2. WATER SYSTEM EVALUATION
2.1 Water System Overview
As discussed in Chapter 1 and displayed on Figure 1.1, the Town has two separate water pressure
zones. The low pressure zone is supplied by MWRA’s Southern High water network via meters #27
and #107. There is also a pressure reducing valve, located on Highland Street at Canton Avenue
between the Town’s high and low pressure zones, that can temporarily supply the low pressure zone.
The vast majority of supply issues in the low pressure zone are the result of water main deficiencies.
The MWRA Southern High water network is reliable. Refer to Section 2.4 for a description of
MWRA’s supply.
The Town’s high pressure zone is supplied by MWRA’s Southern Extra High water network via
meter #55. There is also a “loop” located within the Town of Canton that connects the high pressure
zone main trunk lines and also provides manually actuated emergency connections to the Canton
water distribution system. The piping loop running through Washington Street and Blue Hill River
Road provides several functions. First; the loop has historically supplied Milton water to Canton
customers for the several decades during which entire time the Town of Canton was unable to meet
the demands by its own supply. Second; the loop functions as a hydraulic balance between the Town
of Milton’s three water storage tanks. And three; the loop provides circulation through the more
remote areas of Milton’s water distribution system, which enhances water quality by reducing aged
water. The loop and emergency connections are planned to be valved off by the Town of Canton in
December 2016 as a result of a complicated renegotiation of a five decades old agreement between
the two towns. The impact of Canton disconnecting this loop is included in the analysis presented in
this chapter. The single source of water, the limitations of the Southern Extra High water network
(described in Section 2.4), as well as the condition of the existing water system infrastructure require
careful analysis of the high pressure zone.
The Town has three water storage tanks located within the high pressure zone. Two of the storage
tanks are located off Chickatawbut Road in Quincy and the other is located off Blue Hill Avenue in
Milton. All three tanks are located within the Blue Hills Reservation owned by the Massachusetts
Department of Conservation and Recreation (DCR). The Chickatawbut #1 Water Storage Tank is a
150,000 gallon riveted steel tank constructed in the 1930s. The Chickatawbut #2 Water Storage Tank
is a 620,000 gallon welded steel tank constructed in the 1950s. The Blue Hills Water Storage Tank is
a 600,000 gallon riveted steel tank constructed in the 1930s. The tanks have a combined storage
capacity of 1.37 MG, as shown in Table 2.1.
The overflow elevation at each of the three tanks is 375 feet (USGS) and each tank site is equipped
with an altitude valve. According to the MWRA record information, the hydraulic grade line (HGL)
at meter #55 fluctuates between 375-396 feet (USGS). Given that the HGL at the meter is higher
than the overflow elevation at the water tanks does not allow for the water level to fluctuate within
the water storage tanks unless there is a major disturbance within the water distribution system.
Water age within the tanks is a regular problem and requires the Town to manually drain aged water
periodically due to reduced disinfectant residual levels. This process costs the Town man-hours and
the cost of purchased water that is ostensibly wasted.
2-1
Under the current conditions the three water storage tanks only provide a reserve supply of water
during fire demands or other major disturbances to the Town’s water distribution system. The Town’s
2005 Water System Master Plan states that the Town’s required storage required per AWWA
standards is 0.90 MG, which still holds true today. The required storage volume requirement is
derived from a 3 hour 3,500 gpm fire demand and a 20 percent of fire flow and equalization
component. The Town currently has approximately 0.47 MG in excess storage capacity, which
provides a reasonable factor of safety which can be made available during times of severe fire
demand which might occur simultaneously during peak domestic demand.
TABLE 2.1 – WATER STORAGE TANKS
Blue Hills
Chickatawbut #1
Chickatawbut #2
Pressure
Zone
HIGH
HIGH
HIGH
Height
(ft)
25
30
30
Diameter
(ft)
64
29
60
Overflow
Elevation
(ft)
375
375
375
Material
Riveted Steel
Riveted Steel
Welded Steel
Capacity
(gal)
600,000
150,000
620,000
2.2 Water System Hydraulic Modeling
Hydraulic modeling was utilized to evaluate the existing and proposed water distribution system.
The following assumptions were made:
1. The average day demand (ADD) for the high pressure zone is 1.09 mgd and for the low
pressure zone is 1.57 mgd for an overall Town ADD of 2.66 mgd.
2. The maximum day demand (MDD) for the high pressure zone and low pressure zone are 2.01
and 5.76 mgd, respectively.
3. The HGL at meter #55 fluctuates between 375’ to 396’. To simulate a “worst case” scenario
for existing conditions, the hydraulic simulation used a HGL of 375’.
4. The emergency connections consist of manually actuated valves and are therefore not
considered in the hydraulic modeling.
Simulations were conducted and evaluated to determine the distribution system’s capability of
meeting AWWA and DEP pressure and fire flow standards as well as allowing for the water level in
the water tanks to fluctuate. Recommended fire flows are defined as the recommended minimum fire
flow rate from the distribution system. A minimum of 20 pounds per square inch (psi) must be
maintained under all design conditions per MGL 310 CMR 22 and DEP regulations. DEP Guidelines
also state that the normal working pressure in the distribution system should be approximately 60 psi
and not less than 35 psi. Figures for all simulation runs are on a disc located in Appendix D of this
report. Hydraulic simulation runs #2, #3 and #4 were completed only on the high pressure system
since the proposed changes only affected the high pressure system. A narrative and analysis of the
results for the four hydraulic model simulations are as follows:
2-2
Hydraulic Model Simulation Run #1:
Purpose of Simulation:
 To determine if the water storage tanks are required or if one or all three of the water tanks
could be decommissioned.
Assumptions:
 System Conditions –
Existing
 HGL at MWRA Meter #55 –
375’
 Water Storage Tanks –
Blue Hills Water Storage Tank online, Chickatawbut #1
& #2 offline (total available capacity of 600,000 gallons)
 Tank overflow elevation –
375’
 Canton “Loop” –
Online
Analysis:
 Water pressure, fire flows and water age were analyzed throughout the distribution system
during maximum day demand and including a simulated 2,500 gpm fire demand.
The results of Simulation Run #1 are summarized in Table 2.2a below:
TABLE 2.2a – SIMULATION HYDRAULIC MODEL RUN #1,
Simulation
Run No. Figure No.
1a
1b
1c
1d
1e
1f
1g
1h
2.1a
2.1b
2.1c
2.1d
2.1e
2.1f
2.1g
2.1h
Fire Demand
Press. Zone
Simulated
Condition
None
None
None
2,500 gpm
2,500 gpm
2,500 gpm
2,500 gpm
None
High, Low
High
Low
High
High
Low
Low
High, Low
Pressure
Fire Flow
Fire Flow
Pressure
Fire Flow
Pressure
Fire Flow
Water Age
Results
Adequate
Concerns along Hillside St area
Concerns in several areas inc. East Milton Square
Concerns along Hillside St area & Canton Loop
Concerns in South & Southeast areas
Concerns along Valentine Rd & Smith Rd areas
Concerns along Valentine Rd & Smith Rd areas
Adequate
No Fire Demand:
 Figure 2.1a indicates that there appears to be adequate water pressure above the minimum 35
psi required throughout the water distribution system.
 Figure 2.1b indicates that there are concerns for maintaining a minimum flow of 500 gpm for
fire protection in the Hillside Street area within the high pressure zone during a maximum day
demand.
 Figure 2.1c indicates that there are concerns for maintaining a minimum flow of 500 gpm for
fire protection in several areas including East Milton Square areas in the low pressure zone.
Fire Demand in High Pressure Zone (at Orchard St. and Pleasant St.)
 Figure 2.1d indicates that there are potential concerns for maintaining water pressure above
the required minimum of 35 psi along the Hillside Street area and along the “Canton loop”.
2-3

Figure 2.1e, indicates that there are potential concerns for maintaining a minimum flow of
500 gpm for fire protection in the southern and the southeastern portions of Town with a
simulated fire within the high pressure zone.
Fire Demand in Low Pressure Zone (at Blue Hill Avenue and Hollingsworth Street)
 Figure 2.1f indicates that there would be potential concerns for maintaining water pressure of
the required minimum of 35 psi along Valentine Road and Smith Road area.
 Figure 2.1g indicates that there are potential concerns for maintaining a minimum flow of 500
gpm required for fire protection in the Valentine Road and Smith Road areas.
Water Age
 As shown in Figure 2.1h, water age does not appear to be a major concern under Simulation
#1 conditions.
Overall, BETA would not recommend Simulation Run #1 Alternative for the Town’s high pressure
zone for the followings reasons:
 During a fire demand period, concerns with the distribution system maintaining a minimum of
35 psi away from the impacted area.
 During a fire demand period, concerns with the distribution system maintaining fire flow
protection away from the impacted area.
 The overall concerns with redundancy in the MWRA Southern Extra High System that serves
the Town of Milton’s High Pressure Zone as discussed in Section 2.4.
Hydraulic Model Simulation Run #2:
Purpose of Simulation:
 To determine if installation of a PRV at Meter #55 to lower the HGL from 395’ to 375’ will
allow the three water storage tanks to fluctuate properly while maintaining adequate water
pressure and fire flow protection throughout the high pressure service system in accordance to
AWWA Standards.
Assumptions:
 System Conditions –
Installation of PRV downstream of Meter #55
 HGL at MWRA Meter #55 –
375’
 Water Storage Tanks –
3 online (total available capacity of 1.37 million gallons)
 Tanks overflow elevation –
375’
 Canton Loop –
Online
 During the hydrant flow tests and hydraulic model calibration process, it was noted that there
are water flow restrictions in the Harland and Hillside Street area. In addition, Harland Street
has pipe diameters changing from 8-inch to 12-inch multiple time which is also restricting
water flow in the area. The replacement of these pipe size restrictions is scheduled to be
constructed under the 2015 Water Main Replacement Project. BETA removed these water
flow restrictions and ran simulated hydraulic runs for fire flow and water age, which are
presented in simulation 2.2f.
2-4
Analysis:
 Water pressure, fire flows and water age were analyzed throughout the high pressure zone
during maximum day demand and including a simulated 2,500 gpm fire demand.
The results of Simulation Run #2 are summarized in Table 2.2b below:
TABLE 2.2b – SIMULATION HYDRAULIC MODEL RUN #2,
Simulation
Run No. Figure No.
2a
2b
2c
2d
2e
2f
2.2a
2.2b
2.2c
2.2d
2.2e
2.2f
Fire Demand
Press. Zone
Simulated
Condition
None
None
2,500 gpm
2,500 gpm
None
None
High, Low
High
High
High
High, Low
High
Pressure
Fire Flow
Pressure
Fire Flow
Water Age
No Restrictions
Results
Adequate
Concerns along Hillside St area
Adequate
Concerns along Hillside St area & Canton Loop
Adequate
Adequate
No Fire Demand:
 Figure 2.2a indicates that there appears to be adequate water pressure above the minimum 35
psi required throughout the high pressure service system.
 Figure 2.2b indicates that there are concerns for available water for fire protection in the
Hillside Street area within the high pressure zone during a maximum day demand.
Fire Demand in High Pressure Zone (at Orchard St. and Pleasant St.)
 Figure 2.2c indicates that there are appears to be adequate water pressure above the minimum
20 psi required within the fire demand impact area and above the minimum 35 psi required
throughout the remaining high pressure service system.
 Figure 2.2d, indicates that there are potential concerns for maintaining a minimum flow of
500 gpm required for fire protection in the southern and the southeastern portions of Town
with a simulated fire within the high pressure zone.
Water Age
 As shown in Figure 2.2e, water age does not appear to be a major concern under Simulation
#2 conditions.
Overall, BETA would recommend Simulation Run #2 Alternative as a viable option for the Town’s
high pressure zone. The potential concerns of available water for fire protection can be attributed to
the existing water flow restrictions found during the hydrant flow tests in the Harland/Hillside Streets
and Brush Hill Road areas of Town. BETA ran the model, see Figure 2.2f without the water flow
restrictions and there appears to be adequate fire protection throughout the high pressure zone.
Hydraulic Model Simulation Run #3:
Purpose of Simulation:
 To determine if installation of a new elevated water storage tank with an overflow elevation at
400’ will allow the new water storage tanks to fluctuate properly while maintaining adequate
2-5
water pressure and fire flow protection throughout the distribution system in accordance to
AWWA Standards. The theoretical tank was located at the Chickatawbut tank location.
Assumptions:
 System Conditions –
Installation of a New Elevated Water Storage Tank
 HGL at MWRA Meter #55 –
395’
 Water Storage Tanks –
1 online (total available capacity of 1.2M gallons)
 Tank overflow elevation –
400’
 Canton Loop –
Online
 During the hydrant flow tests and hydraulic model calibration process, it was noted that there
are water flow restrictions in the Harland and Hillside Street area. In addition, Harland Street
has pipe diameters changing from 8-inch to 12-inch multiple time which is also restricting
water flow in the area. The replacement of these pipe size restrictions is scheduled to be
constructed under the 2015 Water Main Replacement Project. BETA removed these water
flow restrictions and ran simulated hydraulic runs for fire flow and water age, which are
presented in simulation 2.3f.
Analysis:
 Water pressure, fire flows and water age were analyzed throughout the high pressure service
system during maximum day demand and including a simulated 2,500 gpm fire demand.
The results of Simulation Run #3 are summarized in Table 2.2c below:
TABLE 2.2c – SIMULATION HYDRAULIC MODEL RUN #3,
Simulation
Run No. Figure No.
3a
3b
3c
3d
3e
3f
2.3a
2.3b
2.3c
2.3d
2.3e
2.3f
Fire Demand
Press. Zone
Simulated
Condition
None
None
2,500 gpm
2,500 gpm
None
None
High, Low
High
High
High
High, Low
High
Pressure
Fire Flow
Pressure
Fire Flow
Water Age
No Restrictions
Results
Adequate
Concerns along Hillside St area
Adequate
Concerns along Hillside St area & Canton Loop
Adequate
Adequate
No Fire Demand:
 Figure 2.3a indicates that there appears to be adequate water pressure above the minimum 35
psi required throughout the water distribution system.
 Figure 2.3b indicates that there are concerns for maintaining a minimum flow of 500 gpm for
fire protection in the Hillside Street area within the high pressure zone during a maximum day
demand.
Fire Demand in High Pressure Zone (at Orchard St. and Pleasant St.)
 Figure 2.3c indicates that there are appears to be adequate water pressure above the minimum
20 psi required within the fire demand impact area and above the minimum 35 psi required
throughout the remaining high pressure service system.
2-6

Figure 2.3d, indicates that there are potential concerns for maintaining a minimum flow of
500 gpm required for fire protection in the southern and the southeastern portions of Town
with a simulated fire within the high pressure zone.
 Water Age
 As shown in Figure 2.3e, water age does not appear to be a major concern under Simulation
#3 conditions.
Overall, BETA would recommend Simulation Run #3 Alternative as a viable option for the Town’s
high pressure zone. The potential concerns of available water for fire protection can be attributed to
the existing water flow restrictions found during the hydrant flow tests in the Harland/Hillside Streets
and Brush Hill Road areas of Town. BETA ran the model, see Figure 2.3f without the water flow
restrictions and there appears to be adequate fire protection throughout the high pressure zone.
Hydraulic Model Simulation Run #4:
Purpose of Simulation:
 The original scope for this report required a review and evaluation of the interconnection
issues between the Town of Milton’s and Town of Canton’s Water systems. The “loop” is
located within the Town of Canton and connects Milton’s high pressure zone main trunk
lines. It also provides manually actuated emergency connections to the Canton water
distribution system. The Town of Milton wanted to ensure that all water demand by the Town
of Canton was accounted for. However, during the winter of 2013/2014, the Town of Milton
revised the scope of this report and requested that BETA evaluate effects of valving off the
Canton “loop”. Hydraulic Simulation Run #4 is based on this scenario.
 To determine if valving off the Canton “loop” and installation of a PRV downstream of Meter
#55 to lower the HGL from 395’ to 375’ will allow the three water storage tanks to fluctuate
properly while maintaining adequate water pressure and fire flow protection throughout the
high pressure service system in accordance to AWWA Standards.
Assumptions:
 System Conditions –
PRV at Meter #55 and Canton Loop Valved Off
 HGL at MWRA Meter #55 –
375’
 Water Storage Tanks –
3 online (total available capacity of 1.37 million gallons)
 Tank overflow elevation –
375’
 Canton Loop –
Offline
 During the hydrant flow tests and hydraulic model calibration process, it was noted that there
are water flow restrictions in the Harland and Hillside Street area. In addition, Harland Street
has pipe diameters changing from 8-inch to 12-inch multiple time which is also restricting
water flow in the area. The replacement of these pipe size restrictions is scheduled to be
constructed under the 2015 Water Main Replacement Project. BETA removed these water
flow restrictions and ran simulated hydraulic runs for fire flow and water age, which are
presented in simulation runs 2.4f & 2.4g.
Analysis:
 Water pressure, fire flows and water age were analyzed throughout the high pressure service
system during maximum day demand and including a simulated 2,500 gpm fire demand.
2-7
The results of Simulation Run #4 are summarized in Table 2.2d below:
TABLE 2.2d – SIMULATION HYDRAULIC MODEL RUN #3,
Simulation
Run No. Figure No.
4a
4b
4c
4d
4e
4f
4g
2.4a
2.4b
2.4c
2.4d
2.4e
2.4f
2.4g
Fire Demand
Press. Zone
Simulated
Condition
None
None
2,500 gpm
2,500 gpm
None
None
None
High, Low
High
High, Low
High
High, Low
High
High
Pressure
Fire Flow
Pressure
Fire Flow
Water Age
No Restrictions/Fire Flow
No Restrictions/Water Age
Results
Adequate
Concerns along Hillside St area
Adequate
Concerns along Hillside St area & Canton Loop
Concerns along Hillside St area
Concerns along Canton Ave area
Adequate
No Fire Demand:
 Figure 2.4a indicates that there appears to be adequate water pressure above the minimum 35
psi required throughout the water distribution system.
 Figure 2.4b indicates that there are concerns for maintaining a minimum flow of 500 gpm
required for fire protection in the Hillside Street area within the high pressure zone during a
maximum day demand.
Fire Demand in High Pressure Zone (at Orchard St. and Pleasant St.)
 Figure 2.4c indicates that there appears to be adequate water pressure above the minimum 20
psi required within the fire demand area and above the minimum 35 psi required outside of
the fire demand area.
 Figure 2.4d indicates that there are concerns for maintaining a minimum flow of 500 gpm
required for fire protection in the Hillside Street area within the high pressure zone during a
maximum day demand.
 Figure 2.4e, indicates that there are potential concerns for maintaining a minimum flow of
500 gpm required for fire protection in the southern and the southeastern portions of Town
with a simulated fire within the high pressure zone.
Water Age
 As shown in Figure 2.4e, there are water age concerns in the Hillside Street area under
Simulation Run #4 Conditions.
Fire Demand in High Pressure Zone (Restrictions Removed)
 As shown in Figure 2.4f, that there appears to be adequate fire flow protection throughout
Town in accordance with the AWWA and DEP standards.
Water Age (Restrictions Removed)
 As shown in Figure 2.4g indicates when the restrictions are removed that water age improves
to less than 10 days in the Hillside Street area.
2-8
Overall, BETA would recommend Simulation Run #4 Alternative as a viable option for the Town’s
high pressure zone. The potential concerns of available water for fire protection can be attributed to
the existing water flow restrictions found during the hydrant flow tests in the Harland/Hillside Streets
and Brush Hill Road areas of Town. BETA ran the model, see Figure 2.2f without the water flow
restrictions and there appears to be adequate fire protection throughout the high pressure zone.
Recommendations
Simulation Run #1 results showed that the decommissioning water storage tanks would leave the
Town vulnerable during a fire demand or a major disturbance in the water infrastructure. BETA does
not recommend Simulation Run #1 as a viable option.
Simulation Runs #2, #3 and #4 are viable options to meet the Town’s storage requirements and are
capable of meeting AWWA and ISO standards. The potential concerns of available water for fire
protection are attributed to existing water flow restrictions in the Harland/Hillside Streets and Brush
Hill Road areas of Town can be resolved by locating and removing the restrictions. Simulation Run
#2 consists of rehabilitating or replacing the existing water storage tanks and installing a pressure
reducing valve at the MWRA Meter #55. Simulation Run #3 consists of decommissioning the three
water storage tanks and constructing a new elevated 1.2 MG tank at an overflow elevation of 400
feet. This alternative may not be feasible because of costs, site constraints and discussions with
Friends of Blue Hills. It was very important that the existing “line-of-site” is not altered with any
tank improvements. The existing tanks for the most part are surrounded by trees and hidden from
view. Simulation Run #4 is similar to Simulation Run #2, except the Canton “loop” is valved off.
Based on the results of the hydraulic modeling, BETA recommends installing the PRV downstream
of MWRA Meter #55 and rehabilitating and or replacing the existing water storage tanks. In addition
to promoting tank fluctuation by reducing the incoming pressure, the PRV has an added benefit of
control. The PRV will be equipped with a “close” function so the high pressure zone can be supplied
off the tanks. The valve will utilize a normally open (i.e. fail open) solenoid valve on its control pilot
tubing. The solenoid valve will be energized through a supervisory control and data acquisition
(SCADA) system based on the water levels in the storage tanks. Controlling the PRV will promote
turnover within the tanks and still provide necessary emergency storage.
2.3 Seasonal Water Age Issues in Tanks
BETA has examined the seasonal aged water issues in the water storage tanks. Contributing factors to
aged water in a storage tank are insufficient turnover rate and poor mixing of the water. Insufficient
turnover rate within Milton’s storage tanks can be attributed to the existing 385 feet (median) HGL of
the water system at MWRA meter #55. The HGL at this MWRA meter typically fluctuates between
375 and 396 feet while the overflow elevation at the tanks is 375 feet. This situation does not allow
the water in the tanks to turn over or fluctuate due to the higher pressure from the MWRA water
system supply. BETA’s recommendation to resolve this problem is to install a PRV downstream of
MWRA meter #55 which will lower the HGL as well as provide control as described above. This
will promote the water levels in the tanks to fluctuate on a regular basis and resolve the aged water
issues within the tanks.
2-9
In addition to having the water levels fluctuate within the water tank(s), BETA recommends adding a
mixing system within the tank(s). Mixing systems look to reverse the effect that occurs when cool
dense water enters from the inlet pipe, which settles on the bottom of the tank while warmer more
buoyant water rises to the top of the tank. This temperature difference results in little natural mixing
occurring. There are several types of mixing systems available including a PAX Water Mixer that is
installed at the bottom of the tank and creates a vortex condition to mix the water. Another mixing
method is the Tideflex Mixing System. This is a series of pipes and valves at various angles that are
attached to the sidewall of the tank. The different angles of of discharge of the inlet valves mixes the
water within the tank. BETA recommends the Tideflex mixing system due to passive nature of
operation which uses no power for the mixing to function, and provides long term operation with
little recurring cost to operations, or maintenance.
2.4 Recent Changes in MWRA Storage Facilities and Impacts on Milton’s Storage Needs.
MWRA Water System Overview
MWRA's water originates from the Quabbin Reservoir, located approximately 65 miles west of
Boston, and the Wachusett Reservoir, located approximately 35 miles west of Boston. According to
MWRA, the Quabbin Reservoir alone has sufficient capacity to satisfy four years of demand of its
users. Both reservoirs are filled naturally. Rain and snow fall within the Quabbin, Ware River and
Wachusett watershed and flow via streams into the reservoirs. This water comes into contact with
soil, rock, plants and other material as it follows its path. This process helps to clean the water, and it
can also dissolve and carry very small amounts of material into the reservoir. Watershed protection
and management are the foundations of good water quality. Approximately 75% of the Quabbin,
Ware River and Wachusett watersheds are DCR-owned and protected open space or regulated by the
Watershed Protection Act.
MWRA Water System Improvements
MWRA has made several improvements, described below, to its water treatment, storage and
distribution systems that impact the quality and reliability of the water supply to the Town of Milton.
Water for most MWRA communities, including the Town of Milton, is treated at the John J. Carroll
Water Treatment Plant at Walnut Hill in Marlborough. Water from the Quabbin and Wachusett
reservoirs enters the plant through the Cosgrove or Wachusett Aqueduct. The water is treated with
ozone for disinfection, sodium bisulfite for ozone removal, sodium hydrofluorosilicic for dental
health, sodium carbonate and carbon dioxide for corrosion control, and aqueous ammonia for
chloramine residual. To comply with the Environmental Protection Agency's Long Term 2 Enhanced
Surface Water Treatment Rule, MWRA must add an additional disinfectant at the Carroll Water
Treatment Plant. Under the new rule, all unfiltered water systems must have two primary means of
disinfection. Based on the findings of pilot testing and other research the MWRA has concluded that
Ultraviolet (UV) light disinfection is the strongest and most cost-effective solution. Construction is
underway and due to be completed in spring 2014. The treated water then leaves the plant through
the MetroWest Water Supply Tunnel.
The MetroWest Water Supply Tunnel was constructed was placed online in 2003. This 17.6-mile
long, deep-rock tunnel enhances the security, capacity and reliability of MWRA’s entire water
transmission system. The MetroWest Water Supply Tunnel connects the John J. Carroll Water
2-10
Treatment Plant to the greater Boston area. This is the main transmission line, with the Hultman
Aqueduct serving as the back-up. Rehabilitation of the Hultman Aquaduct was completed in 2012.
The MetroWest Water Supply Tunnel feeds the Norumbega Covered Reservoir in Weston. The new
storage facility is fed water from the MetroWest Water Supply Tunnel through an onsite shaft rising
400'.
The 115-million gallon below ground Norumbega Covered Reservoir in Weston was placed online in
2004. This reinforced concrete reservoir is one of the largest in the country. Storing water in covered
tanks increases protection against potential contamination by airborne pathogens, wildlife and algae,
as well as restricting access from potential vandals, terrorists and saboteurs.
The MetroWest and Hultman Water Supply Tunnels combine to feed Boston and the surrounding
communities via several branches. MWRA’s Southern Spine is the major water distribution pipeline
for Milton, Quincy and the Southeast corner of Boston. Parts of the Southern Spine were built in the
early 1900s. Some sections are very old and unlined; they have been functioning at only 50% of their
original carrying capacity for years because of tuberculation (rust build-up and pocking) along the
pipeline walls. As part of their capital improvement plans, MWRA identified several improvements
to the Southern Spine:





Section 22 South (Completed 2005) - Rehabilitated 11,000 feet of 48-inch water main from
Copeland Street, Quincy to the Blue Hill Reservoir.
Section 22 South 1A (Completed 2005) – Rehabilitated 4,400 feet of water pipeline from
Copeland to Adams Street in Quincy
Section 107, Phase 1 (Completed 2009) – Installed 4,400 feet of new 48-inch pipeline from
East Milton Square to Furnace Brook Parkway at the Milton/Quincy line
Section 107, Phase 2 (Completed 2013) – Replaced 9,200 feet of 48-inch diameter water
mains from Dorchester Lower Mills to East Milton Square; cleaned and relined 4,000 feet of
water main.
Section 22 North (Scheduled to begin in 2019) – Clean and line 17,300 feet of water main.
The Southern Spine ultimately feeds the new Blue Hills Covered storage facility located on the east
side of the land occupied by the old Blue Hills Reservoir. The Blue Hills Reservoir was originally
constructed in the 1950’s but was removed from service in 1981 due to contamination from birds and
animals. The new storage facility was constructed in 2010 and consists of two 10-million gallon
underground storage tanks. The tanks were constructed to equalize water pressure during periods of
peak demand and work in conjunction with surface mains and the Chestnut Hill emergency pump
station to supply water to the Southern High (SH) service area in the event that the Dorchester Tunnel
requires repair. The Blue Hills storage tanks can also supply water to the Town of Milton’s low
pressure service zone if the northern portion of Section 22 is shut down because of a break or repairs.
Summary
MWRA’s SH water system has adequate storage and redundancy to reliably satisfy the water
demands of Milton’s low pressure zone. In particular, the construction of the Blue Hills covered
storage tanks and improvements to the Southern Spine ensure a dependable water service to the low
pressure zone.
2-11
MWRA’s Southern Extra High (SEH) water system does not have adequate storage or redundancy to
reliably satisfy the demands to the communities it provides service to if a major disruption within its
water infrastructure were to occur. The SEH water system serves the communities of Canton,
Dedham, Norwood, Stoughton, Westwood, as well as portions of Brookline, Milton, Newton and the
Roslindale and West Roxbury sections of Boston. According to reports published by MWRA in
2008, the average day water demand of the SEH communities is 11.6 million gallons per day (MGD)
and the maximum day demand is 24 MGD. There are two storage tanks that service the SEH service
area, Bellevue Tank 1 and Bellevue Tank 2. The total storage of these tanks is 6.2-millon gallons,
which is significantly lower than the average day demand. Further highlighting the deficiency is the
fact that the overflow elevation for the 2.5 million-gallon Bellevue Tank 1 is 25 feet lower than the
overflow elevation for the newer 3.7-million-gallon Bellevue Tank 2, limiting its useful capacity.
Addressing the SEH deficiencies has been assigned a Priority One under MWRA’s Water Master
Plan due to potential critical threat the public health that could result from a failure of this single
transmission system. The MWRA’s major goal is to provide system redundancy by constructing a
secondary means of supplying the service area to reduce vulnerabilities and enhance operational
flexibility. Many of the improvements that would improve redundancy and reliability to Milton’s
high pressure zone are in the study and planning phase. Ultimately, additional pumping and storage
are required.
Given the sate of the MWRA storage system, it is recommended that Milton proceed with providing
emergency storage tank facilities to serve its own high pressure zone, which is discussed in the
following parts of this report section.
2.5 Existing Water Storage Tank Evaluation
The Town engaged the services of Utility Services Group, Inc. (USG) to inspect the three water
storage tanks in the spring/summer of 2014. The purpose of the inspections was to determine the
condition of the coatings, structure and to evaluate the tank for compliance with current sanitary
guidelines, safety and security regulations and guidelines in accordance with AWWA, DEP, OSHA
and related state and federal agencies.
Below is a summary of the USGs findings and recommendations:
Blue Hills 600,000 Gallon Water Storage Tank
 The interior and exterior coating systems are in adequate condition. The existing coatings
should offer an additional 2-3 years of acceptable protection. The tank should be re-inspected
in approximately 3 years. (The inspection report includes analytical analyses of the coatings
that indicate the presence of chromium and lead)
 In order to maintain the structural integrity and sanitary condition of the tank as well as its
safety and security, USG recommended the following improvements be made for an estimated
cost of $68,000:
o Remove finial ball assembly on the roof and replace with a freeze resistant,
vacuum/pressure relief vent assembly.
2-12
o Secure existing roof ladder into a stationary position by welding vertical standoffs to
the side rails of the ladder and in turn to the roof. Once completed the wheel
assemblies as well as the retention band around the finial ball will be removed.
o Install an appropriately sized overflow assembly. The opening of the overflow pipe
will be equipped with a bolted flange and flapper assembly and a #4 mesh screen.
o Remove the existing screening between the shell rim angle and roof then fit and weld
¼” steel plate along the entire roof to shell perimeter opening to effectively seal this
area.
o Replace missing and/or loose bolts with new bolt assemblies to ensure continued
structural integrity of the roof.
o Replace the existing roof hatch with a new hatch assembly comprised of a raised neck,
hinged cover with downward laps and a locking assembly.
o Remove all remaining elastomeric sealer along the junction between the shell and
foundation, blowing out all loose debris, corrosion and water then reapply an
elastomeric urethane sealant along the entire perimeter of the shell to foundation
junction in such a manner so as to effectively seal this area until the exterior surfaces
are schedule for more comprehensive maintenance.

The following work should be completed under a future rehabilitation project:
o Complete removal and replacement of the interior and exterior coatings.
o Install a second roof hatch approximately 180º from the existing roof hatch.
o Current US Dept. of Homeland security guidelines state that all water tank sites be
fenced and “Tampering with this facility is a Federal Offense” signs be posted on and
around the site.
Chickatawbut #1 150,000 Gallon Water Storage Tank
 Due to the age and overall degradation of existing coatings it was recommended that all
exterior surfaces of the tank be rehabilitated as soon as feasible to do so.
 In order to maintain the structural integrity and sanitary condition of the tank as well as its
safety and security, USG recommended the following improvements be made for an estimated
cost of $328,000:
o Complete removal and replacement of the interior and exterior coatings. (The
inspection report includes analytical analyses of the coatings that indicate the presence
of chromium and lead).
o Remove finial ball assembly on the roof and replace with a freeze resistant,
vacuum/pressure relief vent assembly.
o Remove the existing screening between the shell rim angle and roof then fit and weld
¼” steel plate along the entire roof to shell perimeter opening in order to effectively
seal this area.
o Install an appropriately sized overflow assembly. The opening of the overflow pipe
will be equipped with a bolted flange and flapper assembly and a #4 mesh screen.
o Any pitting and/or metal loss representing a 35% or greater reduction in corresponding
plate thickness or significant sectional loss of a rivet head should be spot and/or seal
welded in such a manner so as to ensure 100% fusion with the parent metal and bring
areas flush with the original plate surfaces. At this time it is estimated that less than
(500) pits and (300) rivets will require welding repairs.
2-13
o The spider rod and center hub assembly located within the tank should be completely
removed and once the rods are removed from the shell all remaining holes should be
sealed by either welding steel plates over the holes or installing bolted connections
within the holes.
o Replace the existing shell manhole cover support davit assembly.
o Install a secondary shell manhole approximately 180º from the existing manhole
to ensure compliance with current OSHA Confined Space Regulations.
o Remove the existing elastomeric sealant along the perimeter junction between the base
plate and foundation. Then re-seal junction with a new elastomeric sealer once the
exterior surfaces have been blast cleaned and re-coated.

USG recommended the following work be considered as part of the rehabilitation project (not
included in the above price and scope of work):
o The existing roof hatch should be replaced with a new AWWA and Chapter 8
compliant roof hatch assembly with a raised neck and a hinged, downward
overlapping cover equipped with a locking hasp.
o All loose and/or missing outer roof perimeter retention bolts should be replaced with
new bolts in order to ensure all holes are sealed.
o The shell is equipped with an open access ladder with no fall prevention system or
anti-climbing device present. A flexible cable fall prevention system should be
installed and a safety sleeve and harness provided during climbing.
o In order to help prevent unauthorized access to the top of the tank consideration
should be given to installing a hinged, lockable ladder gate that encloses the bottom 8’
of the shell ladder.
o Current US Dept. of Homeland security guidelines state that all water tank sites be
fenced and “Tampering with this facility is a Federal Offense” signs be posted on and
around the site.
Chickatawbut #2 620,000 Gallon Water Storage Tank
 Due to the age and overall degradation of existing coatings it is recommended that all exterior
surfaces of the tank be rehabilitated within the next two years.
 In order to maintain the structural integrity and sanitary condition of the tank as well as its
safety and security, USG recommended the following improvements be made for an estimated
cost of $574,000:
o Complete removal and replacement of the interior and exterior coatings.
o Remove finial ball assembly on the roof and replace with a freeze resistant,
vacuum/pressure relief vent assembly.
o Remove the existing screening between the shell rim angle and roof then fit and weld
¼” steel plate along the entire roof to shell perimeter opening to effectively seal this
area.
o Install an appropriately sized overflow assembly. The opening of the overflow pipe
will be equipped with a bolted flange and flapper assembly and a #4 mesh screen.
o Any pitting and/or metal loss representing a 35% or greater reduction in corresponding
plate thickness or significant sectional loss of a rivet head will be spot and/or seal
welded in such a manner so as to ensure 100% fusion with the parent metal and bring
2-14
o
o
o
o

areas flush with the original plate surfaces. At this time it is estimated that less than
(500) pits and (300) rivets will require welding repairs.
The spider rod and center hub assembly located within the tank should be completely
removed. Once the rods are removed from the shell all remaining holes should be
sealed by either welding steel plates over the holes or installing bolted connections
within the holes.
Replace the existing shell manhole cover support davit assembly.
Install a secondary shell manhole approximately 180º from the existing manhole
to ensure compliance with current OSHA Confined Space Regulations.
Remove the existing elastomeric sealant along the perimeter junction between the base
plate and foundation. Seal the junction with a new elastomeric sealer once the exterior
surfaces have been blast cleaned and re-coated.
USG recommended the following work be considered as part of the rehabilitation project (not
included in the above price and scope of work):
o The existing roof hatch should be replaced with a new AWWA and Chapter 8
compliant roof hatch assembly with a raised neck and a hinged, downward
overlapping cover equipped with a locking hasp.
o All loose and/or missing outer roof perimeter retention bolts should be replaced with
new bolts in order to ensure all holes are sealed.
o The shell is equipped with an open access ladder with no fall prevention system or
anti-climbing device present. A flexible cable fall prevention system should be
installed and a safety sleeve and harness should be provided.
o In order to help prevent unauthorized access to the top of the tank consideration
should be given to installing a hinged, lockable ladder gate that encloses the bottom 8’
of the shell ladder.
o Current US Dept. of Homeland security guidelines state that all water tank sites be
fenced and “Tampering with this facility is a Federal Offense” signs be posted on and
around the site.
Due to the costs associated with rehabilitating tanks that are 60-90 years old we recommend that
replacement be evaluated. Refer to Section 2.7.
2.6 Recommend Improvements to Telemetry for Tank Monitoring
There is currently no functioning instrumentation for the water storage tanks. According to the Town,
the Chickatawbut storage tanks initially had functioning chart recorders that would log tank level via
a dedicated copper line leased from the phone company. This system proved unreliable and has not
been utilized for many years. The Blue Hills Water Storage tank has never had instrumentation.
Town personnel must physically visit each of the tanks to determine the water level within the tanks.
Water storage tanks, under normal function, experience water level fluctuation on a regular basis.
Proper operation of water tanks necessitate continuous monitoring and logging of levels in order to
document and trend the fluctuations in order to determine proper water turnover within the tanks and
ensure that minimum water elevations are maintained. A new supervisory control and data
acquisition (SCADA) system should be implemented to monitor the storage tanks and future pressure
2-15
reducing valve. The SCADA system will provide the Town operations personnel “real time” tank
level and pressure reducing valve status (Open or Closed). The system can also provide alarm
notification to alert operations personnel of potential water supply issues (i.e. tank low level).
Data measured at the remote locations through level and/or pressure sensors at the tanks and at limit
switch at the pressure reducing valve is transmitted to a “head end” computer system, which can be
located at Department of Public Works. At that location, the data is displayed, stored and
disseminated and alarm notifications are generated. SCADA systems are available that utilize
wireless transmission and do not rely on the antiquated leased copper lines. Several technologies are
available that include unlicensed radio, licensed radio, and cellular.



Unlicensed Radio – Transmit data on the 900MHz frequency band. The radio must have a
power output of less than 1 watt. These systems typically require higher antennas (Water
tanks work well) and repeaters due to the restricted transmission power.
Licensed Radio – Transmit data on the 220MHz frequency band recently opened up by the
FCC solely for municipal SCADA systems. These systems require antennas, though typically
not as high as the unlicensed radio.
Cellular – Transmits data via third party cellular transmission towers. These systems have
significantly lower capital costs but require monthly maintenance fees.
As part of the SCADA system preliminary design, a “Radio Path Analysis” should be completed to
assess the feasibility and capital costs associated with implementing the radio systems.
2.7 Water Storage Tank Alternative Analysis and Recommended Improvements
An evaluation that compares the costs of tank rehabilitation to the cost of replacement was
completed. The installation of an elevated water storage tank was not conducted because of high
costs, site constraints and discussions with Friends of Blue Hills. It was very important that the
existing “line-of-site” is not altered with any tank improvements. The existing tanks for the most part
are surrounded by trees and hidden from view.
Tank replacement would require demolition of the existing tanks and construction of new tanks of
similar height. New tanks would be constructed at the existing sites, located on Massachusetts
Department of Conservation and Recreation (DCR) property. Each site is limited in area and access.
In addition, we assumed that no additional impact to DCR property would be permitted.
Bolted Glass Fused Steel (BGFS) Tank and Concrete Tank technologies are currently being
evaluated. Budgetary cost information for concrete tanks was also considered. Due to the existing
site constraints, the concrete panel walls, normally cast onsite and raised into position, will need to
be cast at an offsite location. We anticipate the offsite casting of the wall panels will result in higher
capital costs for the concrete tank alternative. The following life cycle cost analysis was conducted
utilizing budgetary information for BGFS tank construction.
The BGFS tank technology has been utilized for water storage tanks for over thirty years and consists
of bolting together and erecting factory manufactured and coated steel panels. The area required for
construction is generally limited to the tank foundation. The bottom tank ring is cast into the
2-16
foundation and subsequent rings are then assembled and hydraulically raised. The factory-applied
silica glass coating forms a hard, inert barrier for both the interior and exterior tank surfaces to guard
against weather and corrosion. Glass fused to steel is impermeable to liquids and vapors. The coating
doesn’t need painting for the life of the Tank. According to the manufacturer, the factory coating is
designed to last in excess of 80-years. According to AWWA D103 “Factory-Coated Bolted Carbon
Steel Tanks for Water Storage”: “Tanks with factory applied coatings and bolted construction have a
long life expectancy. Regular inspection and repair of damaged or deteriorated areas may be the
determining factors in the length of tank life”. Maintenance involves regular inspection for damage
by vandalism (thrown rocks, bullets, etc.). Damaged to the coating must be patched within one year
to prevent corrosion of the steel plates resulting in excess glass coating failure. The patching process
involves applying a factory supplied compound to the damaged area.
Budgetary capital costs have been developed for alternatives for water storage tank rehabilitation and
replacement. A life cycle cost analysis (LCCA) was conducted to factor in not only the up front, or
capital cost of the alternative, but also costs associated with estimated future improvements as well as
the future cost of replacement. Incorporating the LCCA to calculate the Net Present Worth of the
infrastructure is necessary to properly compare the actual costs of the alternatives.
The following alternatives for each tank location were evaluated:
Blue Hill Water Storage Tank Alternatives
 Alternative #1 – Demolish and replace the existing riveted steel tank with a BGFS tank of
identical capacity (600,000 gallons).
 Alternative #2 – Complete the partial rehabilitation identified in USG’s inspection report.
Based on USG’s report, we assume complete resurfacing/rehabilitation will be required in 5
years. Demolition and replacement of the existing riveted steel tank with a BGFS Tank of
identical capacity will occur in 25 years. A salvage value is applied at year 50 based on a 25
year old BSGF tank.
 Alternative #3 – Complete the partial rehabilitation identified in USG’s inspection report.
Based on USG’s report, we assume complete resurfacing/rehabilitation will be required in 5
years. The tank will require resurfacing again at years 25 and 45.
Chickatawbut Water Storage Tanks Alternatives
 Alternative #1 – Demolish and replace the two existing riveted steel tanks with a single BGFS
tank of identical combined capacity (770,000 gallons).
 Alternative #2 – For each tank, complete rehabilitation/resurfacing identified in USGs
inspection report. Demolition and replacement of the existing steel tanks with a single BGFS
Tank will occur in 25 years. A salvage value is applied at year 50 based on a 25 year old
tank.
 Alternative #3 – For each tank, complete the rehabilitation identified in USG’s inspection
report. Based on USG’s report, we assume complete resurfacing/rehabilitation will be
required in 5 years, and again at years 25 and 45.
The following assumptions were made for the analysis:
 Capital costs for both rehabilitation and replacement include budgetary estimates for mixing
systems, perimeter fencing, site work, SCADA equipment and level instruments.
2-17







The LCCA is based on a Real Discount Rate (i) of 1.9%, based on the White House Circular
A-94, Appendix C (revised December 2013). This published discount rate assumes the rate of
return outpaces the rate of inflation.
The LCCA was conducted for a 50 year timeframe.
The lifespan of a new BGFS tank is assumed to be 50 years. The manufacturer estimates the
actual life to be in excess of 80 years, as long as potential damage to the coating is addressed
within a year of occurrence.
The salvage value of a new BGFS tank depreciates linearly over the lifespan of the tank. At
year 50 the tank is worth 0$.
The lifespan of a rehabilitated tank is assumed to be 20 years, at which resurfacing or
replacement would occur. There is no salvage value for a rehabilitated tank.
Annual operations and maintenance costs is assumed to be similar for all tanks and was
therefore neglected.
There is potential for lead and/or chromium contamination within the soils around the existing
water storage tanks. The evaluation of the soil is pending DCR permitting. Water storage
tank work is exempt from notification at 310 CMR 40.0317(8). However, management and
disposal of excess contaminate soil is possible and therefore anticipated. Tank replacement
will require foundation removal and replacement due to current structural code requirements.
Budgetary cost estimates presented in Tables 2.3 and 2.4 include a $100,000 placeholder for
hazardous soil management/disposal.
Cost information is presented on Tables 2.3 and 2.4. The summarized life cycle cost analysis is
presented on Table 2.5.
2-18
Table 2.3
Blue Hills Water Storage Tank Alternatives
Opinion of Probable Cost
October 2014
Unit
Meas. Quantity Unit Price
Description
Replace with New Bolted Steel Tank
Demolition
Rock Removal
New 600,000 gallon Tank
Interior Mixing System
Hazardous Materials Management
Piping/Valves
Perimeter Fence
Site Work
SCADA Telemetry w/ Solar
Level Instrument
Mobilization/Demobilization
Contingency (20%)
LS
CY
LS
LS
ALLOW
EA
LF
LS
LS
LS
LS
TOTAL
PRESENT WORTH (P/F, i%, 25)
SALVAGE VALUE (@25 YRS OF AGE) (P/F, i%, 50)
SALVAGE VALUE (50 YRS OF AGE) (P/F, i%, 50)
Rehabilitate
Rehabilitation Identified in USG Inspection Report
Interior Mixing System
Perimeter Fence
SCADA Telemetry w/ Solar
Level Instrument
Mobilization/Demobilization
Contingency (20%)
TOTAL
Future Resurfacing
Rehabilitation Identified in USG Inspection Report
Mobilization/Demobilization
Contingency (20%)
TOTAL
PRESENT WORTH (P/F, i%, 5)
PRESENT WORTH (P/F, i%, 25)
PRESENT WORTH (P/F, i%, 45)
2-19
Estimate
1
500
1
1
1
1
300
1
1
1
1
$20,000
$200
$525,000
$30,000
$100,000
$60,000
$50
$10,000
$25,000
$5,000
$50,000
$20,000
$100,000
$525,000
$30,000
$100,000
$60,000
$15,000
$10,000
$25,000
$5,000
$50,000
$188,000
$1,128,000
$704,619
-$220,075
$0
LS
LS
LF
LS
LS
LS
1
1
300
1
1
1
$68,000
$50,000
$50
$25,000
$5,000
$10,000
$68,000
$50,000
$15,000
$25,000
$5,000
$10,000
$34,600
$207,600
LS
LS
1
1
$542,000
$30,000
$542,000
$30,000
$114,400
$686,400
$624,750
$428,768
$294,265
0.6247
0.3902
0.3902
0.9102
0.6247
0.4287
Table 2.4
Chickatawbut Water Storage Tanks Alternatives
Opinion of Probable Cost
October 2014
Unit
Meas. Quantity Unit Price
Description
Replace with New Bolted Steel Tank
Demolition
Rock Removal
Hazardous Materials Management
New 770,000 Gallon Tank
Interior Mixing Systems
Piping/Valves
Perimeter Fence
Site Work
SCADA Telemetry w/ Solar
Level Instrument
Mobilization/Demobilization
Contingency (20%)
LS
CY
ALLOW
LS
LS
EA
LF
LS
LS
LS
LS
SUBTOTAL
PRESENT WORTH (P/F, i%, 25)
SALVAGE VALUE (@25 YRS OF AGE) (P/F, i%, 50)
SALVAGE VALUE (@50 YRS OF AGE) (P/F, i%, 50)
Rehabilitate
Rehabilitation Identified in USG Inspection Report
Interior Mixing Systems
Perimeter Fence
Interior Mixing Systems
SCADA Telemetry w/ Solar
Level Instrument
Mobilization/Demobilization
Contingency (20%)
SUBTOTAL
PRESENT WORTH REHAB ONLY (P/F, i%, 25)
PRESENT WORTH REHAB ONLY (P/F, i%, 45)
2-20
1
300
1
1
1
1
500
1
2
2
1
$30,000
$200
$100,000
$600,000
$30,000
$30,000
$50
$10,000
$25,000
$5,000
$50,000
$30,000
$60,000
$100,000
$600,000
$30,000
$30,000
$25,000
$10,000
$50,000
$10,000
$50,000
$199,000
$1,194,000
$745,847
-$232,951
$0
1
2
500
2
2
2
1
$902,000
$50,000
$50
$50,000
$25,000
$5,000
$60,000
$902,000
$100,000
$25,000
$100,000
$50,000
$10,000
$60,000
$249,400
$1,496,400
$563,446
$386,695
0.6247
0.3902
0.3902
LS
LS
LF
LS
LS
LS
LS
0.6247
0.4287
Estimate
Table 2.5
Water Storage Tank Future Replacement
50-Year Present Worth Analysis Summary
October 2014
Resurfacing
(5 Years)
Resurfacing or
Replacement
(25 Years)
Resurfacing
(45 Years)
Salvage Value
(50 Years)
1,128,000
207,600
207,600
$
$
$
$
$
$
704,619
428,768
$
$
$
294,265
$
$
$
$ 1,128,000
(220,075) $ 1,316,895
$ 1,555,384
1,194,000
1,496,400
1,496,400
$
$
$
$
$
$
745,847
563,446
$
$
$
386,695
$
$
$
$ 1,194,000
(232,951) $ 2,009,296
$ 2,446,540
Capital Cost
Blue Hills Water Storage Tank
Alternative 1 $
Alternative 2 $
Alternative 3 $
Chick atawbut Water Storage Tank s
Alternative 1 $
Alternative 2 $
Alternative 3 $
624,750
624,750
-
Total Net
Present
Worth
Summary
The LCCA indicates that tank replacement is more cost effective on a total net present worth basis.
The total present worth for the Blue Hills Water Storage Tank is estimated to be $1.1M for
replacement, $1.3M for rehabilitation and replacement at 25 years, and $1.6M for rehabilitation and
continued resurfacing. The total present worth for the Chickatawbut Water Storage Tanks is
estimated to be $1.2M for replacement, $2.0M for rehabilitation and replacement at 25 years, and
$2.4M for rehabilitation and continued resurfacing. The analysis also shows the initial capital costs
are significantly lower for replacing the two Chickatawbut tanks with a single BGFS tank.
2-21