Okotoks – Calgary Regional Potable

Water Pipeline

Pre-design Study

DRAFT

February 13th, 2015

1

Executive Summary

The Town of Okotoks along with other communities in the Calgary sub-region have experienced

rapid growth in recent years. Increased population projections have led Okotoks to seek out a

long term sustainable source of water. To this end the Town commissioned BSEI to complete a

conceptual water servicing review. This conceptual water servicing study was completed in July

of 2013 and studied three primary water sources:

Treated water from the City of Calgary

Raw water from the Bow River

Raw water from the Highwood River.

For each of these sources the Total Cost of Ownership was investigated for both a supplemental

and standalone water servicing strategy.

On the 21st of November 2013 Okotoks’ council voted to support the City of Calgary

supplemental water supply option as identified in the BSEI study. In November of 2014 the City

of Calgary’s Mayor Naheed Nenshi confirmed that the City is prepared to provide Okotoks with

treated water.

As a next step the Town has completed this predesign study of a potable water pipeline between

the City and Town of Okotoks. Some of the predesign studies main goals are to:

To confirm timing requirements of the potable water pipeline and a Zone 4 reservoir.

To investigate potential and preferred alignment options for a pipeline.

To complete some of the preliminary engineering design of a pipeline.

Confirm some of the assumptions made in the BSEI study.

Some of the major conclusions from this predesign report are as follows:

A water pipeline is required ASAP. With current licenses and production capacity, water

supply shortages may be experienced as soon as 2016. Interim water supply servicing

strategies (including the current water queuing policy) will be required to manage these

shortfalls until a pipeline can be constructed.

The preferred pipeline alignment runs adjacent to Highway 2A from the intersection of

Macleod Trail and 210 Avenue SE to Okotoks’ Zone 3 reservoir.

Negotiations are required with the MD/AT over service road right of way use and access.

From a water storage perspective the construction of Zone 4 North reservoir can be

deferred 5-15 years. For future servicing and system reliability purposes there is an

independent need for a South reservoir that may further defer timing of the Zone 4N

reservoir.

The preferred pipeline material for a 25 year design horizon is 500mm-DIPS DR11

HDPE 4710 or 450mm-DIPS DR18 PVC.

The Town should consider upsizing the pipeline. The material cost difference to upsize

the pipeline by one diameter is less than $1.5M dollars. This represents less than 5% of

the total project cost and a capacity increase of 59% in HDPE and 31% in PVC.

A budgetary estimate for the pipeline is $31.5M.

2

Table of Contents

1. Current and Historical Water Consumption, License Capacity and Production.

1.1. Historical Water Consumption

1.2. License Capacity

1.3. Historical Water Production

2. Regional Waterline Supply Requirements

2.1. Population Projections

2.2. Supplemental Regional Water Pipeline Requirements

2.3. Reservoir Requirements

3. Pipeline Alignment

3.1. Pipeline Okotoks Zone 3N Urban Alignment Options

3.2. Pipeline Line Sizing and Booster Requirements

3.3. Pipeline Material Recommendation

3.4. Pipeline Upsize Recommendation

3.5. Pipeline Control Discussion

3.6. Construction and Design Standards and Specifications.

4. Cost

5. Conclusions

1. Current and Historical Water Consumption, License Capacity and Production.

1.1. Historical Water Consumption

Okotoks has been very proactive when it comes to water use and conservation. The Town

was recognized by the Federation of Canadian Municipalities as the 2015 winner in the water

category for its programs and initiatives to significantly reduce water use. Consumption in

litres per capita per day (Lppd) from Jan 1st, 2010 to Sep 14

th, 2014 is shown in Figure 1

below. The resulting data has been smoothed with a 3 day moving average to minimize any

daily irregularities that can be compensated through reservoir equalization and to assist in

determining the maximum daily design flow as per the Alberta Environment Sustainable

Resources Development (AESRD) Standards and Guidelines for Municipal Waterworks,

Wastewater and Storm Drainage Systems (SGMWWSDS) definition (3 day average). The

average consumption for this period is 266 litres per person per day (Lppd).

Figure 1: Daily Average Consumption per Year

2010 – 274 Lppd

2011 – 262 Lppd

2012 – 288 Lppd

2013 – 247 Lppd

2014 – 260 Lppd

The maximum daily consumption is approximately 450lppd as shown in Figure 2. These

consumption average and maximum peak factors for Okotoks are lower than other

comparable Alberta communities.

3

Figure 2: Daily Consumption per Capita (3 day moving average)

1.2. License Capacity

Okotoks’ Water Treatment Plant (WTP) diverts raw water from the Sheep River tributary of

the South Saskatchewan water basin. Ground Water Under the Direct Influence (GWUDI) of

surface water is pumped with shallow wells into the WTP. Okotoks’ current licensed

maximum diversion rate is 3293Ml/year. Approximately eight percent (8%) of the raw water

is lost to process losses such as backwashing and rinsing the filters leaving a maximum of

3030Ml/year of available treated water from Okotoks’ current licenses.

1.3. Historical Water Production

Okotoks’ WTP currently has limited production capacity. Specifically the WTP has limited

raw water capacity. Well gross daily production in cubic meters from 2010 to 2014 is shown

in Figure 3 below.

Net production capacity (less process losses) of the WTP from 2011 to 2014 is shown in

Figure 4. The current operational maximum WTP production capacity is 12Ml/day based on

peak single day actual production of the water treatment plant as shown in figure 4. A peak

capacity of 12Ml/day is optimistic as historically the plant does not have a history of

sustaining this rate for multiple days. It is assumed that with continued well maintenance and

operational improvements that this peak capacity can be sustained throughout the design

horizon.

150

200

250

300

350

400

450

500

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Co

nsu

mp

tio

n (

lpp

d)

2010 2011 2012 2013 2014

4

Figure 3: Daily Total Well Production

Figure 4: Net Daily Total Water Treatment Plant Production

3,000

5,000

7,000

9,000

11,000

13,000

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

We

ll P

rod

uct

ion

(m

3/d

ay)

2010 2011 2012 2013 2014

4,000

5,000

6,000

7,000

8,000

9,000

10,000

11,000

12,000

13,000

14,000

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Ne

t P

rod

uct

ion

(m

3/d

ay

2011 2012 2013 2014

5

2. Regional Waterline Supply Requirements

Due to limited current water supply the Town is targeting having a pipeline operational as

soon as possible. Allowing some time for approvals, funding and construction the town is

targeting an operational pipeline in 2018.

A 25 year design horizon has been selected for the regional water pipeline to align with the

SGMWWSDS and the Alberta Municipal Water/Wastewater Partnership (AMWWP) Water

for Life grant requirements. The pipeline ultimate design year will be 2043.

2.1. Population Projections

Two independent studies have been recently completed and both make growth projections.

The Conceptual Water Servicing Review, BSEI July 28, 2013 reviewed population

projections and assumed a linear growth rate of 1271.5 persons per year. The Town of

Okotoks Growth Study and Financial Assessment, O2 Planning and Design February 2014

assumed that the Town of Okotoks would receive a constant 4% share of the growth in the

Calgary Regional Partnership (CRP) region. Both models have been plotted in the Figure 5

below. At the end of our design horizon the projections lie within 10% of each other. As

these models do not differ significantly, this report will assume the more conservative linear

growth of 1271.5 persons per year.

Figure 5: Comparison of growth rates of 1271.5 persons/year and 4% of CMP growth

-

10,000

20,000

30,000

40,000

50,000

60,000

70,000

1990 2000 2010 2020 2030 2040 2050

Pro

ject

ed

Po

pu

lati

on

Year

1271.5 persons/year 4% of CRP growth

6

2.2. Supplemental Regional Water Pipeline Requirements

Figure 6 below projects water requirements from 2014 to 2043 based on the following:

Okotoks’ population in the 2014 municipal census was 27,331 persons. Population

growth is projected at1271.5 persons/year throughout the 2014-2043 period.

Total yearly water use is determined by multiplying population by 266 Lppd + 5% for

yearly variation = 279 Lppd.

Required Pipeline Yearly Supplement is determined by subtracting yearly water use from

current Maximum licensed yearly WTP production.

Maximum daily water demand is determined by multiplying population by 450lppd.

Pipeline daily Supplement is determined by subtracting Maximum WTP Daily

Production from Maximum Daily Water Demand.

Pipeline Instantaneous Supplement assumes 90% utilization of the pipeline. This is to

account for operational imperfections and any errors between theoretical and actual

pipeline performance.

As shown in Figure 6 below, if growth projections are met yearly current license capacity will

begin to be exceeded in 2016. Interim water solutions including the current water queuing policy

are being explored to bridge the gap in license capacity and raw water WTP capacity between

now and an operational pipeline. Some investigation of the costing for interim servicing options

has indicated that there are substantial costs associated with interim solutions. Specifically it is

becoming more difficult to drill additional wells that yield decent production capacity. It has

been suggested that interim servicing costing could greatly exceed $1million/year costs. Due to

the costing and short term complexity it is recommended that a pipeline is constructed as soon a

possible.

7

Figure 6: Yearly and Instantaneous Projected water requirements

Year Pop.

Total Yearly Water

Use

Maximum WTP

Licensed Water

Production

Required Pipeline Yearly

Supplement

Maximum Daily

Water Demand

Maximum WTP Daily Prod.

Pipeline Daily

Supplment Req'd

Pipeline Instant.

Supplement Req'd

(ML/yr) (ML/yr) (ML/yr) (ML/day) (ML/day) (ML/day) L/s

2014 27331 2786 3,030 - 12.3 12.0 0.3 3.8

2015 28603 2916 3,030 - 12.9 12.0 0.9 11.2

2016 29874 3045 3,030 16 13.4 12.0 1.4 18.6

2017 31146 3175 3,030 146 14.0 12.0 2.0 25.9

2018 32417 3305 3,030 275 14.6 12.0 2.6 33.3

2019 33689 3434 3,030 405 15.2 12.0 3.2 40.6

2020 34960 3564 3,030 534 15.7 12.0 3.7 48.0

2021 36232 3694 3,030 664 16.3 12.0 4.3 55.4

2022 37503 3823 3,030 794 16.9 12.0 4.9 62.7

2023 38775 3953 3,030 923 17.4 12.0 5.4 70.1

2024 40046 4082 3,030 1,053 18.0 12.0 6.0 77.4

2025 41318 4212 3,030 1,183 18.6 12.0 6.6 84.8

2026 42589 4342 3,030 1,312 19.2 12.0 7.2 92.1

2027 43861 4471 3,030 1,442 19.7 12.0 7.7 99.5

2028 45132 4601 3,030 1,571 20.3 12.0 8.3 106.9

2029 46404 4731 3,030 1,701 20.9 12.0 8.9 114.2

2030 47675 4860 3,030 1,831 21.5 12.0 9.5 121.6

2031 48947 4990 3,030 1,960 22.0 12.0 10.0 128.9

2032 50218 5119 3,030 2,090 22.6 12.0 10.6 136.3

2033 51490 5249 3,030 2,220 23.2 12.0 11.2 143.7

2034 52761 5379 3,030 2,349 23.7 12.0 11.7 151.0

2035 54033 5508 3,030 2,479 24.3 12.0 12.3 158.4

2036 55304 5638 3,030 2,608 24.9 12.0 12.9 165.7

2037 56576 5768 3,030 2,738 25.5 12.0 13.5 173.1

2038 57847 5897 3,030 2,868 26.0 12.0 14.0 180.4

2039 59119 6027 3,030 2,997 26.6 12.0 14.6 187.8

2040 60390 6156 3,030 3,127 27.2 12.0 15.2 195.2

2041 61662 6286 3,030 3,256 27.7 12.0 15.7 202.5

2042 62933 6416 3,030 3,386 28.3 12.0 16.3 209.9

2043 64205 6545 3,030 3,516 28.9 12.0 16.9 217.2

In order for the City of Calgary to assess whether they could provide Okotoks with treated water

they requested Okotoks to submit projected water demands. They were provided with projected

demands of 767ML/year and 4.6ML/peak day in 2021 and 2954ML/year in 2038 (these demands

are slightly skewed as end of calendar year population projections were used vs. census May

populations).

8

2.3. Reservoir Requirements

Okotoks currently has three reservoirs and a total of 21Ml of reservoir storage. SGMWWSDS

outlines the minimum required reservoir storage for municipalities with a WTP capable of

satisfying the maximum daily design flow with the following formula:

S = A + B + (the greater of C or D)

Where S = Total storage requirement, m3

A = Fire storage, m

3

B = Equalization storage (approximately 25% of projected maximum daily design

flow), m3

C = Emergency storage (approximately 15% of projected average daily design flow),

m3

D = Disinfection Contact Time (T10) storage to meet the CT requirements, m3

When looking at the three reservoirs as a system the emergency storage requirement is greater

than the Disinfection CT requirement. Thus, if fire storage is subtracted from the total available

storage we will be left with the volume available for equalization and emergency storage. A

detailed evaluation of fire flow requirements in the town of Okotoks is beyond the scope of this

report, however a flow rate of 225l/s will be assumed as this rate is typical for the Town’s

commercial districts. Fire Underwriters Water Supply for Public Fire Protection 1999, tabulates

fire flow requirements vs. the required duration of fire flow. For a flow rate of 225l/s

approximately 3h of storage is required, yielding 2430m3 of fire storage required per reservoir.

Figure 7 below outlines the current total available storage for emergencies and equalization. The

clear well volume has not been included in the available storage as a portion of the South

Reservoir is not available for distribution due to hydraulic pumping complexities in the system

with respect to delivering water to the Zone 2 reservoir.

Figure 7: Current Reservoir Storage

Volume

Fire Storage

Volume for emergency and equalization

South Stage 1 Clearwell 1,031

- m

3

South Reservoir

5,903 2,430 3,473 m3

Zone 2N Reservoir

6,983 2,430 4,553 m3

Zone 3N Reservoir

7,115 2,430 4,685 m3

Total Volume

21,032 7,290 12,711 m3

Storage Available for emergency and Equalization 12,711 m3

The SGMWWSDS reservoir storage formula does not fully apply to a supplemental supply

servicing strategy as it is intended to be used in municipalities that are only supplied by a WTP.

Municipalities that are supplied by a regional pipeline are typically sized for a specific number of

9

emergency days storage. The number of days storage is typically enough to repair a pipeline

break on the waterline during a maximum demand day period. Typically sizing is based on an

acceptable risk profile and the repair timeline of a broken pipeline. This is typically between 1-3

days storage. The supplemental supply strategy that has been selected reduces the operational

risk of a WTP failure or a pipeline break as an alternate service is available to supply partial

demand through either failure event.

As two sources are available and standard process design for municipal waterworks excludes

double jeopardy failures, reservoir storage should be sufficient to cover the larger of the

SGMWWSDS supply requirements or a sufficient number of days storage of the supplemental

pipeline maximum daily volume requirement.

Figure 8 outlines the minimum AESRD SGMWWSDS reservoir storage requirements and the

number of days of maximum supplemental supply storage available based on current reservoir

capacity. It is clear that currently there is enough current storage capacity to satisfy

SGMWWSDS minimum capacity requirements until 2043. Additional reservoir capacity is

required between 2022 and 2035 to satisfy the requirement for multiple days of pipeline

supplemental storage. Reservoir storage should be designed to a much shorter design horizon ie.

10 years and constructed in phases to mitigate operational issues as outlined in SGMWWSDS.

It is suggested that an additional north reservoir as outlined in the BSEI report is not required at

the time of pipeline construction. Until the Zone 4N reservoir is required the pipeline could tie

into the existing Zone 3N Reservoir.

Ultimately a Zone 4N reservoir will be required and the pipeline should be designed to fill this

future Reservoir. Timing of the construction of the Zone 4N reservoir will have to be

coordinated with other additional reservoirs in the updated 10 year capital plan. This

coordination would include the requirements for a future reservoir on the South End of Okotoks

(required to service future annexed growth areas and for distribution network reliability). The

additional storage gained in the South Reservoir may further defer the timing requirements of a

north reservoir.

10

Figure 8: Reservoir Timing and Sizing Requirements Year Pop. Average

Daily Water

Demand

Maximum Daily

Water Demand

AENV Current Emerg +

Equil. Storage

AENV Required Emerg +

Equil. Storage

Maximum WTP Daily Prod.

Pipeline Daily

Supplment Req'd

Days of Pipeline

Capacity in Storage

(ML/day) (ML/day) (ML/day) (ML/day) (ML/day) (ML/day) days

2018 32,417 9.1 14.6 12.7 5.0 12.0 2.6 4.9

2019 33,689 9.4 15.2 12.7 5.2 12.0 3.2 4.0

2020 34,960 9.8 15.7 12.7 5.4 12.0 3.7 3.4

2021 36,232 10.1 16.3 12.7 5.6 12.0 4.3 3.0

2022 37,503 10.5 16.9 12.7 5.8 12.0 4.9 2.6

2023 38,775 10.8 17.4 12.7 6.0 12.0 5.4 2.3

2024 40,046 11.2 18.0 12.7 6.2 12.0 6.0 2.1

2025 41,318 11.5 18.6 12.7 6.4 12.0 6.6 1.9

2026 42,589 11.9 19.2 12.7 6.6 12.0 7.2 1.8

2027 43,861 12.3 19.7 12.7 6.8 12.0 7.7 1.6

2028 45,132 12.6 20.3 12.7 7.0 12.0 8.3 1.5

2029 46,404 13.0 20.9 12.7 7.2 12.0 8.9 1.4

2030 47,675 13.3 21.5 12.7 7.4 12.0 9.5 1.3

2031 48,947 13.7 22.0 12.7 7.6 12.0 10.0 1.3

2032 50,218 14.0 22.6 12.7 7.8 12.0 10.6 1.2

2033 51,490 14.4 23.2 12.7 7.9 12.0 11.2 1.1

2034 52,761 14.7 23.7 12.7 8.1 12.0 11.7 1.1

2035 54,033 15.1 24.3 12.7 8.3 12.0 12.3 1.0

2036 55,304 15.4 24.9 12.7 8.5 12.0 12.9 1.0

2037 56,576 15.8 25.5 12.7 8.7 12.0 13.5 0.9

2038 57,847 16.2 26.0 12.7 8.9 12.0 14.0 0.9

2039 59,119 16.5 26.6 12.7 9.1 12.0 14.6 0.9

2040 60,390 16.9 27.2 12.7 9.3 12.0 15.2 0.8

2041 61,662 17.2 27.7 12.7 9.5 12.0 15.7 0.8

2042 62,933 17.6 28.3 12.7 9.7 12.0 16.3 0.8

2043 64,205 17.9 28.9 12.7 9.9 12.0 16.9 0.8

3. Pipeline Alignment

The Town has met with the City of Calgary’s water resources department to discuss an

appropriate tie-in location for a regional water pipeline. The most appropriate tie-in location

is between the roadway and property line on the NE corner of the intersection of Macleod

Trail and 210 Avenue SE. The absolute static pressure of this tie in location is at 1115.6m

when the elevated storage is full and 1112.6m at the reserved storage level.

Potential alignments between the intersection of Macleod trail and 210 Avenue SE and the

Town of Okotoks Zone 3N Resevoir were investigated. Five alignments were explored as

11

shown in Figure 9 and a summary of the pros and cons of each alignment is outlined in

Figure 10.

Alignment options along 32nd

Street East and 32nd

Street west options were discarded

because of the additional distance required to route a pipeline along these routes and because

the presence of other buried cable right-of-ways along 32nd

Street East.

An alignment adjacent to the rail road was also explored to see if it would be possible to

eliminate the need for a booster station by following the more gradually graded rail road.

This rail road alignment was discarded because it did not eliminate the need for a booster

station and introduced the requirements for additional rail road crossings and travel through

environmentally sensitive lands.

The three remaining alignments were shortlisted for further comparison as displayed in

Figure 11.

The Highway 2A alignment proposes to follow the highway service road corridor

between the two tie-in locations.

The high pressure gas alignment proposes to run adjacent to the existing high pressure

gas line between Calgary and Okotoks.

The Range Road 295 alignment proposes to follow the Range Road 295 right of way,

much of which presently does not have a road constructed in.

A digital elevation model (DEM) consisting of topographic light detection and ranging

(LiDAR) information was purchased from AltaLIS with 15m post spacing / 30cm accuracy

and is underlain in a colour gradient in the backgrounds of Figure 9 and 11. The LiDAR

DEM data was extrapolated along each of the shortlisted alignments and elevation profiles of

these alignments are shown in Figure 12. Fine tuning of the alignments and survey data will

be required at the detailed design phase of this project. It is expected that field survey data

and alignment adjustments may differ somewhat from the LiDAR DEM, but for the purposes

of predesign the LiDAR data is likely sufficient.

Through examining Figure 12 a few generalized conclusions can be made about each route as

summarized in Figure 10:

The HWY 2A route is the smoothest and has the least elevation gain.

The RR295 is the longest and has several abrupt changes in elevation. Field survey

of the RR295 route reveals that this route has the most challenging terrain and has

some difficult site access issues.

The high pressure gas line alignment bisects and crosses multiple parcels - land

owner consultation is expected to be the most difficult with this option adding

concerns over project timing and the cost of land acquisition.

When reviewing Figure 10 the HWY 2A option emerges as the preferred option.

12

Figure 9: Conceptual Pipeline Alignments

Legend HWY 2A (Preferred) High Pressure Gas RR295 32nd Street East/West Rail Road

13

Figure 10: Alignment Pro and Con Summary

Route Pro Con

Hwy 2A

(Preferred Alignment) Distance ~ 16.5km

Good equipment access

Dealing Primarily with

one jurisdiction for

Right of way acquisition.

Potentially limited

additional fees for land

acquisition.

High Pressure Gas Distance ~ 16.2km

Complex Landowner

Negotiation with

potential concerns over

widening bisected

parcels.

Extended Period for land

acquisition.

High land acquisition

costs.

Right of way must be

wide enough for site

access

RR295 Distance ~ 18km

Dealing Primarily with

one jurisdiction for

Right of way acquisition

Challenging terrain and

site access. (Increased

costs).

32nd

Street East/West Distance > 21km

Buried Cable Utility

ROW on 32nd

Street

East.

High parcel

fragmentation on 32nd

Street East.

Rail Road Distance > 20km

Multiple RR crossings

Environmental

Senstivity

Complex Terrian

River Crossing

14

Figure 11: Shortlisted Conceptual Pipeline Alignments

Legend HWY 2A (Preferred) High Pressure Gas RR295

Calgary Tie In

Okotoks Zone 3N Tie In

Future Zone 4N Reservoir (Potential Location)

15

Figure 12: Elevation profiles of shortlisted conceptual Pipeline Alignments (Proposed Construction Profile)

1000

1050

1100

1150

1200

0 2500 5000 7500 10000 12500 15000 17500 20000

Ele

vati

on

(m

)

Length (m)

HWY 2A - Preferred RR295 High Pressure Gas

16

3.1. Pipeline Okotoks Zone 3N Urban Alignment Options

Several conceptual alignment options exist to tie into the Zone 3N Reservoir within the Town of

Okotoks as shown in Figure 13 below. All alignments will disrupt traffic and residents on the

Bannister Gate/Drive or Milligan corridors. Selection of the ultimate alignment within the town

boundary will be part of the detailed design exercise and will take into account several factors

including: available space in the roadway, coordination with other required utility upgrades, cost,

technical feasibility and impact to residents.

Figure 13 – Pipeline C Urban Alignment Options

Bannister Gate

Good Shepard

Zone 3 Reservoir

Milligan Drive

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3.2. Pipeline Line Sizing and Booster Requirements

Pipelines are typically designed for a number of parameters including but not limited to fluid

velocity, working/surge pressures and cyclic loading. An iterative design approach calculating

pressure losses at available pipe sizes was taken to arrive at a final minimum pipe ID of 439mm

(17.3”). The Design Parameters at this sizing are shown in Figure 14. Figure 14 assumes that

the HWY 2A alignment is selected and is designed to the ultimate future scenario, which would

be to fill the future Zone 4N reservoir. The design flow rate of 217 L/s is the instantaneous

supplement requirement from Figure 6 in 2043. The highlights of Figure 14 include a 1.4m/s

flow velocity and a pressure boost of 102.2m of water required at approximately 5.5km from the

Calgary tie in location.

Figure 14 – Pipeline Design Parameters.

Description METRIC UNITS IMPERIAL UNITS

Instantaneous Flow 217 l/s 3443 USGPM

Hazen-Williams Coefficient of Pipe [PVC = 150] 150

150 Internal Diameter of pipe 439.4 mm 17.3 in

Pipe Flow Velocity 1.4 m/s 4.7 (ft/s)

Linear Pressure drop 3.2 m of H2O/km 1.4 (psi/1000ft)

Pressure at Beginning of Pipeline (ASL) 1112.6 m 3650.3 ft Length to pipeline to future Reservoir (HWY2A Alignment) 15.5 km 50852.9 ft

Pressure drop 49.8 m of H20 163.2 ft of water

Elevation of Final Reservoir 1165 m 3822.2 ft

Booster Requirement 102.2 m of H20 335.3 ft of water

Proposed Booster Location (from Calgary Tie In) 5.5 km 18045 ft

Figure 17 displays the conceptual future pipeline profiles to a future Zone 4 reservoir along with

a hydraulic gradeline of a 439.4mm/17.3” ID pipeline at design conditions. A teed-off valve

would be included in the design to accommodate this future installation of this reservoir.

3.3. Pipeline Material Recommendation

Pipelines materials and wall thickness are selected to operate within the design pressures of a

pipeline. Figure 18 displays the gauge pressure of a pipeline along the HWY 2A alignment in

PSI. Figure 15 displays the calculated operating pressures and the expected surge pressure or

“water hammer” expected from a rapidly closing valve or pump failure. In the predesign study a

single pressure surge event has been contemplated. The detailed pipeline design should include

analysis of transient effects along the pipeline and cyclic loading.

Although calculation for surge pressure is included in the design all efforts in the final design

should be made to eliminate the opportunity for hammer as it adds risk to the system and

sometimes reduces the lifespan of the pipeline. These reductions should include some if not all

18

of the following: variable frequency drives (VFD’s) on booster pump motors, surge tanks,

control systems, slow closing valves, pressure reliefs, maximum flow rate control and

installation of combination air/vacuum release valves.

Figure 15: Highway 2A alignment material allowable pressures

Description METRIC UNITS IMPERIAL UNITS

Material PVC HDPE 4710 PVC HDPE 4710

Size 450mm - DR18 500mm - DR11 18" - DR18 20" - DR11

Instantanous Dynamic Modulus of Pipe (kPa , PSI) 2,757,903 1,034,214 400,000 150,000

Pipe Internal Diameter (mm , inches) 439 443 17.30 17.44

Thickness (mm , inches) 27.4 49.9 1.08 1.96

Pipe Flow Velocity (m/s , ft/s) 1.4 1.4 4.7 4.6

Wave Velocity (m/s , ft/s) 394 328 1292 1076

Surge Pressure (kPa , PSI) 563 462 82 67

Maximum Operating Pressure (kPa , PSI) 1,133 1,133 164 164

Allowance for control shutdown (kPa , PSI) 138 138 20 20

Surge Pressure + Operating (kPa , PSI) 1,834 1,732 266 251

Allowable Pressure (kPa , PSI) 1,620 1,379 235 200

Allowable Recurring Surge Pressure (kPa , PSI) 448 689 65 100

Total allowable Recurring Surge Pressure (kPa , PSI) 2,068 2,068 300 300

High Density Polyethylene (HDPE type 4710) is considered as an alternate potential material to

Polyvinyl Chloride (PVC) in Figure 15. Due to differences in internal diameter a 500mm HDPE

pipe sized with Ductile Iron Pipe Standards (DIPS) is equivalent in internal dimensions to a

450mm PVC pipe. Table 15 summarizes that for the pressures expected a minimum size class of

DR11 should be selected for HDPE and a minimum size class of DR18 should be selected for

PVC.

HDPE has some advantages to PVC pipe as it is typically fused with few joints, is tougher (ie.

has increased tensile elongation prior to breaking, better impact resistance, better rapid creep

resistance, surge and cyclic resistance) experiences slightly less surge pressures, can be

directionally drilled/pulled and can potentially be installed straight-cut reducing ROW and

excavation requirements. Initial cost comparisons have shown some potential for cost savings

for HDPE construction.

Ultimately pipe material selection is part of the pipeline detailed design. Final pipe selection will

be affected by the final design details, preferred installation method and cost of material at the

time of construction. HDPE should be considered as an alternate to PVC at the detailed design

phase of this project.

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3.4. Pipeline Upsize Recommendation

It is worth considering upsizing the pipeline to accommodate a potential for additional future

regional users and/or growth beyond the 25 year design horizon. A comparison of flow rates and

the populations that can be serviced by a pipeline upsized one nominal pipe diameter is

summarized in Figure 16 below. For the purpose of evaluation the pressure drop is held

approximately constant for the upsized diameter and flow rates are increased.

Figure 16: Comparison of flow rates and equivalent populations that can be serviced by

pipeline upsized one nominal pipe diameter.

Pipe Type HDPE 4710 HDPE 4710 PVC PVC Pipe Size 500mm-DIPS 600mm-DIPS 450mm - DIPS 500mm - DIPS Pressure Class DR11 DR11 DR18 DR18 Instantanious Flow 217 345 217 285 L/s

Population Equivalent* (450LPPD @ 90% utilization) 37538 59616 37498 49248 Persons

Hazen-Williams Coefficient 150 150 150 150 Internal Diameter of pipe 442.9 529.0 439.4 487.7 mm

Pipe Flow Velocity 1.4 1.6 1.4 1.5 m/s

Linear Pressure drop 3.09 3.06 3.20 3.19 m of H2O/km

*Population Equivalent reflects the population that can be served solely by the pipeline.

The material cost difference to upsize the pipeline by one diameter is less than $1.5M dollars.

This represents less than 5% of the total project cost and a capacity increase of 59% in HDPE

and 31% in PVC.

3.5. Pipeline Control Discussion

Although control of the pipeline is part of the detailed design, this report will briefly explore two

control strategies that can be used for the pipeline and booster station. The first control strategy

would have an open pipe into the receiving reservoir and to turn the booster station pumps on/off

with remote control based on the receiving reservoir level. The second control strategy would be

to run the booster station on VFD pressure control independent of the reservoir and to open/close

an independent slow moving valve at the receiving reservoir based on reservoir level. There is

the possibility of doing a hybrid option but the predesign will focus on discussion of the two

different control strategies.

In the first scenario the pipeline after the highpoint will drain (or be on vacuum) after pump

shutdown. One of the advantages of this control design is that the pressure in the pipeline will

on average be lower after the system highpoint and that the system does not in normal operation

have to worry about rapid valve closures. However this control design has a few inherent

weaknesses. These weaknesses include the following:

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The system is dependent on the communications link. If there is a communication or

power failure the system may not run properly leading to manual operation or reservoir

overfill/low level.

On shutdown or pump failure the pipeline could experience vacuum conditions and

collapse the pipeline. Pipelines typically do not have good resistance to vacuum

conditions. This collapse risk is somewhat analogous to a straw – if someone plugs the

end of the straw and blows, it is hard to burst, however if they suck the straw may

collapse. A slow pump ramp-down will be required and transient analysis may

recommend installation of a fly-wheel (non-standard pump design) to mitigate the effects

of pump/power failure. Failure of a vacuum/combination valve could also lead to

similar vacuum conditions

Large volumes of air increases hammer risk. The exhaust of air rate needs to be

controlled. Joints are often designed to prevent the escape of water. Air can escape

from joints at higher rates than water leading to hammer when the water reaches the leak

location. Also air is compressible and can introduce new dynamics to transient analysis.

Risk of contamination. When the pipeline drains the vacated space is filled with air and

at zero gauge pressure. Although the introduction of air poses a very minor risk a larger

risk presents itself if there is a small pipeline leak (such as at a flange or gasket) and

groundwater is present. It is possible that contaminated groundwater could enter the

pipeline.

In the second scenario the valve will close and the pressure will gradually build up from the

valve to the booster station until the pumps reach their programmed shut down pressure.

Although this system will experience higher pressures and cyclic loading, this design is superior.

Some of the highlights of this design include:

An independent somewhat simplified control system. This system is not sensitive to

communication failure or power failure. The actuated valve at the reservoir should be

designed to be normally closed.

There is little air introduced to the system after commissioning.

Easier detection of minor leaks. If pumps are cycling when the line is shut in, this is

indicative of a leak (likely a leak could be from a check valve but it could also be a valve

or the pipeline itself).

Sensitivity to rapid valve closure will have to be mitigated with high quality control

valves, VFD Pump control, surge tanks and pressure reliefs.

Control for chlorine monitoring and trim should also be contemplated and designed into the

pipeline booster station or receiving reservoir. Long water transmission times within the pipeline

could lead to reduced free chlorine residuals at the receiving reservoir. Pipeline design should

accommodate chlorine residual testing and addition, if required.

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3.6. Design and Construction Standards and Specifications

The Town of Okotoks uses the 2014 City of Calgary Standard Specifications for Waterworks

Construction. Detailed design and construction will need to conform to these standards.

In addition the following standards must be adhered to within the Town of Okotoks municipal

boundary:

2013 Town of Okotoks General Design and Construction Specifications

2012 City of Calgary Standard Specifications for Roads

2012 City of Calgary Landscape Construction Guidelines.

3.7. Conservation and Reclamation Study

This pipeline is a Class I pipeline and under Alberta Environment Environmental Protection

Guidelines it requires a Conservation and Reclamation (C&R) approval prior to any surface

disturbance. Obtaining this approval is beyond the scope of this predesign report.

Figure 17: Future Elevation Profiles and Pipeline Hydraulic Gradeline (439.4mm/17.3” ID) to future Zone 4 Reservoir (Ultimate Design Condition)

1000

1050

1100

1150

1200

0 2500 5000 7500 10000 12500 15000 17500 20000

Ele

vati

on

(m

)

Length (m)

HWY 2A - Preferred RR295 High Pressure Gas Absolute Pipeline Pressure

Tee-in location for future Zone 4 Reservoir fill pipeline

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Figure 18: Operating Guage Pressure Profile in PSI of Highway 2A alignment to Future Zone 4 Reservoir (Ultimate Design Condition)

0.0

20.0

40.0

60.0

80.0

100.0

120.0

140.0

160.0

180.0

200.0

0 2000 4000 6000 8000 10000 12000 14000 16000 18000

Pre

ssu

re (

PSI

)

Horizontal Distance (m)

Tee-in location for future Zone 4 Reservoir fill pipeline

4. Cost

Updated budgetary cost projections for a potable water pipeline are included below. This table

includes some additional costs not included in previous estimates such as urban pipeline

construction, reservoir tie in (included in urban costs), metering stations, potential directional

drilling and land acquisition costs. There is some uncertainty over land acquisition, directional

drilling requirements and additional Municipal District (MD) / Alberta Transportation (AT)

design considerations as negotiations with the MD/AT over pipeline alignment have not yet

begun. As such this estimate is still a high level budgetary estimate. Additional budgetary cost

refinement is required at the detailed design stage of this project.

Figure 19: Pipeline budgetary cost projections

Quantity Unit Cost Subtotal

Pipeline Rural Cost 15000 m 1,100$ $/m 16,500,000$

Pipeline Urban Cost 1500 m 2,100$ $/m 3,150,000$

Booster Station 1 ea 2,000,000$ $/ea 2,000,000$

Metering Station 1 ea 700,000$ $/ea 700,000$

Land acquisition (if required) 76 acres 40,000$ $/acre 3,040,000$

Subtotal 25,390,000$

Professional Services (Consulting, C&R, Land Agents etc.) 8% 2,031,200$

Contingency 15% 4,113,180$

Total Budget 31,534,380$

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5. Conclusions

Some of the major conclusions from this predesign report are as follows:

A water pipeline is required ASAP. With current licenses and production capacity, water

supply shortages may be experienced as soon as 2016. Interim water supply servicing

strategies (including the current water queuing policy) will be required to manage these

shortfalls until a pipeline can be constructed.

The preferred pipeline alignment runs adjacent to Highway 2A from the intersection of

Macleod Trail and 210 Avenue SE to Okotoks’ Zone 3 reservoir.

Negotiations are required with the MD/AT over service road right of way use and access.

From a water storage perspective the construction of Zone 4 North reservoir can be

deferred 5-15 years. For future servicing and system reliability purposes there is an

independent need for a South reservoir that may further defer timing of the Zone 4N

reservoir.

The preferred pipeline material for a 25 year design horizon is 500mm-DIPS DR11

HDPE 4710 or 450mm-DIPS DR18 PVC.

The Town should consider upsizing the pipeline. The material cost difference to upsize

the pipeline by one diameter is less than $1.5M dollars. This represents less than 5% of

the total project cost and a capacity increase of 59% in HDPE and 31% in PVC.

A budgetary estimate for the pipeline is $31.5M.

Prepared By: Third Part Review By:

Senior Engineer Principal / Project Engineer

Town of Okotoks BSEI Consulting

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