Building Offset Code Analysis 152 and York Streets Thornton, Colorado · 2015-03-27 · 1 Building Offset Code Analysis 152nd and York Streets Thornton, Colorado Prepared For: Jansen

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Building Offset Code Analysis 152nd and York Streets Thornton, Colorado

Prepared For:

Jansen Strawn Consulting Engineers

45 W. 2nd Avenue

Denver, CO 80223

Prepared By:

Kerry L. Madigan, P.E.

Sr. Fire Protection Engineer

Veritas Fire Engineering, Inc.

12364 West Alameda Parkway, Suite 135

Lakewood, Colorado80228

Rev. 0: February 3, 2014

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Introduction

Veritas Fire Engineering was tasked by Jansen Strawn Consulting Engineers, Inc. to investigate fire and building code requirements with respect to building offset from two oil wells and associated equipment, and potential variances to such code-mandated building offsets for new building construction. The two existing oil wells are regulated by Colorado Oil and Gas Conservation Commission. The Authority Having Jurisdiction (AHJ) with respect to building offset requirements from oil wells is the City of Thornton Fire Department and the applicable adopted codes are:

2012 International Fire Code (IFC)

2012 International Building Code (IBC)

2012 Thornton Fire Code Amendments.

This code analysis summarizes the findings of Veritas Fire Engineering with respect to fire and building code requirements for building offset and allowable variances. Veritas Fire Engineering will examine the following topics within this document:

Building offset distances as mandated by code requirements

Alternative materials and methods to reduce separation distances

Levels of safety of the proposed alternatives to determine equivalency.

Alternatives must provide an equivalent level of safety to adjacent buildings and occupants and must be

approved by the AHJ in accordance with code requirements. Applicable chapters within the 2012 IFC

and amendments include, but are not necessarily limited to:

Chapter 50 Hazardous Materials General Provisions

Chapter 57 Flammable and Combustible Liquids.

The applicable National Fire Protection Association (NFPA) Standards include, but are not necessarily

limited to:

NFPA 30 Flammable and Combustible Liquids Code (2008 Edition).

In addition to code documents, the following sources are referenced in this code analysis:

Flammable and Combustible Liquids Code Handbook – NFPA 30 (2008 Edition)

SFPE Handbook of Fire Protection Engineering (4th Edition).

Code Mandates The 2012 International Fire Code (IFC) addresses well location, to include offset for buildings, within Chapter 57 Flammable and Combustible Liquids, Section 5706 Special Operations, subsection 5706.3 Well Drilling and Operating. Storage tanks associated with the drilling process must also comply with the following sections of Chapter 57:

Section 5703 General Requirements

Section 5704 Storage

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Well Location and Data

EXISTING STRIPPER WELLS – NORTH YORK #13-12 and #14-12 The two existing oil wells (including a common separator and oil tank) under investigation are regulated by the Colorado Oil and Gas Conservation Commission, and well data is available from the Colorado Oil and Gas Information System (COGIS). The oil wells are identified as the NORTH YORK #13-12 and the NORTH YORK #14-12 wells, and both of these wells are operated by Bayswater Exploration and Production LLC. The precise well locations are depicted in the following table:

Well Name Latitude Longitude

NORTH YORK #13-12 39.974729 -104.954674

NORTH YORK #14-12 39.974961 -104.954636

These oil wells will be located (subsequent to annexation) within the City of Thornton in Adams County, near the intersection of 152nd and York streets. The common separator feeds a 285-barrel crude oil storage tank. A stripper well is an oil well having a production rate of less than 10 barrels per day of oil, and less than 60,000 cubic feet of natural gas per day. Both of the above wells are stripper wells, having low production rates. EXISTING OIL WELL – WRIGHT # 1 Another existing oil well with a separate tank battery location is regulated by Colorado Oil and Gas Conservation Commission and well data is available from the Colorado Oil and Gas Information System (COGIS). The oil well is identified as the WRIGHT #1 and the separator facility is identified as the WRIGHT #1 TANK BATTERY, and both of these are operated by Bayswater Exploration and Production LLC. The precise locations are depicted in the following table: Well / Facility Name Latitude Longitude

WRIGHT #1 39.970225 -104.961736

WRIGHT #1 TANK BATTERY 39.970249 -104.961734

The WRIGHT #1 TANK BATTERY consists of two small facilities: a separator and a 300 bbl storage tank.

The WRIGHT #1 well is more than 500’ to the East of York St and so will not be considered within the

scope of this analysis.

The separator at the WRIGHT #1 TANK BATTERY is not considered within the scope of this analysis

because it is at a greater distance from the road than the crude oil storage tank, and because the

separator containment area is much smaller than the tank containment area. Surface area within the

containment area directly affects heat release rate (HRR) and flame height of a potential pool fire.

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Well Location and Data (Continued)

NORTH YORK #13-12 and #14-12 PRODUCTION DATA Recent monthly output data for these oil wells was obtained from COGIS and is depicted below:

Comingled Comingled Average Average Density Density

Well Year Month Oil (BOPM) Gas (MCFM) Oil (BOPD) Gas (MCFD) (API) (kg/m3)

North York 13-12 2013 January 25 0.8 0.0

North York 13-12 2013 February 125 946 4.5 33.8 54.1 762.3922

North York 13-12 2013 March 54 2752 1.7 88.8 46 797.1831

North York 13-12 2013 April 62 3313 2.1 110.4 45.6 798.9836

North York 13-12 2013 May 62 1491 2.0 48.1 45.1 801.2458

North York 13-12 2013 June 2 1146 0.1 38.2 46.1 796.7342

North York 13-12 2013 July 55 1047 1.8 33.8 47.7 789.6205

North York 13-12 2013 August 158 1025 5.1 33.1 47.7 789.6205

North York 13-12 2013 September 58 1721 1.9 57.4 48.7 785.2386

North York 13-12 2013 October 74 2079 2.4 67.1 47.1 792.2732

North York 13-12 2013 November 81 1727 2.7 57.6

North York 13-12 2013 December 0.0 0.0

North York 13-12 2013 Average 75.6 1724.7 2.50 56.8 47.6 790.4

Average Average Density Density

Well Year Month Oil (BOPM) Gas (MCFM) Oil (BOPD) Gas (MCFD) (API) (kg/m3)

North York 14-12 2013 January 50 1.6 0.0

North York 14-12 2013 February 90 67 3.2 2.4 54.1 762.3922

North York 14-12 2013 March 69 196 2.2 6.3 46 797.1831

North York 14-12 2013 April 55 1813 1.8 60.4 45.6 798.9836

North York 14-12 2013 May 55 364 1.8 11.7 45.1 801.2458

North York 14-12 2013 June 0.0 0.0 46.1 796.7342

North York 14-12 2013 July 0.0 0.0 47.7 789.6205

North York 14-12 2013 August 153 1025 4.9 33.1 47.7 789.6205

North York 14-12 2013 September 49 851 1.6 28.4 48.7 785.2386

North York 14-12 2013 October 58 1027 1.9 33.1 47.1 792.2732

North York 14-12 2013 November 65 841 2.2 28.0

North York 14-12 2013 December 0.0 0.0

North York 14-12 2013 Average 71.6 773 2.36 25.4 47.6 790.4

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Process and Storage Description –North York #13-12 and #14-12

There are two separators within the separator facility surrounded by a compacted soil berm. Output

from the two wells is routed to a common gas/liquid separator by underground pipelines. The natural

gas output from the gas/liquid separator is routed offsite via underground natural gas pipelines.

The liquids from the gas/liquid separator flow into an oil/water/gas separator. The gas from the

water/oil/gas separator goes to a continuously burning flare. The oil from the water/oil/gas separator is

routed to the 285-barrel oil storage tank by an underground pipeline. The water from the water/oil/gas

separator is routed to the produced water storage tank by an underground pipeline.

The storage facility associated with the two wells contains a 285-barrel oil storage tank with an outside

diameter of 15.5 feet and a produced water storage tank with an outside diameter of 10.0 feet. A

significant portion of each tank is below grade, thereby reducing the volume requirement for secondary

containment.

Any additional gas that comes from the oil storage tank is routed to the flare by underground pipeline.

Veritas Fire Engineering conducted a site visit to the wells on January 20th, 2014 and observed or

confirmed the following:

The aforementioned tank dimensions (diameters) were measured;

Secondary containment is provided with earthen berms (compacted soil), and the berms

appeared to be well maintained;

Two containment areas are in place, a small containment area surrounding the separator, and a

larger containment area surrounding both the crude oil and produced water tanks;

Containment areas appeared to be adequate to account for the portions of tank volumes that

are above grade;

There is no fencing around either the separator containment area or the containment area for

the crude oil and produced water tanks;

Crude oil at this well location is sweet crude, not sour crude, according to Bayswater;

The crude oil tank was labelled with an NFPA diamond in accordance with NFPA 704;

With respect to a potential pool fire in a containment area, the tank containment area (because of the larger surface area) represents a greater hazard than the separator containment area.

The dike dimensions were measured and the average depth was estimated in order to determine each respective containment area, A:

ATC = 1552 ft2 (Surface area of tank containment) ASC = 438 ft2 (Surface area of separator containment)

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Process and Storage Description – North York #13-12 and #14-12

(Continued) The tank footprint areas for the crude oil and water tanks were determined from the tank diameters as:

ACrude = 187 ft2 (Surface area of crude oil tank footprint) AWater = 79 ft2 (Surface area of water tank footprint)

The liquid surface area available in the event of a pool fire, Ap, in the tank containment area is determined using the relationship Ap = ATC - (ACrude + AWater). Thus, in the event of a pool fire in the containment area, the surface area of the pool is determined to be Ap = 1286 ft2.

Storage Description – Wright # 1 In the aforementioned site visit, Veritas Fire Engineering observed or confirmed the following with

respect to the tank storage containment area across York street, surrounding a 300-barrel oil tank and a

produced water tank:

Tank dimensions were measured, however the circumference (rather than the diameter) of the

crude oil tank was measured and found to be CCrude= 37.6 ft. The diameter of the water tank

was measured as DWater = 10 ft.

Secondary containment is provided with earthen berms (compacted soil), and the berms

appeared to be well maintained;

The secondary containment area surrounded both the crude oil tank and the water tank;

The containment area appeared to be adequate to account for the portion of the tank volumes

that are above grade;

There is no fencing around the containment area;

Crude oil at this well location is sweet crude, not sour crude, and the tank was labelled to

denote sweet crude;

The crude oil tank is labelled with an NFPA diamond in accordance with NFPA 704.

The dike dimensions were measured and the average depth was estimated in order to determine the respective containment area, A, as:

ATC = 1298 ft2 (Surface area of tank containment) The tank footprint areas for the crude oil and water tanks were determined from the tank dimensions as:

ACrude = 113 ft2 (Surface area of crude oil tank footprint) AWater = 79 ft2 (Surface area of water tank footprint)

The liquid surface area available in the event of a pool fire, Ap, in the tank containment area is determined using the relationship Ap = ATC - (ACrude + AWater). Thus, in the event of a pool fire in the containment area, the surface area of the pool is determined to be Ap = 1136 ft2.

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Code Requirements for Building Offset 2012 IFC WELL LOCATION REQUIREMENTS Chapter 57 of the 2012 IFC within Section 5706.3 Well Drilling and Operating addresses building offset within Section 5706.3.1 Location. Section 5706.3.1 mandates compliance with inner Section 5706.3.1.3 Buildings which is quoted in part:

“Wells shall not be drilled within 100 feet of buildings not necessary to the operation of the well”.

Section 5706.3.1.3 Buildingsalso has an inner section 5706.3.1.3.1 Group A, E or I Buildings that applies to these particular occupancy groups, which is quoted:

“Wells shall not be drilled within 300 feet of buildings with an occupancy in Group A, E or I”. Although these quotations address drilling of wells in the proximity of buildings, the same distances apply with respect to constructing a building in the vicinity of a well. This is mandated in Section 5706.3.1 Locationwithin inner Section 5706.3.1.3.2 Existing Wells, which is quoted in its entirety:

“Where wells are existing, buildings shall not be constructed within the distances set forth in Section 5706.3.1 for separation of wells or buildings”.

Section 5706.3.1.3.2 Existing Wells has been amended by the AHJ, Thornton Fire Department. The amended section is quoted below (with amended information underlined):

“Where wells are existing, buildings shall not be constructed within 200 feet of wells. Reductions in required separations may be approved based on alternative materials and methods that provide an equivalent level of safety to adjacent buildings and occupants. The alternative methods and materials shall be presented by a professional engineer or licensed architect, as applicable, as determined by Development Engineering and the Thornton Fire Department”.

STREETS AND RAILWAY OFFSET The 2012 IFC within Chapter 57, Section 5706.3 Well Drilling and Operating addresses additional location requirements beyond that of buildings. For example, if a new facility intends to incorporate streets or railways, compliance with inner Section 5706.3.1.2-Streets and Railways mandates an offset distance of 75 feet from either a street or railway.

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Code Requirements for Building Offset (Continued)

STORAGE TANK LOCATION Storage tanks associated with the drilling and well operations shall be in accordance with the 2012IFC and the Thornton Amendments to the IFC. Section 5706.3 Well Drilling and Operating addresses these mandates within Section 5706.3.5 Storage Tanks, which is quoted in its entirety:

“Storage of flammable of combustible liquids in tanks shall be in accordance with Section 5704. Oil storage tanks or groups of tanks shall have posted in a conspicuous place, on or near such tank or tanks, an approved sign with the name of the owner or operator, or the lease number and the telephone number where a responsible person can be reached at any time.”

This section has been amended by the Thornton Fire Department. The amended Section 5706.3.5 is quoted in its entirety and the amended portion of the code has been underlined:

“Storage of flammable or combustible liquids in tanks shall be in accordance with Section 5704, except that production tanks and associated on-site production equipment shall be located at least 350 feet from any building not necessary to the operation of the well and at least 500 feet from a building with an occupancy of Group A, E, or I. When production tanks and associated on-site production equipment are existing, main buildings shall not be constructed within the distances set forth in this section for separation of production tanks and associated on-site production equipment. Reduction in required separations may be approved based on alternative materials and methods that provide an equivalent level of safety to adjacent buildings and occupants. The alternative methods and materials shall be presented by a professional engineer or licensed architect, as applicable, as determined by the City. Oil storage tanks or groups of tanks shall have posted in a conspicuous place, on or near such tank or tanks, an approved sign with the name of the owner or operator, or the lease number and the telephone number where a responsible person can be reached at any time.”

BUILDING OFFSET These code requirements mandate that a new building cannot be constructed within 350 feet of an existing well for most occupancies. However, the offset distance must be increased to 500 feet if a new building (or a portion thereof) incorporates one or more of the following occupancies: Group A – Assembly, Group E – Educational, Group I – Institutional.

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Alternative Methods and Materials CODE PROVISIONS The 2012 IFC does not provide a specific exception for the building offset requirements from oil wells;however,there is a general provision within the code that allows for administrative modifications. The 2012 IFC within Chapter 1 Scope and Administration addresses such alternatives within Section 104 General Authorities and Responsibilities within inner Section 104.9 Alternative Materials and Methods, which is quoted in its entirety:

“The provisions of this code are not intended to prevent the installation of any material or to prohibit any method of construction not specifically prescribed by this code, provided that any such alternative has been approved. The fire code official is authorized to approve an alternative material or method of construction where the fire code official finds that the proposed design is satisfactory and complies with the intent of the provisions of this code, and that the material, method or work offered is, for the purpose intended, at least the equivalent of that prescribed in this code in quality, strength, effectiveness, fire resistance, durability and safety.”

Inner section 104.9.1 Research Reports of Section 104.9 allows provision for technical reports, such as this code analysis, to assist with the approval of administrative modifications and is quoted in its entirety:

“Supporting data, when necessary to assist in the approval of materials or assemblies not specifically provided for in this code, shall consist of valid research reports from approved sources.”

ANALYSIS TO JUSTIFY ALTERNATIVE METHODS In consideration of an alternative distance for building offset, in accordance with the above code provisions, two critical aspects will be evaluated within this code analysis, the potential for:

Radiant Heat Exposure (See Appendix A Radiant Heat Exposure to Humans and Property)

Exposure to Toxic Vapors (See Appendix B Toxic Vapor Exposure from Crude Oil Fire Gases).

Potential exposure to toxic vapors will consider both pre-fire (spills without ignition) and post-fire conditions. With respect to large, open pools of hydrocarbons involved in a fire, thermal radiation exposure represents the greatest hazard. Crude oil is a complex mixture that contains many hydrocarbons. Thermal radiation exposure hazards are quantifiable if the heat release rate (HRR) and flame height of a pool fire are known, or can be predicted base on containment surface areas.

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Properties and Classifications of Natural Gas

NATURAL GAS IS COMPRISED OF METHANE Natural gas is a hydrocarbon gas mixture of predominantly methane (CH4), the simplest alkane; however, natural gas commonly includes varying amounts of slightly higher alkanes (ethane, propane, butane, etc.). The composition of natural gas (prior to any processing) also includes very small quantities of carbon dioxide, nitrogen, and in some cases hydrogen sulfide. Hydrogen sulfide is not present at the facilities under investigation in this code analysis. Natural gas extracted from oil wells is called casinghead gas or associated gas. CLASSIFICATION AND PROPERTIES OF METHANE Methane (CAS # 74-82-8), the primary component of natural gas, is classified as a flammable gas in accordance with the 2012 IFC, and is ignitable in a relatively narrow concentration range of 5 to 15 %. Methane is an odorless, colorless gas at ambient conditions. (The smell of natural gas used in home is attributable to an added odorant, typically a sulfur compound). Alkanes, such as methane, are non-toxic and do not pose health hazards. Flammability (and in some scenarios, explosion) is the chief hazard. Methane is violently reactive with some oxidizing materials and with halogens (chlorine and bromine). Although not a toxic material, methane gas can displace atmospheric oxygen in an enclosed space. Asphyxia may result if the oxygen concentration is reduced below approximately 16 percent, at high methane concentrations. The concentration of methane at which asphyxiation risk is a factor is much higher than the 5–15% concentration in a flammable or explosive mixture. Therefore flammability and potential for explosion are considered the primary hazards of methane. NATURAL GAS IGNITION AND BURNING Natural gas is considered a clean burning fuel because it is predominantly methane that burns. The chemical reaction for complete combustion of methane is: CH4 + 2 O2 → CO2 + 2 H2O (ΔH = −50 kJ/g) The byproducts of methane combustion (carbon dioxide and water) are therefore not hazardous (neither toxic nor flammable).

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Properties and Classifications of Crude Oil ORGANIC MIXTURE

Crude oil is a very complex non-homogenous mixture of chemical species comprised primarily of organic compounds, to include: n-hexane, heptanes, octanes, nonanes, benzene, toluene, xylene, cyclohexane, and many other materials, including light alkanes such as methane and ethane. Many of the materials found in crude oil are carcinogens, such as benzene.

Inorganic materials, such as hydrogen sulfide (H2S), may or may not be present in crude oil. With respect to acute inhalation hazards, the most hazardous component of crude oil is hydrogen sulfide, present in sour crudes, but not in sweet crudes. According to the SFPE handbook, the density of crude oil will typically range from 830 to 880 kilograms per cubic meter (kg/m3). However, crude oil for the North York wells averages 790 kg/m3.

FIRE CODE CLASSIFICATION Crude oil has a flashpoint between 194 °F and 248°F and sources such as HMEx have depicted crude oil as a Class IIIB Combustible Liquid. Within the 2012 IFC classifications Combustible IIIB liquids are based on the definition provided in Chapter 2 Definitions, Section 202 General Definitions, for liquids having a flash point greater than 200 °F. The oil at the North York facility is much lighter than typical crude oils, so additional care may be needed. The density of the crude oil at the North York facility (790 kg/m3) is more similar to kerosene (790 kg/m3) than the SFPE range for crude oil. Kerosene is categorized as a Class II or IIIA combustible liquid. VAPOR PRESSURE AND POTENTIAL VAPORS Crude oil has a vapor pressure varying between 40-800 mmHg at 20°C and thus some vapors will emanate from the surface at ambient temperature and atmospheric pressure conditions, particularly vapors of the lighter components. Immediate exposure to crude oil vapors in an outdoor environment (with no confined spaces) may cause irritation to the skin and eyes, but is not life threateningin the case of sweet crudes unless ignition of the lighter components occurs. Crude oil is a very complex non-homogenous mixture, meaning it is not a solution (therefore, not a uniformly dispersed mixture). Components of the non-homogenous crude oil mixture include light organic compounds, such as light alkanes, to include methane and ethane. Therefore, vapors above a crude oil surface can be ignited if the light fractions are emanating from the surface within the flammable range of such components.

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Properties and Classifications of Crude Oil (Continued)

CRUDE OIL IGNITION AND BURNING Smoke and Toxic Vapors In the event that crude oil ignites, prolific quantities of smoke are released into the atmosphere. Crude oil fires tend to have very dark smoke that is highly visible; butwill also contain invisible hazardous gases. Toxic gases that are released in a crude oil fire include:

Sulfur dioxide (SO2);

Nitrogen dioxide (NO2);

Carbon monoxide (CO).

These chemicals are especially harmful to young persons, old persons, pregnant women, persons with asthma and other groups in a population of greater vulnerability. (See Appendix B Toxic Vapor Exposure from Crude Oil Fire Gases). Thermochemical and Empirical Constants The SFPE Handbook, Section 3 Hazard Calculations, Chapter 1 Heat Release Rate, identifies crude oil properties in Table 3-1.21 Pool Burning:Thermochemical and Empirical Constants for a Number of Common Organic Fuels. These properties are depicted in the table below: Fuel Type Heat of Combustion Mass Loss Ratea Productb of kβ

Δhc m∞ kβ

Crude oil 42.5 to 42.7 MJ/kg 0.060 kg/(m2s) 0.62 (1/m) Note a: the asymptotic mass loss rate per unit area as the pool diameter approaches infinity. Note b: the product (multiplication) of the extinction-absorption coefficient, k, and the beam-length corrector, β. Heat Release Rate in a Pool Fire With respect to pool burning,Chapter 1 Heat Release Rate provides a well correlated equation with respect to most organic liquids, such as crude oil:

Q = Δhcm∞(1 – e-kβD)A Un-numbered equation depicted on Page 3-37 of the SFPE Handbook Where: Q is the heat release rate (HRR) of the pool fire m∞ is the asymptotic mass loss rate per unit area (see above table)

D is the diameter of a circular pool, or equivalent diameter of a non-circular pool (m); A is the area of the pool fire (m2). Note: An error was discovered in the this un-numbered equation as depicted in the 4

th edition of the SFPE Handbook, the minus

sign “-“ was omitted in the exponent kβD.

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Properties and Classifications of Crude Oil (Continued)

BOIL-OVER LIQUIDS

NFPA 30 Flammable and Combustible Liquids Code(2008 Edition) within Chapter 3Definitions defines a boil-over in Section 3.3.5 Boil-Over which is quoted in its entirety:

“An event in the burning of certain oils in an open-top tank when, after a long period of quiescent burning, there is a sudden increase in fire intensity associated with expulsion of burning oil from the tank.”

Appendix A of NFPA 30, within Section A.3.3.5 Boil-Over, provides additional information which is quoted in part:

“Boil-over occurs when the residues from surface burning become more dense than the unburned oil and sink below the surface to form a hot layer which progresses downward much faster than the regression of the liquid surface. When this hot layer, called a “heat-wave”, reaches water or water-in-oil emulsions in the bottom of the tank, the water is first superheated and then boils almost explosively, overflowing the tank.”

A superheated vapor is a vapor that has been heated above its boiling point corresponding to a given pressure. Superheated vapors have tremendous potential energy, as in the case ofsuperheated water vapor used to power a steam engine. The presence of these superheated vapors clearly distinguishes boil over as a much more severe occurrence than simpler phenomena such as:

Slop over: minor frothing that occurs when water is sprayed onto the hot surface of a burning oil;

Froth over: a non-fire occurrence in which water in a tank contacts hot viscous oil where upon mixing the water is converted to steam causing some of the tank contents to overflow.

Oils subject to boil-over are comprised of fractions (components) with a wide range of volatility (differing boiling points), including lighter fractions (methane, ethane, etc.) and viscous liquids and residues. These characteristics are typical of most crude oils, and crude oil must be considered a boil-over liquid unless it can be demonstrated otherwise for specific crude. This boil-over characteristic of crude oil will be evaluated with respect to potential hazards in the siting of the oil tanks and separators associated with oil wells.

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Potential Failure Scenarios The potential failure scenarios include the following incidents:

Crude oil tank failure without ignition

Separator failure without ignition

Crude oil tank failure with ignition

Separator failure with ignition

Oil well fire

Crude oil tank failure with explosion.

The separator contains substantially less crude oil than the tanks and the containment area for the separator is of substantially less surface area than the tank containment area. The separator containment area is located in the same vicinity as the tank containment area. Clearly, with respect to crude oil hazards, a liquid release (either with or without ignition) is more problematic in the tank containment areas. With respect to natural gas hazards, the separation operation presents a greater hazard than the crude oil tank.

These scenarios are evaluated with respect to the potential for radiant heat exposure and toxic vapor exposure. Some scenarios will not involve radiant heat exposure (oil tank failure without ignition).

Information regarding pool fires, the point source method, and calculation methodology will be presented prior to addressing the ignition failure scenarios.

Tank Failure without Ignition- North York #13-12 and #14-12, Wright #1

The threat to human life due to oil tank failure with no ignition is low because:

The containment dike will prevent the spread of liquid and limit the surface area of crude oil that can evaporate from the surface, thereby reducing vapors that pose inhalation hazards;

In outdoor environments the concentrations of harmful vapors are lower than in indoor locations or other confined areas, as contaminants are diluted in the abundance of air;

If dermal exposure to crude oil were to occur, it is expected to be of limited contact and short duration, and therefore not immediately dangerous to life and health;

Ingestion is not considered a plausible route of entry to the body of any potential victims.

In the event the tank fails without ignition the primary considerations are to minimize ignition sources and conduct appropriate clean up procedures. If regular site visits are conducted, tank failure would be noticed relatively quickly and therefore long-term exposure would not be expected for any persons near the tank storage area.

Separator Failure without Ignition - North York #13-12 and #14-12, Wright #1

The dike surrounding the oil storage tank provides a greater surface area of liquid (in the event of a spill) than the dike surrounding the product separator, thus a leak with no ignition will only be analyzed for the storage tank area. Ignition sources should be avoided to prevent escalation to an ignition scenario. However, natural gas will dissipate rapidly in the outdoor environment. Natural gas is non-toxic and not expected to represent a toxicity hazard.

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Pool Fires and Point Source Model POOL FIRES Liquid spills of crude oil, if ignited, are assumed to be pool fires, fires involving liquid fuels confined by physical boundaries, having a liquid depth greater than one centimeter (cm). The three preliminary steps in evaluating the hazards associated with pool fires are to determine:

Pool size:the surface area and of the pool and the depth of confined liquid, from secondary containment dimensions, room size, etc.;

Fire growth: when a pool is ignited, a period of transient fire growth occurs;

Fire size: in terms of heat release rate (HRR) and flame height.

The SFPE Handbook within Section 3 Hazard Calculations addresses the point source model within Chapter 10 Fire Hazard Calculations for Large, Open Hydrocarbon Fires, and is quoted in part:

“To predict the thermal radiation field of flames, it is customary to model the flame by a point source located at the center of the real flame.”

Nomenclature and geometrical considerations for the point source model are depicted in Figure 3-10.15 of the SFPE Handbook and reproduced below as Image 1:

Let P = H/2. From the Pythagorean Theorem: R2 = L2 + P2 From right triangle trigonometry: Ө = tan-1(OPP/ADJ) = tan-1 (P/L)

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Calculation Methodology for Radiant Heat Flux METHODOLOGY OVERVIEW With respect to the failure scenarios that involve a pool fire with crude oil, the radiant heat flux must be determined to enable an assessment of the radiant heat hazards. In order to calculate the radiative heat flux we must first calculate the following with respect to a pool fire in accordance with the provisions of the SFPE Handbook:

Equivalent Diameter, D, of a non-circular pool fire

Heat release rate (HRR), Q, of the pool fire

Radiative fraction, Xr, of the HRR

Radiative Energy Output

Flame Height,H, of the pool fire.

When the above information is known, the radiative output of the flame can be calculated and this in turn will allow for determination of the following with respect to the pool fire scenario:

Equivalent point source

Radiative heat flux.

When the radiative heat flux is known, the radiation exposure hazard can then be evaluated with respect to the information in Appendix ARadiant Heat Exposure to Humans and Property. EQUIVALENT DIAMETER

The equivalent diameter, D, is calculated from:

D = ( 4A/π)0.5 Equation (A)SFPE Handbook Section 3 Chapter 10 Equation (11)

HEAT RELEASE RATE The heat release rate, HRR, of a pool fire can be calculated according to:

Q = Δhcm∞ (1 – e-kβD)A Equation (B) Un-numbered equation depicted on Page 3-37 of the SFPE

Handbook Where: Q= heat release rate for pool fires burning in the open m = mass burning rate per unit surface area for the fuel (infinite pool) ΔHc = net heat of combustion (assumed for crude oil to be 42.6 MJ/kg, See page 9) kβ (See Page 9) A = area of the pool (m2) D = Equivalent diameter (m) RADIATIVE FRACTION

The radiative fraction of the energy output is computed from:

Xr = 0.21 – 0.0034D Equation (C) SFPE Handbook – Equation depicted within Figure 3-10.16

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Calculation Methodology for Radiant Heat Flux (Continued)

RADIANT ENERGY ATTRIBUTABLE TO POOL FIRES

The radiative energy output is given by:

𝑸𝒓𝒐 = 𝑿𝒓 ∗ 𝑸𝒐 Equation (D) SFPE Handbook Section 3 Chapter 10 Equation (15)

FLAME HEIGHT COMPUTATION OF POOL FIRES

The flame height is calculated using Equation E depicted below; however, the A2 factor must be corrected using Equation F to account for any elevation above sea level and for any other temperature of interest in an analysis (other than 293 K).

𝑯 = 𝑨𝟐𝑸𝒐𝟐/𝟓

− 𝟏.𝟎𝟐𝑫 Equation (E) SFPE Handbook Section 3 Chapter 10 Equation (13)

𝑨𝟐 = 𝑨𝟏 ∗𝑻𝟐

𝑻𝟏

𝟑/𝟓∗

𝑷𝟏

𝑷𝟐

𝟐/𝟓Equation (F) Adjustment equation to correct A2 factor

Where: H = flame height (in meters)

Qo = Heat release rate (HRR) of pool fire burning in the open (kW) D = Equivalent diameter (m) A1 = 0.235 at standard atmospheric temperature and pressure (293 K and 760 mmHg) T1 = 293 K (ambient temperature of 68 F) T2 = Temperature of interest for evaluation (K) P1 = 760 mmHg (ambient pressure at sea level) P2 = Pressure at elevation of interest RADIATIVE HEAT FLUX

Image 1 of (See Page 15) is used to find the radiative heat flux to a target a distance “L” from the pool fire with the point source model. This is calculated using Equation G depicted below:

𝒒𝒐" = 𝑸𝒓𝒐∗𝐜𝐨𝐬∅

𝟒𝝅𝑹𝟐 Equation (G)SFPE Handbook Section 3 Chapter 10 Equation (12)

Where: qo” = radiative heat flux (units?)

Qor = radiative energy output of the fire (kW)

P = H/2 L = horizontal distance from target to point source (m)

𝑅 = 𝐿2 + 𝑃2 = direct distance from point source to target (m)

∅ = 𝑡𝑎𝑛−1 𝑃

𝐿 = angle between normal line to target and the line-of-sight to the point source

In addition to solving for the radiant heat flux, Equation (G) can also be used to iteratively solve for the distance L, at which a tenability level (known heat flux) will be present.

18

Tank Failure with Ignition - North York #13-12 and #14-12

In order to provide the most conservative calculations, tank failure is assumed to occur when the 285-barrel tank is full. This assumption implies that either the entire surface area (or most of it) within the containment area (minus the tank footprints) could provide flammable and combustible vapors tosustain a pool fire. The pool area, A, of1286 ft2 was presented earlier in this code analysis (see page 4), and this was converted to square meters for calculation purposes; thus A = 119m2. Veritas Fire Engineering obtained the following results for calculations based on the properties of crude oil, the pool area, A, of 119 m2 and in accordance with the calculation methodology presented earlier in this code analysis: Description Variable Equation Calculation Result

Equivalent Diameter D Equation A 12.3 m

Heat Release Rate (HRR) Q Equation B 304,164 kW

Radiative Fraction Xr Equation C 0.168

Radiative HRR Qr Equation D 51,144 kW

Correction Factor A2 Equation F 0.267

Flame Height H Equation E 29.1 m

Definitions from the point source model yield the following:

P = H/2, thus P = 14.6 m

R = L2 + P2 = L2 + (14.6)2, thus R = L2 + 213.2

Ө = tan-1 (P/L), thus Ө = tan-1 (14.6/L)

Equation (G) was presented previously as:

𝒒𝒐" = 𝑸𝒓𝒐∗𝐜𝐨𝐬 ∅

𝟒𝝅𝑹𝟐 Equation (G) SFPE Handbook Section 3 Chapter 10 Equation (12)

and is rearranged using the point source relationships and substituting the value obtained for Qr in the above table as:

q =51,144*Cos[tan-1(14.6/L)] 4∏(L2 + 213.2) Equation (H) – Revision of Equation (G)

The resulting Equation (H) is an expression for q, the radiative heat flux, in terms of L, the horizontal distance to the center of the flame in a pool fire. This equation can be used to determine a minimum distance, Lm, from the fire based on a tenable level of radiant heat as presented in Appendix A of this code analysis. In Appendix A, information from the SFPE Handbook was presented that indicates the tenable level for radiant heat, qT, as 2.5 kW/m2; however a safety factor is desired in this code analysis, so Lm is determined based on a lower q value of qT = 2.0 kW/m2. Substituting qT = 2.0 kW/m2 into Equation (H) and then solving for Lm in an iterative solutions resulted in Lm = 41 m, and after unit conversion:

Lm = 135 ft - Minimum distance from flame to insure tenability

19

Tank Failure with Ignition–Wright #1

In order to provide the most conservative calculations, tank failure is assumed to occur when the 300-barrel tank is full. This assumption implies that either the entire surface area (or most of it) within the containment area (minus the tank footprints) could provide flammable and combustible vapors to sustain a pool fire. The pool area, A, of1136 ft2 was presented earlier in this code analysis (see page 5), and this was converted to square meters for calculation purposes; thus A = 106 m2. Veritas Fire Engineering obtained the following results for calculations based on the properties of crude oil, the pool area, A, of 106 m2 and in accordance with the calculation methodology presented earlier in this code analysis: Description Variable Equation Calculation Result

Equivalent Diameter D Equation A 11.6 m

Heat Release Rate (HRR) Q Equation B 270,936 kW

Radiative Fraction Xr Equation C 0.171

Radiative HRR Qr Equation D 46,195

Correction Factor A2 Equation F 0.267

Flame Height H Equation E 27.9 m

Definitions from the point source model yield the following:

P = H/2, thus P = 13.9 m

R = L2 + P2 = L2 + (13.9)2 , thus R = L2 + 194.6

Ө = tan-1 (P/L), thus Ө = tan-1 (13.9/L)

Equation (G) was presented previously as:

𝒒𝒐" = 𝑸𝒓𝒐∗𝐜𝐨𝐬 ∅

𝟒𝝅𝑹𝟐 Equation (G)SFPE Handbook Section 3 Chapter 10 Equation (12)

and is rearranged using the point source relationships and substituting the value obtained for Qr in the above table as:

q =46,195*Cos[tan-1(13.9/L)] 4∏(L2 + 194.6) Equation (H) – Revision of Equation (G)

The resulting Equation (H) is an expression for q, the radiative heat flux, in terms of L, the horizontal distance to the center of the flame in a pool fire. This equation can be used to determine a minimum distance, Lm, from the fire based on a tenable level of radiant heat as presented in Appendix A of this code analysis. In Appendix A, information from the SFPE Handbook was presented that indicates the tenable level for radiant heat, qT, as 2.5 kW/m2, however a safety factor is desired in this code analysis, so Lm is determined based on a lower q value of qT = 2.0 kW/m2. Substituting qT = 2.0 kW/m2 into Equation (H) and then solving for Lm in an iterative solutions resulted in Lm = 39 m, and after unit conversion:

Lm =128 ft - Minimum distance from flame to insure tenability

20

Tank Failures with Explosion Scenario

A crude oil vessel explosion is not likely to occur under normal circumstances. Though flammable concentrations of gas can occur from crude oil, an explosion is not likely due to the lack of ignition sources.

In the event of a pool fire in the containment area, such a fire would have to burn for many hours (if not days) in order to transfer enough heat to the tank to reach the potential for explosion. Veritas Fire Engineering believes this is not a likely scenario because:

The fuel in the containment area is likely to be consumed before the tank heats to the point of explosion;

Crude oil fires produce dark smoke that will be observed and thus the fire department will be notified and respond prior to the tank heating to the explosion point;

Explosions are not known to occur frequently with respect to crude oil tanks.

In September 2011, the U.S. Chemical Safety and Hazard Investigation Board issued Report No. 2011-H-1, Public Safety at Oil and Gas Storage Facilities. This report concluded that members of the public, unaware of the explosion and fire hazards associated with the tanks, unintentionally introduce ignition sources for the flammable vapor, leading to explosions. Increased security measures will be recommended in order to avoid these circumstances.

Separator Failure with Ignition

In the event of ignition at the separator, natural gas (predominantly methane) or crude oil vapors will have ignited; however methane burns cleanly and does to evolve toxic gases when it burns. The separator is a small process vessel and contains both liquid and natural gas; therefore the quantity of natural gas in the separator is quite limited. Additionally the containment area wherein a potential pool fire could occur is small relative to the size of the tank containment area and therefore this incident is bounded by the analysis of the tank failure pool fire. Any offset distance acceptable for the crude oil tank, which is in the immediate vicinity, is a suitable offset for the separator.

Oil Well Fire

A fire occurring at an oil well would likely be a pressurized jet fire wherein the incident radiative heat flux would need to be evaluated to determine offset distances.

A review of the well production report shows that very little of the product is natural gas. A potential fire scenario would be a well equipment failure allowing natural gas to flow at full capacity resulting in a vertical jet fire. A jet fire is not expected to continue for a significant time due to the cycling nature of the well and the extremely low production of these wells. This scenario will not be analyzed.

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Findings, Conclusions, and Recommendations

A pool fire within the crude oil containment area is a plausible worst case scenario for the 285-barrel oil tank fed by the North York #13-12 and #14-12 wells. The recommended building offset from this containment area is 135 feet as demonstrated by calculations in this code analysis.

A 300-barrel oil tank, Wright #1, has a plausible worst case scenario of a pool fire within the containment area. The recommended building offset from this containment area is 128 feet as demonstrated by calculations in this code analysis.

Any of the other failure scenarios are either of significantly low risk, or would necessitate a lesser offset distance than the distances quoted above.

The code required setbacks and calculated setbacks are summarized below:

Equipment Code Required Setback Calculated Setback

(includes safety factor)

Well Heads – N York 200 ft N/A (bounded by tank

calculation)

Well Head – Wright #1 200 ft N/A (bounded by tank

calculation)

Common Separator- N York 350 ft 82 ft

Separator – Wright #1 350 ft N/A (bounded by tank

calculation)

Storage Tank for North York 350 ft 135 ft

Storage Tank for Wright #1 350 ft 128 ft

Upon thorough analysis Veritas Fire Engineering recommends the following items to ensure the safe

operation of the existing stripper well site with regards to items addressed with in this report.

Six foot security fencing is suggested to be added to the site. New fencing around the well head,

separator, and tanks, provided with lockable gates, would provide the highest level of security

to deter tampering. The additional security is suggested because of the increase in population

in the area due to the construction of new housing in the vicinity of the well site.

Additional placarding is suggested around the site. “No Smoking” signage is suggested to be

added at all equipment locations.

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Appendix A

Radiant Heat Exposure

To Humans and Property

Human Exposure to Radiant Heat

Threshold values for the effects of exposure to radiant heat must be determined. Experimental data for various exposure intensities and times is provided in The SFPE Handbook of Fire Protection Engineering (4th Edition) in the following table:

Table 2-6.19 Data on the Effects of Exposure to Radiant Heat

Relevant data from the table is depicted below:

Heat Flux Time to Effect(s)

kW/m² W/cm²

Minutes

Erythema/Pain Burn Full Burn

150 15 1 2.5 4

100 10 2 4 6

50 5 4 7 >15

40 4 4.5 9 >15

35 3.5 5 9.5 >15

30 3 6 10 >15

3.4 0.34 Limit for Blood to Carry Away Heat

2.5 0.25 Tenability Limit

Property Exposure to Radiant Heat

An analysis for loss of property must be done in addition to effects on human life. Structures could potentially be, conservatively, Type V wood construction with asphalt roof materials. The pilot ignition of wood varies based on the species of wood, grain orientation, and moisture content of the wood.

Radiant heat flux of 12.5 kW/m2will be used as the lower limit for pilot ignition of wood used in the construction of the homes. The tenability limit for humans is much lower that the pilot ignition of wood; thus 2.5 kW/m2 will be the maximum allowed radiative heat flux.

23

Appendix B

Toxic Vapor Exposure from Crude Oil Fire Gases

Should the crude oil ignite, a relatively large amount of smoke would be released into the atmosphere. Crude oil fires tend to have very dark smoke. Toxic vapors in addition to the smoke are released during the combustion of crude oil.

These chemicals include: sulfur dioxide (SO2), nitrogen dioxide (NO2), and carbon monoxide (CO). These chemicals are especially harmful to young persons, old persons, or pregnant women.

The Table below includes data from National Ambient Air Quality Standards (NAAQS) and Colorado Ambient Air Quality Standards (CAAQS). The attached data indicates the air quality standards as accepted by Colorado for the release of these toxins.

Sulfur dioxide and nitrogen dioxide are both toxic to the eyes and respiratory tract if inhaled. Carbon monoxide, while non-irritating, becomes toxic if inhaled by displacing oxygen cells from blood cells and limiting the ability of blood cells to carry oxygen within the body. Current testing of the crude oil extracted from this well site is not currently available to determine the potential chemical release quantities; however in the event of a crude oil fire residents are not likely to be exposed to smoke for long periods of time.

Pollutant Avg.

Period Primary NAAQS

Nitrogen Dioxide 1 - hr 100 ppb

Nitrogen Dioxide Annual 53 ppb

Carbon Monoxide 1 - hr 35 ppm

Carbon Monoxide 8 - hr 9 ppm

Sulfur Dioxide 1 - hr 75 ppb

Sulfur Dioxide 3 - hr 0.5 ppm

Particulate Matter < 10μm 24 - hr 150 μg/m3

Particulate Matter < 2.5μm 24 - hr 35 μg/m3

24

Appendix C

Site Photos

North York Battery Tank and Produced Water Containment

25

North York Battery Separator

26

North York Wells

27

Wright #1 Battery