SR - - PURCHASE OF PAX MIXERS FOR RESERVOIR 2 AND RESERVOIR 101. SUBJECT
Purchase and installation of the PAX mixers from D &H Water Systems for Reservoir 2 and
Reservoir 10.
2. SUMMARY
Authorize the purchase and installation of the PAX mixers from D &H Water Systems to address
water stratification in Reservoir 2 and Reservoir 10.
3. RECOMMENDED ACTION
Approve the purchase and installation of the PAX mixers from D &H Water Systems in an
amount not to exceed $98,374.
4. FISCAL IMPACT
Funds are available to cover the cost of the purchases as follows:
600.8011.51401.00000 Repairs to Buildings and Fixed Equipment $ 32,671
600.8011.51232.00000 Electricity for Water Pumps $392,686
5. STRATEGIC PLAN GOAL(S)
1 Provide for a safe community:
b. Provide and maintain infrastructure necessary to ensure the safety of the public.
2. Be a fiscally healthy community:
d. Effectively manage and develop City assets.
3. Provide outstanding public service:
b. Provide facilities and services to meet customer expectations.
6. GENERAL PLAN IMPLEMENTATION
Infrastructure Element Goal 6.0: Ensure water, sewer, and storm drain systems that meet the
needs of residents and businesses.
Policy 1.1: Provide sufficient levels of water, sewer, and storm drain service throughout the
community.
Economic Development Element Goal 6.0: Provide sufficient infrastructure to support
anticipated economic development and growth.
Policy 6.1: Provide public improvements to support commercial, industrial and institutional
uses.
7. DISCUSSION and BACKGROUND
Over the last few years minor, yet persistent, concerns have emerged regarding decreased water
turnover and lack of water mixing in some of the City's water reservoirs. Operationally, the
water levels in the system's reservoirs are kept as high as possible for operational readiness and
emergency preparedness. In maintaining higher storage levels, turnover and mixing of water is
minimized and can develop stratification of the water in the reservoirs. This situation can and
usually does have a negative effect on overall water quality in the system. Continual water
quality testing has indicated that while the water quality remains at a safe quality level, overall
quality can decline in some reservoirs due to the lack of turnover of the water and the
stratification in the tanks. Decreased water quality is more prevalent during the hotter summer
months as the water stratification can intensify with warmer temperatures.
To counter this trend, the Water Division continues with its program of installing tank mixers in
selected reservoirs where stratification is more likely to occur. As of today, six out of the
fourteen reservoirs in the water system have some type of mixing device installed. Reservoir 2
and Reservoir 10 are identified as the next two reservoirs in need of the mixing devices.
Through research and from discussions with neighboring water agencies with the same concerns,
three different mixing systems and manufactures (PAX, Tank Shark, and Solar Bee) were studied
to determine the most advantageous application for the City of Orange's needs. These mixing
systems utilize different technology and physical methodology to move water around in the
reservoir. Solar Bee mixing system uses a submersible electric motor to draw water in from the
side and discharging it to the top, creating a bubble like effect. The Tank Shark mixing system
uses an external motor to pressurize the water through specially designed nozzles creating a
spraying effect. The PAX mixing system uses an internal motor with stainless steel impellers to
create a swirling effect.
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In 2010, the Tank Shark mixing system was installed at Reservoir 8 with acceptable, but not
optimal results. Reservoir 8, with a capacity of three million gallons, achieved complete mixing
within a 48 hour period. In 2012, the PAX mixing system was installed at Reservoir 5 with
excellent results. Reservoir 5, with a capacity of five million gallons, was able to achieve
complete mixing within a 24 hour period. Four reservoirs in the water system have an in -house
circulation system installed for cost saving reasons; however, they are not achieving optimal
results. Of the three systems studied, the PAX mixer with SCADA control was deemed the most
effective system due to its mechanical feasibility, power consumption, short mixing time, ease of
set up and maintenance, warranty, and manufacturer support.
PAX is a proprietary product of D &H Water Systems, who is the sole manufacturer and
distributor, staff negotiated and achieved a price reduction from D &H Water Systems. Staff is
proposing the purchase and installation of two additional PAX mixers at Reservoir 2 and
Reservoir 10 in an amount not to exceed $98,374.
8. ATTACHMENTS
Contract Agreement
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