HomeMy WebLinkAbout0. HPR DAM Installation and OM. rev 9.30.25 (1) (1)_Redacted CLARITY
RESOURCES GROUP
Oxygenation&Aeration Specialists
Harvey's Place Reservoir Diffuser Air Mixing (DAM)
Installation and Operation & Maintenance
PREPARED FOR: Mark Seelos (South Tahoe Public Utility District)
PREPARED BY: Paul Gantzer(Clarity Resources Group)
DATE: September 30, 2025
Summary:
The following document is presented to Mark Seelos of the South Tahoe Public Utility District
(STPUD) regarding installation and operation & maintenance (O&M) of the diffuse air mixing system
(DAM) installed during the weeks of July 21 — 25, 2025 in Harvey's Place Reservoir. The DAM system
consisted of a direct injection compressed air system with a geochemical augmentation line to add
aluminum chlorohydrate (ACH) or other phosphorus binding equivalent.
• Completely mix the entire water column to promote oxygen distribution to the bottom
waters to prevent the formation of anoxic conditions because of organic decomposition
from accumulated organic sediment along the bottom.
• Geochemical augmentation header that parallels the DAM for distribution of aluminum
chlorohydrate (ACH)or equivalent phosphorous binding agent to the water column.
206.999.1878/1405 Winslow Lane,Madison,WI 53711 PGantzer@gmaii.com/www.clarityrg.corn
HARVEY'S PLACE RESERVOIR DIFFUSER AIR MIXING SYSTEM INSTALLATION AND OPERATIONS&MAINTENANCE
Table of Contents
Background ...............................................................................................................3
DirectGas Sparging................................................................................................3
Geochemica) Augmentation..................................................................................4
SystemInstallation ....................................................................................................5
Diffuser Testing/Operation..................................................................................6
Diffuser Air Mixing System Operation&Maintenance................................................7
Inspections.............................................................................................................7
Supply Pipe and Porous Hose Inspection...............................................................7
Raising the Diffuser Systems..................................................................................9
Deploying the Line Diffuser Oxygenation System................................................11
Diffused Air Mixing Operation Guidelines.................................................................12
Phosphorus Binding Dosing/Operation Guidelines....................................................12
HARVEY PLACE RESERVOIR DIFFUSED AIR MIXING SYSTEM INSTALLATION AND OPERATIONS&MAINTENANCE
Background
Harvey's Place Reservoir is managed by the South Tahoe Public Utility District (STPUD). The
reservoir is approximately 163 acres with a maximum depth of approximately 54 feet. The reservoir
is used for storage of secondary treated wastewater. Ensuring that the reservoir has suitable water
quality is a management concern.
Management goals have been identified as follows:
• Eliminate summer stratification by maintaining a fully mixed water column,
• Use a linear diffused air mixing system suspended above the bottom to deliver gaseous
air to the deepest part of the reservoir,
• Create bubble plumes that mix the entire water column in less than 4 days, and
• Provide a mechanism to add phosphorus binding agent to control and decrease total
phosphorus (TP) loading.
The following operations and maintenance manual provides operation guidelines to operate
the diffused air mixing system installed during the weeks of July August 21—24, 2025.
Direct Gas Sparging
The diffused air mixing (DAM) system installed in Harvey's Place Reservoir is a line diffuser
(Figure 1) that injects compressed air directly to the deepest section of the reservoir. This strategy
was proposed because it is the most effective method to thoroughly mix the entire reservoir volume
in less than four days.
A plume model was used to determine key parameters to optimize water column circulation
using bubble-plume diffuser technology(Figure 2). The key parameters were water circulation,depth
of maximum plume rise (DMPR), and depth of equal density (ED). Water circulation was used to
ensure the entire volume of the reservoir is adequately circulated once every four days. The DMPR
was used to identify that the plume reaches the water surface to promote full water column mixing.
The ED was used to determine the depth the plume water will fall back to when it falls away from the
plume after reaching the DMPR.
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HAR EY PLACE RESERVUR DIFFUSED AIR WING SYSTEM INSTALLATION AND OPERATIONS&MAINTENANCE
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Figure 3;Example of a diffuser air mixing(DAM)systems showing a line-diffuser
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Figure 2:Example of a plume model prediction showing the plume (orange lines)reaching the
surface
Geochemical Augmentation
Geochemicai augmentation is a method to add a binding compound to permanently
inactivate nutrients such as phosphorus,the key component for cyanobacteria growth. Geochemical
augmentation dosing was not part of the scope of this project.
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HARVEY PLACE RESERVOIR DIFFUSED AIR MIXING SYSTEM INSTALLATION AND OPERATIONS&MAINTENANCE
System Installation
The diffused air mixing system installation was conducted during the week of July 21 - 24,
2025. All piping was installed above grade between the building and the water edge (Figure 3) and
sleeved in 6-inch HDPR SDR 17 pipe. Piping below the water edge were mounted to concrete anchors.
Images of the snorkel assembly showing the 10-ft section of 3" bend back are shown in figure 4.
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Figure 3: Images showing the piping.facing bulling(left)and water(right).
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Figure 4: Images of the snorkel assembly during initial installation.
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HARVEY PLACE RESERVOIR DIFFUSED AIR MIXING SYSTEM INSTALLATION AND OPERATIONS&MAINTENANCE
Diffuser Air Mixing System Operation & Maintenance
The following section covers operation and maintenance of the DAM system. This section
explains the basics to recover and deploy the system; however,this procedure is not recommended
unless under the explicit supervision of Clarity or equivalent line installer. Any damage from raising
or re-deploying the system without proper supervision as recommended will not be covered under
the warranty.
Maintenance is to be performed on an as-needed basis. Typically,the DAM system does
not require maintenance unless there are ten or more observed boils or there are 100 or more feet
of dead spots (no visible bubbles) at 55 SCFM, maximum design air flow rate.
The porous hose used for diffused air mixing systems typically have a 10-to-15-year useful
life cycle. Unless damage(boils) or numerous dead spots are observed a common guideline is to
budget$2-$3 per linear foot per year to replace the porous hose after the designated useful
lifecycle.
Inspections
Prior to start-up, a general walk-down of the air supply system should be made to verify
operational readiness. After the initial start-up,the bubble pattern of the underwater portion of the
system can be inspected from shore pending calm conditions on the water,otherwise by boat.
Supply Pipe and Porous Hose Inspection
Inspection for underwater leaks should be conducted while the line diffuser is in operation
near the design flow rate of 55 SCFM. The small bubbles from the diffuser will be visible on the
water surface during calm periods. The bubble pattern on the surface is slight and hard to see
under some conditions; however, a damaged hose or leaking connection will create a readily visible
bubble pattern or boil. Examples of a normal bubble pattern and surface boils resulting from a
broken porous hose are shown in Figure 6.
The bubble plumes can be viewed from the air, a boat, or the shore and should be uniform
along the length of the diffuser with slight variations of the intensity of observed bubbles. The
bubble pattern may be less continuous at air flow rate less than the design flow rate.
HARVEY PLACE RESERVOIR DIFFUSED AIR MIXING SYSTEM INSTALLATION AND OPERATIONS&MAINTENANCE
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Figure 6:Example of typical bubble pattern during normal operation at design flow rate(left)and a
typical boil from a broken porous hose section(right).
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HARVEY PLACE RESERVOIR DIFFUSED AIR MIXING SYSTEM INSTALLATION AND OPERATIONS&MAINTENANCE
Raising the Diffuser Systems
Although the DAM system is very easy to float to the surface, it is highly recommended that
this is not performed unless under the explicit supervision of Paul Gantzer or equivalent line installer.
The problem does not lie in raising the system to the surface, but in the re-deployment to (1) make
sure it is placed back in the proper position. Any damage from raising or re-deploying the system
without proper supervision as recommended will not be covered under the warranty. If the system
is brought to the surface care should be taken to secure it in place to prevent it from being moved out
of position during even the slightest wind events. The following outlines the basics to float the system.
First ensure the cap on the buoyancy line located under the green valve box cover is installed
(Figure 6). The cap corresponds to the location to "flood"the system when deployed. A compressed
air line will be needed to be connected between the buoyancy isolation valve and the air receiving
tank inside the building.
To float the oxygenation system,connect a compressed air hose to the blue handled isolation
valve on the air receiving tank (Buoyancy from Air Receiver) and then to the connection on the
buoyancy(Buoyancy to Reservoir),which is the red valve assembly in the middle of pipes exiting the
building (Figure 7). Open the "Buoyancy from Air Receiver" valve and then slowly throttle the
"Buoyancy to the Reservoir"" valve open to pressurize the line, which will void the buoyancy line of
water,floating the system. Remember to exercise care when throttling the valve to the reservour to
not over pressurize the buoyancy line per the guidelines in the "Harvey's Place Reservoir Diffused Air
Mixing components and Drawings." It is suggested to have someone monitor the progress of the
system coming to the surface to throttle the air going to the line. As much as the system can come
up quickly, too fast may result in undo stress on the line. Once the system is on the surface, close
both buoyancy valves, and secure the line in the lake as previously noted.
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HARVEY PLACE RESERVOIR DIFFUSED AIR MIXING SYSTEM INSTALLATION AND OPERATIONS&MAINTENANCE
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Figure 7: Image of the buoyancy connection to be capped before applying compressed air to "float"
the system.
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Figure 8: Images showing the connection between the diffuser buoyancy isolation valve(Buoyancy
to Reservoir)and the air connection on the back of thereceiving tank with the compressed air fitting
(Buoyancy from Air Receiver).
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HARVEY PLACE RESERVOIR DIFFUSED AIR MIXING SYSTEM INSTALLATION AND OPERATIONS&MAINTENANCE
Deploying the Line Diffuser Oxygenation System
As stated previously it is highly recommended floating the system is not performed unless
under the explicit supervision of Paul Gantzer or equivalent line installer. The problem lies in the re-
deployment to make sure it is placed back in the proper position. The following outlines the basics to
deploy the DAM system.
Before starting, make sure there are adequate staff to support the deployment. This should
include at least five people, three boats for holding the diffuser in place, a pump operator, and
someone moving or holding the supply section in place. Once the staff is in place, make sure the
buoyancy isolation valve (Figure 8) in the building are closed. A 2" trash pump can be used as the
water source to flood the buoyancy line when it is time to sink it. The trash pump should be connected
to a bypass assembly(Figure 8)to allow the pump to be running but not having water being discharged
to the buoyancy pipe. This will ensure that the pump assembly is ready when the DAM system is in
place.
Position the DAM system over their respective location(s) and hold in place with down ropes
on both ends and in the middle. A down rope is a rope that goes from an anchor point on shore or
boat around the piping and back to shore or the boat. This is so once the system is deployed the ropes
can be retrieved sans diving. The supply going out to the active section will need to be managed as
the system is deployed. Once the system is in position begin pumping water into the buoyancy pipe
by opening the valve to the buoyancy line on the"bypass assembly"and closing the bypass(Figure 9).
Monitor the deployment rate and location, adjusting flow as necessary to place the system in the
proper place. Once the system is deployed, continue pumping water through the buoyancy line for
another 15 — 20 minutes to ensure all air is expelled from the buoyancy line. This is particularly
important if, during the deployment,the pumping rate is throttled or stopped.
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Figure 9: Image showing the isolation valve on the buoyancy line to be closed before operating the
pump to flood the buoyancy line and sink the diffuser.
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HAR EY PLACE RESERVUR DIFFUSED AIR WING SYSTEM INSTALLATION AND OPERATIONS&MAINTENANCE
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Figure 10 Image of the buoyancy connection to deploy the diffuser.. Image shoves how to connect
the "'bypass assembly"to buoyancy connection ection using oar trash pump to deploy the diffuser..
Diffused Air Mixing Operation Guidelines
Operation of the DAM system was engineered to maintain the entire water column
homogenized with respect to temperature. In doing this, it allows oxygen from the atmosphere to be
added to the water column via surficial oxygen transfer,thus circulated throughout the reservoir.
Phosphorus Binding Dosing/Operation Guidelines
Operation of the chemical feed system to add an additional phosphorus binding went, such
as ACH',or equivalent should parallel the DAM system operation, however,not be continuous. Dosing
and geochemical augmentation operation are not part of the current scope.
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