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Home My WebLink AboutBLD96-01359 Washrack Design Review - BLD Letters / Memos - 11/20/1996 00 --6eeee 00016 MASON COUNTY PUBLIC WORKS DIRECTOR/COUNTY ROAD ENGINEER Shelton,Wuhuom"584 DATE: November 20, 1996 INTER-DEPARTMENTAL COMMUNICATIONS TO: Pam Bennett Cummings, DCD - Planner FROM: Alan A. Tahja, P/W- Co. Hydr. Engr. SUBJ: Washrack Design Review NAME: Skookum Lumber Company -c.b9tb-1?�1 Pam, Review of the proposed washrack, fuel tank pad, and oil storage building design raised a concern that the proposed fuel tank pad is proposed to be constructed flat. I have contacted Doug Ecklund and discussed this with him, and he has agreed to revise his design to address my concern. Under Puget Sound Water Quality Authority standards, areas with a potential for delivering petroleum contaminated water are required to be isolated so that stormwater runoff can be treated. Mr. Ecklund has agreed to specify that instead of the concrete slab being constructed perfectly flat, it will be constructed with a crease down the middle, so that stormwater landing on the fuel tank pad is delivered to the washrack floor area which delivers its collected runoff to a water oil separator. With this minor revision, the proposed facilities raise no concerns. Please feel free to contact me at County extension 461 if you have additional concerns or questions. Sipcerely, z an A. Tahja File: H:\WP\STRMWTR\REVIEWS\SLC-WASH.RCK uLAAVISA . JEROME W. MORRISSETTE & ASSOCIATES INC., P.S. 1700 Cooper Point Rd. S.W., #62 (360) 352-9456 Olympia, WA 98502-1110 FAX 352-9990 October 24, 1996 Mr. Alan Tahja, P. E. j ZO- Mason County Public Works Department M9S�NCONUWN Y RDAO P. O. Box 1850 Shelton, WA 98584 RE: Skookum Lumber Vehicle Washrack/JWMA#94116 Dear Mr. Tajha: Please fine attached two copies of plans and supporting documentation for the above mentioned project for review and approval. This project provides for the construction of a vehicle washrack. This facility is intended to provide for several functions: • Washdown area for the Mill's log loader and other wheeled machinery. The intent is to lessen the amount of oil and grease that would otherwise be dropped on the ground. • Provide for covered lubricating oil storage (currently some lubricating and hydraulic oil drum storage is uncovered). • Provide a future vehicle fueling area to replace the existing fueling area. This project includes the construction of a concrete washrack slab and catch basin, a concrete valve box, wash water holding tank, an oil water separator, and a tight-line drain to an existing surface interceptor drain. Also included is an oil storage building and a concrete slab for the future tank. A significant portion of the project area is currently paved. The additional impervious surface generated by this project will be 3,400 square feet. This project is intended to comply with the provisions of the Stormwater Master Plan prepared for this site as a Department of Ecology requirement. RECEIVED N 0 V 0 6 1590 MASON CO. PLANNING DEPT. PROFESSIONAL CONSULTING SERVICES CIVIL AND MUNICIPAL ENGINEERING AND PLANNINGj, Valuing will 1 be provided so that wash water collected from the con crete slab will be directed to the holding tank. Storm drainage collected from the slab will be directed through a coalescing oil water separator and then to an existing interceptor drain. The interceptor consists of a concrete vault with a bar grate and a tight-line drain line to an existing swale. When the water level in the holding tank approaches the level of the inlet pipe an alarm will sound. When the alarm sounds, the holding tank will be pumped by a licensed waste hauling firm. The pumped water will be disposed of off site in accordance with regulatory agency requirements. The oil water separator is rated by the manufacturer to accommodate a flow of 160 gpm with efficient quality of 10 ppm oil. The area of the slab is 1728 square feet. The oil water separator can accommodate the slab runoff generated by an 8.6 in/hr storm: 8.6/hr x 1728 sf x 1ft/12 in x 1hr/60 min. x 7.48 gal/cf= 154 gpm or <160 gpm The isopluvials map for this vicinity shows approximately 7 in/hr for the 100 year 24 hour storm (see attached). Please do not hesitate to call should you have any questions. Sincerely, Doug Eklund, P.E. Senior Project Engineer DE/mp Enclosures Attachments cc: Mr. Tucker Smyth, Skookum Lumber Company 941161tr.doc 577-CPS OIL / WATER SEPARATOR 1,050 SO.FT.-EFFECTIVE COALESCING AREA 555 G.P.M.-MAXIMUM PROCESS FLOW COVER No. 57-2-342P - ---- --1-'- - - -- 171.1-1-1 2,540lbs. - -1-1-1-1-1-1- -I-1-I _______ 1_1_, ____ ___ -1-I-1-I_.- _ _ _ _ _ _. -- _ _ _ _ _ -.- _. _ _ _ - _ _ _ _ _ - __ _ I_-_-_---- ---i-- _ OUTLET PIPE WITH SAMPLING TEE - 2 BY OTHERS FIBERGLASS HOLD-DOWN CHANNEL / I � I BASE ASSEMBLY I / � No. 577-CPS 7,700 lbs. 7'-0' -r r OUTLET WEIR INLET PIPE WITH ELBOW ° �nr j BY OTHERS OIL RETAINING BAFFLE x 6'-0• # Q 0 _ .O 0 T-0" G 0 4'-6" COALESCING MEDIA, INLET WEIR * ITEMS SHOWN ARE SUBJECT TO CHANGE WITHOUT NOTICE. UTILITY VAULT GO. FOR DETAILS SEE REVERSE SIDE. Copyright 1992 124 Issue:April, 1992 • 57 -CPS OIL/ WATER SEPARATOR 1,050 SO.FT.-EFFECTIVE COALESCING AREA 555 GPM-MAXIMUM PROCESS FLOW T-0" i I rrrrrrrrrr/ Or�-r')- r ��♦ i r�i�i�i�r�i r�i i i i i i i i r ♦��/�r�r�r�r�r�r��\\ rrrrrrrrrrrrrrrrr ��\\N��\�� rrrr/rrrrrrrrrrrr ��♦ rrr/rr/rrrrrrrrrr ��pii`r`i`r i�r�ir�r�i� rrrrrrrrrrrrrrrrr ��•-�� PLAN VIEW U.V.Co.2-342P DIAMOND PLATE COVERS FINISH GRADE EL. ! OIL RETAINING BAFFLE FIBERGLASS \ HOLD-DOWN CHANNEL \ OUTLET PIPE INLET I.E. —, WITH SAMPLING TEE > BY OTHERS OUTLET LE. INLET PIPE WITH ELBOW BY OTHERS 14 4'-0" p a WATER DEPTH a D D I i INLET WEIR D 0 .� v '0 vp •0 p o •0 v •Ovp COALESCING MEDIA SECTION AA> L OUTLET WEIR STRUCTURAL NOTES: INFORMATION NEEDED: 1.CONCRETE:28 DAY COMPRESSIVE STRENGTH f'c=4500 psi INLET PIPE SIZE- 2.REBAR:ASTM A-615 GRADE 60 OUTLET PIPE SIZE• __ 3.MESH:ASTM A-185 GRADE 65 GRADE ELEVATION- 4.DESIGN:ACI-318-83 BUILDING CODE INLET INVERT ELEVATION-— ASTM C-857"MINIMUM STRUCTURAL DESIGN OUTLET INVERT ELEVATION- LOADING FOR UNDERGROUND PRECAST CONCRETE UTILITY STRUCTURES' 5.LOADS:H-20 TRUCK WHEEL w/30%IMPACT PER AASHTO BASIC DESIGN INFORMATION: GENERAL NOTES: INFLUENT CHARACTERISTICS- 1.ALL BAFFLE/WEIR PLATES TO BE MILD STEEL,GALVANIZED OIL SPECIFIC GRAVITY OPERATING TERMERATURURE=45' 2.WATER DEPTH=4'•0" INFLUENT OIL CONCENTRATION=100 ppm 3.CONTRACTOR TO: MEAN OIL DROPLET SIZE(MICRONS)=130 GROUT IN ALL PIPES FLOW EFFLUENT SUPPLY&INSTALL INLET&OUTLET PIPES(INCLUDING PIPE ELBOW&SAMPLING TEE) RATE QUALITY FILL w/CLEAN WATER PRIOR TO"START UP"OF SYSTEM VERIFY ALL BLOCKOUT SIZES and LOCATIONS 4.REFERENCE U.V.Co.CATALOG MODEL 577•LA 160 GPM 10 ppm 124.1 Oldcastle Precast Oil-Water Separators Flow-Ratings and Geometrical Data for Standard Configurations The tables below may be used for guidance in choosing appropriate separator sizes.Models similar to those shown here.as well as custom models are available from all Oldcastle Precast manufacturing locations.Because of differing requirements of customers in different regions.some variations may exist between the standard features of models indicated here and those provided at each Oldcastle manufacturing location. Additional intermediate,larger and smaller sizes may also be available.Contact your local Oldcastle representative for guidance.Oldcastle Precast Inc.reserves the right to make modifications without notice in the course of technological progress and in response to customers'needs. .a,-., :: —,.fir•- >�a .r^-�_..i. ., +"-'+Y. €"w'd' model: 48-CPS Y, . ; . .. Nominal Capacity 1000 gallons Nominal Dimensions Standing Water Depth 4 feet Vertical Plate Spacing 18.5 plates per foot Imo! 1�4 Horizontal Oil Separation Area 555 square feet ' 1 Performance �' Critical Ott_dro et FoN r (Gallons peg inwe 4 (feet firm tnute)a � H gh Perf ormance'reaEme6t` O EY1.. -♦ - ♦ Standard Treatment a _ .. 0.03 137t URI Maxtmum_Ftow(Surger 4 Pipe Diameters for Standard and High Inlet 6' Performance Treatment Flow-rates$ Outlet 8kt model: 612-CPS - f r _.. LAMA, . Nominal Capacity 2200 gallons Nominal dimensions 4 feet Standing Water Depth Vertical Plate Spacing 18.5 plates per foot l; 1665 square feet Horizontal Oil Separation Area q 6 Performance��`�1 nUcat ott�ro let=� ro ,a Filse Rate I a or>�s eu y�.tifeetpermin e 12' High Performance Treatment " Standard Treatment 0.033 41 1 � yy�y,Y X�^E -.ice'^-••�SSY�. /�. � � ..S'• 'y„�y„Tn vc- �-^�� "� M � r �-,t. t 4.:��, 56a'" '► = '� 6MaximUmftot(Suge �„ s"r. �;��„-, '� •" 1 � Pipe Diameters for Standard and High Inlet 8" —- - Performance Treatment Flow-Rates � Ou?'.et 10" .. ..,- «-tea G�^.,�;:�•-•-,�^• r� .}�"�T � model: . .816-CPS .� u.W. �5..�. r '� .__ ' �_•„,. �. L.. ,, `"tom YEW Nominal Dimensions �Nominal Capacity 4000 gallons Standing Water Depth 4 feet Vertical Plate Spacing 18.5 plates per foot �I __ _ I i� Horizontal Oil Separation Area 81 2775 square feet rl I Performance�' EdUoiE}rop o f -r �" ,� sa ems" LGaitonspet rrtt 16' High Pe ormancm. reneriEt4 27 Standard Treatment 0.033- 750 "► I 6,, r MaximurrlNowSurge Pipe Diameters for Standard and High Inlet 10" r Performance Treatment Flow-rates# Outlet 12" t Flow ratings are calculated on the basis of the provision of horizontal separation area according Hazen's surface-loading theory and are in accordance with the American Petroleum Institute's principles for separator sizing—API Publication 421, February 1990. $ Flow-rates in excess of the maximum surge value given above can result in stripping of captured oil from coalescing plates.The pipe sizes given above are suitable for flow- rates up to the Standard Treatment flow-rate for this model.Flow-rates in excess of this level may require larger pipes and hydraulic analysis of downstream conditions to ensure that the outlet pipe can carry water at the maximum flow-rate required without excessive head building up inside the separator chaff erdcastle Precast Inc.1996_ _ 0 Oldcastle Oil-Water Separators - Guidelines for Design, Installation and Operation page 1 Flow-Ratings and Geometrical Data inside front for Standard Configurations cover Understanding Separator Performance 2 How oil-removal effectiveness varies Droplets in the 10-300 micron range Basic measures of separator performance Effluent water quality standards Horizontal Separation Area 4 Hazen's principle of Surface Loading Why "horizontal area" (and not depth) Using Hazen's principle to size a separator Rating and Sizing Separators 6 Selecting an appropriate performance Determining the design flow-rate Determining the effective horizontal separation area required Horizontal separation area of simple retention tanks and ponds Horizontal separation area of a coalescing-plate separator Stokes' Law 8 Determining critical rise-rates The Stokes' Law equation How accurate is Stokes' law? Using Stokes' law Example Calculations 10 Installation 12 Planning for site-drainage and location of oil-water separator Planning Installation Connection of pipe fittings Operation and Maintenance 15 Note on Safety Role and Function of Separator Inspection Servicing and Maintenance 10 Essentials for a successful and cost-effective inside rear oil-pollution prevention plan for surface runoff cover ©Oldcastle Precast Inc.1996 Oil-N/ater Separators - Guidelines for Design. Installation and Operation oldcastle:- Page 2 Understanding Separator Performance How oil-removal effectiveness varies SEPARATOR Effectiveness measured by Critical Oil•Dropiet Rise-Rate: Many factors affect separator performance. Large performance [INFLUENT 1 feet per minute 0.200 0 033 0.011 differences not only exist between different separator designs and C models, but also between identical separators that are used in `"oiiferenaal i -- - E E different environments and separators that are subjected to _.; Droplet Size _Magnification: = C @ mt Distributions 10X (approx.) .a in = a� different incoming oil-water mixtures. The quantity of oil in the / �\ o influent, its density (specific gravity) and water temperature all _ �, / 250 mg/1- EFFLUENT influence the performance of gravity separators. However, though significant, these factors are still not nearly as important as the o `s physical nature of the oil-water mixture itself:the degree to which a, m the oil is dispersed in the water: the size of the oil-droplets. .9 •• All. p 10 mry'I g mry'I <1 mryl It is convenient to divide the different forms of oil-water mixtures ,W ZM sou _ 250 mryl into the following four main categories: N c 140 mgA • The oil is a slick or film on the surface —In this case it has d 01 J 1 a already separated from the water c 0 0•. 10 mg/l s mg I • The oil is made up of relatively large drops —greater than 300 I u micronst in diameter (approximately) and globules dispersed I 250mry1- 220 mgfl throughout the water o y • The oil exists as small droplets (greater than 10 microns in a _ = 90mW diameter, less than -300 microns in diameter) I o °• _ 10 Mg/1 • The oil exists as extremely small particles(less than 10 microns) ,w ro xa u � and emulsions Figure 1: Comparison of oil-removal. effectiveness of three Most oil-water mixtures in runoff will tend to be a combination of separators for three different dispersions of oil. these forms. The first two can be removed from water using the Note: the above data assumes influent oil with a specific ration of 250 mg/liter= and most rudimentary form of retention-vessel type oil-water separator gravity of 0.88 at a concent (sometimes referred to as a "spill-trap"). Although the quantity of water at a temperature of 50' F. oil in this form can be substantial, its removal alone is seldom sufficient for safeguarding today's more stringent effluent water- Droplets in the 10 - 300 micron range quality standards for grease and oil. As mentioned above, it is in their ability to remove droplets within The third form—droplets between 10 and 300 microns—can make this range that oil-water separators differ most from each other. up a significant quantity of the oil in runoff and is more difficult to Figure 1 (above) shows the concentration of oil to be expected in remove. It is in their ability to remove this oil that individual the effluent from three different separators subjected to three separators differ most from each other. See next section below. different influent oil dispersions. As the same oil volume is dispersed as smaller and smaller droplets. the effectiveness of The fourth form of oil-water mixture usually occurs significantly each separator decreases. The oil removal rates illustrated are after intense mechanical mixing or when surfactants, solvents or typical of separators available today. Separator performance is detergents are present. Significant quantities of this form of oil- characterized by its critical oil-droplet rise-rate (defined below). water mixture can be avoided by preventing the use of detergents The 'High Performance' separator above clearly offers the best and by not using devices such as centrifugal pumps upstream of performance and would therefore provide the greatest safeguard the separator. Otherwise more costly treatments may be for effluent water quality standards. However, when flow-rates are necessary—such as biofiltration or physio-chemical methods. very large, this level of performance may not be the most economical solution. See choosing the section entitled, 'Choosing a suitable "critical rise-rate" value. t A micron (or 'micrometer') is a unit of length equal to one thousandth of a t lOil concentration precise term,isb parest ts meaer sured million", s tee in mg liter intended toms per an millimeter.(There are e hum microns in one inch.50 microns is the approximate the same thing.Environmental regulations use mg,liter. limit of detection for the human eye. ©Oldcastle Precast Inc.1996 0 Oldcastle Oil-Water Separators - Guidelines for Design. Installation and Operation Page 3 Understanding Separator Performance (continued) Basic measures of separator performance Effluent water quality standards All gravity separators rely on the tendency of droplets of oil to rise Effluent standards are quantitative limits placed on the amount of in water (because of their natural buoyancy). They are "caught" polluting substances allowed in water.Alone, they cannot be used either when they make contact with and adhere to the surface of a to define separator performance.This is because the performance solid object(such as a coalescing plate)or when they enter a layer of all separators is dependent upon physical characteristics of the of stationary water at the top of the separator chamber. oil-water mixture going into a separator and not just their relative quantities. The Critical(Oil-Droplet) Rise-Rate Most separators can produce an effluent that meets a water The rise-rate of an oil-droplet is the natural speed of ascent it has quality standard—if the conditions are right.Unfortunately, it is also as it rises —the droplet's "terminal velocity". A separator, at a true that no separator can guarantee that the effluent will never certain flow-rate, will capture all droplets that have rise-rates exceed stringent standards —unless very strict control over what above a certain value. This value is the critical rise-rate of the goes into it can also be guaranteed. This is because it is separator at that flow-rate. The critical rise-rate is a convenient impossible to predict what the nature of the influent oil-water performance measure for any gravity separator - the way you mixture characteristics will always be.What a good separator can describe the separator's effectiveness at removing oil. It is do, however, is reduce the probability of the effluent being out of usually measured in feet per minute. The lower it is, the more compliance significantly. In order to judge how well a separator is effective the separator will be at removing oil and safeguarding a likely to do this, basic performance measures such as its critical certain water quality standard. rise-rate (as described above) must be determined. Only these types of performance measures are independent of the Note:The term "surface loading"is sometimes used to mean the environmental conditions of any particular application. same thing as the term "critical rise-rate" (or "critical settling rate" in the case of sedimentation). However, the term "surface Choosing a suitable 'critical rise-rate" value loading" is more usually a measure of the flow-rate through a gravity separation chamber divided by the chamber's area (on Critical rise-rates for separators can be chosen with values plan). Though sometimes the same, these values are not ranging from as little as 0.01 feet per minute to as much as half a necessarily identical as will be seen in the section entitled foot per minute. The value you choose will depend on the intended "Hazen's Principle of Surface Loading". function of the separator (as part of a site surface-water pollution prevention strategy), likely influent characteristics (oil quality and The Design Flow-rate dispersion characteristics), effluent water quality standards and the sensitivity of the receiving environment. The critical rise-rate changes as the flow-rate of water though a separator is increased or decreased.Therefore,to be meaningfully Values at the lower end of the scale(0.01 feet per minute)are best applied to a particular separator design, a critical rise-rate value chosen when design flow-rates can be kept reasonably low and must also be accompanied by a design flow-rate ("maximum where a very high performance is desirable.The upper end of the operating flow-rate") value for which it applies. When the flow scale (0.5 feet per minute) would only be appropriate where the through the separator is increased, the critical rise-rate of the unit emphasis is on providing a low-cost unit for occasional spill increases (i.e.the performance decreases).Conversely:when the interception where the spilled oil is unlikely to be dispersed flow-rate is reduced, the critical rise-rate is reduced (i.e. the significantly. performance increases). More frequently, however, the best approach has been to choose The Effective Horizontal Separation Area an intermediate value to balance costs and benefits. Large retention-tank separators in the past used to be designed with If you use a compatible set of units and divide the design flow-rate critical rise-rates of the order of 0.2 feet per minute. But the of a separator by its corresponding critical rise-rate you get an concentration of oil in the effluent from these devices has answer that has units of area.This number represents the effective frequently been found not to meet today's more stringent horizontal separation area of the separator. standards.In applications that have to meet standards of the order of 10 mg/l, a value of 0.033 feet per minute(the rise-rate of a 60 This number is convenient because it changes little with flow-rate. Micron, 0.88 S.G., oil droplet in 500 F water) has been found to be So it is essentially a single number that can be used to quantify the a suitable choicet removing a substantial portion of oil and effectiveness of any separator. Separators that provide the safeguarding effluent quality to meet these standards in almost greatest amount of effective horizontal separation area generally every case provided that proper control is exercised over the use have the highest performance. Another advantage of the concept of detergents and other problem substances. of effective horizontal separation area is that it may be estimated t Washington State Department of Ecology recommends this value for coalescing- from the basic geometry of the oil-water separation chamber and plate separators used in Stormwater applications—Stormwater Management Manual for the Puget Sound Basin,February 1992.The American Petroleum its components. Institute also suggests 60 Microns as a typical design oil-droplet size in the -Horizontal Separation area is covered later in more detail. treatment of oil-refinery waste-waters—Design and Operation of Oil-Water Separators.API Publication 421, 1990. ©Oldcastle Precast Inc.1996 Oil-Water Separators - Guidelines for Design, Installation and Operation 0 oldcastle Page 4 Horizontal Separation Area Hazen's Principle of Surface Loading In 1904 Allen Hazen firmly established the principle of how the Uniformly distributed, effectiveness of a sedimentation tank varies directly with the rate laminar flow of flow through it, divided by its plan areat This principle is not only valid for sedimentation processes, but applies to all liquid gravity-separation processes, including oil-water separation. Non-uniformly distributed laminar flow Uniformly distributed, laminar flow When the flow is laminar and uniformly distributed throughout the Turbulent Flow separation chamber cross-section (See figure 2), the critical rise- rate is equal to the flow-rate divided by the area of the separation ' pool. Q Figure 2: Illustrations of uniform-laminar, non-uniform laminar VT=AH and turbulent flow. —where AH is the horizontal separation area (in square feet) as Why "horizontal area" (and not depth) described above,Q is the flow-rate through the separator(in cubic feet per minute) and VT is the critical rise-rate(in feet per minute). Hazen's principle has been experimentally validated. It is also simple to derive analytically using basic hydraulic equations of Hence, the critical rise-rate (or settling-rate) for many separation continuity.The following is a derivation of Hazen's principle using devices is frequently taken as being equal to the surface loading. a simple gravity separation flow-model. The "surface loading" on a gravity separation chamber is (by definition)equal to the flow-rate through the chamber divided by its Consider the illustration in Figure 3 of a simple rectangular oil- area(on plan). water separation chamber. The separation pool volume is composed of two zones or layers: a stationary liquid-layer and a Other flow regimes moving liquid layer.Any water passing through the separator forms part of the moving liquid layer.The top layer is kept stationary by Flow is rarely perfectly uniform —although it is reasonable to the presence of an oil-dam (or"scum board") before the outlet of assume it is in some instances. In other cases, however, eddies the separator.The depth,d,is the maximum distance an oil-droplet and turbulence are significant, especially at higher operating flow- will have to rise in order to reach the boundary between the rates. Such deviations from uniform, laminar flow serve to reduce stationary and the moving liquid layer.We will see, shortly, that it the efficiency of gravity separation processes substantially. In is not necessary to know exactly what "d" is. order to account for this, a design factor, F, is incorporated into Now, consider an oil-droplet moving through this separation Hazen's equation: � chamber.This droplet has two velocity components as illustrated q = F — in Figure 3:a vertical componet and a horizontal component. The M VT vertical velocity component is its natural rise-rate or "terminal —where AH,Q and VT are the same as in the equation used above velocity". An oil-droplet naturally rises in water because of its and F is a dimensionless factor(always greater than or equal to 1) buoyancy. Equations, such as Stokes' law, can be used to to account for inefficiencies due to non-unifom flow. calculate the rise-rate of any oil-droplet on the basis of its size and density,as well as other properties of the water.The symbol,VT, is F cannot be less than 1 because the performance of a gravity used here to represent this velocity component. The horizontal separator cannot be greater than that predicted by Haze n's velocity component of this droplet(represented by the symbol V.), principle (which assumes ideal conditions). The American is the same as the horizontal velocity of the surrounding water that Petroleum Institute recommends different values between 1.2 and carries it along. 1.75 for traditional retention-tank (baffle-type) separators'. Many coalescing-plate separators and separators designed to ensure If the oil-droplet can rise as far as the boundary between the optimal flow distribution have near-ideal flow-conditions in the moving liquid layer and the stationary layer, it will be captured. separator chamber: so that F is taken as being equal to 1 (or is because its horizontal velocity will drop to zero to match the omitted entirely).In the design of circular clarifiers(like those used surrounding still water in this layer. But if the oil-droplet is not given in municipal water-treatment projects), F can also be taken as enough time, it will pass out of the separation chamber before A being equal to 1, because the flow-regime is essentially uniform- has a chance to reach this boundary and will not be caught. radial. Another way of stating this is: if the time required for separation is greater than the residence time of the water in the separator, the t A common error in sizing gravity separation devices is to assume that performance is directly proportional to the vessel volume or the residence time of liquid in the droplet will not be "caught". chamber.While true for some reaction vessels,it is not in this case. API Publication 421—Design and Operation of Oil-Water Separators,1990 0 Oldcastle Precast Inc.1996 10 Oldcastle Oil-Water Separators - Guidelines for Design, Installation and Operation ==::- page 5 Horizontal Separation Area (continued) A separator must be designed so that even if the droplet comes Now we can write: into the chamber at the very worst location(i.e.at the bottom of the C•d Condition to ensure separation: — < V- separator), there will still be enough time for it to rise up the full B•d-L distance, d, to the boundary between the stationary and moving water layer.We will call this the required time to ensure separation Notice how the depth, `d', now appears in both the numerator or simply "the separation time" (represented by "ts") . and the denominator of the left-hand-side expression.This means it cancels out of the expression—showing that the depth of the The amount of time available for the droplet to do this is called the separation chamber is not critical to separator performance. residence time —the time the water spends in the separator chamber(represented by "t;'). In other words, to ensure removal Now, it is easy to rearrange the expression that remains to get of this droplet,the separation time must be less than the residence Hazen's principle.The horizontal area of the separation chamber time.We can therefore call the following expression our first basic is equal to its length multiplied by its width: condition for ensuring separation of this droplet: B L = A Condition to ensure separation: is < tr We know the speeds in each direction and the maximum distances, d and L (See figure 3 below). We also know that, for Condition to ensure separation: Q < V- motion in a straight linet at a constant speed, the time taken is A„ simply the distance divided by the speed. So, —This was an analytical proof of Hazen's principle. is = d L VT and tr = VH So now we can write: Using Hazen's principle to size a separator So sizing a separator requires that we first select a flow-rate to be Condition to ensure separation: a- < processed and, then, a critical rise-rate based on our expectations V_ ' V. for the oil water mixture to be separated. Dividing the first by the We can then rearrange this expression and write second gives us the effective separation area needed: Condition to ensure separation: V" d < V- A"=a L V- Now, the basic principle of conservation of matter (known in fluid mechanics as "the continuity principle") tells us that the A separator can, therefore, be sized to provide this separation superficial horizontal velocity of the water (the actual horizontal area either as the plan area of its water surface or—much more velocity in uniformly distributed flow) is equal to the volumetric efficiently— as the sum of the plan-areas provided by stacks of flow-rate (0) divided by the area of the vertical flow cross-section: horizontally extending coalescing plates.This is outlined in more detail in the next section. V" A, - B d t In reality there will be some velocity variations with water depth in a separator chamber and hence the trajectory of a rising droplet will not be a straight line,but a curve. Accounting for this fact,however,significantly increases the complexity of the algebraic analysis needed. without altering the conclusions.The assumption that the horizontal velocity does not change with depth was therefore considered a reasonable simplification. Boundary �_� Horizontal Separation Area between stationary liquid layer(above) and moving liquid layer(below) -7 ,. Vertical Component of Oil Droplet Velocity =Terminal Rise-Velocity of Droplet I' (Gravity Separation) I n Area of Vertical An r Flow Cross-section a s. Horizontal Component - ? I of Oil Droplet Velocity =water Velocity e Length=L Figure 3 Model of a flow-through gravity separation process ©Oldcastle Precast Inc.1996 0 oldcasste Oil-Water Separator - Guidelines for Design. Installation and Operation Page 6 Rating and Sizing Separators Selecting an appropriate performance Example: In order to size a separator it is first necessary to know what kind of performance is necessary. The performance of a separator is Determine the design flow-rate for a separator on the basis of a measured in terms of the rise-rate of the slowest rising droplet the one-hour, half-inch design rainfall intensity on a half-acre paved separator is certain to remove from water flowing at the area: separator's maximum operating flow-rate (or design flow-rate). Paved Area C =0.9 This value is known as the critical rise-rate of the separator. See i =0.5 in./hr= 0.5 ft/min =0.000694 ft/min. the section entitled, 'Understanding Separator Performance', 12.60 for more information on this. A=0.5 acres= (0.5)•(43560) sq. feet=21780 sq. feet Determining the design flow-rate Q = (0.9).(0.000694).(21780) cubic feet/min The design flow-rate is the maximum operating flow-rate for the = 13.61 CFM separator. In runoff applications, the flow-rate through a separator 1 Cubic Foot=7.48 gallons can be expected to vary over time. It is common therefore to Q= (13.61)•(7.48)GPM design the separator for the maximum possible flow-rate. But this =102 GPM is not necessarily appropriate. If the main source of water is from washdown processes, the maximum flow-rate can be equated to Determining the effective horizontal separation the maximum water supply rate.If the main source of water is from area required rainfall, this cannot be done directly. Once suitable values for design flow-rate and critical rise-rate Stormwater Runoff have been selected, it is easy to calculate the effective horizontal separation required. Just divide the first by the second (making The most convenient method (known as the rational method), for sure that their units are compatible first) as follows: calculating flow-rates of storm runoff from small areas uses the following simple equation. Example: , Q = C I A Q is the flow-rate What is the effective separation area required to ensure the C is a dimensionless factor that accounts for the permeability and removal of droplets with rise-rates of 0.033 feet/minute and greater roughness of the surfaces (taken as 0.9 for paved areas) at a flow-rate of 100 gpm? i is the design rainfall intensity (usually expressed as inches per Solution: hour A is the area of the site exposed to rainfall. Design flow-rate = 100 gpm = 13.37 cfm = 13.37 feet3 minute Note: feet Critical rise-rate = 0.033 minute The design rainfall intensity value is carefully selected on the basis of local rainfall data(including times of concentration etc.)and also Effective horizontal design flow-rate on the basis of providing the optimal economic design. A common separation area critical rise-rate method is to choose a rainfall intensity that would allow treatment of 90%or 95 of all the water leaving the site. 13.37 fee t31 minute 0.033 feet..minute Because it is costly to treat large flows of water,it is recommended that only those areas that are at risk of contamination from oil and = 405 fee t2 grease should be allowed to drain through the separator. Water quality devices are often designed for flow-rates substantially less In this example over 400 square feet of effective separation area than the flow-rates assumed for rest of the conveyancing system. is required to provide a separator with a design rise-rate of 0.033 It is seldom necessary (or feasible) to treat all of the water from feet / minutet.. This implies that if a traditional retention vessel or very high intensity rainstorms. This is especially valid in areas pond is to be used, its area on plan will have to be of the order of where the majority of pollutants are transported during the first 400 square feet. If it is not possible to properly control circulation flush. Large water flows may be either detained upstream of the (non-uniform distribution of flow through the unit), its area may oil-water separator or allowed to by-pass it using suitable flow- have to be increased to more than five hundred square feet to splitting and recombination structures. Local guidelines for sizing make up for resulting inefficiencies.The other option is to use an should be consulted in any case. efficient coalescing-plate oil-water separator. ©Oldcasne Precast Inc.1996 I '0 01d.a5cie - Oil-Water Separators -Guidelines for Design. Installation and Operation Page 7 Rating and Sizing Separators (continued) Horizontal separation area of simple retention ;.:..:..:: .� tanks and ponds In traditional retention-tank systems, ponds and clarifiers, the horizontal separation area is closely related to the area of the separation chamber measured on plan as shown in Figure 4.The flow through a retention tank is often not uniform and a design �y factor is usually necessary (See Hazen's Principle of surface loading— page 5). Baffles and vertical flow distributors may be included in the design of such units to limit turbulence and non- Figure 4 The horizontal separation uniform flow distribution. area provided by a simple retention tank (baffle-type) Note: vertical plates used for this purpose do not add to the separator. amount of separation area in a separator chamber. Separation area can only be provided by continuous boundaries that project horizontally across the separator chamber. 11 Horizon tal separation tion a rea of a coal esci n9-plate e -_ separator = In a coalescing plate separator the entire cross-section of flow through the separation chamber is divided into many thin water layers b horizontally extending plates. Each one of these layers / Y Y Y 9 P Y acts like an individual separation chamber.The separation area of each of these layers is the same as the plan-areatof each plate as shown in Figure 5. Figure 5 The horizontal separation area provided by an inclined The easiest way to calculate the total area is to determine the and corrugated plate `horizontal separation-area density' of the plate-stack first.This is the amount of horizontal area (square feet) found in one cubic foot of stack. If the average vertical spacing of the plates, sp is known in inches —see figure 6— the horizontal separation-area 3, density, aH, can be found using the following rule: Separation Horizontal area 12 " y aH ' Area = (square feet) = S" 'o density in 1 cubic foot x The overall horizontal area, AH is then found by measuring the total volume(based on its gross dimensions—see Figure 7)of the Figure 6 The vertical spacing of submerged plate-stack and multiplying it by aH : an inclined coalescing- plates AH= Vgross•aH =(B•L•H) •a H In addition to providing a very large amount of horizontal separation area in a small volume, coalescing plate-stacks, when f I II ! I properly positioned, promote more evenly distributed flow ;, r throughout a flow chamber.It is usually assumed that the effective horizontal area provided by coalescing plates is simply the sum of I H ice ,! � r their plan-areas(or projected areas).In other words,a value of 1.0 is assumed for the design factor, "F" (as explained on page 4). ! - B L t Inclinations and corrugations give strength and rigidity to coalescing plates and make them easier to maintain.However,while the plates themselves are neither Figure 7 Gross dimensions of a stack of flat nor horizontal.fluid continuity and the incompressibility of water means that coalescing plates each one still creates a horizontal separation area equivalent to the parallel- projection of its undersurface area onto a horizontal plane(its area"on plan"). 0 Oldcastle Precast Inc.1996 `+r oldcastle Oil-Water Separators - Guidelines for Design. Installation and Operation Page 8 Stokes' Law Determining Critical Rise-rates It is not always necessary to do a Stokes' law calculation in order to size a gravity separator or rate its performance. Appropriate --- critical rise-rate values may be obtained directly by experiment. 400 Alternatively, if specific data about the likely oil-water mixtures o entering the separator are unavailable, recommended values may Y be used. Experience and analysis can also determine the value 300 — chosen. Remember that the final choice of critical rise-rate in assumed for any design will not only determine the ultimate 200 effectiveness of the separator, but also its size and cost — E especially when flow-rates through the separator are expected to o — F be substantial. Cl 100 t3oundar at 50 F Bou�dsrY 0 p` I Stoke's law accurately calculates It is common to actually list oil characteristics (such as density, p the -rate-of droptets irr i shaded region droplet size etc.) when defining the performance of a separator. This would seem a practical approach except that many more 0.5 0.6 0.7 0.e 0.9 variables controlling separator performance now need to be Specific Gravity of Oil quoted with them (e.g. water viscosity and critical droplet size). Figure 8:The curves represent the boundaries (for water 50 OF Unless all of these values are provided, the separator cannot be and 70 OF) below which Stokes' law is known to predict assessed for performance. When they are provided, the equation droplet rise-rate with negligible error. known as Stokes' law can used to convert these variables into a critical rise-rate value.This value is the same regardless of the oil- How accurate is Stokes' Law? water mixture characteristics. It is the value you can use to compare any two gravity separators. Stokes' law is derived from Newton's laws of particle and fluid mechanics and it applies only to objects rising or falling in a fluid Stokes' Law under certain conditions known as Stokes'flow conditions.These The following equation, often referred to as Stokes' law, can be conditions are that the object must be spherical in shape, and used to accurately calculate the rise-rate ('terminal rise sufficiently small and slow-moving so that microscopic turbulence velocity') of a droplet of oil of known density in water of known and "boundary layer" effects do not come into play in the vicinity viscosity: of the rising or falling object. V _ g•(Pw-P, )•d' Fortunately, Stokes' law is almost perfectly suited to the design of 18 a most gravity oil-water separators.This is true for two reasons.First, The symbols used in the equation represent values as follows: because of oil's natural hydrophobicity and the phenomenon of surface tension, small droplets of oil are spherical in shape. VT =the rise-rate (or terminal velocity') of the oil-droplet Second, although there may exist a significant portion of larger (cm/s or ft/sec) droplets for which Stokes' flow conditions will not be satisfied as g =the acceleration due to gravity (in cm/s'- or ft/secz) they rise, the smaller oil droplets that are most critical to separator Po = the density of oil (g/cm'or Ibm/ft) performance nearly always lie within that range for which pw = the density of the water (g/cm' or Ibm/ft') Stokes' law is known to be accurate (as illustrated in Figure 8 d = the droplet diameter (in cm or ft) above). u is the absolute viscosity of the water(g/cm.sec or Ibm/ft-sec). Stokes' law will only be useful in predicting the rise-rates of Note: Metric units have also been given here because they are droplets rising in still water or where the flow regime is laminar. commonly used for Stokes'law calculations. You can use either Laminar flow is where the water moves as 'layers' with no metric (CGS) units or customary (FPS) units (but not both at the vertical mixing, circulation or turbulence. The idea is simple.The same time!). droplet must be able to rise vertically —from 'laye r' to 'I aye r' _ , _ :_. - __ without interference. Turbulence and eddying simply undo the Unit Conversion: process of separation.Laminar flow is a prerequisite for any gravity 1 cm= 10,000 Microns=0.3937 in , �s separation process. Density of water(approximately} 1 g/cm' 62.4 Ibm Density of oil Specific Gravity of oil x Densityof water, y s In summary, if the oil-droplet in question is within the range of Viscosity units: 1 g/cm.sec 0.1 Pa sec 1 Poise= 100 cP w sizes and densities shown in the shaded portion of the graph in 1 Ibmlft-sec •14 88164,Poise= 1488.164 cP Figure 8, and the flow regime is laminar, Stokes' law is accurate Acceleration due to gravity=981 em/s2or 32.2 feet per second'per and reliable. second y ©Oldcastle Precast Inc.1996 l�oldcastle= Oil-Water Separators - Guidelines for Design. Installation and Operation Page 9 Stokes' Law - continued ® Using Stokes' Law Temperature Absolute Correction factor g Viscosity for use with Stokes' I aw is an equation of four variables.To calculate the rise- o o Poise Figure 9 rate of an oil-droplet, all you need to do is plug in appropriate F C (=g/cm.$) values for each of the four variables on the right-hand side of the 40 4.4 0.0155 0.85 equation: the density of the oil, the density of the water, the 45 7.2 0.0143 0.92 diameter of the oil droplet(which we know to be a sphere)and the absolute viscosity of the water. Care needs to be taken to ensure 50 10.0 0.0132 1.00 correct values are chosen for each of these using the correct units. 55 12.8 0.0122 1.08 Viscosity: 60 15.6 0.0113 1.16 65 18.3 0.0106 1.25 The value for viscosity used in this version of Stokes' law is the absolute viscosity of the water. This is measured in poise, 70 21.1 0.0099 1.33 centipoise, g/cm.s (grams per centimeter-second), Pa.s (Pascal seconds) or Ibm/ft-sec. Be careful with values given which are Table 1: Relationship between viscosity and temperature of described as "kinematic viscosities" (measured in Stokes, water centiStokes or slugs). These must be converted to the appropriate "absolute viscosity" value before this version of the Shortcut method: Stokes' law equation can be used. Figure 9 below was derived using Stokes' law. It may be used to Values for the viscosity of water may be taken from Table 1 for estimate the rise-rate of a droplet of oil of a given size and density most conditions. Notice how the viscosity of water changes when the water is at a temperature of 50' F. For temperatures dramatically with temperature. At higher temperatures, water other than 500 F, the correct rise-rate value can be obtained by becomes less viscous and therefore provides less resistance to multiplying values taken from Figure 9 by the appropriate the motion of particles - so that they separate more easily. correction factor given in Table 1 (above). 0.4 O /00 0.3 a� ,0 E a 0.2 w 0 90 6 s6' 0.1 S G_0' 0 30 60 90 120 ® Droplet Size (Microns) Figure 9: Rise-rate versus droplet size for oil-droplets of various specific gravities in water at 50° F ©Oldcastle Precast Inc. 1996 l J 0 ofdcasti. Oil-Water Separators - Guidelines for Design. Installation and Operation Page 10 Example Calculations Example 1 Example 3 Calculate the rise-rate of a 60 micron droplet of oil that has a Size a suitable rectangular cross-sectioned retention tank (API specific gravity of 0.888 in water at a temperature of 50OF. oil-water separator) for a critical rise-rate of 0.033 feet1min at its operating flow-rate of 100 gallons per minute. What size circular Solution: unit would be required to provide the same separation d = 60 Microns =60 pm = 60 — 1.97 x 10,4 feet effectiveness? (1000)(25.4)(12) — We will assume 20% inefficiency due to non-uniform flow Temperature=50 OF distribution (short circuiting), turbulence etc. The viscosity of water is related to temperature. Table 1 In other words, we will use a design factor of 1.2t (page 9), tells us that at 50 OF Viscosity=0.0132 poise Effective horizontal _ Actual horizontal area provided For Stokes' law we need to use compatible units separation area 1.2 Since 14.882 poise = 1 Ibm/ft-sec: Require aplan-area= 1.2 0 0.0132 Ibm/ft-sec. =8.87 x 10 4 Ibm/ft sec V T p 14.882 a In example 2, we found =405.2 ft' Density of water= 62.4 Ibm/ft (= P) r Specific gravity of oil =0.888 Density of oil = (0.888)(62.4) Ibm/ft' Actual plan area of separation chamber required ) _ (1.2)(405.2) ft' = 486.3 ft' = 55.4 Ibm/ft' (= Po Acceleration to gravity: Inside width of retention tank=8 feet g = 32.2 ft/sec' 3.486 g(P„ -p� )d z . . Length required (at least) = feet = 60.8 feet i Stoke's law: V- = 8 ' 18 u A circular unit(with central inlet and level perimeter discharge) V_ (32.2)(62.4- 55.4)(1.97 x 10 ft sec 4)Z can be assumed not to have any significant inefficiencies, = / (18) (8.87 x 10-4 ) because the flow is uniform radial. The unit will have a circular inlet chamber at its center with a 0.00055 ft/sec diameter(d in equation below) of approximately 2 feet which must Example 2 be included when calculating the area of the circular chamber: Calculate the effective horizontal separation area required to Diameter required = 4 (A + rz d' capture all droplets with terminal velocities greater than or equal r 4 to that of a 60 micron droplet of 0.888 specific gravity oil in water at a temperature of 50 OF, flowing at 100 gallons per minute. _ (405.2 + n(2') > 4 Solution: = 22.8 feet In example 1, we already calculated the terminal rise velocity of this oil-droplet/water combination according to Stokes'law Clearly both of these approaches involve the creation of very V_ = 0.00055 ft/sec. large structures: = (0.00055)(60) ft/min. 23 feet = 0.033 ft/min. a 6t�e Q = 100 gallons per minute (1 cubic foot=7.48 gallons) Q _ fe 100 ft'/min 7.48 = 13.37 ft3/min Effective horizontal separation area required Ah — Q — 13.37 = 405.2 ft 2 VT 0.033 t This is similar to the design approach for this type of separator recommended by the American Petroleum Institute(Publication 421, 1990) ©Oldcastle Precast Inc.1996 10 Oldcastle Oil-Water Separators - Guidelines for Design, Installation and Operation Page 11 Example Calculations (continued) Example 4 Example 5 (continued) Check if the following Oldcastle separator is adequate for the For a critical rise rate, V-, of 0.033 ft/min. same performance requirements of example 3 (Vertical plate , spacing = 18.5 per vertical foot). Maximum flow rate, O = V- AH = (0.033 ft/min)(555 ft ) - — = 18.32 ft'/min (18.32)(7.48) GPM � 21 137 GPM loom jLn 2 4' Example xample 6 Plate spacing: 18.5/vertical foot If the concentration of oil entering the separator was known to be 12 0 250 mg/liter and information about the droplet size distribution of Vertical spacing between plate centers = = .649 in. the oil entering the separator revealed that typically 2% of the oil 12 18.5 by volume in Example 1 is less than 60 microns,what would be the Horizontal area density=a., = 0.649 ft per cubic foot of stack concentration of oil in the effluent from a separator operating to provide a design rise-rate of 0.033 ft/min.? = 18.5 ft'per cubic foot of stack (This rule was given on page 7) Solution: Notice how the number of plates per vertical foot is numerically At 50' F(0.888 s.g. oil), a separator operating to provide a identical to the horizontal area density in square feet per cubic design rise-rate of 0.033 feet per minute removes all droplets foot. This is always the case (So it is not really necessary to do >60 microns in diameter this calculation). Total horizontal separation area > Fraction of original volume not removed <2 _ (18.5 ft'/ft'td,J(4 fts,d,,)(2 ft;,,,)(3.75 ft; ,) = 555 ftz Concentration of oil in effluent< (250 mg/liter)(0.02) ,•,This separator exceeds the performance requirements =4� Concentration of oil in effluent<5 mg/liter 555 -405.2 With the limited information given, we can only use an Additional margin of performance provided = 405.2 inequality expression (i.e. one with '<') to describe the effluent concentration. = 36.9 % Example 5 What is the design rise-rate of the Oldcastle separator in Example 4 at 100 gallons per minute? What size oil-droplet does this correspond to (oil specific gravity = 0.888, water temperature = 50'F)?What is the maximum flow-rate that can be put through this separator for a design rise-rate of 0.033 ft/min.? Solution: Critical rise-rate= V- = Q = 13.37 ft/min. A 555 = 0.024 ft/min = 0.0004 ft/sec. To calculate the size droplet to which this corresponds, we rearrange the Stokes' Law equation (see example 1): d _ 18 a VT _ (18) (8.87 x 10° )(0.0004) feet g(pw-P� ) (32.2)(62.4 -55.4) = 1.68 x 10' feet = 51.3 microns ©Oldcastle Precast Inc.1996 r • 0 Oldcastle _:;_ Oil-Water Separators - Guidelines for Design. Installation and Operation Page 12 Installation Planning for site-drainage and oil-water separator location t t The Drainage Plan Careful planning of paved areas and their drainage can „'r Runoff fromroofs and significantly contribute to successful control of pollutants. See uncontaminated figure fi 10.Consider the following: a �/ areas routed g g separately • Vehicles, equipment and storage vessels and activities that pose a risk of oil-discharge should be limited to a single location if possible • Drainage from roofs and green areas that are unlikely to have oil-Water Separator the same pollution problems should be routed separately—This reduces flow-rates and treatment costs for contaminated water. catchoasins r Drains Figure 10: Example of site-drainage plan for runoff • If occasional excessive flows of water are unavoidable, allow for treatment (The area shaded in grey is identified where runoff by-passing of excess water to prevent flows from exceeding the from the pavement has the potential to be contaminated). maximum surge capacity of the separator unit and other treatment system components —By-passing can be achieved with the help of detention structures and limited surface flooding 6 as illustrated in Figure 13. Alternatively a flow-diversion and -- . recombination structure can be constructed. Your local _ Oldcastle manufacturer may be able to provide a custom � solution for you, such as a separator with integrated by-passing LA A A features, as illustrated in Figure 11. - _--- C B I Location of separator --__ . A-A -8_6 When planning a suitable location for the oil-water separator, keep Figure 11: Oldcastle Separator with integrated by-pass. the following in mind • The top of the separator should be located at a ridge or crown in the pavement—Risers can be provided to create tops to any grade level desired (See Figure 12). • When planning for on-site detention (controlled. limited �— flooding), the flow constriction must be placed upstream of the �; oil-water separator —Do not position flow-constriction devices downstream of the separator or plan for any backup of flow in the separator chamber(See Figure 13.) • Make sure that there is room for access by maintenance vehicles to the separator --To enable convenient, regular maintenance as necessary Figure12: Locate the separator at a crown in the pavement. • Locate the separator where it may be conveniently accessed by personnel —Where it is unlikely to become permanently covered by stored materials, vehicles or machinery Note: The information presented here is for guidance purposes only and is not intended as a detailed instruction manual. It is the responsibility of the owner or contractor to ensure compliance with all applicable federal,state and local codes and regulations. 0 Oldcastle Precast Inc. 1996 0 Oldcastle , Oil-Water Separators - Guidelines for Design. Installation and Operation page 13 Installation (continued) Planning the Installation of separator Maximum Water Level Dry weather Level Overflow Oldcastle oil water separators require the same care with installation as any similar reinforced-concrete environmental structure. Contact your local Oldcastle representative for specific guidelines and equipment required to install a particular model. In Flow-contriction device any case, you should comply with applicable codes and -installed u stream of separator regulations.Things to plan ahead for are: Figure 13: Surface detention to control flow-rates • Excavation —In deep excavations, it is important that the excavation is kept properly shored. Clearance is required to allow for projecting 6"Minimum pipe fittings as well as the concrete vault (See figure14). ~ Finished 2 x Pipe Diameter Grade • Proper bedding preparation —The installed separator unit must ultimately be supported by _ undisturbed or well-compacted soil that is unlikely to settle significantly. Care needs to be taken to ensure that the bedding material is properly screeded and compacted to provide a firm, _' Inlet Outlet level foundation for separator vault. - - '-- - _� • Use of proper lifting equipment —Smaller Oldcastle units are installed by boom truck operators — — _ __ ----1______ from your local Oldcastle Precast manufacturing facility. Larger sizes will require a crane to lower the unit in place. — Backfill evenly Bedding Material on on all sides Undisturbed soil • Correct positioning of vault with respect to incoming and outgoing pipes Figure 14 Planning separator installation —Your Oldcastle Precast representative can advise you on suitable pipe-sizes and arrangements • Correct placement of gaskets between vault base, top-section and riser-sections —Your local Oldcastle Precast manufacturer can recommend a durable, water- and oil-tight joint if necessary for your application. Special care needs to be taken in areas that are prone to high water-tables to prevent infiltration of water into the separator chamber. The joint between riser sections in a concrete vault must be clean before application of any gasket. Gaskets must be resistant to oil and hydrocarbon compounds. Check with the manufacturer to ensure that the gasket is suitable for the application.Ask your Oldcastle representative for advice in mounting gaskets between concrete sections. • Even backfilling before filling with water • Protection of internal components during construction work on Note: the surface __DUring site construction work, sediments and debris should be " Proper installation is critical to the long-term safe fnte sand P 9- safety,� 9MY. kept out of the separator durability of an oil-water separator. It is not difficult to do with the right tools and equipment. Ensure that you compiy,,with • Sealing of pipe connections at all points in the drainage system appropriate engineering specifications as well 'as,, the Durable, non-corrosive water-tight seals are essential to the recommendations of your Oldcastle Precast representative. functioning of separators. Some special guidelines are given ©Oldcastle Precast Inc.1996 0 Oldcastle -_ Oil-Water Separators - Guidelines for Design. Installation and Operation page 14 Installation (continued) Connection of Pipe fittings: Roughened or profiled Diameter of cast surface as ror cored hole Pipe fittings for oil-water separators must be oil- and water- tight. grout"key" Expansion Ring Where possible, Oldcastle Precast prefers to ship separators with tee-sections and pipes already Installed and sealed, so that all the Epoxy surface -- p p y� primer for PVC 1 owner or contractor has to do is provide the external coupling to the outside drainage system.Occasions do arise, however, when Z — Non-shrink it is necessary to leave the installation of pipes until after the unit Hydrocarbon 'Take-up"clamp has been installed. In this case the separator is shipped with resistant grout s Flexible filler Flexible"boot" cored or cast-in holes. In this case, it is the responsibility of the 1 customer or contractor to provide an adequate seal that is both Water stop durable and flexible enough to function properly for the full range bonded to (e) pipe (b) of allowed construction tolerances. Ask your local Oldcastle Precast representative for advice on this issue. Figure 15: Typical pipe-wall seals for PVC pipe: (a) using a non-shrink grout and (b) using a proprietary "boot" Pipe to Wall Seals system. In both cases careful preparation of surfaces of pipes and concrete and the choice of suitable adhesives and When installing pipes and tees into the separator vault, it is primers for each material is essential to the creation of a important to provide a good seal to reduce risks of liquid in-flow or good seal. out-flow at the pipe-wall seal. There are variety of methods for insuring a durable, well-sealed connection. Figure 15 shows two Ring gasket suitable ways to do it. Whatever method used, the integrity and durability of the seal depends on the quality of preparation, !� 1 workmanship, the durability of the materials used as well as the provision of a rigid foundation under the vault-structure and piping. compatible pipe sections (a) Pipe-to-Pipe Seals Coupling See Figure 16. Most pipe manufacturers have their own recommendations for how best to achieve pipe-to-pipe seals. Again,the key to achieving a good durable seal lies with the quality _1r777'Take-up"clamps of surface preparation, workmanship, the durability of materials used and the provision of proper bedding material for the vault- sleeve Gasket (b) structure and pipes. When you use proprietary methods, check with the manufacturer to make sure that the seal is durable and Figure 16: Pipe to pipe seals outside separator and for can withstand hydrocarbons and water. Follow the pipe- connecting internal "tees" and extensions: (a) using manufacturers instructions when using proprietary products. proprietary `bell' ends or pipes and (b) a typical sleeve coupling arrangement. Tees and Pipe-extensions inside vault The tee-sections and pipe extensions play important roles in the +Ireeboardfunctioning of the separator.They allow proper venting of incomingflow and controlled turbulence dissipation in the inlet chamber as well as providing additional containment for oil that becomes trapped in the separator. It is important, therefore, that they are attached using properly sealed, bonded (or mechanically joined) connections just like the external pipe fitting connections. They must be installed so that they extend to the correct elevations, providing sufficient freeboard and baffling of water flowing out of the separator. See Figure 17 Extention below surface =oil-dam at outlet =flow deflector at inlet Figure 17: Tee-sections required at inlet and outlet ©Oldcastle Precast Inc.1996 `'r oldcastle Oil-Water Separators -Guidelines for Design, Installation and Ooeration Page 15 Operation and Maintenance Note on Safety Inspection Always exercise caution when dealing with underground Regular inspection is the key to ensuring that an oil-water installations, oil and other hazardous substances. The details of all separator does its job well. The internals of Oldcastle's necessary safety precautions cannot be covered in detail here. separators are easily viewed simply by opening the large access Remember, however, that the following may be necessary: doors and looking inside. Doing so, in most cases, takes only a minute. • Precautions when handling oils and other substances —Some oils are potentially hazardous substances The inspection frequency required for separators varies from application to application. It depends on the quantities of oil • Fire-prevention measures around oil released at the site. During the first few months of operation, it is advisable to inspect the separator once a week to determine the • Measures to avoid accidents when inspecting or entering rate of accumulation of solid material and oil in the unit. If the underground installations —Seek advice from a health and activity on the paved area which drains through the separator is safety expert if you are in doubt about correct safety procedures fairly consistent, then the frequency of inspection can be reduced to as little as once every three months. • Compliance with local, state and federal safety regulations 1.Oil Buildup Role and function of a separator Measure the thickness of the layer of oil that has built up on the surface of the separator.It should be removed before it reaches Oldcastle's oil-water separator may be thought of simply as a a depth of two inches. highly efficient gravity-separation device, that is capable of removing extremely small droplets of oil that would otherwise be 2.Solids Accumulation carried on through the drainage system.The separator does not Use a long pole to determine sludge build-up on the bottom — destroy the oil or other pollutants it captures. It traps and provides judged by the resistance felt when you attempt to push the pole O1 temporary storage for them. to the bottom of the separator chamber. If more than six inches of sludge has accumulated at the bottom of the unit, it requires The use of an oil-water separator is recognized by the EPA, state cleaning out. and local environmental agencies as a Best Management Practice (BMP).The separator will serve its purpose best when seen as a 3. Presence of debris and floatable materials in the inlet chamber component of a larger strategy to protect runoff water quality. An The inlet chamber must be kept clear. This chamber and its oil-water separator is a part of the site drainage system and will openings are important for dissipating turbulence and only do its job well if the other parts (i.e. catchbasins, grit- distributing the flow of water through the separator. The inlet chambers, pipes etc.) are performing their functions properly too. chamber also acts as a last line of defense for the separator against heavy grit, floating and settling debris. Excessive Though a separator for the most part requires little human amounts of these in the separator is an indication of problems intervention to work,it does need periodic inspection,cleaning and with the system upstream that should screen out these preventive maintenance.The amount of maintenance required will materials. vary with each application. It is the responsibility of the separator owner to ensure that his separator inspection and maintenance 4.Water Level in the unit plan suits the application requirements and that this plan is Check that the water level has not risen excessively inside the properly carried through. The owner can reduce maintenance unit.The water level inside the separator should never rise more costs by making changes to work practices that generate than twelve inches above its standing level(unless the separator excessive quantities of sediments and oil releases. has been designed to allow for additional freeboard).The static water level should be the same as the level of the invert of the outlet pipe (or outlet weir—if one is present).An excessive rise i — - _-- in water level during operation is an indication of blockage either -~ downstream of the separator or within the coalescing plates themselves. - \ 5.The Whole System v Inspect catch-basins,other units and drained areas upstream of separator.The level of the top of solid material in the base of grit Fig 19: Gravity(or buoyancy)causes droplets of oil dispersed in chambers and catchbasins should be well below the level of the the water to rise up and separate from water. The film of oil invert of the pipe leaving the catch basin.Make sure that paved that develops on the surface must be removed periodically continued overleaf 0 Oldcastle Precast Inc.1996 0 Oldcastle Oil-Water Separators - Guidelines for Design. Installation and Operation page 16 Operation and maintenance (continued) Inspection (continued) Maintaining the coalescing plates areas draining to the catchbasins are free of large quantities of sand and dirt and other materials that could interfere with the The coalescing plates in an Oldcastle separator are designed to system such as detergents, solvents, and antifreeze agents. operate for long periods without requiring maintenance. These substances cause oils to become more thoroughly mixed Inclinations and channels in the plate stacks enable solid particles with water so that greater quantities of the oil are dispersed as to settle out of the system and oil to gradually flow to the water extremely small droplets (< 10 Microns), emulsions and even surface. solutions. While in this state, oils have little tendency to separate. In the event of the separator receiving a heavy silt load, it may be necessary to clear the plate-stacks of this material with a hose Servicing and Maintenance (high-pressure if necessary). This can be accomplished without moving the plate-stacks. It is not necessary to completely clean Periodic cleaning and preventive maintenance is essential to the the plates in order for them to work properly. proper functioning of oil-water separators. Removing and Installing Coalescing-Plates Oil Removal from the surface Sometimes it is desirable to completely remove the plate-stacks for closer inspection of the chamber or intensive maintenance if Oil that is removed from a separator should be stored separately nuisance substances were introduced into the separator or if the as a potentially hazardous material. If possible, store it safely with plates become damaged. The plate-stacks Oldcastle uses are other used oils and recycle it.Oil can be removed from the surface modular and may be lifted easily through the separator access of the water in oil-water separators by a number of means: doors.Take care to ensure that they are replaced correctly with the proper components securing them in place in their correct • Wet vacuuming positions like those shown in Figure 19 below. This is the quickest and most convenient method for frequent oil- removal from a separator. Most industrial wet/dry vacuum cleaners are suitable for this. Entry into the separator is not ) necessary and special extensions and skimming attachments are available for doing this job. • Using skimming devices Many skimmer devices are available that have low energy requirements.The simplest is a rope or belt skimmer where an Lifting eyes for Bracing member adsorbent belt (or looped rope) is fed continuously through the Plate-stacks oil/water surface in the separator. Skimmers are useful only in situations where there is constant oil-buildup in the separator. They are slow and require frequent inspection and Surface-Stabilizing Baffle maintenance. \ • Bulk pumping of the entire separator contents ,I In some cases (especially after an accidental bulk spill of oil), it is best to obtain the services of a professional tank cleaning company, who usually removes a separator's entire contents (oil,water and solids) using special vacuum trucks.This material is then delivered to a licensed treatment facility where the oils, solids and classifiable materials can be extracted and recycled or safely stored. Solids Removal from separator chambers coalescing Plate-stack Modules Bulk pumping of sludge that collects at the bottom of the oil water separator is recommended if the level of solids buildup inside the separator chamber exceeds six inches.This is best achieved using the services of a professional tank cleaning company.This type of cleaning should not be expected to be necessary more than once Figure 19: Internal components need to be properly a year. If excessive sludge buildup is a problem, it may be due to positioned in the separation chamber problems with catchbasins and grit-chambers upstream of the separator ©Oldcastle Precast Inc.1996 J l�ofdcasue Oil-Water Separators - Guidelines for Design, Installation and Operation 10 essentials for a successful and cost-effective oil-pollution prevention plan for surface runoff from your site 1. Start now—Don't wait until a neighbor or environmental official raises their concerns with you. Investigate your work practices. As time goes on people are becoming less and less tolerant of avoidable runoff pollution and penalties for non-compliance are becoming more and more severe. 2. Install an oil-water separator —which provides reliable, measurable performance, maintainability and durability 3. Create a contingency plan for dealing with small and large releases of oils and polluting substances --You can start by looking up local tank-cleaning companies and enquiring about their services and how quickly they can respond. When a spill or accident occurs that poses a potentially hazardous situation, your priority is to minimize damage. Implement a suitable cleanup procedure promptly and document the incident. Chances are you will have completely averted the risk of any serious environmental damage. Instead of seeing the incident as a "disaster", take pride in the success of your contingency clean-up plan. 4. Get tough on all liquids and materials that could be carried into your drainage system—Maintain a clean shop. Keep litter, sand, soil, etc. off paved areas. Also, keep a close watch for the following liquids that can damage the functioning of an oil-water separator: antifreeze agents, degreasers, detergents, alcohols and solvents. 5. Pay attention to your oil-water separator and the rest of the drainage system and clean and maintain it promptly when necessary —Inspect your oil-water separator regularly (it should only take a minute). Also check your catchbasins and other structures. Find the safest, most convenient method you can use to clean them out as needed. 6. Service your drainage system promptly —Do not wait until the system is full of oil or solids. Oil should be removed before it reaches a level of 2 inches. Do not use a separator or any other part of the drainage system as a receptacle for used oil. Do not leave the separator or other parts of the drainage system full of large quantities of oil for long periods of time'. 7. Store used oil and oil removed from separator together in a safe, well contained location for hazardous wastes and have it sent to a licensed recycling facility —In parts of the country, people are profiting from the sale of waste oil.There may be similar opportunities in your area. 8. Inspect your machinery and liquid storage regularly and undertake preventive measures for early detection and prevention of leaks from corroded or worn parts—Preventive maintenance of your vehicles' equipment saves you money by reducing costly repairs and downtime. It also reduces the cost of maintaining your runoff treatment system and enhances its reliability. 9. Reduce risks that help you reduce costs —When more environmentally sound work-practices and source control measures are adopted, the separator and other components of your treatment system require less and less maintenance. Regular separator servicing should not be a time-consuming or costly activity. Maintaining your separator this way reduces the need for more costly and intensive overhaul at a later stage. 10. Take responsibility for your own effluent—No-one else has the power you have to control runoff pollution from your site. So it is your responsibility.Oldcastle's oil-water separator represents the state of the art in gravity- separator design, but it is still only a tool to help you control your water quality.There is no technology that can automatically take care of all of your water quality worries.Avoid over-reliance on oil-level sensors and alarms, leak detection equipment etc.Such devices may be unreliable in the long run and may provide you with a false sense of security. There is no substitute for visually inspecting your drainage system on a regular basis (which should only take a minute anyway). t Storing large quantities of oil and other potentially hazardous liquids in an open hydraulic system is strongly discouraged and illegal in many parts of the country.As well as creating a fire and safety hazard, environmental risks remain.Double-walled containment of oil-water separator chambers does not constitute secondary containment of liquids because the system is open.Oil and other materials can be re-entrained into the effluent as a result of blockage-induced surge or turbulence, the accidental release of interfering substances(e.g detergents) into the separator and the occurence of other unpredictable physical,chemical or microbiological reactions at the oil-water interface. ©oldcastle Precast Inc.1996 The Oldcastld • . 1. a Ill 0 Illy se• I .1I• for Durability, Performance and Servicability 1 ; „�r. • Precision-formed, high quality reinforced concrete retention ' 4 structure —Nothing compares to an Oldcastle precast vault that is specially designed for the strength, water-tightness and the durability needed for water-treatment structures • Modular M-PakTm Coalescing Plate Stacks —the state-of-the-art in coalescing plate design ' --xovide more horizontal separation area in a smaller volume than any / other available media —specially formed for continuous self-clearing of oil and solids to make maintenance easier;easily upgraded Large double doors Ex '` —in cast aluminum or galvanised steel; capable of supporting the H20 -, vehicular loading �~ —allow easy daylight inspection and regular cleaning without entry —enable convenient servicing using wet vacuum equipment .k'<.. c —allow transfer of large components and equipment �\ ` • Optimum configuration of baffles and openings tt: --developed after extensive trials and test-runs and in-house hydraulic analysis —promote evenly distributed laminar flow conditions throughout separation chamber for optimum performance • In-flow Control Chamber —Dissipates turbulence —Collects heavy grits and floatable debris. • Tee-sections at both inlet and outlet provide convenient sampling points,secondary oil c tainment and full venting of incoming water. Catchbasin I "* qr„ Grit Settling High Efficiency Chamber Separator Catchbasin High Efficiency/High Performance Unit standard oil-water separator installed with grit chamber upstream Standard Treatment Unit-restricted flows (Deep Installation with risers) Oldcastle's oil-water separators meet the needs of a wide range of run-off applications: 0 High performance removal of fugitive oil Catchbasin from storm and washdown water, Spill Interceptor , Spill interceptor installation • Interception capacity for accidental surface upgradable to higher-performance water treatment releases • Enhanced pretreatment for biological and physio-chemical purification systems ?"7"'1 NO, Catchbasin Flow-splitting - or manhole Chamber Oil-water Separator Flow recombination Stormwater Treatment with Catchbasin Sediment Chamber upstream diversion of large flows Selpa a'o� Biological/Physio•Chemical Treatment Upstream protection of biofiltration treatment systems When you put all of the pieces of the puzzle together, the ad The Challenge of a Real Environmental Problem Achi( in( Where most of the oil in water comes from: The Simple i It is a well known fact that chronic hydrocarbon contamination of surface water results more from The first coalE small quantities of oil from regular fugitive sources than from large accidental spills.Fugitive sources thin layers. BE include leaking containers, machinery, vehicles and similar releases that are difficult to avoid. coalescing pl; property.Thot. How much is too much? When water Current environmental water quality standards for oil and grease are frequently set at levels as low as 5, 10 and 15 mg/liter'This is about half Why traditional spill interceptors won't a teaspoon of oil in a 55 gallon drum of water. Traditional spill interceptors—simple retention tank baffles to trap floating oil on the surface—play a us What oil in stormwater looks like: secondary containment role in the event of a large Because much of the oil that gets into water is quickly broken up into tiny accidental spill.However, unless they are extremely droplets, you often don't notice it at all.Only when you inspect a sample they are unlikely to safeguard normal stormwater of water can you make out tiny spheres.In fact droplets of oil range in size discharges from from one or two to several hundred exceeding today's microns'. In many cases this stringent standards for means that to meet effluent oil and grease. Small oil _ standards,separators have to at droplets separate very least be capable of removing The Real slowly from water and all droplets of oil down to 50 or Science are more likely to pass 60 microns and this is not right through one these easy. of Oil-Water vessels. Separation What is gravity oil-water separation? How long does it take for oil to separate? Oils are hydrophobic which means that they do not Stokes' law tells us how quickly (or slowly)small oil- dissolve in water. Instead, when oil is well mixed with droplets rise.A 60 micron droplet typically takes half an hour to rise a distar water, it exists as a near-suspension of tiny spherical just one foot in still water. So one of these is unlikely to get trapped on the droplets. Oil is lighter than water and for this reason, surface of a simple retention vessel unless the vessel is extremely large (ar even though an oil droplet may be smaller than your eye provides plenty of retention time) or the water flow-rate is kept low. can see, it rises up (slowly) in the water. Gravity separation is achieved, therefore, by creating the right Horizontal Separation Area conditions (laminar flow) in a flow-chamber where these Besides Newton and Stokes, many engineers droplets are given enough time to reach a horizontal have made important contributions to the treatment— 3 surface where they will no longer be carried along by science of separation processes—none more so develops is iasil� moving water. than Allen Hazen at the beginning of this century. be removed using He is attributed with the discovery of the principle Isaac Newton's laws of fluid and particle mechanics of "surface loading": that the effectiveness of a Gravit accurately describe the behaviour of these droplets (He simple gravity separation device is directly Coale: didn't just discover gravity, you know). Because of his proportional to the area (on plan) of the separation laws we know that these oil-droplets rise at constant (or sedimentation) chamber divided by the flow-rate. speeds (or "terminal velocities"). They do not This is true for all liquid gravity separation processes. It is because of Haze accelerate (for the same reason that parachutists do not principle that we know that a if a retention vessel is to continuou6l continue to accelerate beyond a "terminal velocity" droplets as small as 50 and 60 microns from water, it will have to an ai. on when they are falling to earth). Harvey Stokes is of at least 4 square feet for every GPM' of flow through it. specifically responsible for deriving the accurate mathematical formula (known as "Stokes' Law") that Hazen,confirmed that the performance of a separator is independent of the dE we use for calculating the rising(or falling)velocity of tiny of water in the separation tank. As early as 1904, he suggested the valu spherically shaped objects like oil-droplets. dividing a chamber vertically using a large number of horizontal plates to incre performance—increasing what we refer to as horizontal separation area. t The concentration of pollutants.like oil,is nearly always measured in $ What's a micron?A micron is a measure of length used to measure very milligrams per liter(mg,1).The less precise term "parts per million"is small distances. One micron (or micrometer) is one thousandth of a used to mean the same thing.Environmental regulations invariably use millimeter or one inch divided by 25.400. 50 microns is the approximate limit advantage of Oldcastle's separator becomes clear. What it means to have :t -ing High-Efficiency Gravity Oil-Water Separation idea of Coalescing Plates ale more efficient oil-water :)alescing plates were just flat panes of glass stacked in a tank:dividing the water into many separator: Because glass is hydrophobic, oil tends to adhere to it whereas water does not. Modern plates are made with durable, tough plastics, like polypropylene, that have the same hough corrugated and inclined (to improve serviceability), the principle is exactly the same. When you can get the iter flows through a separation chamber with coalescing plates spanning its cross- section, it gets divided into may thin layers.Each layer acts like an same oil-removal individual separation chamber with droplets only having to rise as rk: far as the underside of one of the plates to be "caught". performance with this — inks with useful Squeezing more horizontal area into a smaller separator. ge Oldcastle provides more plates in a smaller separator volume than iely large anyone else.Using Facet's M-Paks we can provide as much as 31 I �r square feet of horizontal separation area in a single cubic foot. Combine this with the hydraulic integrity of a well designed, space-efficient, ,..that you could rectangular concrete vault previously only get tl Wt — and you have the most this— " ,✓ efficient separator ever developed! Making It Practical stance of If you can't maintain it, you don't want it e Although high performance is necessary for safeguarding today's (and effluent standards, it is not enough. Everyone knows that water treatment systems are only going to work as well as they are serviced and maintained. That is where Oldcastle's oil-water separator once again stands out.The key advantage of going with a vault design —long favoured by engineers in the field of water ?hat you can look inside and inpect the separator while it is operating.The film of oil that -sly skimmed off the surface of the water using standard wet/dry vac equipment.Sludge can YOU have a numhc'( ',t Jng regular septic tank pumping equipment. :vity separation—not filtration! extra advantages... lescing plate separators are gravity separation devices—not filters. Even though stacks of coalescing plates appear to occupy a large amount of space inside the separation chamber, they do not reduce the area of the flow ze n's cross-section significantly and do not result in a significant pressure- ?move drop. In addition, to avoid plugging, the coalescing plates Oldcastle What are you going to q plan uses have been designed with inclinations and channels to enable solid particles that settle out in the plate-stacks to slide to the bottom with all that extra space of the chamber.The oil collects on the underside of the coalescing depth plates and gradually forms a film that flows upwards— eventually lue of making its way undisturbed to the water surface in the separator ;rease chamber. In other words, gravity works with the plates to allow them to self-clear. • Flow-rate is currently measured in GPM (Gallons per Minute). 1 GPM = �4 0.00223 CFS(Cubic feet per second)=3.788 I min.(liters per minute)=63.1 x 10`'m-'s(meters cubed per second). The contamination of our water resources with hydrocarbons is an especially difficult problem to solve because of the '*is widespread use of petroleum products. For reasons such as this; the influence of NPDES (National Pollutant Discharge Elimination System) is spreading to more and more � industries and businesses including those in the commercial and retail sectors. An effective surface-water pollution a ,; 1 prevention strategy of some kind will eventually be required of every business that manages its own property. WR To meet this need, Oldcastle has developed a very special oil-water separator: designed for run-off situations where oil- _ contamination from fugitive sources is an ongoing risk. Unmatched for its oil-removal effectiveness, compactness, and functional layout, Oldcastle's separator sets the standard for this environmental technology. Oldcastle's coalescing-plate separator is like no other separator being sold today.-See for yourself the advantages that make it the best product of its kind: performance achievable technology.energy-efficient gravity-based modular, removedseparation media—easily and retrofitted and .. allow future upgrading Precision-formed, high-quality, reinforce d-concre te construction—ideal for below-grade installations (access doors can support heavy vehicular loading) Entry • the separator1 1 inspection —No confined space worries! and maintenance _ '4Complete • through opened access doors—regular inspection and timely service easily managed i No special equipment or additional attachments necessary for inspection, monitoring and servicing needs Non-corrosive materials used throughout—no need to worry about a rusting tanks (separators are exempt from federal requirements for Underground Storage Tanks) •+ Occupies mlnlmal landspace Lsr _ O Manufacturing plants are located throughout the country Location Phone Fax •• WESTERN SrATES • - • Arizona Chandler 602-963-2678 602-899-1937 _ California Fontana 909-428-3700 909-823-4113 • • • •, • Pleasanton 510-846-8183 510-846-4904 - • Oregon Wilsonville 503-682.2844 503-682-2657 • • , Washington Auburn 206-839-3500 206-735-4201 MOUNTAIN STATES Colorado Littleton `• 303-791.1100 303-791-1120 - • •• • •-•• Idaho Idaho Falls— 208-522-6150 208-522-9701 -• • •• Nampa 208-465-0176 208.465-7129 - • • , Utah Ogden 801-399-1171 801-392-7849 , NORTHEASTERN SrArES Connecticut Avon' 203-673-3291 203-673-8425 - • -• • • ,• ••• Massachusetts Rehoboth' 508-336-7600 508-336-7707 New York Manchester-" 716-289-3530 716-289-9263 South Bethlehem',.. 518.767-2269 518-767-9390 Pennsylvania Telford' 215.257-8081 215-453-1671 • • SOUTHEASTERN STATES Florida Cape Coral 941-574-8896 941-574-1419 • • �•:. Georgia Stone Mountain 770-493-5420 770-493-5425 North Carolina Greensboro 910.668-2481 910-668.0857 _ • - • Virginia Fredericksburg' 540-898-6300 540-898-2389 Some Oldcastle Precast companies(indicated above)also use • • • • • the following trade-names: ®•UTILMY VAULrCOMPANY .LLII Rotondo Precast' AMCOR Spancrete Northeast' ILI) Oldcastle • '