[et_pb_section fb_built=”1″ custom_padding_last_edited=”on|tablet” _builder_version=”4.16″ _module_preset=”default” positioning=”none” horizontal_offset_tablet=”” horizontal_offset_phone=”” horizontal_offset_last_edited=”on|tablet” custom_margin=”0px||||false|false” custom_margin_tablet=”” custom_margin_phone=”” custom_margin_last_edited=”on|desktop” custom_padding=”0px|||0px|false|false” custom_padding_tablet=”|||25px|false|false” custom_padding_phone=”” da_disable_devices=”off|off|off” global_colors_info=”{}” custom_padding__hover_enabled=”on|desktop” custom_padding__hover=”0px|||0px|false|false” theme_builder_area=”post_content” da_is_popup=”off” da_exit_intent=”off” da_has_close=”on” da_alt_close=”off” da_dark_close=”off” da_not_modal=”on” da_is_singular=”off” da_with_loader=”off” da_has_shadow=”on”][et_pb_row _builder_version=”4.16″ _module_preset=”default” width=”100%” global_colors_info=”{}” theme_builder_area=”post_content”][et_pb_column type=”4_4″ _builder_version=”4.16″ _module_preset=”default” global_colors_info=”{}” theme_builder_area=”post_content”][et_pb_text _builder_version=”4.27.6″ _module_preset=”default” global_colors_info=”{}” theme_builder_area=”post_content”]<\/p>\n
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Prior to assigning probability of failure ratings to each asset,\u00a0utility\u00a0staff\u00a0should\u00a0create a\u00a0<\/span>probability of failure rating structure<\/span>. Once the rating structure is created, staff will rate the probability of failure of each asset using the rating structure. When assigning a probability of failure rating to an asset there are four failure modes to consider:\u00a0<\/span>\u00a0<\/span><\/p>\n Green and gray assets\u00a0will\u00a0likely take\u00a0different paths\u00a0toward failure.\u00a0Gray assets typically have a finite life, and with data and good record keeping, that life cycle can be estimated. As equipment wears, gray assets will require increased\u00a0maintenance and repairs.\u00a0Green assets are designed to become more resilient and effective as vegetation matures and adapts to local resource cycles. The flexible and adaptable nature of green assets extends their\u00a0<\/span>life cycle<\/span>\u00a0and often their performance level over time.<\/span>\u00a0<\/span><\/p>\n In both green and gray assets, performance may diminish; however, green assets can often be\u00a0revitalized\u00a0but gray assets\u00a0generally cannot.\u00a0Life-cycles\u00a0of green and gray assets can be challenging to\u00a0determine. Gray assets have several variables to consider, but can\u00a0generally be\u00a0estimated,\u00a0whereas\u00a0green assets have an indeterminate lifespan that can be\u00a0impacted\u00a0by\u00a0variations in maintenance\u00a0and\u00a0extreme situations (e.g., weather-related incidents).<\/span>\u00a0<\/span><\/p>\n [\/et_pb_text][et_pb_toggle title=”Failure modes for green assets” _builder_version=”4.27.6″ _module_preset=”default” global_colors_info=”{}” theme_builder_area=”post_content”]<\/p>\n All four modes do occur for green assets; however, failure is more often referenced as \u201cdegraded<\/span>\u201d.<\/span>\u00a0<\/span>Green assets\u00a0<\/span><\/span>have living, complex, and dynamic components to them and may not fit into the same definitions and rating structure<\/span>s as gray\u00a0<\/span><\/span>assets.<\/span><\/span>\u00a0<\/span><\/span><\/span>As the asset management practice with green infrastructure matures,\u00a0<\/span><\/span>utilities<\/span>\u00a0<\/span>will have a better idea of various asset lifespans and potential likelihood of failure.<\/span>\u00a0<\/span><\/span>For now, it is necessary to make the best educated guess.<\/span><\/span>\u00a0<\/span><\/p>\n [\/et_pb_toggle][et_pb_image src=”https:\/\/swefc.unm.edu\/iamf\/wp-content\/uploads\/2021\/04\/Flood.jpg” title_text=”Flood” _builder_version=”4.27.6″ _module_preset=”default” hover_enabled=”0″ border_radii=”on|25px|25px|25px|25px” locked=”off” global_colors_info=”{}” theme_builder_area=”post_content” sticky_enabled=”0″][\/et_pb_image][et_pb_text _builder_version=”4.27.6″ _module_preset=”default” theme_builder_area=”post_content” hover_enabled=”0″ sticky_enabled=”0″]<\/p>\n Review the descriptions of each failure mode and the variables that can influence each.\u00a0<\/span><\/span>Staff<\/span>\u00a0<\/span>can reference these modes when creating their\u00a0<\/span><\/span>utility\u2019s<\/span>\u00a0<\/span>rating structure.<\/span><\/span>\u00a0<\/span><\/p>\n [\/et_pb_text][et_pb_text _builder_version=”4.27.6″ _module_preset=”default” theme_builder_area=”post_content” hover_enabled=”0″ sticky_enabled=”0″]<\/p>\n Mortality\u00a0Failure\u00a0means\u00a0the asset physically fails or is unable to perform its function.<\/span><\/b>\u00a0<\/span><\/p>\n Mortality\u00a0can occur due to the natural deterioration of an asset over time, or it can be sudden and unpredictable,\u00a0such as an asset\u00a0being\u00a0run\u00a0over by a car\u00a0or damaged by severe weather.\u00a0Some examples of mortality failures include leaks, stuck valves,\u00a0vegetation\u00a0or soil stripped during a storm\u00a0event\u00a0and plastic pipe failure.\u00a0There are two types of assets to consider: active assets and passive assets.<\/span>\u00a0<\/span><\/p>\n Active assets usually have moving parts,\u00a0require human intervention, and often require power or fuel. Active assets usually\u00a0fail with use rather than time. Failure for active assets is related to overall run time, frequency of starting and stopping, and frequency and skill of maintenance.\u00a0Similar assets in the same system can vary in deterioration based on their physical location and its characteristics.<\/span>\u00a0<\/span><\/p>\n Passive assets\u00a0use natural\u00a0or physical processes that do not usually require human intervention, power, or fuel to\u00a0operate. Passive assets\u00a0usually fail with time because they are in constant service; however, their failure times vary significantly depending on the environment\u00a0where\u00a0they are located.\u00a0\u00a0Failure for passive assets is\u00a0often\u00a0related to soil characteristics, bedding conditions, asset material, exposure to\u00a0weather\u00a0and other environmental factors.\u00a0<\/span>\u00a0<\/span><\/p>\n Below is a list of factors that\u00a0impact\u00a0the probability an asset will fail due to\u00a0mortality. Click on\u00a0each factor to learn more.<\/span><\/p>\n [\/et_pb_text][et_pb_text _builder_version=”4.27.6″ _module_preset=”default” theme_builder_area=”post_content” hover_enabled=”0″ sticky_enabled=”0″]<\/p>\n [\/et_pb_text][et_pb_accordion _builder_version=”4.27.6″ _module_preset=”default” hover_enabled=”0″ locked=”off” global_colors_info=”{}” theme_builder_area=”post_content” sticky_enabled=”0″][et_pb_accordion_item title=”Asset Condition” open=”on” _builder_version=”4.27.6″ _module_preset=”default” hover_enabled=”0″ global_colors_info=”{}” theme_builder_area=”post_content” sticky_enabled=”0″]<\/p>\n As an asset consistently performs its function, the\u00a0<\/span><\/span>asset\u2019s<\/span>\u00a0<\/span>condition will begin to deteriorate. As the\u00a0<\/span><\/span>asset’s<\/span>\u00a0<\/span>condition deteriorates, it will be more likely to fail. This pattern is\u00a0<\/span><\/span>somewhat different<\/span>\u00a0<\/span>for green assets using living plants. Initially, the condition may be lower, but it improves over time as the vegetation becomes established. As vegetation\u00a0<\/span><\/span>remains<\/span>\u00a0<\/span>established, the condition of that asset may stay the same or continue to improve. However, without proper maintenance or due to environmental factors (drought, disease, soil deterioration) these green assets can be subject to condition deterioration as well. It is important, therefore, to make the best possible attempt to give the assets a reasonable\u00a0<\/span><\/span>condition<\/span>\u00a0<\/span>assessment and update it at least annually. Assets with better condition ratings will be less likely to fail than those with lower condition ratings.<\/span><\/span>\u00a0<\/span><\/p>\n [\/et_pb_accordion_item][et_pb_accordion_item title=”Repair History” _builder_version=”4.27.6″ _module_preset=”default” hover_enabled=”0″ global_colors_info=”{}” theme_builder_area=”post_content” open=”off” sticky_enabled=”0″]<\/p>\n Staff should track the repair history of an\u00a0asset\u00a0including when and where the repair occurred and why it was needed. This information should be as specific as possible to\u00a0assist\u00a0staff in understanding how mortality occurred. Past failure is not completely predictive of future failure, but it can provide some\u00a0indication\u00a0of the probability of future failure, especially if detailed information on the past failures is collected and reviewed. Other information can also be tracked to improve system knowledge such as how the failure was\u00a0determined, details about how the mortality\u00a0occurred\u00a0and field observations that may help explain the failure. Work orders and maintenance reports provide\u00a0insight into what can happen with a given asset, and they can also help a system figure out how much downtime is associated with mortality failure.<\/span>\u00a0<\/span><\/p>\n [\/et_pb_accordion_item][et_pb_accordion_item title=”Operations and Maintenance History ” _builder_version=”4.27.6″ _module_preset=”default” hover_enabled=”0″ global_colors_info=”{}” theme_builder_area=”post_content” open=”off” sticky_enabled=”0″]<\/p>\n Knowledge of how the asset was\u00a0<\/span><\/span>operated<\/span>\u00a0<\/span>and maintained will provide information about how likely the asset is to fail. The lack of adequate maintenance is likely to shorten an asset’s useful life and cause premature failure.\u00a0<\/span><\/span>Similarly, knowledge of how the asset was operated will help determine the asset\u2019s likelihood of failure.<\/span>\u00a0<\/span>An asset that is subject to harsh operation (e.g., frequent starts and\u00a0<\/span><\/span>stops,<\/span>\u00a0<\/span>operation outside of design specifications) is more likely to fail than one that is\u00a0<\/span><\/span>operating<\/span>\u00a0<\/span>within design standards.<\/span><\/span>\u00a0<\/span><\/p>\n [\/et_pb_accordion_item][et_pb_accordion_item title=”Asset Useful Life” _builder_version=”4.27.6″ _module_preset=”default” hover_enabled=”0″ global_colors_info=”{}” theme_builder_area=”post_content” open=”off” sticky_enabled=”0″]<\/p>\n Over time, assets can deteriorate. This is always the case for gray assets. However, some green assets improve over time as vegetation grows and becomes more established. There is no “magic age” at which an asset can be expected to fail. An asset’s useful life is highly related to the conditions of use, the amount of maintenance, the original design, construction techniques, and the type of material used in construction. The useful life estimates developed in the Current State of the Assets\u00a0<\/span><\/span>component<\/span>\u00a0<\/span>of Asset Management help provide information on the probability of failure. If the asset is close to the end of its useful life, it can be expected to fail. If it is far from the end, it is much less likely to fail.\u00a0<\/span><\/span>Useful<\/span>\u00a0<\/span>life is a better metric to use than\u00a0<\/span><\/span>actual<\/span>\u00a0<\/span>age of the asset because it is more indicative of the end of life. In some cases,\u00a0<\/span><\/span>very old<\/span>\u00a0<\/span>assets can still have a significant amount of life left and low probability of failure compared to newer assets, depending on many other factors<\/span>.\u00a0\u00a0<\/span><\/span>\u00a0<\/span><\/p>\n [\/et_pb_accordion_item][et_pb_accordion_item title=”Major Potential Disruptions” _builder_version=”4.27.6″ _module_preset=”default” hover_enabled=”0″ global_colors_info=”{}” theme_builder_area=”post_content” open=”off” sticky_enabled=”0″]<\/p>\n The likelihood of some natural hazard events is\u00a0<\/span><\/span>relatively well\u2010established<\/span>\u00a0<\/span>in existing datasets and studies, though climate change is adding a layer of uncertainty. For example, climatic and hydrologic studies provide reliable estimates of the probability of large floods based on documented past events. Systems can plan for plausible future frequencies and magnitudes of hazard events like floods or droughts or other events that may lead to gray and green asset mortality. Another major potential\u00a0<\/span><\/span>disruption<\/span>\u00a0<\/span>that could lead to asset mortality is power failures. Although these may be unpredictable, if they have happened multiple times in the past they should be factored\u00a0<\/span><\/span>in<\/span>\u00a0<\/span>the likelihood of failure for the future.<\/span><\/span>\u00a0<\/span><\/p>\n [\/et_pb_accordion_item][et_pb_accordion_item title=”Experience with a Similar Asset” _builder_version=”4.27.6″ _module_preset=”default” hover_enabled=”0″ global_colors_info=”{}” theme_builder_area=”post_content” open=”off” sticky_enabled=”0″]<\/p>\n Although probability of failure is asset and site specific, some guidance\u00a0<\/span><\/span>regarding<\/span>\u00a0<\/span>probability of failure can be gained by examining experience with similar assets. If similar assets experienced failure via mortality in the past, that should be investigated and considered in the likelihood of mortality failure for current and future similar assets.\u00a0<\/span><\/span>\u00a0<\/span><\/p>\n [\/et_pb_accordion_item][et_pb_accordion_item title=”Historical Knowledge” _builder_version=”4.27.6″ _module_preset=”default” hover_enabled=”0″ global_colors_info=”{}” theme_builder_area=”post_content” open=”off” sticky_enabled=”0″]<\/p>\n If staff have any\u00a0<\/span><\/span>additional<\/span>\u00a0<\/span>knowledge\u00a0<\/span><\/span>regarding<\/span>\u00a0<\/span>the asset and what might prevent it from performing its function, it should be considered when assigning the probability of failure rating. This type of information may include knowledge of poor design,\u00a0<\/span><\/span>construction<\/span>\u00a0<\/span>or manufacturing practices used at the time the asset was installed, or knowledge of inadequate materials or vegetation used.<\/span><\/span>\u00a0<\/span><\/p>\n [\/et_pb_accordion_item][\/et_pb_accordion][dsm_icon_divider _builder_version=”4.27.6″ _module_preset=”default” theme_builder_area=”post_content” use_icon=”on” font_icon=”||fa||900″ hover_enabled=”0″ sticky_enabled=”0″][\/dsm_icon_divider][et_pb_text _builder_version=”4.27.6″ _module_preset=”default” hover_enabled=”0″ global_colors_info=”{}” theme_builder_area=”post_content” sticky_enabled=”0″ custom_padding=”||0px|||”]<\/p>\n Capacity Failure\u00a0means\u00a0the asset is still operational but is unable to provide the physical capacity needed.<\/span><\/b>\u00a0<\/span><\/p>\n Some examples of capacity failure are\u00a0combined\u00a0sewer\u00a0overflows,\u00a0\u00a0fluvial\u00a0flooding, precipitation exceeding drainage, reduced flow, inadequate\u00a0well, a storage tank with insufficient capacity, and exceedance of soil capacity. The\u00a0magnitude\u00a0of stormwater discharged\u00a0in\u00a0and around,\u00a0urban areas often\u00a0approaches\u00a0unmanageable levels that can overwhelm the capacity of\u00a0stormwater infrastructure.\u00a0Green assets are often installed to expand urban stormwater management capacity, but they too can experience similar capacity failures if the quantity of stormwater exceeds design capacity.\u00a0<\/span>\u00a0<\/span><\/p>\n Assets may also experience capacity failure due to improper planning or design.\u00a0For example, poorly designed bioswales can result in insufficient stormwater management capacity which may result in local flooding or the inability of an asset to keep up with infiltration.\u00a0These types of capacity failures can result in\u00a0a\u00a0decrease\u00a0in\u00a0water quality as\u00a0additional\u00a0pollutants are added to\u00a0the system.\u00a0Capacity failure also occurs if there is a lack of adequate flow or a significant reduction in source.\u00a0<\/span>\u00a0<\/span><\/p>\n Capacity failure has internal and external factors.\u00a0<\/span>\u00a0<\/span><\/p>\n [\/et_pb_text][et_pb_text _builder_version=”4.27.6″ _module_preset=”default” theme_builder_area=”post_content” hover_enabled=”0″ sticky_enabled=”0″]<\/p>\n [\/et_pb_text][et_pb_accordion _builder_version=”4.27.6″ _module_preset=”default” hover_enabled=”0″ locked=”off” global_colors_info=”{}” theme_builder_area=”post_content” sticky_enabled=”0″][et_pb_accordion_item title=”Asset Condition” open=”on” _builder_version=”4.27.6″ _module_preset=”default” hover_enabled=”0″ global_colors_info=”{}” theme_builder_area=”post_content” sticky_enabled=”0″]<\/p>\n As the\u00a0<\/span><\/span>asset’s<\/span>\u00a0<\/span>condition deteriorates, it may not be able to process\/hold\/treat the same capacity. For example, corrosion on the inside of pipes can reduce the cross-sectional area of the pipe. It is important, therefore, to give the assets a reasonable\u00a0<\/span><\/span>condition<\/span>\u00a0<\/span>assessment and update it at least annually.\u00a0<\/span><\/span>\u00a0<\/span><\/p>\n [\/et_pb_accordion_item][et_pb_accordion_item title=”Experience with a Similar Asset ” _builder_version=”4.27.6″ _module_preset=”default” hover_enabled=”0″ global_colors_info=”{}” theme_builder_area=”post_content” open=”off” sticky_enabled=”0″]<\/p>\n Although probability of failure is asset and site specific, some guidance\u00a0<\/span><\/span>regarding<\/span>\u00a0<\/span>probability of failure can be gained by examining experience with similar assets. Other similar assets will give staff an idea about the capacity an asset can process.<\/span><\/span>\u00a0<\/span><\/p>\n [\/et_pb_accordion_item][et_pb_accordion_item title=”Demand and Population ” _builder_version=”4.27.6″ _module_preset=”default” hover_enabled=”0″ global_colors_info=”{}” theme_builder_area=”post_content” open=”off” sticky_enabled=”0″]<\/p>\n Demand and population are constantly fluctuating, at least a small amount, but occasionally there may be significant increases or decreases. A sudden increase in demand or rapid\u00a0<\/span><\/span>population growth\u202fcan result in\u202freduced pressure, inadequate\u00a0<\/span><\/span>supply<\/span>\u00a0<\/span>or\u202finadequate storage capacity.\u202fThis may also occur if a large water user or wastewater customer is added to the service area, causing a rapid increase in demand.<\/span><\/span>\u00a0<\/span><\/p>\n [\/et_pb_accordion_item][et_pb_accordion_item title=”Historical Knowledge ” _builder_version=”4.27.6″ _module_preset=”default” hover_enabled=”0″ global_colors_info=”{}” theme_builder_area=”post_content” open=”off” sticky_enabled=”0″]<\/p>\n If staff have any\u00a0<\/span><\/span>additional<\/span>\u00a0<\/span>knowledge\u00a0<\/span><\/span>regarding<\/span>\u00a0<\/span>the asset, it should be considered when assigning the probability of failure rating. This type of information may include knowledge of design,\u00a0<\/span><\/span>construction<\/span>\u00a0<\/span>or manufacturing practices used at the time the asset was installed or knowledge of materials or vegetation used. Capacity failures may have occurred previously during certain types of events or in certain conditions.\u202fFor example,\u202fa failure in a sewage pump\u00a0<\/span><\/span>station that<\/span>\u00a0<\/span>occurs every time the rainfall is more than 1 inch per day.\u202f<\/span><\/span>\u00a0<\/span><\/p>\n [\/et_pb_accordion_item][et_pb_accordion_item title=”Major Potential Disruptions ” _builder_version=”4.27.6″ _module_preset=”default” hover_enabled=”0″ global_colors_info=”{}” theme_builder_area=”post_content” open=”off” sticky_enabled=”0″]<\/p>\n Some parts of the country or areas within a city\/town are more prone to major disruptions. These disruptions include natural hazards (e.g., earthquakes, hurricanes,\u202fflooding, fires), power failures, equipment failures, or transmission main failures and can result in a reduction in system capacity, supply\u00a0<\/span><\/span>\n
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Factors that may contribute to mortality failure:<\/span><\/span><\/h3>\n
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Factors that may contribute to capacity failure:<\/span><\/h3>\n