ground are set out in the MSR. Applicable to the Village are the

effluent standards for discharges to marine waters. Discharge to ground and the use of

reclaimed water are not feasible options for the Village. The standards for effluent

discharges to marine waters are summarized in Table 4-1

163.11 ©2010 Page 4-3

TABLE 4-1 STANDARDS FOR EFFLUENT DISCHARGES TO MARINE WATERS

Parameter Receiving Water

Open Embayed

Treatment Requirement Secondary Secondary

Effluent Quality

• BOD5 45 , mg/l 45

• TSS, mg/l 45 45

• pH 6.0 – 9.0 6.0 – 9.0

• Disinfection (1)

• Total P, mg/l

(1)

- 1.0

• Ortho P – mg/l

(2)

- 0.5

• Ammonia

(2) (3)

(3)

(1)

Recreational waters; MPN = 200/100 ml fecal coliform at edge of IDZ.

Shellfish bearing waters ; MPN = 14/100 ml fecal coliform at edge of IDZ.

(2) Requirement may be waived if environment impact study so justifies. (3)

Maximum concentration to ensure non toxic effluent based on “back calculation” from end of outfall

pipe to edge of IDZ.

Embayed waters are defined as marine waters located shore side of a line up to 6 km long

drawn between two points on a continuous coastline; or located so that the maximum

width of sea access by any route is less than 1.5 km wide; or marine waters in which

flushing action is considered inadequate by the manager.

The initial dilution zone (IDZ) in marine waters refers to the area within a 100 m radius

of the end of the outfall pipe.

163.11 ©2010 Page 4-4

4.3 Wastewater Flow Projections

Based on the Section 2.3 pump station flow analysis, the following unit flows have been

selected for concept design purposes:

• Average Annual Flow (AAF) = 500 lpcd

• Maximum Month Flow (MMF) = 750 lpcd

• Maximum Day Flow (MDF) = 1200 lpcd

MDF is used for process design of treatment plants (other than aerated lagoons that utilize

MMF). Plants are sized for the projected 20 year design flow with due consideration for

performance during initial years of operation and for equipment useful life.

The treatment plant concept design will utilize the following design criteria.

Design Population = 1250

Design Flow (MDF) = 1500 m3

/d

Sewers and pumping stations must be designed for the projected 20 year Peak Flow,

calculated as follows:

• Peak Flow = P x a x f + C + I

• Where: P = tributary population

a = ADWF (per capita)

f = peaking factor =

10004

100018

P

P

+

+ to maximum of 4

C = institutional / commercial / industrial flow

I = infiltration and inflow = 46 L/mm dia./km/day

163.11 ©2010 Page 4-5

4.4 Wastewater Quality

There are no data that can be used to quantify the Village’s raw sewage (BOD5, TSS,

NH3

, etc.).

For treatment plant concept design the following design criteria, representative of normal

domestic sewage, will be used.

• Influent BOD5

• Influent TSS = 200 mg/l

= 200 mg/l

• Influent NH3 = 25 mg/l

• Influent Total P = 6.0 mg/l

• Influent Fecal Coliform = 5 x 106

• Secondary Effluent Fecal Coliform = 500,000 MPN/100 ml

MPN/100 ml

4.5 Treatment Options

There are a number of technologies that can provide a secondary level of treatment to

produce effluent that will meet the MSR criteria for BOD5

/TSS = 45 mg/l and the 96 hr

LC50 = 100% toxicity criteria.

Most wastewater treatment systems include some form of physical pre-treatment to

remove trash (plastics, rags, etc.) from the raw wastewater. Many also include primary

gravity settling tanks to separate crude biological solids from the raw wastewater

(primary treatment). Crude solids that are collected at the bottom of the primary settling

tank require further treatment, usually by biological processes. The settled wastewater

leaving the primary tanks enters the biological (secondary) treatment process train. For

some smaller systems, septic tanks may be used to provide primary treatment. Primary

treatment normally removes about 50% of the solids and 30% of the oxygen demand

(BOD5) from the raw wastewater.

163.11 ©2010 Page 4-6

Biological (secondary) processes in wastewater treatment systems rely on bacteria to

metabolize oxygen-demanding degradable organic material(BOD5) in the wastewater.

The process bacteria may be cultured in suspension in the process liquid (usually referred

to as activated sludge systems), or in a slime layer attached to some solid media

(sometimes referred to as fixed or attached growth systems). Secondary treatment

removes up to 95% of the solids and the BOD5

from the wastewater.

Depending on the treatment requirements, the system may also be designed to achieve

filtration of the effluent to remove residual solids, disinfection, and /or removal of

nitrogen and phosphorus.

Bacteria that are produced in secondary treatment are usually separated from the treated

process liquid in secondary gravity settling tanks (often referred to as clarifiers). The

clarified, treated liquid flows out of the secondary clarifier over a weir, and the settled

biological (bacterial) solids are collected at the bottom of the settling tank. Biological

solids must be periodically removed from the system and subjected to further treatment

(e.g., composting or digestion prior to beneficial use), or disposed of to landfill.

Many variants of suspended growth and fixed growth biological treatment are available.

Brief descriptions of some of these are outlined hereafter.

1.

Activated Sludge Process

In the activated sludge process, primary treated (2 hours detention) wastewater flows to a

basin where it is mixed with a culture of bacteria that grow and develop in suspension in

the process liquid. Dissolved oxygen is normally provided to the process liquid by a

submerged grid of aeration piping with diffusers that continuously supply fine bubbles of

air to the process liquid (floating mechanical aerators/mixers that entrain air from the

atmosphere may also be used). The aeration basin (typically 6-8 hours detention) is

163.11 ©2010 Page 4-7

followed by a clarifier where the process bacteria are separated from the treated liquid by

gravity settling. The bacteria that settle to the bottom of the tank are collected and

pumped back to the aeration basin, and the treated water exits the clarifier via a surface

overflow weir. In some cases, primary treatment is not used, and the aeration basin is

made larger (typically 18-24 hours detention) to compensate for the additional load; this

is referred to as extended aeration activated sludge. Excess process bacteria are removed

(wasted) from the process to maintain steady-state conditions; the excess bacteria mass is

commonly referred to as waste activated sludge (WAS).

Activated sludge processes can produce relatively high quality effluent. However, careful

attention to process operation is needed to control the biological solids inventory in the

system. Nuisance surface foams may develop, especially with extended aeration process

variants. The bacterial solids are also subject to infestation by filamentous organisms,

which inhibit gravity settling and may degrade effluent quality.

Conventional activated sludge is used at Comox and Kimberley.

2.

Sequencing Batch Reactor (SBR)

The Sequencing Batch Reactor (SBR) system is a version of the extended aeration

activated sludge process. SBR systems (also called fill and draw reactors) operate on the

same basic principles as extended aeration activated sludge systems; that is, the process

bacteria and the wastewater are mixed and aerated in the aeration basin, followed by

gravity settling to separate the solids from the treated liquid. However, in activated

sludge systems, aeration and gravity settling are carried out in two separate basins; in

SBRs, both processes occur in sequence in a single basin. The benefit is a “small

footprint” area requirement for the treatment works.

The SBR system normally includes five steps in sequence in a single basin, as follows:

163.11 ©2010 Page 4-8

a) fill/react (intermittent mixing and aeration during filling);

b) react (mixing and aeration);

c) settle (mixers and aerators shut off);

d) decant or draw (decanting of the clarified liquid from the surface of the tank); and

e) idle.

Excess solids are removed from the bottom of the tank during the decant step. Since the

system can only accept raw wastewater during the fill step, more than one basin (or a

storage basin) is required to treat a continuous flow of wastewater. A programmable

control system automatically controls the five step process. The SBR does not require

recycling of settled biological solids to the aeration basin; this eliminates the need for the

return pumping loop that is required for conventional activated sludge process.

Otherwise, advantages and disadvantages of the SBR process are similar to conventional

activated sludge.

The SBR process is used at Britannia Beach.

3.

Ecofluid Process

The Ecofluid system includes an extended aeration activated sludge process, followed by

an upflow sludge blanket for separation of the biological solids from the treated liquid

instead of a clarifier. Raw wastewater enters an aerated trap for removal of debris, and

then flows to the aeration basin, where suspended growth bacteria metabolize oxygen-

demanding substances (BOD5). The liquid leaving the aeration tank is directed to flow

upward through the bottom of a V-shaped weir located near the surface of the liquid in

the aeration tank. A layer of settled biological solids (sludge blanket) develops at the

bottom of the V. Biological solids in the process liquid leaving the aeration basin are

retained as the liquid passes upward through the sludge blanket, and the treated clarified

liquid flows out over the top of the weir. Waste biomass from the process is said to be

completely stabilized, due to the long sludge age of the process. High hydraulic flows

163.11 ©2010 Page 4-9

may cause the sludge blanket solids to be carried over the weir with the effluent,

degrading effluent quality. Otherwise, advantages and disadvantages of Ecofluid are

similar to those described for activated sludge and SBR.

Ecofluid technology is used at several ski resorts and strata housing developments in

British Columbia.

4.

Rotating Biological Contactor (RBC)

The rotating biological contactor (RBC) is a series of closely-spaced plastic disks

attached to a central shaft. The shaft is mounted so that the disks are partially submerged

in the wastewater. Fixed growth bacteria develop in a slime layer attached to the plastic

disks. Turning of the shaft alternately contacts bacteria with the wastewater and the air.

An anaerobic (un-aerated) primary section for gravity settling/digestion of crude solids

and equalization of flows is normally included upstream of the tank containing the RBC,

with a clarifier downstream of the RBC for separation of biological solids from the

treated liquid. Settled biological solids may be re-circulated to the RBC tank.

Fixed growth processes such as RBC are reported to be more resistant to toxic shocks

than suspended growth (activated sludge) processes. The RBC process also requires

relatively little operator attention compared to activated sludge and its variants, power

demand is lower, and the settling qualities of the bacterial solids are better. On the other

hand, the RBC process takes more space than an equivalent activated sludge system.

RBC units are in use at Lund and at several Indian reserves within British Columbia.

5.

Integrated Fixed Film Activated Sludge (IFAS)

IFAS is a hybrid version of the activated sludge process that includes both suspended

growth and fixed growth components. Neutrally buoyant solid media particles are added

163.11 ©2010 Page 4-10

to the aeration basin, and fixed growth bacteria develop in a slime layer attached to the

media; this supplements the BOD5

removal by suspended bacteria. Clarifiers are

required to separate the biomass from the treated liquid. The media is prevented from

flowing to the secondary clarifiers by tubular screens installed in the aeration tanks.

Biomass separated from the treated liquid may or may not be returned to the bioreactor.

All IFAS systems require adequate preliminary treatment design. Primary treatment or

fine screening will avoid ragging and material build-up on the media in the aeration basin,

and clogging of the dispersed media and retaining screens. Proper mixing is required for

solids suspension and oxygen diffusion.

The IFAS system requires less space than conventional activated sludge, and effluent

quality is typically higher. However, the cost of IFAS is greater than for an equivalent

activated sludge or RBC system.

6.

Membrane Bioreactor (MBR)

The membrane bioreactor (MBR) consists of a biological reactor with suspended

(activated sludge) biomass and separation of bacterial solids from the treated liquid by

fine-pore membranes. The treated wastewater is separated from the mixed liquor by the

process of membrane filtration rather than in a secondary clarifier as in conventional

systems. High concentrations of biological solids can be maintained in the aeration basin,

which reduces the aeration basin size compared to conventional activated sludge. The

treated effluent is drawn through the membrane by pumping. By replacing secondary

clarifiers, membranes avoid issues of filamentous sludge bulking and other settling and

clarification problems. However, membranes require adequate scouring, chemical

cleaning and upstream fine screening to prevent solids from adhering to the membrane

fibres causing fouling or plugging. Energy demand is higher than for other processes, and

membranes must be replaced on a regular basis; these factors lead to higher treatment

costs than for most other processes. Effluent quality is excellent due to the fine-pore

filtration.

163.11 ©2010 Page 4-11

The City of Powell River utilizes a membrane plant.

7.

Aerated Lagoons

This technology requires about 25 days hydraulic detention time and consequently a large

area is needed. The benefit is a low construction cost (providing ground conditions are

suitable) and simple, reliable, low cost operation and maintenance. A two cell, balanced

cut and fill construction with polyethylene liner is normally provided along with a

submerged diffused aeration system. Effluent clarification takes place at the end section

of the second operating cell. TSS levels are typically higher in lagoons than other

technologies; thus the MSR allows lagoon effluent to have TSS = 60 mg/L.

Biosolids are left to accumulate in the bottom of the cells. Normally removal is needed

after 10-20 years. Removal involves dewatering the cells, removal and drying of the

biosolids and their disposal to landfill.

Aerated lagoons service many communities in the Province, including the City of Duncan

and the Town of Smithers.

163.11 ©2010 Page 4-12

8.

Oxidation Ditch

Between 18 to 24 hours detention time is used for oxidation ditch treatment. Two ditches

and two clarifiers are normally provided for liquid treatment. The ditches can be either

concrete or lined earthen cells. An aerobic digester is needed for biosolids treatment and

the biosolids requires dewatering for disposal.

This facility is similar to the plant that serves Port Edward and Campbell River.

4.6 Effluent Disposal

In the Long Term Water and Sewerage Plan report (D&K 2000), a section on effluent

disposal was presented. It is repeated hereafter because it remains relevant to siting of a

Village outfall.

Previous reports (Stanley 1979, 1980, 1981) included oceanographic studies and

discharge modelling for two outfall location options; off Smith Point and off the log

dump. The 1981 report noted the following:

“In discussion with physical oceanographers, local fisherman and upon review of the

bathymetrics of Skidegate Inlet and Bearskin Bay, in particular, it became apparent that

an outfall from the MacMillan Bloedel location (log dump) would discharge the sewage

to a point where adequate flushing cannot occur. The sewage would impinge on the

shoreline very soon after discharge in the flood and would not be able to flush out of the

funnel shaped bay on the ebb tide.

The marine studies were therefore concentrated on the Smith Point outfall site because it

was closer to the mouth of the inlet and could discharge in deep water well clear of land.

The oceanographic studies included sea bottom profiling, water column analysis for

temperature and conductivity, current drogue tracking and current meter measurements.

163.11 ©2010 Page 4-13

Of note, the currents generally parallel the shoreline. On the flood tide, the currents are

westward into Bearskin Bay. On the ebb tide, the currents are eastward out of Bearskin

Bay toward Skidegate Inlet.

Also of note and importance was the that inshore of 900 m from Smith Point, the ebb tide

directed the drogues onto the beach at the south west side of Haida Point. Considerable

driftwood was also noted in this area. For this reason the existing outfall was extended

to 1200 m offshore from Smith Point. On the flood tide, drogues released 1100 m from

Smith Point tracked south of Maple Island toward Mandle Channel.

Current meter readings at the 1100 m location from Smith Point showed a typical current

of 0.4 to 0.25 knots.

Dye studies conducted at the 1100 m station indicated that if the effluent plume surfaced

(following initial dilution), the dispersion before reaching Maple Island on the flood

would be 10 to 20 fold and greater than 34 times before reaching Haida Point on the ebb.

At the time of the oceanographic studies (March 4, 1981) there was little stratification in

the water column. Summer conditions would likely result in stratification. Bottom

profiling along the existing outfall alignment indicates 1.5 to 2.0 m of soft “mud”

underlain by “firmer material” that is 2.0 to 3.0 m thick which is underlain by bedrock.

Biological composition of the sea bottom was reported as limited to “in faunal benthic

organisms” (worms and clams). No organisms living on the sea bottom were noted.

Dilution and dispersion modelling indicated an initial dilution following discharge

ranging from 120:1 to 2210:1 (stratified conditions). Under un-stratified conditions the

initial dilution ranged from 140:1 to 840:1. Total dilution (initial and dispersion) would

be a minimum of 1200:1 at Maple Island, the nearest land mass. It should be recalled,

163.11 ©2010 Page 4-14

however, that the drogue studies indicate the effluent plume will pass south of Maple

Island and not impact on the Island.

The 1981 studies were thorough and well done. The selection of the outfall discharge

1100 m off South Point is supported and complies with the requirements in the MSR.

Any new outfall within Bearskin Bay should discharge in similar water conditions.”

4.7 Treatment Plant Siting Criteria

The site for a treatment plant should be isolated from residential development and public

use areas. Ideally a site within industrial zoned land or within agricultural land should be

selected. The status of First Nations lands must be considered in site selection.

Because influent and effluent pipes to and from the site will have useful lives of over 50

years the site should be sized for a long term use; 50 years minimum, 100 years desirable.

For the Village, as noted in Section 3.2, Table 3-1, the 25 year high growth population

projection is 2,000 people. A site suitable for minimum 3,000 people should be selected.

Based on a “small footprint” type of treatment plant (SBR, Ecofluid, etc.) the useable

portion of the site should be about 0.11 ha in size for a long term population of 3,000.

With a 30 m buffer area around the treatment units the area requirement increases to 0.86

ha. Long detention treatment such as aerated lagoons requires considerable more area, a

minimum of 6.0 ha for 3,000 people, including 30 m buffer zone.

To minimize pumping, the site should be near sea level. To minimize groundwater

control the site should be above the 200 year flood level or be capable of being

economically floodproofed.

Site topographically should be gently sloping. Soil conditions must accommodate plant

structural loading and should allow conventional excavation and dewatering.

163.11 ©2010 Page 4-15

The inter-relationship between influent sewers to the plant and the effluent pipeline and

ocean discharge location must be considered to achieve a cost effective pipeline system.

Also important, is the outfall must be located in an area that provides good integration of

the effluent into the seawater mass. The outfall location must minimize impact on

fisheries resources and recreational use of the water.

The potential use of reclaimed water (industrial process water, irrigation water, etc.)

should be considered in siting the plant to maximize potential reuse opportunities.

Siting must consider the potential for odour and noise nuisance at the nearest residential

or public use area. The impact of plant construction on surface water and groundwater

and on fisheries and wildlife resources must be considered.

The site must not impact archaeological sites.

4.8 Treatment Plant Site Options

The siting criteria were reviewed with Council members and staff at the initial meeting

held March 15, 2010. A number of sites were considered. There is no obvious preferred

site. Only small sites are available near the existing outfall (Smith Point). A relatively

large site exists on the log sort property that would allow a less expensive form of aerated

lagoon treatment for an initial stage plant, however, a part of the conveyance system

needs to be rebuilt, a new outfall would be required and this site remains active and is not

for sale. A site may be found in the area between Smith Point and Skidegate Landing

(Central Area) that requires about a 1.2 km extension of the conveyance system. Two

sites in the Skidegate Landing may be found that require a 3 to 4 km extension of the

conveyance system and a new outfall. The extension of the conveyance system has the

benefit of allowing service to properties between Smith Point and Skidegate Landing.

163.11 ©2010 Page 4-16

In order to provide information needed to make a decision on the best general location for

a future Village owned treatment plant, four siting options were selected as follows:

1. Smith Point Area

2. Central Area

3. Skidegate Landing West Area

4. Skidegate Landing East Area

In addition, joint treatment and disposal with the Skidegate Band will be considered.

163.11 ©2010 Page 5-1

SEWAGE TREATMENT AND DISPOSAL – FEASIBILITY STUDY 5.0 TREATMENT AND DISPOSAL OPTIONS

In this section, a concept level design is developed for each of the four potential sites for a

Village owned treatment plant. The option of joint treatment and disposal with the Skidegate

Band is also concept designed. The section concludes with an evaluation of the treatment and

disposal options.

Finding a large parcel of land that meets the treatment plant siting criteria will be challenging.

For the purpose of this feasibility level study the “small footprint” treatment technologies (SBR,

Ecofluid, etc.) have been selected. Even so, in order to provide for a long term service

population of 3,000, a site should desirably be minimum 0.9 ha (allows 30 m setback) and at the

very least 0.3 ha (reduces setback to 10 m). It is assumed the Village will be able to acquire a

minimum 0.6 ha parcel. Included in the cost estimates is $500,000 for land purchase.

The concept designs for the Village owned options are based on an initial stage design population

of 1,250 people. Included are the needed extensions/modifications to the sewage conveyance

system, a “small footprint” treatment plant for the site, and either use of the existing outfall at

Smith Point or the provision of a new outfall.

For the Skidegate Band joint treatment option; the extension of the conveyance system to

Skidegate, the upsizing of the Skidegate conveyance system to also include the Village’s sewage

flows and the apportionment of the Band’s treatment plant and outfall costs (based on the relative

design population/flow for the Skidegate Band and Village) are included in the concept design.

163.11 ©2010 Page 5-2

5.1 Treatment Plant Concept Design

For the purpose of this feasibility study, it has been assumed that a small site may be

acquired for a Village owned treatment plant. A “small footprint” SBR technology has

been selected for the treatment plant.

Included in the treatment works are the following:

• Influent mechanical screening with screenings dewatering;

• Provision for future grit removal, if needed;

• Two SBR tanks, each sized for 75% of MDF;

• One aerobic digester;

• Biosolids dewatering press and storage bin;

• Control building to house influent screen; biosolids dewatering equipment, office

area, washroom, work bench area, electrical/control room, blower room;

• Outside standby generator;

• Odour control works for influent screening and biosolids dewatering;

• Roof structure over SBR and digester tanks.

Tankage for the SBR and digester would be cast-in-place concrete. Building construction

would be architectural concrete block with metal roof.

Initial stage (1250 people) capital and operation and maintenance (O&M) costs are

detailed in Appendix 3 and summarized as follows:

• Capital Cost $4,550,000

• O&M Cost $96,500/year

163.11 ©2010 Page 5-3

5.2 Option 1 – Smith Point Area

The benefit of a treatment plant site near Smith Point is that the required extension of the

sewer system is minimum and the existing outfall can be used. The challenge will be to

find a site that is sufficiently large to provide for even a “small footprint” treatment

technology.

Existing Pump Station No. 5 can be used to pump sewage to the treatment plant. At the

treatment plant site an effluent pump station is needed along with a section of land outfall

to connect to the existing 200 mm marine outfall.

This option is illustrated on Figure 5-1. Initial stage construction (1,250 people) cost

estimates follow. Details are provided in Appendix 3.

Capital Costs

• Treatment Plant $4,550,000

• Conveyance System and Outfall $649,000

• Treatment Plant Site

Total $5,699,000

$500,000

O&M Costs

• Treatment Plant $96,500 / year


Total $114,500 / year

/ year

163.11 ©2010 Page 5-4

5.3 Option 2 – Central Area

The sewage collection system must be extended about 1.2 km to service a site in the

Central Area. Existing Pump Station No. 5 can be re-used along with a 200 mm

forcemain extension to the treatment plant. The existing outfall at Smith Point can be

used by pumping the treatment plant effluent in a 200 mm land section of outfall that is

placed in the influent forcemain trench.

Figure 5-1 illustrates this option, cost estimates are provided in Appendix 3 and are

summarized as follows.

Capital Costs


• Conveyance System and Outfall $1,255,000


Total $6,305,000

$500,000

O&M Costs




/ year

163.11 ©2010 Page 5-5

5.4 Option 3 – Skidegate Landing West Area

A site near Haida Point is assumed. This allows for a new outfall to be constructed near

Haida Point to the 30 m depth in Skidegate Inlet. The existing outfall would revert to an

emergency overflow status for Pump Station No. 5.

Pump Station No. 5 would be fitted with new pumps. A 200 mm forcemain will extend

3.1 km from Pump Station No. 5 to the treatment plant site. The treatment plant site is

assumed to be at a high enough elevation to allow gravity discharge of effluent to the

outfall.

Figure 5-1 illustrates this option. Cost estimates are detailed in Appendix 3 and are

summarized hereafter.

Capital Costs




Total $7,158,000

$500,000

O&M Costs




/ year

5.5 Option 4 – Skidegate Landing East Area

163.11 ©2010 Page 5-6

Similar to Option 3, Pump Station No. 5 will be fitted with new pumps and a new 200

mm forcemain will extend 4.2 km to discharge to the treatment plant.

A new outfall will be constructed near Image Point to discharge into 30 m of water in

Skidegate Inlet. The treatment plant site is assumed to be at a high enough elevation to

allow gravity discharge of effluent to the outfall.


summarized as follows:

Capital Costs




Total $7,803,000

$500,000

O&M Costs




/ year

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SEWAGE TREATMENT AND DISPOSAL

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New Outfall

OPTION 4 - Skidegate East:

OPTION 3 - Skidegate West:

SkidegateLanding

ImagePoint

OPTION 2 - Central Area

OPTION 1 - SMITH POINT:

N

HaidaPoint

200


Gravel Road Surface


Manhole

Lift Station


LEGEND

30

200

200

Proposed Forcemain200


163.11 ©2010 Page 5-7

5.6 Option 5 - Joint Treatment with Skidegate Band

This option entails conveying the Village’s sewage to the Skidegate Band’s wastewater

treatment plant (WWTP) that is located at the north end of the Reserve, some 11 km from

the Village’s sewer system.

The Band’s sewage collection system (DNA 2004) starts at Second Beach (museum area)

where a small lift station and 100 mm forcemain convey sewage past First Beach to the

Band’s Lift Station No. 1. Lift Station No. 1 pumps through a 100 mm forcemain to a

gravity sewer with discharge to Lift Station No. 2. Finally, Lift Station No. 2 discharges

through a 200 mm and 250 mm forcemain to the Band’s WWTP.

At present, there are about 900 residents serviced by the Band’s WWTP. The treatment

plant is designed for 1200 people with provision to add a third treatment unit that will

increase the capacity to 1800 people. The associated effluent outfall is a combination of a

250 mm land section and a 200 mm marine section terminating in 50 m of water 1000 m

from shore. The outfall has capacity for about 2700 people. Pump Station No. 2 has a

design capacity for about 900 people.

Connected to the Village’s sewage system are about 860 people at present. The 20 year

design population is 1250 people.

Based on the design populations for the Village (1250 people) and the Band (1200

people), the Band’s pumped conveyance system is too small to also allow conveyance of

the Village’s sewage to the WWTP.

In order to convey Village sewage to the Band’s WWTP it will be necessary to upgrade

the Village’s Pump Station No. 5 (existing outfall) and extend a 200 mm forcemain to a

new Village Pump Station No. 6 located in the vicinity of the Band’s Lift Station No. 1.

163.11 ©2010 Page 5-8

From the Village’s new Pump Station No. 6, a 200 mm forcemain would extend along the

foreshore (near high tide line) to the Band’s WWTP.


summarized as follows:

• Conveyance System $5,857,000

Capital Costs

• Conveyance System $40,200 /yr

O&M Costs

The capital cost of the Band’s WWTP is reported to be $3.4 million (2007 construction)

and the current operating cost about $80,000/year (DNA 2010). The outfall (land and

marine sections) is estimated to cost $600,000. Based on contributing design

populations, the Village should pay about 50% of the costs to utilize the Band’s existing

WWTP and outfall.

• Existing WWTP $1,700,000

Capital Costs

• Existing Outfall

$2,000,000

$300,000

• Existing Treatment Plant $40,000 /yr

O&M Costs

• Existing Outfall

$41,000 /yr

$1,000 /yr

If the Village connects to the Band’s WWTP the existing serviced population will

increase to about 1800, which compares with the plant capacity of 1,200 people. The

163.11 ©2010 Page 5-9

outfall capacity is about 2700 people. Assuming the WWTP is expanded to service 2,400

people, then the cost will be in the order of $4.5 million. Cost sharing at 50% results in

the following added costs to the Village:

• Expand WWTP $2,250,000

Capital Costs

• Added Cost (allowance) $10,000 /yr

O&M Costs

In summary, the estimated cost to the Village to implement joint treatment and disposal

with the Skidegate Band is as follows:

• Conveyance System $5,857,000

Capital Costs

• Existing WWTP and Outfall $2,000,000

• Expand WWTP

$10,107,000

$2,250,000

• Conveyance System $40,200 /yr

O&M Costs

• Existing WWTP and Outfall $41,000 /yr

• Added Cost for WWTP Expansion

$91,200 /yr

$10,000 /yr

163.11 ©2010 Page 5-10

5.7 Evaluation

Cost estimates for the treatment and disposal options are compared in Table 5-1.

TABLE 5-1 TREATMENT AND DISPOSAL COMPARISON – INITIAL STAGE COSTS

Option Capital Cost ($) Operating Cost ($/yr) Life Cycle Cost ($)

1. Smith Point Area

1

5,699,000 114,500 7,126,000

2. Central Area 6,305,000 115,100 7,739,000

3. Skidegate Landing West 7,158,000 113,100 8,567,000

4. Skidegate Landing East 7,803,000 115,300 9,240,000

5. Joint Treatment Skidegate Band

10,107,000 91,200 11,243,000

1

20 year, 5% discount rate (pwf = 12.46)

For an initial stage, the least cost options are the Village owned treatment plant sites at

either the Smith Point Area or in the Central Area. The disadvantage of these two sites is

that when the Village elects to provide sewage service between Smith Point and

Skidegate Landing, there will be a need to provide a pumping station at Skidegate

Landing and to extend a forcemain to the treatment plant site.

The added cost to provide the Skidegate Landing pump station (5 HP pumps located near

ferry terminal) and forcemain (150 mm) (allows for 250 people) to connect to the Option

1, 2 and 3 treatment plant sites is noted in Table 5-2. Also presented in Table 5-2 are the

total costs for Options 1, 2 and 3 inclusive of the Skidegate Landing conveyance system.

163.11 ©2010 Page 5-11

TABLE 5-2 COST TO PROVIDE CONVEYANCE SYSTEM FROM SKIDEGATE LANDING

TO SITE OPTIONS 1, 2 AND 3

Option Capital Cost ($) Operating Cost ($/yr) Life Cycle ($)

Added Cost

1. Smith Point Area 1,712,000 15,000 1,899,000

2. Central Area 1,320,000 15,000 1,507,000

3. Skidegate Landing West 612,000 14,000 787,000

Total Cost

1. Smith Point Area 7,411,000 129,500 9,025,000

2. Central Area 7,625,000 130,100 9,246,000


If a pumped conveyance system is extended from Skidegate Landing, the Option 1 life

cycle cost increases to $9,025,000, the Option 2 life cycle cost increases to $9,246,000

and Option 3 to $9,354,000. Based on life cycle costs, site Options 1 to 4 are similar.

Option 5 is the most expensive at $11,243,000.

Options 3 to 5 have the benefit of providing a means of servicing all properties between

Smith Point and Skidegate Landing with the pumped conveyance system at the outset of

construction. The disadvantage is the initial stage higher capital cost.

Not included in the cost estimates is the collector sewer system needed to service

properties between Skidegate Landing and Smith Point. This system will entail a series

of gravity collector sewers and small pump stations that discharge into the pumped

conveyance system forcemain.

In terms of treatment plant siting criteria for a Village owned plant; Site 1 is in a

residential area, Site 2 has a few homes in the area, Site 3 is undeveloped at present but is

subdivided into many small lots (presumably residential or highway commercial) and Site

4 is in an industrial area. Site 4 is best suited for a treatment plant. Should the Village

163.11 ©2010 Page 5-12

select a treatment plant site in a non-industrial area, then the OCP should make provision

to limit residential and public use development in the near vicinity of the treatment plant.

No archaeological impact assessment work has been done for this feasibility study. In

this regard, all options can be considered equal.

No oceanographic studies have been carried out for this report. Sites 3 and 4 at Skidegate

Landing will require a new outfall and its impact on the marine receiving environment

will need to be assessed. In principle, however, effluent discharge into Skidegate Inlet

should provide better opportunity for effluent dispersion than the existing outfall in the

more confined waters of Bearskin Bay. For Option 5, the required outfall expansion

would parallel the existing outfall which is understood to be well sited (DNA, 2010).

163.11 ©2010 Page 6-1

SEWAGE TREATMENT AND DISPOSAL – FEASIBILITY STUDY

6.0 SUMMARY, CONCLUSIONS AND RECOMMENDATIONS

A brief summary of the study findings, conclusions and recommendations are presented in this

section.

6.1 Summary and Conclusions

The Village presently houses about 960 people of which about 870 residents are serviced

with a sewage collection system. Raw sewage is discharged near Smith Point through an

outfall into Bearskin Bay. The unserviced area between Smith Point and Skidegate

Landing utilizes septic tanks and the ferry terminal a holding tank.

In 2009, Environment Canada issued an Inspector’s Direction under the Fisheries Act

which requires the Village to develop a plan for sewage treatment and disposal by

December 31, 2010.

The existing sewage collection system is well maintained and has adequate capacity for

present day needs. The flow records at the outfall Pump Station No. 5 are not reliable and

a flow meter should be installed.

Population in the Village has decreased from 1222 in 1996 to an estimated 960 in 2010.

The draft OCP projects a 25 year growth between 1250 and 2000 people. For the concept

designs in this study, a 20 year population of 1250 people (year 2030) has been used.

163.11 ©2010 Page 6-2

Current Provincial and Federal regulations require a secondary level of treatment for an

effluent discharge into marine waters. For this study, a sequencing batch reactor (SBR)

form of secondary treatment has been selected for development and evaluation of

treatment and disposal options.

Four site options for a Village owned treatment plant were identified. A fifth option

considered was joint treatment with the Skidegate Band.

The five options compare as follows:

TABLE 6-1 TREATMENT AND DISPOSAL COMPARISON – TOTAL COSTS

Option Capital Cost ($) Operating Cost ($) Life Cycle ($)

1. Smith Point Area 7,141,000 129,500 9,025,000

2. Central Area 7,625,000 130,100 9,246,000


4. Skidegate Landing East 7,803,000 115,300 9,240,000

5. Joint Treatment Skidegate Band

10,107,000 91,200 11,243,000

A Village owned treatment plant will cost between $7.4 to $7.8 million (depending on

treatment plant site location), relative to $10.1 million for joint treatment with the

Skidegate Band.

Considering treatment plant siting criteria, the Skidegate Landing East site followed by

the Central Area site are favoured.

6.2 Recommendations

A flow meter should be installed in Pump Station No. 5 to provide more accurate flow

data for future treatment plant design. Budget $15,000.

163.11 ©2010 Page 6-3

The existing outfall should be dive inspected to determine its condition; particularly for

continued use. This task is included in 2011 Village budget.

The Village should meet again with the Skidegate Band to receive Band comments on the

joint treatment option, to review the contents of this final report and to determine the

Band’s position on the merits of joint treatment. Budget $2,500 if consultant attendance

is required.

The Village should initiate a public consultation process to obtain input on the treatment

and disposal options. Budget $5,000 if consultant attendance and illustrations are

required.

Following the public consultation process, the Village should select a favoured treatment

and disposal option. If a Village owned treatment plant option is selected, then the

Village should initiate the process for obtaining a treatment plant site. This process will

entail site inspection, geotechnical work, archaeological work, etc. to determine site

suitability. Once the site location is known, a budget can be developed to assist the

Village with the technical assessment of the site.

Finally, this report should be forwarded to Environment Canada prior to December 31,

2010 for their information and records.

VILLAGE OF QUEEN CHARLOTTE SEWAGE TREATMENT AND DISPOSAL – FEASIBILITY STUDY

APPENDIX 1 REFERENCES

(D&K 2000) Skeena Queen Charlotte Regional District, Queen Charlotte / Skidegate Landing

Management Committee, Long Term Water and Sewerage Plan for Queen Charlotte City, Dayton & Knight Ltd., December 6, 2000

(DNA 2004) Skidegate Band Council, Skidegate Sewage Treatment System, Design Brief,

David Nairne and Associates, January 2004. (DNA 2010) Personal Communication, Giorgio Caon, P.Eng., August 2010.


APPENDIX 2 ENVIRONMENT CANADA INSPECTORS DIRECTION


APPENDIX 3 COST ESTIMATES

163.11 ©2010 Page A3-1


OPTION 1 – SMITH POINT 1.

Capital Costs

• Upgrade P.S. No. 5; 2-10 HP $50,000 • Forcemain; 200 mm, 250 m x $275/m $69,000 • Land Outfall; 200 mm, 250 m x $200/m $50,000 • Highway Crossing, allowance $30,000 • Effluent P.S.; 2-10 HP

$499,000 $300,000

• 30% Engineering and Contingency

$150,000

TOTAL $649,000 2.

Operating Costs

• Power – 20 HP x 33% x $350/HP-year $2,300 • Labour - Daily – 0.5 hr x $50/hr x 260 days $6,500

- Quarterly – 8 hr x $100/hr x 4 days $3,200 • P.S. Annual Service $5,000 • Outfall – Dive Inspection, 5 year cycle

$1,000

TOTAL $18,000 /yr 3. Treatment Plant Site, allowance $500,000 OPTION 2 – BOAT LAUNCH 1.

Capital Costs

• Upgrade P.S. No. 5 and genset; 2-15 HP $75,000 • Forcemain; 200 mm, 1200 m x $275/m $330,000 • Land Outfall; 200 mm, 1200 m x $150/m $180,000 • Rock Excavation; 500 m3 x $100/m3

• Highway Crossing, allowance $30,000 $50,000

• Effluent P.S.; 2-10 HP $965,000

$300,000


$290,000

163.11 ©2010 Page A3-2

TOTAL $1,255,000 2.

Operating Costs



$1,000

TOTAL $18,600 /yr 3. Treatment Plant Site, allowance $500,000 OPTION 3 – SKIDEGATE WEST 1.

Capital Costs

• Upgrade P.S. No. 5 and genset; 2-25 HP $150,000 • Forcemain; 200 mm, 3100 m x $275/m $853,000 • Land Outfall; 250 mm, 300 m x $325/m $98,000 • Rock Excavation; 1,300 m3 x $100/m3


• Marine Outfall; 250 mm, 400 m $1,621,000

$300,000


$487,000

TOTAL $2,108,000 2.

Operating Costs



$1,000

TOTAL $16,600 /yr 3. Treatment Plant Site, allowance $500,000

163.11 ©2010 Page A3-3

OPTION 4 – SKIDEGATE EAST 1.

Capital Costs

• Upgrade P.S. No. 5 and genset; 2-40 HP $250,000 • Forcemain; 200 mm, 4200 m x $275/m $1,155,000 • Land Outfall; 250 mm, 250 m x $325/m $82,000 • Rock Excavation; 1,800 m3 x $100/m3


• Marine Outfall; 250 mm, 400 m $2,117,000

$300,000


$636,000

TOTAL $2,753,000 2.

Operating Costs



$1,000

TOTAL $18,800 /yr 3. Treatment Plant Site, allowance $500,000 TREATMENT PLANT 1.

Design Criteria

• Population – 1250 • Design Flow – 1500 m3

• Effluent BOD/d

5

/TSS – 45 mg/L

2.

Capital Costs

• Site Works $750,000 • Head Works $250,000 • SBR/Digester Tanks $1,000,000 • Biosolids Dewatering $350,000 • Odour Control $100,000 • Control Building $750,000

163.11 ©2010 Page A3-4

• Electrical/Controls $3,500,000

$300,000

• 30% Engineering and Contingencies

$1,050,000

TOTAL $4,550,000 3.

Operating Costs

• Labour – Daily 3 hrs x $50/hr x 260 days $39,000 • Power – 50 HP x $350/HP-year $17,500 • Materials and Service, allowance $20,000 • Biosolids Disposal, allowance $15,000 • Administration

$5,000

TOTAL $96,500 /yr OPTION 5 – JOINT TREATMENT WITH SKIDEGATE BAND

Pumping Stations and Forcemain

1.

Capital Costs

• Upgrade P.S. No. 5 and genset; 2-50 HP $300,000 • New P.S. No. 6 and genset; 2-60 HP $450,000 • Forcemain; 200 mm, 11,000 m x $275/m $3,025,000 • Rock Excavation; 3,800 m3 x $100/m3

• Highway Crossing, allowance $380,000

$4,505,000 $350,000


$1,352,000

TOTAL $5,857,000 2.

Operating Costs


- Quarterly – 16 hr x $100/hr x 4 days $6,400 • P.S. Annual Service

$8,000

TOTAL $40,200 /yr

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