U.S. Department of the Interior Bureau of Reclamation Technical Service Center Denver, Colorado March 2012

Facility Vulnerability Assessment for Senator Wash Pumping Plant

Invasive Quagga and Zebra Mussels U.S. Bureau of Reclamation Lower Colorado Region Yuma Area Office

U.S. Department of the Interior Bureau of Reclamation Technical Service Center Denver, Colorado March 2012

Facility Vulnerability Assessment for Senator Wash Pumping Plant

Invasive Quagga and Zebra Mussels

Prepared for Reclamation’s Yuma Area Office

Mission Statements

The mission of the Department of the Interior is to protect and provide access

to our Nation's natural and cultural heritage and honor our trust responsibilities

to Indian Tribes and our commitments to island communities.

___________________________

The mission of the Bureau of Reclamation is to manage, develop, and protect

water and related resources in an environmentally and economically sound

manner in the interest of the American public.

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Disclaimer

The information provided in this report is believed to be appropriate and accurate for the specific

purposes described herein, but users bear all responsibility for exercising sound engineering judgment in

its application, especially to situations different from those reported. References to commercial products

do not imply endorsement by the Bureau of Reclamation and may not be used for advertising or

promotional purposes.

Cover Photo: View of Senator Wash Dam.

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Contents

Executive Summary .............................................................................................. 1 Findings............................................................................................................. 1 Recommendations ............................................................................................. 1

Introduction ........................................................................................................... 3 Purpose and Objectives ..................................................................................... 3 Brief Project Description .................................................................................. 3

Background on Potential Invasive Mussel Impacts .......................................... 3

Assessment Findings ............................................................................................. 6 Susceptibility to Infestation .............................................................................. 6

Water Quality .............................................................................................. 6 Recreation ................................................................................................... 7

Vulnerability of Features at Senator Wash Dam .............................................. 8

Spillway ...................................................................................................... 8 Intake Structures ......................................................................................... 8

Large Gates and Valves ............................................................................ 10 Large Diameter Piping .............................................................................. 11 Air Vents ................................................................................................... 12

Well Water ................................................................................................ 14 Cooling Systems ....................................................................................... 14 Small Diameter Piping and Associated Valves ........................................ 15

Instrumentation ......................................................................................... 18

Drainage Systems...................................................................................... 20

Conclusions .......................................................................................................... 23

Recommendations ............................................................................................... 23 Monitoring and Detection ............................................................................... 23 Response Planning .......................................................................................... 24

Facility Protection Options ................................................................................ 24 Gate and Valves ........................................................................................ 24 Cooling and domestic water systems ........................................................ 24

Air Vents ................................................................................................... 24 Outlet works intake structure .................................................................... 24

Sump system(s) ......................................................................................... 25

Bypasses, piping systems, penstock and turbine drains ............................ 25

Small diameter piping ............................................................................... 25

Appendix A .......................................................................................................... 26 Facility Vulnerability Checklist ...................................................................... 26 System Walkthrough Checklist....................................................................... 30

Appendix B .......................................................................................................... 34 Management Options for Quagga & Zebra Mussel Infestations .................... 34 Actions to consider prior to detection of mussels: .......................................... 34 Actions to consider following detection of mussels: ...................................... 35

1

Executive Summary

The purpose of this assessment is to provide Reclamation management and project staff with

information regarding the vulnerability of facility features to invasive mussel impacts. This

report is not intended to be a risk assessment or prediction of the potential for a future mussel

impacts. Instead, it is intended to assist project management and staff in anticipating and

planning for impacts should a future infestation occur.

Findings

Systems at Senator Wash are relatively complex and, depending on levels of infestation, certain

key features that were assessed will be susceptible to mussel–related impacts requiring

considerably increased maintenance and/or retrofit for facilities protection to maintain

operability. In particular, the systems that appear to be most vulnerable include the intake

structures, sump pump systems, and small diameter piping containing raw water such as bypass

lines, and drain lines. Accelerated corrosion by mussel colonies on submerged metallic surfaces

with damaged or degraded coatings may also be expected. While it is currently uncertain, the

potential for mussel settlement in drainage systems (including structure under drains and drain

outlets with the potential for back flooding) should also be considered and closely monitored.

Quagga mussels have been sparsely found in the pumping plant and reservoir for several years,

and to date, their numbers have remained low. Potential factors mitigating mussel impacts that

were identified during the site visit included extended high seasonal water temperatures and

concomitantly low dissolved oxygen levels at the outlet works. The validity of these factors

remains to be verified. With this in mind, these initial recommendations and options for

facilities protection are provided to assist with preliminary planning and budgeting as a

precaution should the mussel infestation become problematic. It should be noted that various

options for facilities protection exist and selection of the best option will depend on a number of

considerations including operational flexibility, design requirements, project constraints, and

cost.

Recommendations

The following recommendations are provided for consideration:

Adult mussels have already been identified in Senator Wash Pumping Plant and Reservoir.

If not already done, it is important to a develop response plan to address further infestation as

soon as possible. This can include regional, basin-wide, or local project response plans. If

regional or basin-wide plans are developed, they should include details regarding

coordination of local (i.e., project specific) response actions. Management options have been

included in Appendix B along with links to other response plans and response planning

guidelines developed by the National Parks Service.

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A monthly monitoring program is also recommended to be established for (1) measuring

larval densities using plankton net sampling and (2) settlement rates using quantitative

methods by means of substrates along with routine inspection of underwater structures (e.g.,

outlet works intake structures). This post-introduction monitoring provides information on

the population development of the infestation and allows for a rough idea of if and when

certain facilities features will become impacted. Typically intake structures will be impacted

first followed by internal piping and related systems and equipment. Continued monitoring

can also be used to anticipate future changes in the mussel population, to refine maintenance

schedules or dynamics, and to possibly track ecological impacts attributable to mussels.

It is recommended that future water quality sampling and analyses be conducted at regular

intervals and include monthly (and continuous where possible), calcium, pH, temperature and

dissolved oxygen (DO) profiling in Senator Wash Reservoir to further ascertain

environmental conditions and the potential for mitigating factors.

Study of these environmental factors suspected of migrating mussel impacts is recommended

to determine why such a large disparity exists between these facilities (very light) and those

upstream at Parker Dam (very heavy). Understanding of these dynamics may explain and/or

help predict whether or not mussels may become problematic in the lower reaches.

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Introduction

Purpose and Objectives

The purpose of this assessment is to provide Reclamation management and project staff with

information regarding the vulnerability of facility features to invasive mussel impacts. This

report is not intended to be a risk assessment or prediction of the potential for a future mussel

infestation. Instead, it is intended to assist project management and staff in anticipating and

planning for impacts should a future infestation occur.

Brief Project Description

Senator Wash Dam which was completed in 1966 is located on the Colorado River 18 miles

north of Yuma, AZ and 2 miles upstream of Imperial Dam. The reservoir was created to manage

and improve regulation of Colorado River flows arriving at Imperial Dam. The facility provides

off-river storage of excess flows and is capable of operating in generating or pumping mode.

The dam is an earth-fill structure 93 feet high and 2,342 feet long with a total storage capacity of

13,863-acre feet.

The Senator Wash Pumping Plant is of the indoor type with a reinforced concrete substructure

and steel framed superstructure. Six (including one spare) vertical-shaft, single-suction,

centrifugal, Francis-type pump-turbines with fixed-vane diffuser-type casings are installed in the

plant. Each pump-turbine is directly connected to a vertical shaft, 360-revolution-per-minute,

synchronous motor-generator designed to operate either as a motor or as a generator. Although

originally conceived as a pumping-generating plant, it was designated as a pumping plant in

1977.

When operating as a pumping plant, each 1,750-horsepower pump is designed to operate from 31

feet of head to shut-off head and will deliver not less than 100 cubic feet per second at a total

head of 74 feet while operating at 360 revolutions per minute. Under normal operations, each

unit pumps about 200 cubic feet per second. Normal starting and stopping of the unit is

controlled from the remote control panel at Imperial Dam, which includes all the electrical

control equipment (switching, alarm, and indicating) required for remote operation of the

pumping plant.

Background on Potential Invasive Mussel Impacts

Quagga and zebra mussels (adult lengths average about 1 inch) are unique in that they can firmly

attach to the underwater surfaces using byssal threads. They begin spawning by emitting eggs

and sperm into the water column when water temperature reaches around 10-12ºC (50-54ºF). On

a population-wide basis, egg production occurs in astronomical levels (on the order of 30,000

eggs/female/reproductive cycle). Depending on temperature and environmental suitability,

multiple reproductive cycles may occur in a single year. Fertilized eggs develop into freely

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swimming larvae or veligers (ranging in sizes from 60 to 250 micron) which may be transported

by water currents for many miles. Within a few weeks and if water conditions are suitable, the

veligers will settle (i.e., attach to hard surfaces) and continue growth to adulthood.

Successful settlement is mediated by a number of environmental conditions inherent in the

natural water system. These include calcium, alkalinity and hardness, pH, nutrients, dissolved

oxygen, temperature and conductivity. It should be noted that some of these parameters are

indirect measures of others. For example, alkalinity and hardness are presumptive for calcium

and magnesium. Most important of these seems to be dissolved calcium. It is generally accepted

that highly successful mussel colonization occurs when calcium levels exceed about 24 mg/L.

Successful establishment is more in question when calcium values fall below 10 mg/L. With the

possible exception of nutrients (implied indicators of food supply) in high mountain lakes, the

remainder of listed parameters seems fairly well represented as having adequate levels in

Western waters where data are available. Table 1 provides water quality parameters suitability

criteria for invasive mussels. It should be noted that this information was obtained from various

sources involving zebra mussel specific studies in Europe and Eastern portions of North America

and may not be entirely applicable to water bodies in the Western U.S. Never the less, it

provides an approximate indication of suitability requirements.

Table 1. Presumptive infestation-level suitability criteria for invasive mussels.

Parameter

Low

Probability

of Survival

Infestation Levels

Low Moderate High

Calcium (mg/L) <10 (QM)

<8 (ZM)

10-12 (QM)

8-15 (ZM)

12-30 (QM)

15-30 (ZM) >30

Alkalinity/Total Hardness

(mg CaCO3/L)

<35 (QM)

<30 (ZM)

35-42 (QM)

30-55 (ZM)

42-100 (QM)

55-100 (ZM) >100

pH <7.0

>9.5

7.0-7.8

9.0-9.5

7.8-8.2

8.8-9.0 8.2-8.8

Dissolved Oxygen (mg/L) <3 5-7 7-8 >8

Dissolved Oxygen (% saturation) <25% 25-50% 50-75% >75%

Mean Summer Temperature (oF)

<64

>86

64-68

83-86

68-72

77-83 72-75

Conductivity (μS/cm) <30 30-60 60-110 >110

Salinity (g/L) >10 8-10 5-8 <5

Secchi depth (m) <0.1

>8

0.1-0.2

2.5-8 0.2-0.4 0.4-2.5

Chlorophyll a (μg/L) <2.0

>25

2.0-2.5

20-25 8-20 2.5-8

Total phosphorous (μg/L) <5

>50

5-10

35-50 10-25 25-35

Source: Renata Claudi, RNT Consulting, Inc.

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It should be noted that mean summer temperature does not imply temperature thresholds. The

low-temperature threshold for mussel growth is around 46 ºF. This would imply that mussels

could colonize systems with raw water temperatures greater than about 46 ºF, with a low

probability of survival for temperatures below this threshold. On the upper end, temperatures

greater than about 83-86 ºF for extended periods are not generally expected to support mussel

survival. However, observations in Lakes Mead, Mojave, and Havasu offer reason to suspect

acclimation to higher temperatures by mussel populations in the Colorado River upstream.

Currently an explanation is unknown as to why mussels are not problematic in the Imperial Dam

vicinity at levels seen upstream as near as Parker Dam. Environmental and operational

conditions affecting dissolved oxygen and temperature (and possibly others) of the structures

themselves may also influence veliger settlement and subsequent colonization. Within a facility,

veliger settlement is prevented or greatly reduced in pipes where water velocities continuously

exceed 6 feet per second (ft/s). However, intermittent operations or slower velocities may lead

to successful settlement. Once attached, mussels can sustain that attachment even when flow

velocities exceed 6 ft/s. Ideal areas for mussel colonization are those areas with continuous

flows of moderate velocities (<6 ft/s) and ample supplies of food and oxygen. Piped systems

which are seldom utilized or idle for prolonged periods and which have depleted oxygen are not

generally supportive of successful colonization. A major exception is a situation where leaking

valves allow constant flows and replenishment to such seldom used systems.

Invasive mussels pose serious threats to Reclamation’s infrastructure and operations. Of major

importance to Reclamation facilities is the ability of mussels to rapidly colonize hard surfaces at

densities of tens of thousands per square meter. This heavy accumulation can lead to costly

operations and maintenance problems. Flow restriction is the foremost concern because mussels

can clog water intake structures, such as trashracks, pipes and screens, thereby threatening water

delivery to critical systems at hydropower plants and reducing pumping and conveyance

capacities of water distribution systems.

Major structural impacts caused by quagga and zebra mussels at Reclamation facilities fall into

the following categories:

Flow restriction or blockage – Light infestations can roughen water conveyance surfaces,

reducing the ability to deliver water in desired quantities and in a timely manner. If

accumulation is allowed to progress to extremes, pipes as large as 1-ft in diameter have been

blocked. Accumulations of shells from dead mussels are also problematic in screens, filters

and small diameter pipes, fittings, and valves.

Mechanical damage – Mussel shells can cause abrasive damage to soft materials such as

seals and over time, finely machined surfaces. Removal of attached mussels can cause

damage to surfaces by lifting of coatings.

Chemical degradation of structures – The accumulation of mussel fecal material, digestive

by-products and sediments next to uncoated or damaged coatings on metallic (ferrous)

substrates under large colonies is highly supportive of bacterial colonies which accelerate

corrosion processes.

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Assessment Findings

Susceptibility to Infestation

Water Quality Of importance for estimating potential infestation levels are those parameters necessary for

establishment and growth of mussel populations discussed above (namely calcium, pH, dissolved

oxygen, temperature, and nutrients). Data were not available for Senator Wash Reservoir but

Table 1 shows data from nearby Imperial Dam.

Table 2: Water quality data and suitability for zebra/quagga and mussel infestation at

Senator Wash Dam

Water Quality Parameter Level Infestation Potential

pH 8.34 High

Calcium 82 mg/L High

Total Dissolved Solids 670 mg/L High

Conductivity 1070 µS/cm High

Salinity 683 mg/L High

Asiatic clamshells were observed in the seepage stream just below Senator Wash Dam and in

great abundance in the desilting basins at Imperial Dam. While Asiatic clams have lower

dissolved oxygen and higher temperature tolerances than quaggas, it appears that the water

quality here is borderline to supporting populations of zebra or quagga mussels. Zebra and

quagga mussels have also been observed in limited numbers in the Senator Wash Reservoir but

have yet to experience the explosive population growth that has occurred in nearby locations

such as Parker Dam to the north.

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Figure 1: Asiatic clamshells found in seepage stream below Senator Wash Reservior

One question surrounding Senator Wash Pumping Plant and other facilities nearby is whether or

not mussels will eventually become established as seen upstream. One hypothesis is that the

high summer temperatures and possibly associated low dissolved oxygen levels are sufficiently

effective mitigating factors in mussel reproduction. While sparse observations of mussels on

structures have been observed, it is currently unknown whether a temperature tolerant

subpopulation will begin to grow and thrive over time. Additional study is recommended to

evaluate the biological factors mitigating population in this portion of the Colorado River.

Recreation Senator Wash Reservoir has some recreational boat traffic, which is considered a primary vector

for the spread of invasive mussels. If not already done, it is recommended that signs displaying

information about invasive mussels be placed in conspicuous locations to increase public

awareness and compliance with relevant guidelines. The management responsibility for boat

ramps and land-based recreation is shared among federal (mainly Bureau of Land Management),

state, and Native American agencies. While signs have been provided in the past, no boat

launching sites were visited at the time of the assessment to confirm their presence.

8

Figure 2: Recreational boat traffic on Squaw Lake, a Colorado River backwater area

below Senator Wash

Vulnerability of Features at Senator Wash Dam

While mussels have been observed in sparse numbers in several areas of the facility for several

years, there are apparently some mitigating factors that have limited (and may continue to limit)

mussel populations and hence related impacts. If a more tolerant, successfully adapted

population develops and explosive growth ensues, the following vulnerabilities would be

expected.

Spillway The spillway is at the southeast corner of Senator Wash Reservoir between Senator Wash Dam

and the Squaw Lake Dike. The spillway consists of an inlet channel and uncontrolled concrete

ogee crest structure with bridge overpass. The spillway chute itself is not likely to experience

significant impacts related to mussel fouling owing primarily to the low frequency of operation

such that it remains relatively dry for extended periods of time. The under spillway drain system

could hypothetically be subjected to impacts as well (including clogging) depending on size of

seepage passages from the reservoir. Another more likely pathway for mussel infestation into

this system is through back flooding.

Intake Structures The intake structures (river outlet works and service water) at Senator Wash Dam are some the

most vulnerable and least accessible features of the outlet works (i.e., submerged). The pumping

plant intake structure was partially submerged at the time of this site visit. The trashracks have

been constructed with ½-inch-thick steel bars and 3-inch spacing. There is a manually operated

9

trash rack cleaning system present as well which operates periodically. Trash racks are

removable and can be cleaned manually.

Figure 3: Trash rack at Pumping plant intake.

Figure 4: Manually operated trash rack cleaning system.

10

Figure 5: Rake on the trash rack cleaning system

There is also a trash rake on the pump outlets (outlet works intake structure) but it was entirely

submerged and not accessible for inspection during the site visit. These types of intake

structures are susceptible to nearly complete occlusion from mussel attachment on and between

the grating apertures depending on operating conditions and levels of infestation.

Large Gates and Valves The large gates and valves at Senator Wash include the following:

Hydraulically actuated butterfly valve on penstock (54-inch)

High pressure slide on the discharge tubes

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Figure 6: Hydraulically operated butterfly valve on penstock/discharge piping.

In general, mussel attachment along slide gate guides, sealing surfaces, and seats has the

potential to degrade seal performance and could lead to the inability to fully seat the gate or

valve in certain cases. Although these impacts are not expected to render the gates and valves

inoperable, they will likely increase future maintenance requirements to ensure smooth operation

and adequate seal performance.

Impacts may also be realized on temporarily installed bulkheads and stoplogs. Mussel

colonization of the guides may interfere with or cause increased friction during installation or

removal.

Large Diameter Piping The large diameter piping at Senator Wash Dam consists of 6 individual penstocks/discharge

tubes and 10-foot diameter outlet works conduit. Water velocities in individual pipes are likely

too high, i.e., >6 ft/s, for mussel attachment to occur during operation. The expected velocity of

the conduit will depend on the number of units running but can range from 1.3 ft/s up to 18.1 ft/s

which could allow for colonization to occur during operation depending on the number of units

running. Theoretically, colonization could occur in the individual penstocks when the units are

not in operation but assuming the outages are relatively brief and infrequent, colonization would

likely be limited. It is unclear whether the mussels would then become dislodged during

subsequent high flows.

The effects of fouling in piping include head losses, a nominally reduced discharge capacity, and

the potential for coating damage to occur during mechanical removal depending on the cleaning

method used. Corrosion rates may also be increased due to the presence of large mussel

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populations. This is primarily a concern for areas where the coating integrity has already been

compromised.

Air Vents In general, air vents are of concern since mussel accumulation may have the potential to reduce

vent capacities, particularly for cases when vent diameters are less than 8 inches and intermittent

operation occurs in the system for which air venting is required. Air vents typically serve

multiple purposes including air release during filling or prevention of negative pressures

downstream of the gate to ensure smooth operation of the gate and/or to prevent downstream

pipe collapse during an unbalanced emergency closure. In some cases, venting is also required

to prevent cavitation damage. For emergency gates, the latter is less a concern since unbalanced

emergency gate operation is infrequent, but smooth operation of the gate is still important during

an emergency closure. Air vents were observed on the penstocks just downstream of the butterfly

valves. In addition, an 8-inch air vent piping is provided on the downstream side of the high

pressure gate to release air from or admit air to the outlet pipe

Figure 7: Air vent on pump-generator penstocks.

13

Figure 8: 8-inch air vent piping on outlet works conduit

14

Well Water Two wells were installed around 2007. The wells now provide water for the following systems

which would not be susceptible to mussel related impacts:

domestic (service) water

thrust bearing cooling water

Figure 9: Well water high-pressure system

Cooling Systems The motors are self-cooled with air and each unit has upper and lower guide bearings which are

cooled and lubricated with oil. There is also a thrust bearing which is water-cooled. The thrust

bearing cooling water originally operated from raw water tapped from the penstock but has since

been switched over to well water. However, the old piping is still intact probably to allow for

operational flexibility or as an auxiliary supply

The turbine stuffing box which was previously cooled by raw water has reportedly been replaced

with a mechanical seal.

15

Figure 10: Domestic/cooling water tie-in to raw water tap from penstock.

Figure 11: Mechanical seal that replaced the turbine stuffing box which was previously

cooled by raw water

Small Diameter Piping and Associated Valves During the assessment at Senator Wash Dam, the following small diameter piping systems were

observed:

Cooling (raw) water for pump/generating units (no longer in use)

12-inch outlet works conduit filling line (high pressure slide gate bypass piping and valve)

16

Penstock drain lines

Turbine casing drains

Turbine casing water drain lines

Draft tube drain with 4-in. plug valve

Penstock air injection port piping

The systems mentioned above which convey or contain raw (untreated) water would in general

be subject to impacts from live mussel colonization and/or shell debris. Because of the small

diameter, this piping is highly susceptible to complete blockage. The potential for complete

occlusion increases with decreasing pipe diameter. Frequency of usage can have a mitigating

effect on live mussel settlement. For example, a piping system that is rarely used is unlikely to

have adequate nutrient or dissolved oxygen levels. However these systems may still be subject

to clogging from shell debris. Valves, filters, and other flow disrupters may serve as a choke

point for clogging to initiate. In addition, colonization may prevent complete sealing in valves

on small piping systems.

Figure 12: Turbine casing drains

17

Figure 13: Water drain piping

Figure 14: Penstock drains

18

Figure 15: Air injection port

Instrumentation Reservoir levels are measured in the intake tower via bubbler type system which measures

pressure. In cases where the piping is frequently flushed, mussel fouling and associated clogging

for the entire system will be possible. This has the potential to reduce sensitivity of the reservoir

level measurement system or render it inoperable. Other instrumentation observed during the

assessment included pressure transducers on each penstock in the old powerhouse as well as a

river flow gauge downstream of the facility. Other susceptible instrumentation includes pressure

gages on the turbines and cooling water piping.

Figure 16: Instrumentation cluster on Unit 1.

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In general, any instrumentation including stilling wells or pressure transducers that are directly

exposed to raw water will be susceptible to inoperability or increased measurement errors due to

mussel fouling or shell debris accumulation. All flow measurement devices are susceptible to

errors due to mussel fouling. This includes stilling wells, flumes, level sensors and acoustic flow

meters. The stilling well connections have the potential to become completely occluded by

attached mussels or dead mussel shell debris and surface roughening on flow measurement

flumes due to mussel attachment can alter calibration and degrade accuracy.

Figure 17: Reservoir level instrumentation line

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Figure 18: Instrumentation line on turbine which may be susceptible to clogging from

mussel debris.

Figure 19: Instrumentation port on turbine could be susceptible to mussel impacts.

Drainage Systems The following systems at Senator Wash provide drainage of raw water and may be susceptible to

mussel infestation.

Spillway under-drains

Toe drains

21

Power plant sump and pump systems

Draft tube drainage systems (4-inch piping and plug valve)

Although it is currently uncertain (i.e., hypothetical), the drainage systems for Senator Wash

Dam (including appurtenant structure drains), may also be impacted by mussels depending on

the design of the systems and size of seepage passages. Typically, flow passages to structural

drain systems are extremely small, but if they are sufficient in size to transport larval mussels (>

60 µm) and water chemistry is suitable for survival, there is a possibility for blockage of portions

of the drain system. Toe drains may also be susceptible, particularly in cases where back

flooding is a possibility.

Figure 20: Toe Drain at Senator Wash Dam.

The drainage system sumps have the potential to be contaminated during routine draining of

penstocks or typical equipment leakage. Impacts may range from live mussel attachment and

dead mussel shell debris accumulation in the sumps to mussel fouling of pump intakes, float

switches, and eductor valves. Sump pumps shaft seal water lines may also become clogged and

pumps are generally expected to require increased maintenance to ensure adequate discharge

capacity and seal performance. Colonization of seals in the check valves could potentially

render the valves ineffective resulting in undesirable back flow.

In addition, the sumps also contain an eductor system which utilizes high-pressure water to

create a negative pressure that draws water out of the sumps. Colonization of the piping is

possible as well as clogging of the venture nozzle with shell debris. The system should be

checked periodically and may require occasional cleaning to ensure optimum functionality.

22

Figure 21: Sump pumps

Figure 22: Sumps with gate valves and check valves

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Conclusions

Invasive mussels (quaggas) are already prevalent to the area, but they have not grown to the

proportions seen further upstream. There may be unexplained mitigating reasons for why they

have not become problematic. Should that happen, several critical impacts can be expected at

Senator Wash depending on levels reached by the mussel infestation. The most vulnerable

systems are the intakes, small diameter piping that contain raw water, and air release valves.

Fortunately, the cooling water systems for the thrust bearing have already been converted to well

water. Sump pump systems may also experience mussel related impacts and require increased

maintenance and cleaning.

Initial recommendations and options for facilities protection are provided below to assist with

preliminary planning and/or budgeting should a problematic mussel infestation develop in

Senator Wash Reservoir. It should be noted that various options for facilities protection exist

and selection of the best option will depend on a number of considerations including operational

flexibility, design requirements, project constraints, and cost.

Recommendations

Monitoring and Detection

One question surrounding Senator Wash Pumping Plant and other facilities nearby is whether or

not mussels will become established at problematic levels. So far, mussels have been observed

at Senator Wash but a heavy infestation has yet to occur. In contrast, heavy mussel infestation

has already occurred at other Reclamation facilities such as Parker Dam and Davis Dam which

are both upstream from Senator Wash on the Colorado River. One hypothesis is that the high

summer temperatures possibly associated with low dissolved oxygen are sufficiently effective

mitigating factors in mussel reproduction and/or survival. It is recommended to further study the

biological factors further do determine why such a large disparity exists between these facilities

that are in are relatively close geographic proximity to one another.

It is recommended that the current monitoring plan, via plankton net and water quality sampling,

be continued at Senator Wash Reservoir as well as quantitative monitoring for settlement using

either substrates or routine inspection of underwater structures (e.g., outlet works intake

structures). This monitoring provides information on the development of the infestation and

allows a rough idea of when certain facilities features will become impacted. Typically, intake

structures are impacted first followed by internal piping and related systems and equipment.

Continued monitoring can also be used to refine maintenance schedules or to anticipate future

changes in population dynamics as well as ecological impacts attributable to mussels.

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Response Planning

If not already in place, it is recommended that this report be used in conjunction with the

development of a Response Plan for the possible development of a problematic invasive mussel

infestation. The Appendix provides some management options for response planning, including

links to various response planning guidelines and online examples.

Facility Protection Options

Again, if the level of infestation increases, the following facility protection options would be

worth considering:

Gate and Valves Options to prevent mussel fouling on gate guides and seals for the slide gates are limited to

frequent exercising of the gates. However, doing so could increase wear and subsequent

maintenance requirements to ensure smooth operation and adequate seal performance. Frequent

exercising of valves may also be required to ensure smooth operation and complete sealing.

Cooling and domestic water systems It is recommended to clearly label pipes throughout the facility and develop protocols in order to

prevent cross contamination from occurring between raw and treated (well water) sources.

Air Vents Periodic inspection (and cleaning if necessary) of all air vents will likely be required at more

frequent intervals. While there are few options available (aside from redesign, perhaps using

foul release coatings or copper materials of construction) for ensuring that air vents do not

become occluded due to mussel fouling, routine inspections will provide information on the

extent of the problem and if significant blockage is occurring, retrofit of vent systems should be

considered.

Outlet works intake structure The intake structures trashracks at Senator Wash Dam are critical choke points from the

standpoint of mussel fouling and problematic due to their relative inaccessibility (i.e.,

submerged). However, various options exist including inspection and manual cleaning of the

trashracks either by removing the trashracks or in-place manual cleaning at regularly scheduled

intervals. However, depending on the level of infestation and depth of structures, frequent

cleaning may become expensive. The trashracks on the pumping plant intake have a trash rack

cleaning system which could be retrofitted with a cleaning brush for more effective mussel

removal if colonization ever becomes a problem.

Another option involves the use of foul-release coatings as a proactive strategy to reduce the

maintenance frequency and facilitate cleaning. Various coatings for metallic structures are

currently being tested at Reclamation’s Parker Dam which is heavily infested with quagga

mussels and results to date are promising.

25

Other treatment options to kill mussels (adult and larval) could also be considered. Conventional

treatment using chlorine is not recommended for the outlet works due to the large volumetric

flow rates and associated environmental impacts, but may be worth considering if the intake

structure can be isolated at regular intervals to minimize the amount of treated water. Research

is currently underway to develop environmentally preferred products to kill mussels or prevent

settlement. Results to date are promising and may offer an alternative to conventional chemical

oxidants for treatment on and in a variety of hydraulic structures and water distribution systems.

Sump system(s) A mussel infestation at Senator Wash Reservoir may require more frequent cleanout of

accessible portions of the sump wells, pump intakes, discharge piping and eductor systems to

remove live mussels and/or shell debris. In addition, the float switch should be inspected

periodically to ensure it is functioning correctly. Foul release coatings can help mitigate the

settlement of live mussels on the pump intake, float switch, and piping.

Bypasses, piping systems, penstock and turbine drains All fixed source raw water lines with diameters less than 10 inches may require periodic flushing

and cleaning of these systems at more frequent intervals or order to avoid a significant buildup of

live mussels or shell debris. Otherwise, regular shutdowns of intake systems for manual cleanout

may be required. In most cases, this requires installation of bulkheads followed by dewatering of

the intakes for manual cleanout using high pressure water jetting or other similar technology.

Redesign of the systems, perhaps using foul release coatings or copper materials of construction

may also be considered.

Small diameter piping Where possible or practical, it is recommended that any critical system be retrofitted to utilize an

alternate (treated) water source.

Table 1: Susceptibility of small diameter piping

Equipment Current vulnerability to Mussel

Infestation

Recommended Action if

Infestation occurs

Lines for thrust bearing

cooling water

Systems currently use well water

with little vulnerability; however,

old piping is still intact.

Label pipes and take

precaution to ensure that cross

contamination does not occur

Penstock filling lines (slide

gate bypass piping)

Impacts are possible to likely.

These lines could collect shell

debris and experience blockage.

Frequent manual cleaning may

be required.

Drain systems

Impacts are possible to likely.

These lines could collect shell

debris and experience blockage.

Frequent manual cleaning may

be required.

Penstock air injection

piping

Impacts are possible to likely.

These lines could collect shell

debris and experience blockage.

Frequent manual cleaning may

be required.

26

Appendix A

Facility Vulnerability Checklist

Project Name: Senator Wash Dam, USBR, Yuma Area Office

Prepared by: Tordonato/Nibling Date of Preparation: 2/7/2012

2. Preparation (Step 1) Item No.

Item Status 1

Comments /

Plan to Resolve

1 Planning

1.1 Has the project scope – including definition and

objectives – been prepared? Y

1.2 Has the Project Scope Statement been approved? Y

1.3 Is there a Project Plan against which to measure

progress? Y

1.4 Does the Project Plan address the following areas: Y

1.4.1 Project Scope and Deliverables Y

1.4.2 Project Schedule Y

1.4.3 Project Budget Y

1.4.4 Project Organization and Resources Y

1.5 Were key project stakeholders brought into the Project

Plan? Y

1.6 Were potential customers involved early in the

planning process? Y

1.7 If there are vendors, have they signed off on the

Project Plan? N/A

1.8 If there is an independent oversight contractor, have

they signed off on the Project Plan? N/A

1.9 Is the Project Sponsor function identified and defined?

1.10 Are there alternate persons if key members of the

project are not available or become reassigned?

1.11 Other organization items (please list):

2 Tracking & Monitoring

2.1 Are the various types of reports, their contents,

frequency, and audience defined and communicated to

the Project Team?

Y

2.2 Are the input requirements from Project Team

members clearly documented and communicated? Y

3 Meetings and Input Data

3.1 Have the various meetings, purpose, context,

frequency, and participants been defined and

communicated?

Y

3.2 Have the drawings and documents from the facility

sites been requested? Y

1 Enter one of the following: C (Complete), P (Partially Complete), Y (Yes), N (No); NA (Not Applicable)

27

2. Preparation (Step 1) Item No.

Item Status 1

Comments /

Plan to Resolve

4 Project Assumptions and Constraints

4.1 Are there any key assumptions upon which the

assessment is based and have these assumptions been

documented?

N

4.2 Does the Project have any Constraints such as: N

4.2.1 Facility shutdown schedules?

4.2.2 Facility access limitations and ventilation requirements?

4.2.3 Monitoring issues such as availability of reports from sampling plates set out in previous seasons?

4.2.4 Any training needed for key project staff?

4.2.5 Any pre-project procurement needed for portable field equipment?

3. In-house Review and Preparation for Field Visits (Step 2) Item No.

Item Status 2

Comments /

Plan to Resolve

1 Reviewing

1.1 Have drawings and documents from the facility site

been reviewed? Y

1.2 Have questions arising from the document review been

communicated to and discussed with the site experts? Y

1.3 Did the document review identify any pre-site-visit

activities that should be done such as video inspections

requiring divers or shutdown of equipment that needs to be scheduled?

Y

1.4 Are all pre-site-visit tasks needed to be done at site

completed? Y

1.5 Has the deliverables list been updated based on the

information from the site documents? Y

1.6 Have all system checklist sheets been prepared? Y

2 Enter one of the following: C (Complete), P (Partially Complete), Y (Yes), N (No); NA (Not Applicable)

28

4. Site Visits, Follow-up and Reporting (Step 3)

The general approach should be to follow the path of the water through the site facility. The water

path will become more complicated each time the water branches into a specific system. Follow

each system in turn and you will have covered the complete flow of water through the facility.

Item No.

Item Status Comments /

Plan to Resolve

1 Field Walkthroughs

1.1 Has the pre-meeting at site been completed? Y Presentation on mussels was given

1.2 Were all necessary site staff available? Y

1.3 Have follow-up discussions with staff not available

during the site visit been scheduled and completed? N/A

1.4 Have all the system walkthrough checklists been

completed? N/A

1.5 Have all actions arising from the site meeting and

system walkthroughs been documented and

communicated to the person responsible for the action?

N/A

1.6 Has the draft project report been reviewed by all

contributors? N

1.7 Has the final report been approved for issue? N

1.10 Has the final report been distributed? N

5. Mussel Vulnerability Evaluation - Project Team Contact List

Project Name: Senator Wash Dam, USBR, Yuma Area Office

Some suggestions for the roles of the various team members and the skills or knowledge that would be helpful for each team member are contained

in Appendix A.

Name Title Location Office Phone & E-mail

Fred Nibling Biologist Reclamation, TSC – Environmental Applications & Research, Denver, CO

(303) 445-2202 fnibling@usbr.gov

Dave Tordonato Materials Engineer

Reclamation, TSC – Materials Engineering & Research Laboratory, Denver, CO

(303) 445-2394

dtordonato@usbr.gov

Frank Macaluso General Engineer Yuma Area Office 928-343-8302

Nick Heatwole Environmental Protection Specialist

Yuma Area Office 928-343-8111

29

6. Mussel Vulnerability Evaluation – Sample Facility Deliverables List

Facility Name: Senator Wash Dam, USBR, Yuma Area Office

The deliverables are internal document packages prepared for each system or major structure. Once all deliverables are completed, they are then used to prepare the overall assessment report which would be the only external deliverable. It will be helpful when preparing this list to refer to Appendix D for additional detail about typical systems and components at risk that should be considered.

Major Structure or System

Reference drawings Used Deliverables

.

Continue with systems or structures until all areas in contact with raw water are covered.

30

System Walkthrough Checklist

System or Structure Name:

Senator Wash Dam, USBR, Yuma Area Office

Prepared by: Tordonato Date of Preparation: 2/7/2012

1. Instructions for Using this Document Prepare one of these sheets for each system or major structure identified in the Deliverables list. For each Item No. below, complete all blank fields (see footnotes for Status and At Risk of Mussels columns).

For some of the components such as valves and strainers there may be several in one system. If more than one component needs to be considered add an extra sheet for that particular component group.

Refer to Appendix C for additional information and suggestions about various systems and components.

Add additional rows as required where you identify items that need to be considered and are not covered elsewhere in the list.

2. Walkthrough Checklist Item No.

Item Status 3

At Risk

(yes/no) Comments

1 General for Dams, Reservoirs, Aqueducts

1.1 Are there any membranes, control joints, permeable

construction media, drains, etc. that will let raw water pass?

Y There is seepage through dam

1.2 Are there any air vents? Y Y

1.3 Check if the spillway and appurtenances are always

wet or dry and record duration of dry period. Emergency spillway stays dry

1.4 How much does the water level (i.e. reservoir water

surface elevation) fluctuate? Minimal reservoir fluctuation +/- 1 ft at the

Pumping Plant Intake

Reservoir fluctuation may be up to 20 ft

1.5 Are all potential water seepage paths inspected on a

regular basis? Y Foundation seeps are present near the

pumping plant drains.

2 Water Intake Structures

2.1 Types of intake structures present (more than one may

be present):

2.1.1 Open Canal Direct into Facility (concrete) N

2.1.2 Open Canal Direct into Facility (other material-specify)

N

2.1.3 Forebay (specify lining material) Y Y

2.1.4 Tower (specify construction material) N

2.1.5 Submerged Tunnel or pipe intake (specify construction material)

Y Y

2.1.6 Penstock intakes (specify construction material)

Y Y Reinforced concrete transitioning to Steel

lined.

2.1.7 Fish Barriers N

2.2 Is the floor of any intake structures likely to be covered

with silt or sediment? Possibly

3 Enter one of the following: C (Complete), P (Partially Complete), A (Absent); Y (Yes), N (No); NA (Not Applicable)

31

2. Walkthrough Checklist Item No.

Item Status 3

At Risk

(yes/no) Comments

2.3 Are any structures duplicated to provide a back up? No

2.4 What is the flow velocity range in the structure? Y During operation:

10 ft Conduit: 108 CFS-1425 CFS (1.3 –

18.1 ft/s)

52-inch discharge piping: 108 – 242 CFS

(6.8 – 15.2 ft/s)

2.5 Is the structure accessible for inspection or

maintenance? Y Outage required, dive team required

2.6 Are there any shutdowns to provide easy access and

what is their frequency? Y

2.7 Are there scheduled maintenance cycles and what are

their frequencies? Y Every 6 years

3 Trash Racks, Grates, Screens

3.1 Record spacing, size and material of trash rack bars. Y Y 3” spacing on pumping plant intake side

Unknown spacing on outlet works side

3.2 Are trash racks fixed or easily removable for

maintenance? Y Removable on pumping plant side and at

the reservior

3.3 Is there a planned maintenance frequency for the trash

racks? If so what is interval? N Not a consistent operating interval

3.4 Is there a trash rake or other style of cleaning system? Y On pump intakes: manual operated Gantry

Trash Rake

3.5 Are the rake fingers sufficiently large to remove

mussels from sides of trash rack bars? N

3.6 Record location, material, size and grid spacing of any

small intake grates.

3.7 Are grates fixed or removable for easy maintenance?

3.8 Check if grates at bottom of pipes or channels get

covered with silt or sediment.

3.9 Record location, material, size and grid spacing of any

screens.

3.10 Are screens fixed or removable for easy maintenance?

4 Wells and Sumps

4.1 Location and material of constructions of wells. Y Sump wells on the pumping plant

4.2 Identify level fluctuations in pump wells.

4.3 Distance of pump suction from bottom of wells. Will

pump ingest shells that are transported along the floor

into the well?

Y The distance is known

4.4 Location and material of constructions of sumps. Y Steel piping on sump system

4.5 Is there a float or other instrumentation in sump that

could become covered with mussels? Y Y

4.6 Frequency of sump inspection by plant staff. Monthly inspections

5 Pumps and Turbines

5.1 Is pump motor or turbine generator water or air

cooled? Water cooled motors are at risk. Well water

5.2 Can mussel shells get into wear ring gaps? Y Y

5.3 Does pump have a mechanical seal? Y Well water

5.4 How is the seal flushed during start-up?

5.5 How is the seal flushed during normal running?

32

2. Walkthrough Checklist Item No.

Item Status 3

At Risk

(yes/no) Comments

5.6 Does the turbine or pump have a stuffing box? N Replaced

5.7 Is there a stuffing box lantern ring or other cavity for

cooling and flushing water?

5.8 How is the ring flushed during start-up?

5.9 How is the ring flushed during normal running?

5.10 Check if the motor bearings have water cooled

lubrication? Oil lubricated

5.11 Check if the pump has water cooled bearings? Yes

5.12 Can mussel shells get into the water lubricated bearing

passages? Yes, but not the bearing cooling water

5.13 Do seal or stuffing box cavities have a means of

monitoring or inspection? N/A

5.14 Can seals or stuffing box be cleaned without removing

motor?

6 Piping

6.1 Identify materials of construction for piping. Steel lined penstocks, Belzona

6.2 What is flow velocity range in piping?

6.3 How much time is velocity above 6 ft/sec? Pumps typically run 3-4 days at a time

6.4 How much time is velocity below 6 ft/sec? Plant idle 7-10 days at a time

6.5 Are there any offsets or changes in pipe diameter?

7 Instrument Tubing and Instruments

7.1 Identify any small diameter lines (2” diameter or less)

including material of construction such as:

7.1.1 Flow measurement taps N

7.1.2 Piezometer taps N

7.1.3 Pressure taps Y Various raw water

7.1.4 Sample lines N

7.1.5 Pressure balance lines Y Y

7.1.6 Other – Reservoir El. gage Y Y Bubbler, float well

8 Heat Exchangers

8.1 Identify material of construction of plenum. N/A

8.2 Identify material of construction of tubing. N/A

8.3 What is diameter of tubing? N/A

8.4 What is flow velocity range in tubing? N/A

9 Valves

9.1 Identify all normally open (NO) valves. Butterfly valves

9.2 Can NO valves fail to seal properly if valve seat or

valve face becomes mussel coated? Y Y

9.3 Identify all normally closed (NC) valves Drain valves

9.4 Can NC valves fail to open if valve face becomes

coated with mussels? Y Y Valve may become clogged with mussels

and/or debris

9.5 What is throat diameter of valve? Is it small enough to

become plugged by mussel shells?

10 Strainers and Filters

33

2. Walkthrough Checklist Item No.

Item Status 3

At Risk

(yes/no) Comments

10.1 Identify the style of strainer, material of construction of

strainer body and basket as well as the size of the

basket pores. Typical styles are:

10.1.1 Fixed In-line strainer Y Y Strainer on backup (raw water) cooling line

10.1.2 Duplex strainer N/A

10.1.3 Self-cleaning strainer N/A

10.1.4 Wye (Y) strainer N/A

10.1.5 Other type - specify N/A

10.2 Identify the style of filter, material of construction of

body and filter element, as well as the size of the filter

pores. Typical styles are:

N/A

10.2.1 Self-cleaning filter N/A

10.2.2 Replaceable cartridge filter N/A

10.2.3 Other type - specify N/A

34

Appendix B

Management Options for Quagga & Zebra Mussel Infestations

Concurrent with Prevention & Public Outreach/Education Actions

Most water bodies in the western United States are now at risk of infestation by invasive quagga and

zebra mussels. While the actions taken to prevent or respond to infestation must be tailored to each

specific location, the following activities represent options for consideration as part of any readiness

planning as well as options for dealing with mussels following detection. Information on preventing the

spread of invasive mussels can be found at the 100th Meridian Initiative website http://100thmeridian.org/

and http://protectyourwaters.net. Procedures have also been developed by Reclamation and are documented in Technical Memorandum

No. 86-68220-07-05 Inspection and Cleaning Manual for Equipment and Vehicles to Prevent the Spread

of Invasive Species which provides guidance for inspecting and cleaning vehicles and equipment to help

prevent the spread of invasive species during Reclamation activities. The manual can be found at

http://www.usbr.gov/mussels/prevention/docs/EquipmentInspectionandCleaningManual2010.pdf

Actions to consider prior to detection of mussels:

1. Develop Coordinated Response Plan(s) - This plan would detail policies, command and

authority structure, strategies, communications, roles and responsibilities, and response actions to be

implemented – Involves multiple federal, state, and local agencies and stakeholders. An example

Response Plan for the Columbia River Basin may be found at the 100th Meridian website

http://www.100thmeridian.org/ColumbiaRT.asp. The National Parks Service also has information and

guidelines for prevention and response planning that can be found at

http://www.nature.nps.gov/biology/Quagga/index.cfm.

2. Perform Infestation Risk Assessment(s) – This activity may be completed as standalone or as

part of the Coordinated Response Plan. The purpose is to identify which water bodies are most at-risk

of infestation within the geographic region of interest or management jurisdiction. The likelihood of

infestation is typically based upon recreational usage, nearest known infestation, and the extent to

which environmental conditions (including calcium, pH, dissolved oxygen, temperature, etc…) are

likely to support mussel establishment. This information can be used to prioritize facility vulnerability

assessments (below). A variety of examples for risk assessments are available on the web.

Information specific to environmental suitability based risk assessments is available at the U.S. Army

Corps of Engineers Zebra Mussel Information System (ZMIS) website

http://el.erdc.usace.army.mil/zebra/zmis/zmishelp.htm.

3. Perform Facility Vulnerability Assessment(s) – This activity may be completed as standalone

or following the infestation risk assessment(s) and consists of a detailed inventory of critical water

related infrastructure at a water body and how each component is likely to be affected by mussels

should infestation occur. The results can be used to prioritize facility protection needs and actions. A

facility vulnerability assessment template can be found at www.usbr.gov/mussels/.

35

4. Implement Monitoring Program(s) – Monitoring programs should be considered for high

priority water bodies where infestation is either most likely or would cause significant harm to water

systems or other key resources. Monitoring programs, designed to provide early detection of mussel

larvae (through water sampling and lab analysis), potentially provide 2-5 years of lead time for

planning and implementing protective actions before the infestation impairs operations via adult

settlement on hydraulic structures or within critical systems. Additional information on monitoring

can be found at the U.S. Army Corps of Engineers Zebra Mussel Information System (ZMIS) website

http://el.erdc.usace.army.mil/zebra/zmis/zmishelp.htm.

Actions to consider following detection of mussels:

1. Execute Coordinated Response Plan – Involves notification, information exchange, and

implementation of containment and control actions (i.e., components of the response plan).

2. Increase Monitoring – Transition from monitoring for detection to monitoring with increased

frequency to confirm detection, identify or locate the presence of adults, and track infestation levels.

This activity may also include regular facilities inspections to determine when facilities are being

impacted by adult colonization. This information can guide facilities protection actions and assists in

anticipating ecological impacts for future mitigation planning.

3. Identify and Implement Appropriate Facilities Protection Measures – Identify which

actions or technologies are best suited for maintaining water operations and reducing O&M costs or

other expenses. Various conventional technologies have been used with reasonable success. The

table below provides some conventional as well as experimental options, each of which has

advantages and disadvantages. It should be noted that there are a number of commercial treatment

products that have not been listed, but may be applicable in various situations.

Table 1 – Control and facilities protection options for various applications

Technology Example Applications

Filtration to prevent mussel entry to piped

systems – self-cleaning 40-80 micron filters may

be adequate depending on exclusion requirements.

Exclusion avoids the need for treating infested

systems. †

Low volume systems - Facilities service

water, unit or transformer cooling water,

HVAC, pumped systems, and delivery

pipelines

Ultraviolet (UV) Treatment of water in piped

systems – In-line UV systems are being evaluated

to prevent mussel settlement. UV has additional

water treatment benefits and is not expected to

require discharge permitting †

Low volume systems - Facilities service

water, unit or transformer cooling water,

HVAC, pumped systems, and delivery

pipelines

Chemical Treatments – Injection or delivery of

chemicals (oxidizing and nonoxidizing) to kill

mussels or impair ability to attach to surfaces

Bromine

Chlorine

Chlorine dioxide

Low and medium volume systems - Facilities

service water, unit or transformer cooling

water, HVAC, pumped systems, and delivery

pipelines. Permitting often required for

chemical treatment methods

36

Hydrogen peroxide

Ozone

Potassium salts

Potassium permanganate

Sodium Hypochlorite

Salinity

Alternative Treatments – Alternatives to kill

mussels or impair ability to attach

Thermal

Biological †

Desiccation

Low and medium volume systems – Facilities

service water, unit or transformer cooling

water, HVAC, pumped systems and delivery

pipelines. Desiccation requires capability to

dewater system for extended durations

Coatings to protect exposed surfaces – Prevents

mussel attachment or facilitates cleaning (anti-

fouling & foul-release) †

Hydraulic Structures & Equipment - Gates,

valves, penstocks, intake structures,

trashracks, fish screens

Alternative Materials – To prevent mussel

attachment or facilitate cleaning

Copper

Galvanizing (requires high zinc content)

Intake grating, piping/tubing, heat exchangers,

HVAC systems

Mechanical Removal – For routine maintenance

Mechanical raking/scraping

Hydrojetting/water spraying

Pipeline pigging

Traveling intake screens (self-cleaning)

All structures, systems, equipment, and

instrumentation where access is possible –

Diversion structures, pipelines, trashracks,

intakes, fish screens. For instrumentation,

noncontact methods should be considered

where possible

Redundant Systems – Multiple intakes or

duplicate systems for switching during treatment or

cleaning to provide uninterrupted service

All systems for which retrofit is

possible/practical

† - Experimental - Under development or being field tested/demonstrated

Technologies selection for each application depends on a number of considerations including periodic

or continuous mussel exclusion requirements, operations and maintenance requirements, permitting

requirements, environmental impacts, and cost; to name a few. If conventional technologies are not

applicable then alternatives should be developed and demonstrated as early as possible to meet unique

facilities requirements. Operational strategies may also be available to reduce or eliminate mussel

impacts. However, such strategies are often limited depending on the type of system and available

flexibility. Additional information on control strategies and facilities protection methods may be

found in The Practical Manual for Zebra Mussel Monitoring and Control, R. Claudi & G.L. Mackie,

CRC Press, Inc. (2000) and at the U.S. Army Corps of Engineers Zebra Mussel Information System

(ZMIS) website http://el.erdc.usace.army.mil/zebra/zmis/zmishelp.htm

4. Identify Ecological Impacts – Involves developing and initiating actions to measure and track

ecological changes, develop mitigation plans, and implement long-term mitigation actions (considers

endangered species, food webs, aquatic weeds, water quality, etc…)