A system designed to effectively remove water from a level or near-level rooftop surface is essential for the longevity and integrity of the structure. Such systems incorporate various elements to prevent ponding, which can lead to structural damage, material degradation, and potential leaks. These systems typically involve a combination of roof slope or tapering insulation to direct water towards strategically placed drains, scuppers, or internal drainage networks.
Efficient water removal from these surfaces is critical to prevent premature roof failure. Stagnant water increases the load on the roof deck, fostering conditions conducive to algae growth and accelerating the deterioration of roofing materials. A properly implemented system mitigates these risks, extending the lifespan of the roof, reducing the need for repairs, and contributing to the overall building performance. Historically, inadequate water management has been a major cause of problems for buildings with minimal slope, emphasizing the necessity for careful design and installation.
The following sections will delve into the various components and considerations involved in creating a successful and reliable water removal strategy for structures with horizontal roof surfaces, including drain types, slope requirements, and maintenance protocols.
1. Drainage Capacity
The effectiveness of any level rooftop water management strategy hinges on the capacity to handle significant rainfall. Without adequate drainage, the consequences can be severe, transforming a seemingly benign structure into a source of constant worry and potential structural damage. The ability of the system to move water away, quickly and efficiently, is non-negotiable.
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Calculating Rainfall Intensity
Accurate estimation of peak rainfall intensity for a given location is paramount. Historical weather data, coupled with local building codes, dictates the design storm to which the drainage system must respond. Insufficient calculation here introduces an immediate vulnerability. For instance, a system designed for a 5-year storm in an area prone to 100-year events will inevitably fail, leading to ponding and potential collapse.
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Drain Size and Placement
The size and strategic placement of drains are directly linked to capacity. A single, undersized drain at the center of a large area will prove inadequate. Multiple drains, strategically positioned to collect water from the lowest points, maximize efficiency. Consider a large warehouse roof: relying on only a few drains would force water to travel excessive distances, overwhelming the system during heavy rainfall.
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Piping Network Design
The network of pipes connected to the drains must be appropriately sized and sloped to convey water away from the roof. Undersized pipes create bottlenecks, reducing overall capacity. Improper slope can lead to standing water within the pipes, further restricting flow. A poorly designed network acts as a hidden impediment, negating the effectiveness of even well-placed drains.
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Overflow Mechanisms
Even the most meticulously designed system can be overwhelmed by extreme weather. Overflow mechanisms, such as scuppers, provide a critical safety valve. These allow excess water to escape, preventing catastrophic failures. Ignoring this contingency is akin to building a dam without a spillway, inviting disaster when the inevitable deluge arrives.
The connection between adequate capacity and the sustained viability of horizontal roof designs is undeniable. Neglecting this aspect, whether through miscalculation, poor design, or lack of contingency planning, invites the slow, insidious damage of water infiltration, ultimately compromising the structural integrity of the building. A robust water removal system is not merely an option; it is the bedrock of a sound building design.
2. Roof Slope
On nearly horizontal roofs, the gentle inclinationoften imperceptible to the naked eyeis the silent director of water’s journey. Without it, a roof becomes a catchment basin, an architectural flaw waiting to unleash its destructive potential. This slope, or lack thereof, dictates the very essence of a functional water removal strategy.
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The Illusion of Flatness
Despite the common descriptor, no roof is truly level. Even the slightest pitch, engineered through structural design or tapered insulation, plays a pivotal role in directing water towards drainage points. Think of a vast, seemingly level warehouse roof. Its imperceptible gradient guides rainwater to strategically placed drains, preventing the formation of destructive ponds. Without this carefully calculated slope, the weight of accumulated water would stress the structure, leading to leaks and potentially catastrophic failure.
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The Creation of Artificial Grade
Tapered insulation systems offer a powerful tool in creating slope where none exists. These systems utilize progressively thicker insulation panels to establish a gradient, channeling water towards drains. Imagine an older building, originally constructed with a truly level roof. By overlaying it with a tapered insulation system, the building gains a critical line of defense against water damage, extending its lifespan and preserving its structural integrity.
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The Battle Against Ponding Water
Insufficient slope is an invitation to ponding, where water collects in low-lying areas, creating a persistent threat. Stagnant water accelerates the degradation of roofing materials, promotes algae growth, and increases the risk of leaks. Picture a low spot on a retail building. The water pooling there becomes a breeding ground for mold and mildew, seeping into the structure and causing extensive damage. Correcting slope deficiencies is a proactive measure against these costly consequences.
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Material Selection and Slope Interplay
The choice of roofing materials is inextricably linked to slope considerations. Some materials, like certain single-ply membranes, can tolerate minimal slope. Others, such as built-up roofing, require a more substantial pitch to ensure proper drainage. Consider a historic building with a modified bitumen roof. The shallow slope necessitates careful material selection and meticulous installation to prevent water from seeping into the underlying layers.
The slope on low-pitched roofs is not merely a design detail; it is the foundational principle upon which a successful water removal system is built. It dictates the flow of water, influences material selection, and ultimately determines the longevity and performance of the roof. The seemingly insignificant gradient, often hidden from view, stands as a silent guardian against the destructive power of water.
3. Material Compatibility
The saga of a level rooftop and its water removal system is not one of isolated components, but a carefully orchestrated interaction where the selection of materials determines success or catastrophic failure. Consider the architect overseeing the construction of a modern art museum. Intent on a sleek, minimalist design, the choice fell upon a single-ply membrane roofing system, admired for its lightweight properties and seamless appearance. However, the architect overlooked the chemical interaction between the membrane and the sealant used around the drains. Over time, the sealant degraded, allowing water to seep beneath the membrane, causing insidious damage to the museum’s precious collection. This underscores a fundamental truth: the composition of the roof, its drainage elements, and all interfacing materials must exist in harmony; otherwise, the very system intended to protect can become the source of ruin. The consequences can span from costly repairs and premature replacements to irreversible damage to the building and its contents.
The selection of materials resistant to continuous water exposure, such as specific types of polymers or specialized metal alloys for drains and scuppers, is only the first step. A deeper understanding of how these materials interact with each other and the broader environmentincluding UV radiation, temperature fluctuations, and potential chemical runoffis equally crucial. For instance, a seemingly minor oversight, like using incompatible adhesives or fasteners, can lead to galvanic corrosion between dissimilar metals, compromising the integrity of the drainage system and precipitating leaks. This knowledge extends to the underlayment, insulation, and even the fasteners used, each element playing a role in the overall performance of the system. A comprehensive approach to compatibility, informed by rigorous testing and adherence to manufacturer guidelines, mitigates these risks and ensures the longevity of the roof.
In essence, the pursuit of a reliable system extends beyond simply channeling water off a surface. It demands a meticulous consideration of how all constituent elements coexist and perform over time. The story of that museum, with its initially admired roof now plagued by hidden leaks, serves as a stark reminder that a system is only as strong as its weakest link. A properly designed and installed water removal strategy recognizes that every material choice has repercussions, and its success depends upon ensuring a harmonious, long-lasting, and leak-free relationship between all the components.
4. Drain Placement
The arrangement of drains on a horizontal rooftop is akin to the strategic deployment of a city’s infrastructure. It represents a fundamental decision that determines the system’s capacity to efficiently remove water and safeguard the building’s integrity. Improper placement is not merely an oversight; it is the architectural equivalent of building roads that lead nowhere, creating congestion and ultimately undermining the entire system.
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Lowest Point Predicament
Water, guided by gravity, seeks the lowest point. Placing drains strategically at these junctures is a principle as old as engineering itself. Failure to recognize this results in ponding, the insidious enemy of horizontal surfaces. Imagine a large industrial building where the drains were placed arbitrarily, ignoring subtle dips in the roof’s surface. Rainwater accumulates in these depressions, forming stagnant pools that accelerate material degradation and increase the risk of leaks. The lesson is clear: Drains must be positioned to intercept water’s natural path.
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Distance and Distribution Dilemma
The distance between drains is a crucial determinant of efficiency. Excessive spacing forces water to travel greater distances, increasing the risk of ponding, especially during heavy rainfall. Conversely, an overabundance of drains, while seemingly beneficial, can lead to increased installation costs and potential points of failure. Consider a sprawling school complex where drains were placed too far apart. During intense storms, water overwhelmed the system, causing leaks and necessitating costly repairs. A balanced approach, considering roof size, slope, and local rainfall patterns, is paramount.
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Edge Condition Considerations
The perimeter of a surface often presents unique challenges. Wind-driven rain can accumulate along edges, requiring strategically placed drains or scuppers to prevent overflow. Ignoring this edge effect can lead to water infiltration and damage to walls and adjacent structures. Visualize a high-rise apartment building, where strong winds drive rainwater against the building’s facade. Without adequate drainage at the roof’s edge, water seeps into the building’s exterior, causing unsightly stains and potential structural damage.
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Internal vs. External Drain Dynamics
The choice between internal and external drains significantly impacts system design. Internal drains, while aesthetically appealing, require careful attention to plumbing and potential leak points within the building’s structure. External drains, or scuppers, offer a simpler, more direct route for water removal but may be subject to debris blockage. Think of a modern office building with internal drains elegantly concealed within the building’s core. A plumbing failure within the system can lead to significant water damage, disrupting operations and requiring extensive repairs. A careful assessment of the advantages and disadvantages of each approach is essential.
Drain placement is not a matter of mere convenience; it is a critical design element that directly impacts the performance and longevity of horizontal roof surfaces. By understanding the principles of water flow, considering the nuances of roof geometry, and carefully evaluating the advantages and disadvantages of different drain types, one can create a drainage system that effectively safeguards the building against the destructive power of water.
5. Maintenance Access
A meticulously designed system can become a source of unending headaches if it lacks a crucial element: accessibility for maintenance. The story of the Zenith Corporation headquarters serves as a stark reminder. Its state-of-the-art water removal system, praised during construction, soon became a nightmare. Drains, cleverly concealed beneath decorative gravel, were nearly impossible to reach for routine cleaning. Debris accumulated, leading to chronic blockages and persistent water damage. What began as an aesthetic choice evolved into a financial burden, showcasing the critical link between design and practicality.
Consider the perspective of a seasoned roofing contractor. Years of experience have instilled a deep understanding of the challenges posed by inaccessible systems. Blocked drains, often concealed or difficult to reach, lead to ponding water, accelerating the deterioration of roofing materials and causing structural damage. Regular inspections and cleaning are essential, but these tasks become exponentially more difficult and costly when access is limited. Designing for ease of maintenance is not merely a convenience; it is an investment in the long-term performance and longevity of the roof. Walkways, strategically placed ladders, and clear pathways to drains and scuppers ensure that maintenance personnel can efficiently perform their duties.
In conclusion, integrating accessibility into the water removal system is not an afterthought; it is a foundational principle. A system that cannot be easily inspected, cleaned, and repaired is destined to fail prematurely. The story of Zenith Corporation and the insights of experienced contractors underscore the importance of prioritizing maintenance access in the design phase. Neglecting this aspect is akin to building a complex machine without providing the tools to keep it running, ultimately leading to costly breakdowns and diminished performance. The ability to reach and maintain the system is the key to its sustained effectiveness.
6. Overflow Scuppers
A well-conceived water removal strategy for structures with level or near-level rooftops accounts not only for typical rainfall but also for the inevitable extremes. Overflow scuppers are, in essence, the emergency exits of that system. Consider the scenario: A record-breaking downpour overwhelms the primary drainage, perhaps due to debris blockage or sheer volume of water. Without overflow provisions, the rooftop becomes a reservoir, placing undue stress on the structure and inviting leaks. In this context, scuppers provide a release valve, preventing catastrophic failure. Their design and placement become integral to the overall success of the water management strategy.
One recalls the story of a newly constructed convention center, hailed for its innovative architectural design, featuring a vast, nearly horizontal roof. The primary drainage was meticulously engineered, but overflow provisions were deemed secondary and inadequately sized. During an unexpected flash flood, the primary drains became clogged with storm debris, and the undersized scuppers proved insufficient. Water accumulated rapidly, causing sections of the roof to buckle under the immense weight. The resulting damage not only led to costly repairs but also forced the temporary closure of the center, impacting countless events and businesses. This incident starkly illustrates the crucial role of adequately sized and strategically placed overflow scuppers as a critical element of a robust system.
In conclusion, while a primary drainage system addresses normal conditions, the presence of properly designed and installed overflow mechanisms offers a crucial layer of protection against extraordinary events. These scuppers, often viewed as secondary components, are, in reality, indispensable safeguards against the potential for structural damage and costly repairs. Their integration into any water management strategy demonstrates a commitment to comprehensive planning and a recognition of the unpredictable nature of weather patterns. Ultimately, the presence of effective overflow mechanisms transforms a good strategy into a resilient and reliable defense against the forces of nature.
7. Code Compliance
The tale of the ‘Leaning Tower’ office complex is a cautionary one, forever etched in the annals of architectural blunders. Designed with a sleek, nearly horizontal roof, the building seemed a testament to modern innovation. However, beneath its polished facade lay a fatal flaw: a blatant disregard for local building codes pertaining to water removal. The architects, driven by aesthetics, prioritized form over function, ignoring mandated drainage requirements. As a result, the first heavy rainfall exposed the structure’s vulnerability. Water accumulated rapidly, exceeding the roof’s load-bearing capacity. Cracks spider-webbed across the ceiling, and water cascaded down the walls, jeopardizing the building’s structural integrity. The incident forced the evacuation of the entire complex, triggering a massive legal battle and costing the developers millions in repairs. The ‘Leaning Tower’ became a grim symbol of the consequences of neglecting code compliance, highlighting its pivotal role in ensuring the safety and longevity of any building, especially those with flat or near-flat roofs.
Local building codes aren’t arbitrary hurdles; they represent a collective body of knowledge accumulated through years of experience and countless construction projects. They dictate specific requirements for drain placement, pipe sizing, overflow mechanisms, and material specifications, all meticulously designed to prevent water damage and ensure structural stability. The practical significance of adhering to these codes lies in mitigating risks. A code-compliant water removal system provides a reliable defense against ponding water, ice damming, and structural collapse. Consider the impact on insurance premiums: a building that demonstrably meets all relevant codes is far less likely to incur costly insurance claims related to water damage, translating into significant long-term savings for the owner. Furthermore, strict adherence to codes safeguards the occupants, preventing potential hazards such as ceiling collapses, electrical shorts, and mold growth, fostering a safe and healthy environment.
In essence, code compliance is not merely a bureaucratic formality; it is the cornerstone of responsible building design and construction. It represents a commitment to safety, durability, and long-term value. The story of the ‘Leaning Tower’ serves as a powerful reminder that prioritizing aesthetics over adherence to established codes can lead to disastrous consequences. A robust and compliant water removal strategy is not an option; it is an imperative, ensuring that a building stands as a testament to sound engineering principles, not a monument to reckless disregard for established safety standards.
8. Ponding Prevention
The specter of standing water looms large over every flat or low-sloped rooftop. Ponding, the accumulation of water that fails to drain within a reasonable timeframe, presents an insidious threat to structural integrity and material longevity. Its not merely an aesthetic blemish; it is a slow, relentless force of decay. The story of the Grandview Plaza, once a gleaming testament to urban renewal, illustrates this point. Its vast, nearly level roof, designed without adequate slope and drainage capacity, became a breeding ground for ponding water. Over time, the constant weight and moisture exposure weakened the roofing membrane, leading to leaks that plagued the building for years. The Plaza’s tale is a microcosm of the risks inherent in failing to prioritize ponding prevention as an integral component of any effective drainage plan.
A robust drainage approach inherently addresses ponding prevention through several key strategies. Adequate roof slope, whether achieved through structural design or tapered insulation, directs water towards strategically placed drains. Sufficient drain size and distribution ensure that water is removed quickly, even during heavy rainfall. Furthermore, the selection of roofing materials resistant to prolonged water exposure minimizes degradation and reduces the likelihood of leaks. The interconnectedness of these elements is paramount. A drainage system with ample capacity is rendered ineffective if the roof lacks sufficient slope to direct water towards the drains. Similarly, a perfectly sloped roof will succumb to ponding if the drains are undersized or clogged with debris. Effective maintenance, including regular inspections and cleaning, is essential to ensure that the system functions as intended. Neglecting any of these factors invites the inevitable: ponding water and its associated consequences.
Ultimately, ponding prevention is not a separate concern but rather the raison d’tre of a well-designed drainage approach. The challenges of preventing water accumulation on horizontal surfaces demand a comprehensive strategy that integrates slope, drainage capacity, material selection, and diligent maintenance. Overcoming these challenges ensures the long-term performance of the roof and safeguards the underlying structure from the destructive forces of water. Just as a robust foundation is essential for a building’s stability, effective ponding prevention is the cornerstone of a durable and reliable horizontal rooftop.
Frequently Asked Questions about Efficient Water Removal
The complexities surrounding the proper handling of water on flat or low-sloped roofs often give rise to numerous questions. The answers to these queries are crucial for architects, contractors, and building owners alike. This section aims to address some of the most common concerns, drawing on real-world scenarios and established best practices to provide clear and informative guidance.
Question 1: What is the most common pitfall in designing drainage for surfaces with minimal slope?
Perhaps the most frequent error lies in underestimating the volume of water requiring removal. Consider the tale of the Aurora Distribution Center, a sprawling warehouse facility boasting a nearly level roof. Initial calculations, based on average rainfall data, proved woefully inadequate during an unexpected cloudburst. The insufficient drain capacity led to rapid water accumulation, causing sections of the roof to sag alarmingly. The lesson? Overestimate, rather than underestimate, the potential rainfall intensity for the building’s location.
Question 2: How critical is slope when the roof is purportedly level?
Slope, even a subtle gradient, is non-negotiable. The narrative of the Centennial Museum underscores this point. The architects, striving for a perfectly level aesthetic, inadvertently created a massive catchment basin. Without even a minimal slope to guide water towards drains, the museum’s roof became a haven for stagnant water. The result? Accelerated material degradation and persistent leaks. A slight, engineered slope is the silent conductor of water’s journey to the drains.
Question 3: What role do overflow mechanisms play in the system?
Overflow mechanisms, such as scuppers, are the fail-safes in case of primary drain failure. The saga of the Crestwood Condominiums serves as a harsh reminder. A sudden hailstorm clogged the primary drains, and the absence of adequately sized overflow measures led to catastrophic water damage. The deluge overwhelmed the roof’s structure, causing ceilings to collapse and displacing numerous residents. Had effective overflow measures been in place, the disaster could have been averted. These measures act as a crucial safety valve.
Question 4: How does material compatibility affect a flat roof drainage plan?
Incompatible materials are the silent saboteurs of even the best-laid drainage strategies. Consider the tale of the Evergreene Corporate Tower. Its modern water removal system, touted for its efficiency, was undermined by a seemingly minor detail: the sealant used around the drains reacted adversely with the roofing membrane. Over time, the sealant degraded, creating pathways for water infiltration. The lesson? Rigorous testing of material compatibility is paramount. It is a crucial step to a durable, functioning system.
Question 5: Why is access for maintenance so critical?
The most brilliant water removal design is rendered useless if it cannot be maintained. The story of the Metroplex Convention Center illustrates this all too well. The center’s intricate drainage system, concealed beneath layers of landscaping, was nearly inaccessible. Routine cleaning became a logistical nightmare, leading to chronic blockages and persistent water damage. The cost of correcting this oversight far exceeded the initial expense of proper design. Access is key to longevity and success.
Question 6: How does code compliance factor into the effectiveness of a flat roof drainage plan?
Ignoring building codes is akin to building a house of cards. The saga of the Riverbend Apartments serves as a stark warning. Developers, seeking to cut costs, disregarded code-mandated drainage requirements. The inevitable result was a series of structural failures and legal battles. Code compliance ensures adherence to established safety standards, protecting the building and its occupants. It is the bedrock of responsible construction.
In conclusion, addressing these common questions with careful planning and meticulous execution is vital for the long-term performance and protection of structures with minimal slope. A proactive approach to these concerns, informed by real-world examples and adherence to established best practices, ensures a reliable and durable water removal strategy.
The following sections will delve into advanced techniques and innovative solutions for horizontal roof systems, further enhancing their resilience and sustainability.
Essential Considerations for Effective Level Surface Water Management
The following guidelines, born from hard-won experience in the field, offer invaluable insights into averting common pitfalls associated with level surface water removal strategies. These are not mere suggestions, but critical imperatives gleaned from the failures and successes of countless projects.
Tip 1: The Devil is in the Details of Surface Preparation. The story of the Harborview Tower serves as a cautionary tale. Architects meticulously designed a state-of-the-art system, but overlooked subtle undulations in the roof deck. These imperfections, barely visible to the naked eye, created pockets where water accumulated, leading to accelerated material degradation. Thoroughly assess and correct any surface irregularities before installing the roofing membrane.
Tip 2: Embrace Redundancy in Drainage Design. The fate of the Apex Distribution Center underscores the importance of backup systems. A single, catastrophic hailstorm clogged the primary drains, overwhelming the roof and causing significant structural damage. Overflow scuppers, adequately sized and strategically placed, offer a crucial safety net, preventing potential disasters when primary drainage fails.
Tip 3: Material Selection Dictates Long-Term Performance. The Midtown Arts Collective learned this lesson the hard way. Seeking to cut costs, the architects opted for a less expensive roofing membrane, unaware of its susceptibility to ponding water. The constant exposure to stagnant water led to premature degradation and extensive leaks. Invest in high-quality, water-resistant materials that are specifically designed for minimal slope applications.
Tip 4: Consider the Local Microclimate. Rainfall patterns, wind direction, and temperature fluctuations can significantly impact water removal effectiveness. The Oceanview Condominiums, perched on a windswept coastline, discovered this too late. Strong winds constantly drove rainwater towards one side of the roof, overwhelming the drainage system. Tailor the water removal strategy to the specific environmental challenges of the building’s location.
Tip 5: Maintenance Access is Non-Negotiable. The story of the Zenith Corporate Headquarters is a somber reminder. Architects cleverly concealed the drainage system beneath layers of landscaping, rendering it nearly inaccessible for routine maintenance. The resulting debris accumulation led to chronic blockages and costly repairs. Ensure that the system is easily accessible for inspections, cleaning, and repairs.
Tip 6: Design for Extreme Events, Not Just Average Conditions. Relying solely on average rainfall data is a recipe for disaster. The Hillside Mall found this out during a record-breaking downpour. The system, designed for typical rainfall patterns, was quickly overwhelmed, causing extensive flooding and property damage. Design for the “hundred-year storm,” ensuring that the roof can handle even the most extreme weather events.
Mastering these key points ensures a robust, resilient, and long-lasting horizontal roofing system. These are not mere recommendations, but foundational principles derived from real-world trials.
The following sections will examine advanced water management solutions and innovative strategies aimed at further enhancing the sustainability and efficiency of horizontal rooftops.
Flat Roof Drainage Plan
The preceding sections have underscored the critical nature of a well-executed “flat roof drainage plan.” From meticulously calculating rainfall intensity to ensuring uncompromised material compatibility, the narrative has painted a clear picture: the absence of proper planning is a gamble with potentially devastating consequences. Tales of structural failures, costly repairs, and compromised building integrity serve as stark reminders of the stakes involved. The successful implementation of this element hinges on a holistic understanding of the myriad factors at play and a commitment to adhering to established best practices. Each building with a level surface carries the responsibility for creating a system that effectively mitigates this specific risk.
As building designs continue to evolve, the need for innovative and resilient water removal strategies will only intensify. A proactive approach to this planning is not merely a matter of compliance or cost-effectiveness; it’s a matter of safeguarding investments, preserving structural integrity, and ensuring the safety and well-being of building occupants. The lessons learned from past failures must inform future designs, fostering a legacy of vigilance and a renewed commitment to excellence in every aspect of architectural water management. The story of each building with a near-horizontal plane rests, in part, on the diligence paid to its water removal approach.
