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Bunding

Bunding refers to the construction of secondary containment barriers, typically walls or embankments made from impervious materials like concrete, brick, or steel, surrounding storage tanks or areas where hazardous liquids such as fuels, chemicals, or oils are handled to capture potential leaks or spills.^[1] These structures form a perimeter and often include a sealed floor to create a compound capable of holding escaped substances without allowing infiltration into the ground or surrounding environment.^[2] The primary purpose of bunding is to mitigate environmental risks by providing a backup containment system in case of primary storage failure, thereby preventing soil and water contamination from pollutants that could harm ecosystems and human health.^[3] Regulatory standards, such as those from environmental protection agencies, mandate bund capacity to exceed 110% of the largest single tank's volume or 25% of the aggregate storage volume, whichever is greater, ensuring adequate retention during overflows or ruptures.^[3] Bund walls are typically designed to heights of 0.5 to 1.5 meters, with materials selected for impermeability and durability under hydrostatic pressure testing to verify integrity.^[1] Bunding practices are integral to compliance in industries like petrochemicals, manufacturing, and waste treatment, where failures have historically led to significant pollution incidents, underscoring the causal link between robust secondary containment and reduced ecological damage.^[4] Regular integrity assessments, including leak detection and lining reinforcements, maintain effectiveness, though suboptimal designs or maintenance can undermine protection, highlighting the need for engineering precision over mere regulatory adherence.^[1]

Fundamentals of Bunding

Definition and Engineering Principles

Bunding constitutes a secondary containment system engineered as an impermeable embankment or retaining wall encircling primary storage vessels, such as tanks holding hazardous liquids including chemicals, fuels, or oils, to capture and confine any leakage or spill from the primary container.^[4]^[1] This structure serves as a physical barrier, leveraging gravitational confinement to prevent the uncontrolled dispersion of liquids into the surrounding environment, thereby mitigating risks of soil, water, or air contamination.^[5] Unlike primary containment, which relies on the material and structural integrity of the storage tank to prevent releases, bunding acts as an independent fail-safe layer designed to accommodate the consequences of primary failure, such as corrosion, overfill, or rupture.^[4] The system's efficacy stems from first-principles of fluid dynamics: spilled liquids, governed by gravity and surface tension, pool within the bund's perimeter rather than flowing outward, provided the walls exceed the equilibrium liquid height. Impermeability of the walls and base—achieved through materials resistant to permeation and chemical degradation—ensures no subsurface migration occurs, while the base slopes toward collection points to facilitate detection and recovery.^[2]^[1] Engineering design prioritizes structural stability against hydrostatic forces generated by the contained volume, where pressure at any depth follows P = ρgh (with ρ as fluid density, g as gravitational acceleration, and h as height), demanding walls capable of withstanding lateral loads without deformation or breach.^[6] Bund capacity is calculated to hold at least 110% of the largest tank's volume within the enclosure, accounting for the full potential release plus a margin to avoid overtopping from dynamic effects like wave action or added extinguishing agents.^[4]^[7] This volumetric excess derives from causal analysis of spill scenarios, ensuring the bund's freeboard—the vertical distance from liquid surface to wall crest—prevents overflow under maximum loading, thus maintaining containment integrity through verifiable hydrodynamic limits rather than probabilistic assumptions.^[6]

Historical Development

Bunding practices emerged in the mid-19th century alongside the expansion of the petroleum industry, where rudimentary earthen dikes and walls were employed around early refineries to contain crude oil leaks and prevent uncontrolled spread during processing. These initial measures were largely ad-hoc responses to practical hazards observed in operations starting with the first commercial oil well drilled by Edwin Drake in 1859, focusing on fire prevention and basic spill retention rather than comprehensive environmental protection.^[8]^[9] Formalized bund construction gained traction in the early 20th century, particularly after refinery incidents in the 1910s that demonstrated the risks of uncontained flammable liquids, such as pool fires from tank ruptures; this led to engineered retaining walls designed explicitly for secondary containment to limit fire propagation and liquid escape. Post-World War II, the rapid growth of the petrochemical sector—driven by increased production of synthetic materials and fuels—necessitated widespread adoption of bunds around storage tanks, as facilities scaled up to handle larger volumes of hazardous substances, with traditional concrete or earthen structures providing essential barriers against operational failures.^[10] The 1970s marked a pivotal shift influenced by empirical evidence from spills and the creation of regulatory frameworks, including the U.S. Environmental Protection Agency's 1973 Spill Prevention, Control, and Countermeasure rule, which mandated secondary containment like bunds for aboveground oil storage tanks to avert discharges into waterways, reflecting lessons from events underscoring causal links between inadequate containment and ecological damage. By the 1990s, advancements in risk assessment methodologies supplanted earlier empirical but imprecise sizing (e.g., arbitrary 110% capacity rules), incorporating quantitative analyses of tank overfill probabilities and bund overtopping dynamics to derive more reliable designs grounded in failure data from prior decades.^[11]^[7]^[12]

Design and Construction Practices

Materials Selection

Bunds for liquid containment are primarily constructed using reinforced concrete due to its high compressive strength, typically ranging from 20 to 50 MPa in standard mixes, which supports structural integrity under hydrostatic pressures and soil loads.^[13] However, untreated concrete exhibits permeability to water and chemicals, necessitating liners or coatings to prevent leakage and degradation from aggressive substances like acids or hydrocarbons.^[14] Empirical assessments of concrete durability demonstrate that with adequate reinforcement and protective measures, such as epoxy coatings, bunds can achieve service lives exceeding 50 years in industrial settings, as evidenced by long-term performance in chemical storage facilities where corrosion rates remain below 0.05 mm/year under controlled exposure.^[15]^[16] Steel serves as an alternative for bund walls where rapid erection or higher tensile strength is required, offering yield strengths up to 250-350 MPa for mild steel grades.^[17] Yet, in wet or humid environments common to spill containment, steel suffers from accelerated corrosion, with rates potentially reaching 0.1-0.5 mm/year due to electrochemical reactions involving moisture, oxygen, and contaminants, often necessitating galvanization or frequent maintenance to mitigate pitting and structural weakening.^[18]^[19] Polymeric materials, particularly high-density polyethylene (HDPE) geomembranes used as liners within concrete or earthen bunds, provide superior chemical resistance to acids, alkalis, and solvents, with permeation rates as low as 10^-12 cm/s for many organics.^[20] HDPE's inert nature stems from its non-polar structure, enabling compatibility with over 90% of industrial chemicals without swelling or dissolution.^[21] Trade-offs include vulnerability to UV degradation if not covered, reducing tensile strength by up to 20-30% after prolonged exposure, and lower puncture resistance compared to rigid materials, though thicknesses of 1.5-2 mm mitigate these risks in buried applications.^[22]^[23] Material selection hinges on the stored substance's corrosivity, environmental exposure, and lifecycle costs; for instance, concrete with HDPE liners balances initial affordability—often 20-30% lower than full steel enclosures—with proven containment efficacy, outperforming unlined alternatives in empirical leak prevention studies.^[24] Steel's higher upfront strength is offset by ongoing corrosion mitigation expenses, while geomembranes excel in flexibility for irregular geometries but demand integration with durable substrates to ensure long-term impermeability without reliance on unproven eco-materials lacking field-validated performance.^[25]^[26]

Sizing and Capacity Calculations

Sizing and capacity calculations for bunds prioritize containing the full volume of a catastrophic tank failure while incorporating margins for firefighting foam, precipitation, or minor overfills to minimize overflow risks. Empirical standards typically require bund capacity to equal at least 110% of the largest single tank's volume within the enclosure, providing a 10% allowance primarily for foam application during fire suppression rather than direct historical spill data.^[4] For multiple tanks, capacity must accommodate the greater of 110% of the largest tank or 25% of the aggregate volume of all enclosed tanks, reflecting pragmatic limits to avoid impractically large structures while addressing partial domino-effect failures.^[3] ^[27] Calculations begin by determining the net containment volume, excluding displacements from tank bases and any internal equipment: V_{\text{bund}} = (A_{\text{bund}} - \sum A_{\text{tank}}) \times [h_w](/page/Height) + V_{\text{sloped}}, where A_{\text{bund}} is the bunded floor area, \sum A_{\text{tank}} sums the projected areas of enclosed tanks, h_w is wall height, and V_{\text{sloped}} accounts for any base gradients.^[28] This ensures the bund holds the required spill volume without reliance on external drainage. Wall height h_w is then solved iteratively to satisfy V_{\text{bund}} \geq 1.1 \times V_{\text{largest}}, maintaining hydrostatic equilibrium where liquid head pressure does not exceed wall stability thresholds, typically limiting h_w to 1-1.5 meters for constructability and overtopping prevention.^[29] Freeboard, the vertical distance above maximum liquid level to bund crest, incorporates additional factors like rainfall or wave action from sloshing; U.S. EPA guidelines recommend sizing for a 25-year, 24-hour storm event or equivalent 10% volume margin, often integrated into the 110% rule to curb probabilistic overtopping.^[30] ^[31] In multi-tank setups, complexity rises due to potential cascading spills, prompting sensitivity analyses on sequential failure volumes, though standards cap bunds at around 60,000 m³ total to balance risk against feasibility.^[4] Empirical models, such as those correlating spill-over fraction Q to the ratio of bund height h to liquid depth H, quantify breach probabilities under dynamic conditions, informing height adjustments beyond static volume needs.^[6]

Construction Techniques and Integrity Assessments

Bunds are commonly constructed using reinforced cast-in-place concrete for walls, paired with impermeable concrete bases or geomembrane liners to ensure containment integrity against aqueous liquids.^[32] Prefabricated concrete panels provide an alternative for rapid assembly, featuring dense, low-porosity materials and minimized joints to limit infiltration risks, with installation times reduced compared to on-site pouring.^[33] Leak detection systems, such as sensors placed in the bund base or interstitial spaces for double-walled designs, are increasingly integrated during construction to enable early identification of breaches, aligning with enhanced monitoring requirements in recent regulatory updates.^[34] For new installations, pre-service verification mandates full hydrostatic testing, where the bund is filled with water to a depth of approximately 300 mm and held for 24 hours to measure any level drop indicative of leaks, per guidelines in BS 8007.^[35] Integrity assessments for existing bunds emphasize non-destructive techniques alongside periodic hydrostatic retesting every three years, focusing on root causes like foundation settlement or material degradation rather than surface-level anomalies.^[36] Visual inspections target cracks and erosion, supplemented by methods such as dye tracing in water fills to trace permeation paths without structural compromise.^[37] These protocols reveal higher vulnerability in aged structures, where empirical evaluations indicate substantial leak potentials absent proactive maintenance.^[38]

Primary Applications

Liquid Containment in Industrial Settings

Bunding serves as a primary secondary containment method in industrial settings, particularly within petrochemical refineries and chemical processing facilities, where it encircles above-ground storage tanks holding fuels, oils, and hazardous liquids to capture leaks, overfills, or ruptures.^[4] These structures are engineered to hold at least 110% of the capacity of the largest enclosed tank, providing margin for firefighting foam application during incident response without overflow.^[4] In sectors prone to high-volume liquid storage, such as oil refining, bunding mitigates the risk of uncontained releases that could rapidly exceed 100,000 liters through tank overpressurization or corrosion-induced failures, directing spilled material away from soil and drainage systems.^[39] For large-scale operations, diked areas—often formed by earthen berms or reinforced concrete walls—encompass multiple tanks, creating expansive containment zones that account for spill dynamics where liquids flow outward under gravity until impeded, preventing lateral spread and subsurface infiltration.^[4] In contrast, mini-bunds or spill pallets are deployed for smaller containers like 205-liter drums, utilizing low-profile barriers or grated platforms to trap drips and minor leaks, thereby isolating contaminants at the source before accumulation escalates.^[40] These variants integrate with complementary systems, such as double-skinned tanks featuring integral inner barriers, to form layered defenses against release propagation.^[4] Empirical assessments from regulatory guidance underscore bunding's role in averting groundwater contamination by confining spills to impermeable surfaces for subsequent recovery and disposal, as opposed to permeable ground absorption that exacerbates plume migration.^[39] Industry implementations demonstrate that properly sized and maintained bunds effectively localize releases, reducing off-site environmental migration in contained events compared to unbunded scenarios where spills infiltrate aquifers unchecked.^[4] This containment principle directly counters causal pathways of spill escalation, from initial breach to widespread dispersion, by imposing physical boundaries that enable controlled mitigation.^[41]

Noise and Vibration Barriers

Bunds, constructed from earth or concrete, serve as secondary acoustic barriers by leveraging mass and geometry to attenuate airborne noise from traffic or industrial sources, primarily through sound absorption in the material and diffraction over the barrier's crest. These structures interrupt line-of-sight propagation, compelling sound waves to bend around edges, with attenuation increasing with barrier height and density relative to wavelength. For instance, denser materials like compacted soil or concrete enhance blocking of mid-to-high frequencies (above 500 Hz), where shorter wavelengths interact more readily with the barrier surface.^[42]^[43] Empirical data from highway implementations indicate earth bunds typically yield 5-10 dB(A) overall noise reduction at receiver distances of 50-100 meters, comparable to equivalent-height walls but often 2 dB(A) less effective due to softer crest geometry allowing greater diffraction losses. Optimized designs, such as shaped bunds with sloped or rounded profiles, can boost insertion loss by an additional 5 dB(A) at 1.5-meter receiver heights by minimizing edge scattering, as modeled in traffic noise simulations. Concrete bunds, with higher surface mass, perform similarly but require reinforcement to maintain integrity under erosion or settlement.^[44]^[45]^[46] Vibration mitigation via bunds relies on isolating ground-borne waves through mass loading and decoupling, yet effectiveness diminishes for low-frequency components below 100 Hz, where longer wavelengths propagate through soil with minimal damping—often achieving less than 5 dB reduction without embedded isolators. In industrial contexts, such as near compressor stations, bunds may integrate with fences for hybrid barriers, but standalone earthen designs underperform dedicated vibration trenches or mats for seismic or machinery-induced tremors. Cost analyses favor bunds over walls for large-scale deployments (e.g., $50-100 per linear meter vs. $200+ for concrete panels), though land footprint demands and maintenance for vegetation overgrowth limit applicability in constrained urban sites, where vertical fences provide superior space efficiency without exaggerating ecological benefits.^[47]^[48]^[49]

Regulatory and Compliance Landscape

Global Standards and Requirements

In the United Kingdom, the Control of Major Accident Hazards (COMAH) Regulations 2015 mandate secondary containment systems, such as bunds, for sites handling hazardous substances above specified thresholds, requiring bund capacity to be the greater of 110% of the largest single tank's volume or 25% of the aggregate volume of all tanks within the bund.^[50]^[27] These provisions aim to contain potential releases from tank failures or overfills, with bund walls typically designed to a minimum height of 0.5 meters for effective retention.^[4] In the United States, the Environmental Protection Agency's Spill Prevention, Control, and Countermeasure (SPCC) rule under 40 CFR Part 112 requires secondary containment for bulk storage containers holding oil or oil-like substances exceeding 1,320 gallons in aggregate aboveground capacity, sized to accommodate the full volume of the largest single container plus sufficient freeboard to prevent overtopping from precipitation, often calculated for a 25-year, 24-hour storm event.^[39]^[51] This risk-based approach emphasizes engineered barriers like bunds or double-walled tanks, with flexibility for site-specific alternatives demonstrated to provide equivalent protection.^[39] The European Union's Seveso III Directive (2012/18/EU) establishes a framework for preventing major accidents at establishments with dangerous substances, requiring operators to implement appropriate containment measures as part of safety management systems, though specific bunding capacities are transposed into national regulations often aligning with principles like those in COMAH.^[52] Influenced by incidents including Bhopal in 1984, the directive prioritizes risk assessment for storage facilities, mandating secondary containment to mitigate releases of hazardous liquids.^[52] Across jurisdictions, bunding standards commonly incorporate provisions for rainwater management to prevent dilution or overtopping, such as sloped floors for drainage to dedicated systems or valves that remain closed except during maintenance, ensuring capacity is reserved for spills rather than stormwater accumulation equivalent to design storm events like 1-in-100-year rainfall.^[1] European regulations tend toward prescriptive volume-based mandates, while approaches in regions like the United States and Australia allow more flexibility for performance-based designs, with compliance linked to reduced spill migration through containment integrity.^[2]^[4]

Economic Costs and Regulatory Criticisms

The construction and maintenance of bunds impose substantial economic burdens on industrial facilities, with upgrade costs frequently ranging from £100,000 to over £2 million for sites constrained by space, access, and technical challenges, far exceeding justified expenditures of £1,000 to £20,000 based on quantified harm avoidance over 50-year horizons at incident frequencies around 4×10⁻⁶ per year.^[53] These figures stem from case studies of COMAH-compliant installations, where retrofitting amplifies expenses due to the need for structural reinforcements and compliance validations, often diverting 20-30% of operational budgets toward secondary containment without commensurate reductions in overall spill probabilities.^[53] Ongoing maintenance, including periodic integrity tests and repairs against weathering or seismic events, adds recurrent costs that compound over time, particularly for concrete or steel bunds in corrosive environments.^[54] Regulatory mandates, such as those under COMAH requiring bund capacities of at least 110% of the largest single tank or 25% of aggregate storage (whichever greater), draw criticism for disregarding site-specific risk profiles and probabilistic modeling, resulting in oversized structures that yield marginal spill containment gains relative to their financial demands.^[53] In multi-tank configurations, these rules exacerbate vulnerabilities, as bund failures occur approximately three times more frequently than in single-tank setups, heightening escalation probabilities during fires or overtopping events, as evidenced by 1996 IChemE analyses and subsequent COMAH incident reviews.^[53] Critics argue that such prescriptive standards, applied uniformly without tailored cost-benefit scrutiny, stifle operator-led innovations like advanced primary tank monitoring or alternative mitigations, favoring risk-based approaches that demonstrate ALARP (as low as reasonably practicable) through empirical frequency data over blanket over-design.^[54] This perspective aligns with broader industry calls for deregulation where uniform rules impose inefficiencies, as probabilistic assessments reveal that enhanced emergency response or tertiary barriers often provide superior hazard control at lower net cost.^[53]

Performance and Risk Management

Empirical Effectiveness and Case Studies

Empirical laboratory simulations of 183 bund configurations, including axisymmetric and asymmetric tank failure scenarios, reveal that secondary containment systems effectively manage partial or gradual spills, with overtopping fractions as low as under 2% for asymmetric orifice releases in standard 110% capacity designs. However, sudden catastrophic failures generate surge waves and dynamic pressures up to 16 times static head levels, resulting in overtopping of 14-50% of released volume depending on tank height and release type, underscoring limitations in conventional sizing for high-velocity discharges. High-collar bund modifications mitigate this, achieving under 5% overtopping by dampening wave impacts, though overall performance declines with larger bund radii or lower walls.^[55]^[55] In industrial applications, bunds have demonstrated containment success for operational spills when integrity is maintained. A 2023 case at an Australian chemical facility involved a pump failure releasing approximately 100,000 liters of sulphuric acid mixture into a bund, which fully retained the volume without off-site migration, allowing controlled neutralization and preventing groundwater contamination. Such outcomes highlight the role of routine integrity checks over design capacity alone, as compromised seals or erosion can undermine even oversized systems. Partial successes in modeled refinery scenarios further emphasize that asymmetric leaks—common in corrosion or valve failures—are better contained than full tank ruptures, with dynamic modeling predicting 70-98% retention under non-surge conditions.^[56]^[57] Quantitative risk models incorporating bunds estimate 50-80% reductions in off-site spill volumes by localizing releases, based on source term adjustments in hazard assessments; yet these often rely on static fill assumptions that neglect hydrodynamic overtopping, potentially inflating projected effectiveness for rare high-momentum events. Empirical validation against incidents like the 1988 Ashland Oil spill confirms that while bunds avert minor environmental impacts in 80-90% of controlled releases, regulatory validations understate failure probabilities in unbaffled designs, prioritizing capacity over wave dynamics. Fire scenarios introduce further constraints, as boilover in heated pools can propel burning liquids beyond bund walls via frothover, though containment geometry limits lateral spread to minor fractions in tested configurations.^[55]^[4]^[58]

Notable Failures and Causal Analyses

The Buncefield oil storage depot explosion and fire on December 11, 2005, highlighted bund overtopping risks when firefighting operations overwhelm containment capacity. Initial overfilling of Tank 912 released approximately 300,000 liters of unleaded gasoline, which initially entered the bund, but the ensuing blaze generated excessive firewater and foam volumes that caused one bund to overtop due to inaccessible drainage valves and power failures preventing pumping. This overtopping stemmed from insufficient freeboard to accommodate dynamic firefighting inflows, as standard 100-250 mm allowances proved inadequate under high evaporation rates during fire exposure.^[59]^[60] Root-cause engineering analysis revealed design flaws as primary contributors, including the absence of waterstops in construction joints and unsealed pipe penetrations, which permitted leakage of fuel, foam, and water into adjacent areas. Bund walls, often constructed with non-fire-resistant materials, suffered thermal degradation, exacerbating breaches; for instance, tie bar holes and joints in Bund A lacked proper sealing, allowing progressive failure. These issues were compounded by construction oversights, such as unrepaired leaks identified in prior inspections, underscoring how static volumetric sizing neglects material vulnerabilities under prolonged thermal stress.^[59]^[61] In broader tank farm incidents, poor internal drainage within bunds has facilitated escalation during fires by enabling spilled liquids to pool and spread, igniting secondary pools that impinge on nearby tanks. Engineering reviews of such events attribute recurrent failures to corrosion-induced wall thinning and foundation settlement, which create cracks permitting seepage; maintenance lapses, including inadequate corrosion protection, account for a substantial share of these degradations alongside operational errors. Multi-tank configurations amplify risks through domino propagation, where a single bund breach exposes adjacent vessels to radiant heat, potentially multiplying failure probabilities via shared fire exposure without compartmentalized drainage.^[62]^[63] Post-2005 analyses prompted a pivot to dynamic hydrodynamic modeling for predicting overtopping under spill-fire scenarios, revealing limitations in regulatory freeboard minima that ignore wave dynamics and evaporation. Integrity assessments now emphasize non-destructive testing for joint seals and corrosion mapping, as empirical reconstructions of Buncefield demonstrated that retrofitting with fire-rated liners and enhanced drainage could mitigate escalation by containing thermal weakening. These shifts prioritize causal chain interruption—such as segregated pipe entries—over compliance checklists, reducing reliance on unverified assumptions about material longevity.^[59]^[64]

Environmental and Sustainability Aspects

Pollution Prevention Benefits

Bunding functions as a physical barrier that captures leaked or spilled hazardous liquids, thereby preventing their infiltration into soil, groundwater, or surface waters through direct containment within impermeable walls and bases. Under the U.S. EPA's Spill Prevention, Control, and Countermeasure (SPCC) rule, secondary containment systems like bunds must provide capacity for the entire volume of the largest container plus sufficient freeboard for precipitation, ensuring spills do not discharge into navigable waters or adjoining shorelines.^[39] ^[51] Similarly, guidelines from regulatory bodies such as the UK's Health and Safety Executive specify bund sizing at 110% of the largest tank's capacity to accommodate firefighting foam or minor overflows, directly linking structural design to pollution interception.^[4] The causal efficacy stems from bunds' ability to localize releases, enabling recovery via pumping or absorption before environmental migration occurs, which contrasts with unbunded scenarios where liquids spread uncontained. In facilities compliant with these standards, bunds mitigate risks from tank corrosion, overfills, or ruptures—common failure modes in primary storage—by providing an immediate retention zone, as evidenced by SPCC's focus on averting oil discharges that historically contaminated ecosystems. While comprehensive public datasets on averted volumes remain limited, industry-wide petroleum spill reductions (77% since the 1970s, coinciding with SPCC implementation) underscore secondary containment's role in curbing reportable incidents reaching waterways, though attribution requires isolating bunding from other controls like improved tank integrity.^[65]^[66] Trade-offs involve initial construction impacts, such as localized emissions from concrete pouring or material transport, but these are temporally bounded and outweighed by long-term avoidance of diffuse pollution from unmanaged leaks, which demand extensive soil excavation and groundwater treatment. Regular hydrostatic testing verifies bund impermeability, minimizing failure probabilities and ensuring sustained preventive function without dependence on auxiliary measures prone to inefficacy.^[2] Limitations persist, including overflow risks from undetected primary leaks or seismic events, highlighting that bunding's benefits hinge on proactive maintenance rather than passive assurance.

Re-greening Initiatives and Long-term Impacts

Efforts to re-green industrial bunds typically involve hydroseeding or planting shallow-rooted grasses on earthen slopes to mitigate erosion from rainfall and wind, particularly in non-liner applications where aesthetic integration with surrounding landscapes is prioritized.^[67] Such initiatives, observed in mining and petrochemical sites since the mid-2010s, aim to stabilize soil while reducing visual impact, with empirical tests on analogous slopes demonstrating erosion reductions of 40-80% compared to bare surfaces under simulated rainfall.^[68]^[69] However, these approaches are confined to outer slopes away from containment liners, as deeper-rooted shrubs or trees risk penetrating impermeable barriers, potentially creating seepage pathways that undermine spill retention.^[70] Long-term monitoring of vegetated earthen bunds, drawing from embankment stability studies, reveals heightened maintenance demands, including annual mowing and herbicide application to prevent woody encroachment, with unmanaged growth correlating to 20-30% higher failure rates from root-induced cracking over 10-15 years.^[71]^[72] Bare concrete or armored bunds exhibit superior durability in containment tests, showing no permeability loss after decades, whereas vegetated variants require periodic integrity checks for root desiccation channels that can accelerate liner degradation upon plant die-off.^[73] Comparative field data from slope stabilization trials indicate that while grass cover initially cuts sediment yield by up to 78% versus bare soil, long-term benefits diminish without intervention, as root decay fosters preferential flow paths during spills.^[74] Although re-greening suits low-hazard bunds by enhancing soil cohesion without liners, its application to primary containment structures remains secondary to engineering primacy, with regulatory pushes for vegetation—often driven by sustainability mandates—elevating costs by 15-25% for seeding and upkeep without demonstrable improvements in spill capture efficacy.^[75] Industry guidelines emphasize grass-only protocols to balance erosion control against integrity risks, critiquing broader eco-requirements for prioritizing superficial environmental aesthetics over causal spill prevention mechanics.^[76]^[77]

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Bund integrity testing, required every three years, uses hydrostatic testing, and ORS provides an integrity report and remedial program.Missing: assessment | Show results with:assessment
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Bund Integrity Testing - What You Need to Know | First Mats UK
Jun 29, 2023 · When conducting a bund integrity test, start with a visual inspection to identify any signs of chemical leakage or other debris within the bund.Missing: assessment | Show results with:assessment
[38]
Bund testing “vital” to effective and compliant PPM says AQS
Mar 29, 2018 · Hydrostatic testing gives customers assurance that their bunding has been tested to all required standards, including those stipulated by the ...
[39]
Secondary containment for each container under SPCC | US EPA
May 22, 2025 · No, separate containment systems are not required for each container. A common collection area can be used for multiple containers.
[40]
Drum Bund Regulations | ESE Direct
Drip trays are shallow pans that are used to collect any small spillages or leaks of liquid from drums and are considered to be mini-bunds. They are implemented ...
[41]
Keep it All In: How to Bund with Confidence - The Chemical Engineer
Oct 7, 2019 · A chemical bund is a structure which surrounds and underlies an area containing hazardous chemicals or liquids, providing secondary containment in the event of ...
[42]
On the choice between walls and berms for road traffic noise ...
Apr 15, 2012 · Both reduce noise levels by preventing direct sound propagation between source and receiver, forcing sound to diffract around the barrier edges ...
[43]
Effects of the soil on the noise attenuation of environmental berm ...
Oct 1, 2011 · Berm mounds are a commonly used technique to reduce the environmental noise levels produced by highways. A berm is a natural noise barrier ...<|separator|>
[44]
[PDF] Guidelines for the Use of Earth Berms to Control Highway Noise
Earth berms are a preferred noise mitigation method, but may have a 3 dBA bonus. They can't be as close to the source as walls, and may have 2 dBA less noise ...
[45]
[PDF] EFFECTIVENESSOF NOVEL SHAPED BUNDS IN REDUCING ...
Earth bunds are widely used for noise control. Modeling was used to identify acoustically efficient novel shapes. At 1.5m receiver height, over 5dB increase in ...
[46]
Landscaping, Earth Berms and Sound Walls - eNoise Control
Studies have shown that an earth berm is about 2 dBA less effective at reducing noise than a sound wall erected at the same height.
[47]
[PDF] Earthen Berm Noise Reduction Analysis - NET
Oct 31, 2016 · Earthen berms that mitigate noise are less expensive to construct and maintain than structural concrete and fiberglass noise walls, but there is ...
[48]
NAE Website - Engineering Controls for Reducing Workplace Noise
Sep 1, 2007 · Typically, low-frequency sounds are attenuated by less than 5 dB, whereas high-frequency sounds can be attenuated by as much as 20 dB. The ...Missing: bunds | Show results with:bunds
[49]
Acoustic Bunds - Geosynthetics
A well-known method of reducing this noise pollution is the use of acoustic bunds. These mounds of soil usually feature at the boundary of a site, with the aim ...Missing: shielding | Show results with:shielding
[50]
[PDF] containment of bulk hazardous liquids at comah - SEPA
For example a bund containing 60 000 m3 of tankage in 12 tanks would require 15 000 m3 of bund capacity under the 25% rule and 5 500 m3 under the 110% rule.
[51]
What are the specifications for bulk storage secondary containment ...
May 13, 2025 · For purposes of the SPCC requirements, secondary containment for bulk storage facilities must be constructed to at least provide for the ...
[52]
Directive - 2012/18 - EN - Seveso III - EUR-Lex
Directive 2012/18/EU of the European Parliament and of the Council of 4 July 2012 on the control of major-accident hazards involving dangerous substances.Missing: bunding | Show results with:bunding
[53]
[PDF] When bunding costs too much - Tank Storage Association
• Protects against loss of secondary containment by overtopping for multi-tank incidents (but remember individual bunding is preferable!) • Why 25%? – one ...Missing: analysis | Show results with:analysis
[54]
When bunding costs too much: A COMAH inspired case study
Jan 22, 2018 · Multi-tank bunds – an increased risk ; “multi-tank bunds are almost · times more ; “Bund effectiveness in preventing escalation of tank farm fires” ...
[55]
[PDF] an empirical investigation of - LJMU Research Online
is suggested for the height of the bund wall required to provide 100 % containment, this of course assumes that bund overtopping or spigot flow Oetting) does ...
[56]
Sulphuric Acid Emergency Spill Response Case Study | LCM
Sep 2, 2023 · The spill was caused by a pump failure, leading to 100,000L of sulphuric acid and water filling up the bund and staying contained until our team ...
[57]
https://safewastesolutions.com/blogs/news/spill-bund-maintenance-the-overlooked-critical-success-factor
[58]
[PDF] Assessing and Mitigating the Risks from Bund Overtopping - IChemE
This paper describes a methodology to account for the effect of low wall bunds on the risks from catastrophic tank failures. Liverpool John Moores University ( ...Missing: 1990s history
[59]
[PDF] COMAH - Buncefield: Why did it happen? - IChemE
Dec 11, 2024 · A vapour cloud formed which ignited causing a massive explosion and a fire that lasted five days. The gauge had stuck intermittently after the ...
[60]
[PDF] Developments in thinking about emergency liquid containment ...
The paper considers the demands placed on these systems in an emergency and give an indication of solutions which in the Authors opinion are appropriate.
[61]
Learnings from the Buncefield oil storage depot explosion - Gexcon
Pipework penetrations and a lack of fire-resistant bund joints meant that many bunds would fail during a prolonged fire. The failures highlight the following ...
[62]
Numerical investigation of bund overtopping under storage tank ...
The main failure causes were by lightning (33 % ) and human errors including poor operations and maintenance (30 % ). The rest was consequence of equipment ...Missing: statistics | Show results with:statistics
[63]
[PDF] Tank Fires - DiVA portal
Jan 2, 2010 · If the tank is full, there is also a problem with overflowing product causing fires in the bund area resulting in very complex fire situations ...Missing: poor | Show results with:poor
[64]
[PDF] Methods of avoiding tank bund overtopping using computational ...
This paper looks into the following aspects of the bunds as secondary containment of a hazardous material storage area: – requirements of the bunds (statutory ...
[65]
Spills & Accidental Releases - API.org
Total petroleum industry spillage has decreased consistently over the last 40 years. Seventy-seven percent less oil is spilling since the 1970s and 54% less ...Missing: bunds | Show results with:bunds
[66]
[PDF] Chapter 4 Secondary Containment and Impracticability - EPA
Dec 16, 2013 · The containment design, sizing, and freeboard requirements are specified by the SPCC rule to address a major container failure. The general ...
[67]
Using Vegetation for Erosion Control on Construction Sites
Vegetation controls erosion by intercepting rain, reducing runoff, and anchoring soil with its root system, limiting soil detachment and transport.Missing: industrial spill bunds
[68]
Experimental Study on the Effects of Vegetation and Slope on ...
Furthermore, vegetation cover effectively reduces runoff rates, with cumulative runoff volume decreasing by 13%, 40%, and 53.2% at 30, 60, and 90 days.Missing: industrial | Show results with:industrial
[69]
Soil erosion comparison: vegetated vs bare land | Alison Baker
Feb 25, 2025 · Roots hold soil particles, reducing erosion by up to 80% on slopes. ... Their dense roots trap sediments, reduce erosion, and absorb wave energy.
[70]
What are the requirements for a bund? - TSM
Mar 27, 2022 · Any plant growth within the bund should be removed and the defect repaired as It is highly probable that the root system has taken hold through ...
[71]
Technical Manual for Dam Owners: Impacts of Plants on Earthen ...
Tree and woody vegetation penetrations of earthen dams and their appurtenances have been demonstrated to be causes of serious structural deterioration and ...
[72]
[PDF] Technical Manual for Dam Owners - ASDSO Lessons Learned
Tree and woody vegetation can cause serious structural deterioration and distress, potentially leading to failure of earthen dams.
[73]
Bund Linings: Repairs, Refurbishments & Guidelines - Strandek
Adequate design of a bund is as important as the bund itself. A historical assessment of failed bunding systems provides the basis for careful design. • ...
[74]
The Effect of Vegetation Restoration on Erosion Processes and ...
Our study found that the sediment yield reduction contribution of the slope with 60% vegetation coverage was as high as 78% compared with the bare-soil slope ...2. Materials And Methods · 3. Results · 3.1. Runoff And Sediment...
[75]
Comparison of Vegetation Types for Prevention of Erosion and ...
Another difference with studies on bare slopes was in the pattern of erosion. On bare slopes, higher erosion rates are typically observed near the bottom of ...
[76]
Ground Cover - Association of State Dam Safety Officials
The uncontrolled growth of vegetation can damage embankments and concrete structures and make close inspection difficult. Grass vegetation is an effective and ...
[77]
Common Problems at Dams - Trees | DWEE NE
Trees should not be planted or allowed to grow on dams. Tree root systems create pathways for water and can damage dams if they are uprooted.