Lin, L., C. T. Johnston, E. R. Blatchley. 1999. Inorganic fouling at quartz: water interfaces in ultraviolet photoreactors I: chemical characterization. Water Research 33: 3321 3329.

Linden K. G., G. Shin, and M. D. Sobsey. 2001. Comparative effectiveness of UV wavelengths for the inactivation of Cryptosporidium parvum oocysts in water. Water Science & Technology 43( 12): 171 174.

Meng, Q. S. and C. P. Gerba. 1996. Comparative inactivation of enteric adenovirus, poliovirus and coliphages by ultraviolet irradiation. Wat. Res. 30, no. 11: 2665 2668.

Phillips, R. 1983. Sources and Applications of Ultraviolet Radiation. New York: Academic Press,

Qualls, R. G. and J. D. Johnson. 1983. Bioassay and dose measurement in UV disinfection. Applied and Environmental Microbiology 45, no. 3: 872 877.

Rauth, A. M. 1965. The physical state of viral nucleic acid and the sensitivity of viruses to ultraviolet light. Biophysical Journal 5: 257 273.

Sommer, R., T. Haider, A. Cabaj, W. Pribil, and M. Lhotsky. 1998. Time dose reciprocity in UV disinfection of water. IAWQ Vancouver 1998 Poster.

Wilson, B. R., P. F. Roessler, E. Van Dellen, M. Abbaszadegan, and C. P. Gerba. 1992 Coliphage MS 2 as a UV water disinfection efficacy test surrogate for bacterial and viral pathogens. Proceedings of the Water Quality Technology Conference, Nov. 15 19, 1992, Toronto, 219 235.

Wright, H. B. and Y. A. Lawryshyn. 2000. An assessment of the bioassay concept for UV reactor validation. Disinfection 2000: Disinfection of Wastes in the New Millenium, New Orleans, Louisiana, March 15 18, 2000; Water Environment Federation, Alexandria, Virginia Wright, H. B., E. Mackey, and P. White. 2002. UV Disinfection Compliance Monitoring for Drinking Water Applications. Proceedings of the Water Quality technology Conference and Exhibition, Seattle, November 10  14, 2002. Appendix G. Issues for Unfiltered Systems Unfiltered systems are utilities that use surface water sources and meet the filtration avoidance criteria of the Surface Water Treatment Rule ( SWTR) ( 40 CFR 141.71). The Long Term 2 Enhanced Surface Water Treatment Rule ( LT2ESWTR) requires unfiltered systems to meet overall disinfection requirements ( i. e., Cryptosporidium, Giardia, and virus inactivation) using a minimum of two disinfectants ( 40 CFR 141.721( d)). The information presented in this manual is focused on post filtration applications of UV disinfection; however, the information is also relevant to UV disinfection of unfiltered supplies. In addition, the UV dose requirements presented in section <IP_ADDRESS> are applicable to both filtered water and water supplies that meet the regulatory requirements for filtration avoidance ( 40 CFR 141.729( d)). This appendix identifies issues that are specific to unfiltered applications of UV disinfection. The following issues are of particular interest to unfiltered supplies because they make applying UV disinfection different from post filter locations:

  Water quality ( especially particle content)

  Debris   Ozone residual ( when ozone is applied prior to UV disinfection)

  Off specification requirements recommendations G. 1 Water Quality Differences in the quantity and nature of particles in unfiltered surface water supplies are the most pertinent distinction between post filtration and unfiltered supply water qualities. Typically, the turbidity in unfiltered surface waters is less than 1 nephelometric turbidity units ( NTU). However, the SWTR allows turbidity up to 5 NTU immediately prior to the first point of disinfection application ( 40 CFR 141.71). Several studies have examined the effects of turbidity up to 10 NTU on UV disinfection, including changes in UV absorbance measurements made with a spectrophotometer and inactivation of microorganisms.

Particles in water absorb and scatter UV light to varying degrees based on size and composition. Particles impact the disinfection process in two distinct manners:

1. Particles can decrease the UV transmittance ( UVT) of water and thereby impact UV dose delivery ( section A. 4.1.2).

2. Particle association can shield microorganisms from UV light, thereby changing the characteristics of the UV dose response curve ( section A. 2.6.5).

Christensen and Linden ( 2001) concluded that the light scattering and changes in absorbance caused by turbidity up to 10 NTU can be accounted for when calculating UV dose in collimated beam testing provided that the ultraviolet absorbance at 254 nanometers ( A254) of the sample is measured according to a modified version of Standard Method 5910B ( i. e., without UV Disinfection Guidance Manual G 1 June 2003 Proposal Draft Appendix G. Issues for Unfiltered Systems UV Disinfection Guidance Manual G 2 June 2003 0.45 µ m filtration). Direct reading spectrophotometers, the most common type of spectrophotometer, may overestimate the A254 of water with turbidity greater than 3 NTU, resulting in an overly conservative UV dose calculation ( Christensen and Linden 2002). To reduce this overestimation, an integrating sphere can be installed in a direct reading spectrophotometer that will provide accurate A254 measurements. Regardless of the type of spectrophotometer used, the effects of increased absorbance due to particles can be accounted for in the A254 measurement, which can then be used to determine the design UVT. If an appropriate design UVT is used, the UV reactor will be able to respond to changes in UVT that arise due to particles.

Particles and microorganisms in a water sample are either dispersed or aggregated together. Studies have demonstrated that dispersed coliform bacteria in wastewater are easier to disinfect than aggregated bacteria ( Parker and Darby 1995). To date, research examining the effects of particles in drinking water on UV disinfection has been performed with seeded organisms and particles. It is unknown at this time how well these studies represent naturally occurring microorganism and particle interactions. However, since the concentration of microorganisms in unfiltered sources is typically below detectable limits, methods to examine this phenomenon directly ( without seeding) do not currently exist. Consequently, seeded drinking water studies can only suggest the impact of turbidity on dose response as it relates to the impact of UV light scattering by particles rather than particle association or clumping of microorganisms.

Recent research has shown that particles present in supplies meeting regulatory requirements for unfiltered drinking water do not impact the UV inactivation of seeded microorganisms. Passantino and Malley ( 2001) reported that for unfiltered surface waters, turbidity up to 7 NTU does not affect the inactivation of seeded male specific 2 bacteriophage ( MS2) in bench scale, batch, collimated beam testing. In this study, turbidity was increased by adding natural sediment to waters collected from unfiltered water supplies. Therefore, naturally occurring interactions between particles and microorganisms could not be evaluated. In another study, batch ( bench scale) and continuous flow ( pilot scale) studies showed that turbidity ranging from 0.65 to 7 NTU does not affect the UV dose necessary per log inactivation of seeded MS2, Giardia muris, or Cryptosporidium parvum in unfiltered waters ( Oppenheimer et al. 2002). Womba et al. ( 2002) evaluated the impact of turbidity on UV inactivation of MS2 at the bench and pilot scale. They found that on the bench scale, when the impact of turbidity was accounted for in the UV dose determination, the inactivation of MS2 was not affected by turbidity. However, in this study on the pilot scale, because the lamp intensity and flowrate ( and therefore residence time in the reactor) remained constant, the effects of turbidity were not accounted for in the reactor control strategy. Therefore, the reduction equivalent dose ( RED) observed decreased as turbidity increased.

Unfiltered supplies are also susceptible to algal blooms. Womba et al. ( 2002) monitored algae levels in an unfiltered supply reservoir for over one year and found that algal counts were typically below 30,000 cells/ mL; however one algae event had a higher level of nearly 300,000 cells/ mL. Although not regulated, the presence of algae may interfere with the UV disinfection process. Womba et al. ( 2002) and Passantino and Malley ( 2001) examined the effects of algae on UV disinfection of MS2 at the bench scale in batch, collimated beam testing. Both studies found that up to algal counts up to 70,000 cells/ mL and 42,000 cells/ mL, respectively, do not affect the inactivation of MS2.

Proposal Draft Appendix G. Issues for Unfiltered Systems UV Disinfection Guidance Manual G 3 June 2003 G. 2 Debris Relative to post filter applications of UV disinfection, there may be greater opportunity for debris to be present in the influent to UV reactors in unfiltered applications. Debris entering the UV reactor with sufficient momentum could cause lamp sleeve and lamp breakage. The mass and size of an object that might cause damage is installation specific and depends on UV reactor configuration ( e. g., horizontal versus vertical reactor orientation) and water velocity through the reactor. As such, designs should incorporate features that prevent potentially damaging objects from entering the system; the optimal approach is site specific. Such features could include screens, baffles, or low velocity collection areas. Another option is to install the UV reactors vertically with the inlet closest to the ground, following a low velocity zone. This arrangement will decrease the momentum of larger debris and reduce the risk of lamp breakage. The effects of lamp breakage and methods of minimizing it are discussed in Appendix N.

G. 3 Ozone Impacts on Absorbance Some utilities using an unfiltered source may consider applying ozone in addition to UV disinfection. There are a number of benefits associated with this process combination, including addressing multi barrier disinfection requirements. Additionally, if ozone is added prior to UV disinfection, the A254 of the water can be reduced as shown in Figure G. 1, thereby improving the efficiency of UV disinfection.

Figure G. 1 Impact Of Pre Ozonation On A254 ( Malley 2002).

W a v e le n g th ( n m ) 2 0 0 2 2 0 2 4 0 2 6 0 2 8 0 3 0 0 3 2 0 UV Absorbance ( cm 1)

0 .0 0 .1 0 .2 0 .3 0 .4 0 .5 P re o z o n a te d U V In flu e n t ( n o d e te c ta b le o z o n e re s id u a l) U V I n f lu e n t  N o o z o n e It should be noted, however, that ozone is a strong UV absorber with a molar absorbance value of 0.0677 L/ mg/ cm at 254 nm. Figure G. 2 illustrates the impact of ozone concentration on UVT1 for three baseline transmittance values. If ozone is applied prior to UV reactors and residual ozone enters the UV reactor, the increase in UV absorbance due to ozone residual can be   = 1 UVT 254 10 100 (%) A Proposal Draft Appendix G. Issues for Unfiltered Systems UV Disinfection Guidance Manual G 4 June 2003 significant and should be considered when determining the design UVT. To address this issue, utilities can monitor the ozone residual and add an ozone reducing chemical to maintain the ozone residual below a specified setpoint value ( e. g., 0.1 mg/ L). There are several chemicals that can be used to quench ozone; however, some chemicals ( such as sodium thiosulfate) have a high molar absorbance value ( as shown in Table A. 5, section A. 4.1.3), and thus have the potential to decrease the UVT. Such chemicals should not be used prior to UV disinfection. Sulfite has a lower molar absorbance value and is therefore an acceptable chemical to quench ozone residual. The impact of water treatment chemicals on UV absorbance can be assessed by preparing solutions of various concentration and measuring their UV absorbance using a standard spectrophotometer ( Bolton et al. 2001).

Figure G. 2. Impact of Ozone Residual on UVT ( adapted from Cushing et al. 2001)

60% 70% 80% 90% 100%

0.00 0.25 0.50 0.75 1.00 Aqueous Ozone Concentration ( mg/ L) UVT ( 254 nm; 10 mm pathlength)

Initial UVT = 80% Initial UVT = 87% Initial UVT = 95%

In at least some cases, the increase in UVT resulting from ozone addition will improve overall UV disinfection effectiveness provided that any remaining ozone residual is adequately controlled. Each utility should explore the sequence of disinfectants that best fits their sitespecific objectives and constraints.

G. 4 Off specification Requirements Off specification is when the UV reactor is operating outside of its validated limits. UV installations should be designed with process monitoring and control components ( e. g., alarms, shut off valves) to prevent water from entering the distribution system when a UV reactor is operating outside of validated conditions. Unfiltered systems that use UV disinfection to meet the Cryptosporidium treatment requirement of the LT2ESWTR must demonstrate that at least 95 Proposal Draft Appendix G. Issues for Unfiltered Systems UV Disinfection Guidance Manual G 5 June 2003 percent of the water delivered to the public during each month is treated by UV reactors operating within validated limits ( i. e., operating conditions that have been validated to achieve the necessary log inactivation) ( 40 CFR 141.721( c)). Failure to demonstrate this will result in a treatment technique violation.

The UV reactors are off specification when any of the following conditions occur ( 40 CFR 141.729( d)):

  The flow, UV intensity, or lamp status is outside of the validated range.

  The UVT or UV intensity is outside of the validated range ( if the UV intensity and UVT setpoint approach is used ( section 3.1.5))

  The calculated dose is outside of the validated range at a given flow ( if the calculated dose approach is used ( section 3.1.5))

  All UV lamps in all UV reactors are off because of a power interruption or power quality problem ( as discussed in section <IP_ADDRESS>), and water is flowing through the reactors.

More information on off specification is in section 3.1.3, and compliance information is in section 5.4.1.

G. 5 References Bolton, J. R., M. I. Stefan, R. S. Cushing, and E. Mackey. 2001. Importance of water absorbance/ transmittance on the efficiency of ultraviolet disinfection reactors. Proceedings of the IUVA 1st International Congress, June 14 16, Washington, D. C.

Christensen, J. and K. Linden. 2001. Ultraviolet disinfection of unfiltered drinking water: particle impacts. Proceedings of the IUVA 1st International Congress, June 14 16, Washington, D. C.

Christensen, J. and K. Linden. 2002. New findings regarding the impacts of suspended particles on UV disinfection of drinking water. Proceedings of the AWWA Annual Conference, June 16 20, New Orleans, L. A.

Cushing, R. S., E. D. Mackey, J. R. Bolton, and M. I. Stefan. 2001. Impact of common water treatment chemicals on UV disinfection. Proceedings of the AWWA Annual Conference and Exposition, June 17 21, Washington DC.

Malley, J. P. 2002. Historical perspective of UV use. Presented at the AWWA Water Quality Technology Conference, November 10 14, Seattle, W. A.

Proposal Draft Appendix G. Issues for Unfiltered Systems UV Disinfection Guidance Manual G 6 June 2003 Oppenheimer J., T. Gillogly, G. Stolarik, and R. Ward. 2002. Comparing the efficiency of low and medium pressure UV light for inactivating Giardia muris and Cryptosporidium parvum in waters with low and high levels of turbidity. Proceedings of the AWWA Annual Conference, June 16 20, New Orleans, L. A.

Parker, J. A. and J. L. Darby. 1995. Particle associated coliform in secondary effluents: shielding from ultraviolet light disinfection. Water Environment Research 67: 1065 1075.

Passantino, L. and J. P. Malley. 2001. Impacts of turbidity and algal content of unfiltered drinking water supplies on the ultraviolet disinfection process. Proceedings of the AWWA Annual Conference and Exposition, June 17 21, Washington D. C.

Womba P., W. Bellamy, J. Malley, and C. Douglas. 2002. UV disinfection and disinfection byproduct characteristics of an unfiltered water supply, Project 2747. Denver, C. O.: AwwaRF periodic report.

Proposal Draft Appendix H. Issues for Ground Water Systems The UV installation design, operation, and maintenance principles presented in Chapters 3 and 5 of this manual are focused on the use of UV reactors to disinfect filtered surface water. Most of the information presented in those chapters is also applicable to ground water systems. Additional ground water specific regulatory requirements and recommendations, site issues, hydraulic issues, and water quality issues that affect design and operation are discussed in this appendix.

H. 1 Ground Water Systems Background Regulations should be reviewed to determine the goals and requirements for disinfection. Existing treatment processes and distribution system parameters should also be analyzed before selecting a strategy for integrating UV disinfection into the system.

H. 1.1 Regulatory Background Currently, federal regulations do not require ground water systems to provide primary or secondary disinfection unless the water is a ground water source under the direct influence of surface water ( GWUDI). However, some States require ground water systems to maintain a residual disinfectant in the distribution system. In addition, ground water systems are required to meet the requirements of the Total Coliform Rule ( TCR) ( 54 FR 27544) and the Stage 1 Disinfection and Disinfection Byproducts Rule ( DBPR) ( 63 FR 69390) and are expected to be affected by the upcoming Stage 2 DBPR.

The upcoming Ground Water Rule, as proposed, would require some ground water systems to provide 4 log removal or inactivation of viruses. Systems with significant deficiencies, as determined by States during sanitary surveys, and systems that detect fecal indicators in their source water will be affected. These systems will be required to correct any deficiencies, provide water from an alternative source, or install treatment that provides 4 log removal or inactivation of viruses.

Ground water supplies that are designated as GWUDI, as defined in the Surface Water Treatment Rule ( SWTR), 40 CFR Part 141.2, are classified as Subpart H Systems and must meet the same regulatory requirements as surface water systems. GWUDI systems often use many of the same treatment strategies as surface water systems, including filtration. The issues involved with implementing UV disinfection at filtered water utilities ( including GWUDI) are discussed in detail in Chapters 1 through 5 of this manual. GWUDI systems are subject to the Stage 1 DBPR and would be subject to the upcoming Stage 2 DBPR and the Long Term 2 Enhanced Surface Water Treatment Rule ( LT2ESWTR). Both of these regulations are summarized in section 1.3.

UV Disinfection Guidance Manual H 1 June 2003 Proposal Draft Appendix H. Issues for Ground Water Systems UV Disinfection Guidance Manual H 2 June 2003 H. 1.2 Typical Ground Water System Design Most ground water systems operate by cycling ground water pumps on and off in response to demand or storage capacity. Because significant treatment is not usually necessary beyond secondary disinfection, ground water systems typically do not have a single, centralized treatment system. Many ground water systems pump to storage ( e. g., hydropneumatic tank, elevated storage tank), but some may discharge directly to the distribution system. A production well typically consists of a well pump, and may contain a chlorinator ( for secondary disinfection) and corrosion control equipment ( for Lead and Copper Rule compliance), air release valves, vacuum relief valves, and other ancillary equipment necessary for well operation ( Figure H. 1).

Figure H. 1. Typical Ground Water Well Site Layout UV reactors may be installed at each well in a production system. If multiple wells are located in the same area, centralizing the flow through a common header minimizes the number of UV reactors needed and possibly reduces the project cost. In addition, treatment for other aesthetic issues ( e. g., removal of iron and manganese or stripping of sulfides) may be more effectively accomplished with centralized treatment. An engineering cost analysis should be conducted to compare centralized treatment with the installation of individual reactors at each well.

H. 2 Water Quality Issues Although ground water typically exhibits small variations in water quality, specific parameters need to be analyzed when planning for a ground water system. As with surface water systems, UV absorbance at 254 nm ( A254) and the corresponding UV transmittance ( UVT) is the most important parameter when designing a UV installation because it affects the UV reactor size. In addition, many naturally occurring constituents present in ground water ( e. g., calcium, iron, manganese, aluminum, chloride, carbonate, sulfide, and phosphate) are capable of fouling the lamp sleeves in UV reactors, and these constituents should be monitored. The potential for Proposal Draft Appendix H. Issues for Ground Water Systems UV Disinfection Guidance Manual H 3 June 2003 fouling is greater with medium pressure ( MP) reactors than low pressure ( LP) and low pressure high output ( LPHO) reactors because MP lamps operate at higher temperatures ( section 2.4.2). Mechanical wipers are often effective at removing fouling on the lamp sleeves. In situations where the ground water has detectable levels of iron and manganese, chlorination prior to the UV reactors may cause increased fouling or staining, necessitating chemical cleaning ( Malley et al. 2001). A complete discussion of the relevant water quality parameters and the determination of their design values is presented in section <IP_ADDRESS>.

With ground water systems, it is common for one or more wells to be taken out of service for an extended period due to fluctuations in water demand, ground water quality, operational problems, or other planned and unplanned circumstances. Toivanen ( 2000) reported that the lamp sleeves and internal surfaces of the UV reactors became fouled when the UV reactors were out of service and full of water. The amount of time it takes to foul the UV reactor while off line is site specific and depends on the water quality. At a minimum, it is recommended that the reactors be drained if the UV reactor is off line for more than one week; however, the appropriate period for this could be shorter or longer depending on the water quality. If the UV reactor will be off line for an extended period of time ( longer than 30 days), it is recommended that the reactor be cleaned prior to re starting the UV reactor. Routine shutdown and start up procedures are discussed in section 5.2.3.

H. 3 Off Specification Issues UV reactors must be validated as discussed in Chapter 4 and operated within the conditions determined during validation. When a utility is operating outside of the validated limits, the utility is operating " off specification."

LT2ESWTR includes requirements limiting off specification for compliance with the LT2ESWTR for unfiltered supplies ( 40 CFR 141.721( c)( 2)); however, the rule does not state an off specification requirement for filtered systems or ground water systems. States may develop statewide or site specific requirements off specification requirements for ground water systems.

There are two ways that a ground water system could be operating off specification. First, off specification can occur when the flow, UVT, or UV intensity is outside of the validated conditions. Second, UV lamps can lose arc if a voltage fluctuation, power quality anomaly, or a power interruption occurs. LP lamps generally can return to full operating status within 15 seconds after power is restored. However, LPHO and MP UV lamps exhibit restart times between 4 and 10 minutes if power is interrupted ( Cotton et al. 2002). During these restart times, the water being distributed is inadequately disinfected and is considered off specification.

H. 3.1 Power Quality Assessment A power quality assessment at each well site should be performed to determine if power quality might cause off specification operation. In addition, the reliability of commercial power at remote sites may be less than that of more populated areas. Backup power or an uninterruptible power supply ( UPS) may be needed, depending on the findings of the power Proposal Draft Appendix H. Issues for Ground Water Systems UV Disinfection Guidance Manual H 4 June 2003 quality assessment. If backup power is already available for the well pumps, then the backup power supply should be assessed to determine if sufficient output is available for the UV reactor. However, UPS may also be needed if there are frequent power quality problems. For systems that have storage following UV disinfection, it may be possible to isolate the UV reactor and rely on stored water to meet demand during periods of power failure. Power quality assessments are discussed in more detail in section <IP_ADDRESS>.

H. 3.2 Well Pump Cycling Well pumps may regularly cycle on and off in response to changes in distribution system pressure, causing the UV reactor to also be cycled. Frequent lamp cycling reduces lamp life. Manufacturers recommend that whenever possible lamps remain energized for a minimum of 6 hours ( Dinkloh 2001). In addition, the warm up time when the UV reactor is coming on line is considered off specification until the UV intensity sensor reading reaches the validated value if water is flowing to the distribution system.

Depending on its current operation and direction from the State, the utility may need to consider changing the well pump cycling strategy or incorporate UV reactor controls to reduce off specification time and to meet the needs of the distribution system. The utility should discuss its proposed operating strategy with the UV manufacturer to ensure it is appropriate for the selected UV reactors. While there may be any number of operating strategies that a utility could use, two operational strategies that could be incorporated to sequence the well pumping with the operation of the UV reactor are presented below.

The first strategy is to incorporate a delay that prevents the well pump from starting until the UV reactor reaches its validated UV intensity sensor setpoint ( i. e., no flow through the UV reactor). Under this control strategy there will be a period when the UV reactor will be " on" but no flow will be passing through it. This control strategy is only effective when LP or LPHO reactors are used because their lamps can operate for up to 1 hour under no flow conditions ( Dinkloh 2001) without overheating. However, MP UV reactors may heat the water above the safe operating temperature of 50 degrees Celsius in 1 to 15 minutes, causing the reactor's internal safety devices to shut the reactor off ( Miller 2001). As such, this control strategy may be infeasible for MP reactors unless they incorporate a low flow waste line that allows water to circulate through the reactor in order for MP lamps to reach the validated UV intensity sensor setpoint without overheating. The UV manufacturer should be contacted to confirm that this operational strategy is feasible with or without the waste line.

The second strategy is to provide a system of automated valves that diverts the UV reactor discharge away from the distribution system until the reactor reaches its validated UV intensity sensor setpoint. Then the automated valves are repositioned to direct the water from the UV reactor to the distribution system. This strategy delivers the off specification water to " waste" until the validated UV intensity sensor setpoint is reached. This ensures that sufficient cooling water will flow through MP reactors to prevent overheating and reactor shutdown. For this strategy, the utility needs to develop an approach for managing the water that is wasted during reactor warm up. The water may be wasted to a sanitary sewer, storm sewer, on site disposal or drainage system, or temporary storage tank. The utility should coordinate the discharge location with the State and other involved parties.

Proposal Draft Appendix H. Issues for Ground Water Systems UV Disinfection Guidance Manual H 5 June 2003 Both operational strategies introduce a lag between the time when the pump is initiated and the time when water is introduced into the distribution system. Because of this, existing controls may need to be adjusted to avoid insufficient system pressure or storage during periods of UV reactor warm up. This will be particularly important for those ground water systems that have frequent on off cycles or limited storage.

H. 4 Well Location Issues Ground water production wells are sited in a variety of locations, ranging from urban areas to remote installations. The well location will affect the design and operation of the UV installation, especially if there is limited space.

H. 4.1 Design Considerations As discussed in section <IP_ADDRESS>, the UV reactor should be installed within a building or underground vault if possible to facilitate maintenance and protect sensitive equipment. The need for enclosure of the UV installation will ultimately be based on the manufacturer's recommendations, local regulatory and code requirements, environmental conditions, and sitespecific constraints. Site security should be appropriate to prevent tampering with the equipment and water supply and to protect people from injury ( e. g., electrocution).

Well sites, particularly in urban areas, may be spatially constrained by adjacent development. As a result, the amount of exposed pipe and available area for locating equipment may be limited. In these cases, it may be necessary to modify the pump discharge piping to accommodate a UV reactor. When constructing a UV installation in an extremely confined location, the designer must consider the area necessary for operation and maintenance and the area needed for installation ( e. g., staging areas, personnel, and equipment access). In addition, the inlet and outlet piping should meet the criteria listed in section <IP_ADDRESS> as compared to the validated inlet and outlet piping.

UV reactors are susceptible to damage by suspended sand particles or other debris that may be present in a ground water supply and pass through the well screens. Therefore, it is important to determine if sand, grit, or fines are present in a well supply and if it is necessary to install a sand/ debris trap or removal equipment prior to UV disinfection. Particles flowing through the UV reactor may scratch the lamp sleeves, cause the sleeve wiping mechanisms to jam, or shield pathogens from UV light, thereby decreasing the UV disinfection effectiveness. In addition, larger particles could break the lamp sleeves and lamps ( see Appendix N for lamp breakage issues).

H. 4.2 Operational Issues Because most well sites are not continuously staffed, UV installations may need sufficient automation to allow remote monitoring and operation. Controls and alarms should be designed to ensure that real time operational and monitoring data are communicated to the Proposal Draft Appendix H. Issues for Ground Water Systems UV Disinfection Guidance Manual H 6 June 2003 operators. These factors also emphasize the importance of a power quality assessment and the design of alarms, monitoring capabilities, and backup power facilities.

Disposal of the chemicals used to clean the UV reactors may be an issue if an on line chemical cleaning ( OCC) system is used ( section 2.4.5). If sewer connections or other standard means of disposal are not available, then chemical waste will need to be transported off site for disposal or handled on site. Utilities should consult with chemical suppliers and the State when developing disposal strategies.

H. 5 Hydraulic Issues The hydraulic issues associated with ground water systems include high operating pressures, piping configuration, air entrainment, and the potential of water hammer and surge events.

Many well pumps discharge directly to the distribution system or to elevated or pressurized storage; therefore, the discharge will often be at system pressure. The UV reactor design may need to be modified to accommodate these higher distribution system pressures.

The actual inlet and outlet hydraulics of the UV reactor should be designed to match the validated hydraulics as discussed in section 3.3.1. Space is often limited with ground water installations so valves, flow meters, or other appurtenances may be directly upstream or downstream of the UV reactor. Consequently, these site constraints may need to be considered in determining how the UV reactor should be validated. Detailed discussions of UV installation layout and validation are given in section 3.3.5 and Chapter 4, respectively.

UV reactors should be flooded at all times because air binding can interfere with the UV disinfection process or cause the lamps to overheat. UV reactors should be located downstream of any existing or planned air removal equipment ( if necessary). Otherwise, the UV installation design should include a means for automatically releasing air prior to the UV reactor. The UV reactor may have integral air release valves or valve ports, or air release valves can be installed in the inlet and outlet piping.

Pressure surge events ( water hammer) near the UV reactor may be more likely with ground water systems than surface water systems because of the UV reactor's proximity to the well pumps. Surge events can cause positive or negative pressure transients in the well discharge piping. Negative pressures as small as  1.5 psi may cause the lamp sleeves to break ( Dinkloh 2001). A surge analysis is recommended to determine if surge protection is necessary. Many well sites and distribution systems are already equipped with surge control tanks to dampen surge effects. These tanks may provide sufficient protection for the UV reactors, depending on their location relative to the UV reactors.

Other surge control devices, such as air/ vacuum release valves, may rely on the introduction of air into the system to mitigate surge. As discussed previously, the presence of air can negatively affect the performance of the UV reactors. Air/ vacuum valves should only be used if surge tanks are not an option and the design can eliminate the air prior to the UV reactor ( e. g., install the valve in a section of pipe at a higher elevation than the UV reactor).

Proposal Draft Appendix H. Issues for Ground Water Systems UV Disinfection Guidance Manual H 7 June 2003 H. 6 References Cotton, C. A., R. S. Cushing, and D. M. Owen. 2002. The impact of the draft UV disinfection requirements on UV facility design and operation. Proceedings of the AWWA Annual Conference, June 16 20, New Orleans, LA.

Dinkloh, L. 2001. Wedeco Ideal Horizons. Telephone conversations and email correspondence by Ben Hauck, Malcolm Pirnie Inc., regarding UV reactors. April 25 and August 10.

Malley, J. P., B. A. Petri, G. L. Hunter, D. Moran, M. Nadeau, and J. Leach. 2001. Full scale implementation of UV in groundwater disinfection systems. Denver, CO: AwwaRF Final Report.

Miller, A. 2001. Trojan Technologies. Telephone conversation by Ben Hauck, Malcolm Pirnie Inc., regarding UV reactors. August 10.

Toivanen, E. 2000. Experiences with UV disinfection at Helsinki water. IUVA News 2, no. 6: 4 8.

Proposal Draft Appendix I. Issues for Small Systems The objectives of this appendix are to highlight the issues that small systems face when considering UV disinfection and to reference the more detailed discussion of these issues in this manual.

To be classified as a public water system, a utility must provide water to a minimum of 15 service connections or serve at least 25 people for at least 60 days per year ( 40 CFR 141.2). For the purpose of this appendix, the term small system includes those utilities serving fewer than 10,000 people or having a daily production rate of less than approximately 1.0 mgd. Most of the information regarding UV disinfection in Chapters 2, 3, 4, and 5 is valid for both small and large systems.

I. 1 Is UV Disinfection Applicable to Small Systems?

UV disinfection is applicable to small systems and may be attractive for the following reasons:

  It is a relatively low cost technology for the inactivation of Cryptosporidium ( Cotton et al. 2001).

  Chemical use is little to none.

  Operation is relatively simple and maintenance is low.

  Space needs are small.

Two types of UV reactors can potentially be used by small systems, conventional and point of entry ( POE) devices. Conventional UV reactors are manufactured for a wide range of flows ( e. g., from 20 gallons per minute ( gpm) up to 40 mgd) and are described in section 2.4. POE units are small UV reactors that are installed at the service connection of the customer. POE units contain the same components as conventional low pressure ( LP) installations but are more compact. They are primarily intended for use at individual properties and may be more suitable for utilities with a limited number of service connections. POE units are required to be owned, controlled, and maintained by the utility or by a person under contract with the utility to facilitate proper operation and maintenance and compliance with the treatment requirements ( Safe Drinking Water Act ( SDWA) Section 1412( b)( 4)( E)). The use of POE units may result in higher total costs when compared to a centralized, conventional UV installation for all but the smallest water utilities.

I. 2 What Information is Necessary to Assess the Feasibility of UV Disinfection?

Small systems generally need the same information to assess UV disinfection as larger systems. Chapter 3 describes the planning and design process for a UV installation in a UV Disinfection Guidance Manual I 1 June 2003 Proposal Draft Appendix I. Issues for Small Systems UV Disinfection Guidance Manual I 2 June 2003 conventional plant and discusses each of the elements that should be considered. In general, the utility should answer the following questions when assessing the suitability of UV disinfection:

  What are the disinfection goals and can UV disinfection be used to meet these goals? ( section 3.1.1)

  What are the minimum, average, and maximum flowrates that the UV reactors will need to treat? ( section <IP_ADDRESS>)

  What is the design UV absorbance at 254 nm ( A254) and corresponding design UV transmittance ( UVT)? What is the fouling potential of the water supply? What is the potential for process upset or variability in water quality? Do any of the existing processes have the potential to interfere with the performance of the UV reactors? ( section <IP_ADDRESS>)

  Can the UV reactors be incorporated into the existing hydraulic profile? If not, can the existing operations be modified to accommodate the UV reactors, or does intermediate pumping need to be installed? ( section <IP_ADDRESS>)

  Can the UV installation be incorporated into the existing facility layout? Does a building need to be constructed to house the UV reactors? ( section <IP_ADDRESS>)

  Is the quality and reliability of the electrical power supply adequate? Does a backup power supply or other supplemental electrical equipment need to be installed? ( sections <IP_ADDRESS> and 3.3.4)

  How should the UV reactors be controlled? What level of automation and operational complexity is appropriate? Does the potential for power savings justify using a more complex operating strategy? Is the existing operations staff sufficient? ( section 3.3.3)

  Is the number of UV reactors installed appropriate to efficiently respond to the anticipated range of flowrates? Does the UV installation have the capability to be expanded to meet future increases in demand? Is there sufficient redundancy to allow operating flexibility and to meet the disinfection goals under the operating scenarios? ( section <IP_ADDRESS>)

  How should the UV reactors be procured? ( section 3.2)

  Do the characteristics of the proposed UV application ( e. g., flowrate, UVT, UV intensity) differ from those under which a selected UV reactor was validated? If so, should the selected equipment be validated on site or off site under characteristics that match those of the intended installation? ( Chapter 4 and section <IP_ADDRESS>)

  What is the capital cost of the UV installation? What are the operating costs associated with a UV installation? ( section 3.1.7)

  What is the cost of the UV installation as compared to other disinfection alternatives?

Proposal Draft Appendix I. Issues for Small Systems UV Disinfection Guidance Manual I 3 June 2003   Is there a cost benefit to using POE units as opposed to a centralized UV installation? If so, how should the utility administer the POE units? Is some form of access agreement or water use ordinance necessary to allow administration of the POE units?

I. 3 Do the UV Reactors Need to be Housed in a Building?

If possible, the UV reactors should be constructed within a building to facilitate maintenance and protect the UV reactors. Nonetheless, the need for enclosing the UV reactors will ultimately be based on manufacturers' recommendations, State requirements, and environmental conditions. Although some current UV installations do not have a building ( e. g., Hanovia facility in Australia), local building and electrical codes may necessitate a building or other protection for the electrical equipment. Regardless of whether the UV reactors are enclosed, site security is important to prevent tampering with the equipment and water supply and to protect people from injury ( e. g., electrocution). Section 3.3.4 discusses the electrical equipment issues that should be considered during the planning and design of a UV installation.

I. 4 Do the Components of a Small System Differ from Larger UV Reactors?

The main components of a UV reactor ( including the necessary instrumentation and controls) do not differ between large and small systems. Components of the UV reactor may include the UV lamps, lamp sleeves, UV intensity sensors, ballasts, and cleaning mechanisms, which are described in section 2.4.

Full scale drinking water applications generally use LP, low pressure high output ( LPHO), or medium pressure ( MP) lamps. Small systems may find reactors that use LP or LPHO lamps more economical because they convert power into germicidal wavelengths of UV light more efficiently than MP lamps. Additionally, LP lamps typically have a longer useful life than either MP or LPHO lamps. For small systems, UV reactors with LP lamps are likely to represent the most cost effective disinfection solution. For systems that serve near 10,000 people or treat near 1 mgd, more consideration should be given to LPHO or MP lamps. An additional discussion of the different lamp types is given in section 2.4.2.

I. 5 What are the Power Needs?

The power needs depend on the manufacturer. Common manufacturers' power needs are as follows:

  POE UV units   120V/ 60Hz/ 1 phase   Conventional LP reactors   120/ 208V/ 60Hz/ 3 phase   Conventional LPHO reactors   480V/ 60Hz/ 3 phase   Conventional MP reactors   480V/ 60Hz/ 3 phase Proposal Draft Appendix I. Issues for Small Systems UV Disinfection Guidance Manual I 4 June 2003 Backup power may be necessary, depending on the type of installation that is selected, the power quality at the installation site, and the regulatory requirements for the installation. However, backup power for small systems may not be necessary as some small systems can accommodate a shutdown for longer periods because there is sufficient storage to meet demand. Additional detail on the need for backup power and the factors that should be considered when assessing the power supply are discussed in section <IP_ADDRESS>.

I. 6 Do Small UV Reactors Need to be Validated?

All UV reactors, including POE units, are required to be validated ( 40 CFR 141.729( d)). Small systems will probably purchase UV reactors that have been validated by the manufacturer. UV intensity sensor operating setpoints ( and potentially UVT setpoints) are established at specific flowrates during validation testing. These are the setpoints that the systems are required to operate within to receive inactivation credit. For many small UV reactors and nearly all POE units, UV reactor control will be limited to " on" and " off" with UV reactor shutdown under specific critical alarm conditions. Chapter 4 discusses the UV reactor validation requirements, and Chapter 5 describes operating requirements.

I. 7 How are UV Reactors Monitored?

Monitoring UV reactors ( conventional and POE) is required to ensure that the UV reactors are operating within the validated range ( 40 CFR 141.729( d)). Parameters that must be monitored include flowrate, UV intensity sensor readings, and UVT ( if it is part of the control strategy) ( 40 CFR 141.729( d)). POE units should be equipped with mechanical warnings to ensure that customers are automatically notified of operational problems. Additional detail on monitoring requirements is provided in section 5.4.1.

I. 8 Can the UV Reactors be Operated Remotely?

UV reactors can be operated remotely if the monitoring components provide a 4 20 mA analog output signal and are integrated into a control strategy. Even though UV reactors can be operated remotely, routine inspections and on site maintenance will be necessary to confirm that the UV reactor is operating properly. Provisions for hydraulic and electrical lockout should be provided to enable local isolation and lockout for maintenance. Section 3.3.3 provides additional detail on control strategies for centralized UV installations, and section 5.3 discusses operations and maintenance needs.

If the utility uses POE units, it may be beneficial to telemeter all alarm conditions to a central location to facilitate administration and maintenance of the POE units. However, incorporating this remote capability will likely increase the cost of the UV installation.

Proposal Draft Appendix I. Issues for Small Systems UV Disinfection Guidance Manual I 5 June 2003 I. 9 How Much Maintenance is Needed?

Maintenance is generally limited but will vary depending on the manufacturer and the specific application. Maintenance may include the following activities:

  Periodic calibration verification of UV intensity sensors, UVT meters, or flowmeters   Periodic replacement of UV intensity sensors, UVT meters, or flowmeters ( if applicable), depending on calibration or age of the equipment   Lamp sleeve and reactor cleaning   Replacement of UV lamps and other components   Maintenance of other operating components and the electrical systems Operators should be trained by the UV manufacturer on the proper operation and maintenance of the UV reactors. The utility should consider contracting trained service personnel to maintain the UV reactors if this is not possible. Additional detail on operations and maintenance is given in section 5.3.

I. 10 References Cotton, C. A., D. M. Owen, G. C. Cline, and T. P. Brodeur. 2001. UV disinfection costs for inactivating Cryptosporidium. Journal of the American Water Works Association 93, no. 2: 67 74.

Proposal Draft Appendix J. Pilot Scale and Demonstration Scale Testing In some cases, pilot or demonstration scale testing may be warranted to aid in selection of design criteria. For example, long term UV unit performance will be impacted by lamp aging and sleeve fouling. With increased use, lamp output decreases due to deposition of inorganic material on the outside and inside of the sleeve ( i. e., " fouling"). Fouling reduces the transmittance of the lamp energy to the water. Over time, these phenomena will contribute to a reduction in UV dose. The effect of these parameters should be incorporated into the UV reactor design. A " lamp aging factor" and a " fouling factor" are usually specified by the design engineer. Pilot testing can provide useful information for the development of these factors.

This appendix discusses when pilot or demonstration tests may be needed and the types of tests that may be performed on UV disinfection systems. The purpose( s) of pilot and demonstration testing is to establish or confirm system design factors, test system reliability, and evaluate operation and maintenance ( O& M) needs. The tests described herein may be performed individually or in parallel. Validation of reactor microbial inactivation performance is addressed separately in Appendix C ( Validation Protocol).

J. 1 When Is Pilot or Demonstration Testing Needed?

Pilot and demonstration tests can be used to meet the following three goals:

1. Assess the impact of unusual water quality conditions ( e. g., high calcium or iron concentrations).

2. Improve estimation of safety factors for large water systems for which such an investment can yield a high return in reduced life cycle costs.

3. Gain first hand experience with operating and maintaining a UV installation.

A UV disinfection system should be designed with some knowledge of the likely fouling potential of the water and lamp aging characteristics to ensure the system operates as intended. If the design and the operation protocol do not properly account for the effects of lamp aging and sleeve fouling, the system may go into alarm frequently ( indicating under dosing).

While pilot or demonstration testing may be warranted in some cases, it is becoming less necessary as more performance and fouling information is developed. The need for pilot or demonstration testing should be carefully considered in light of the pre existing data available on both system performance and water quality effects on sleeve fouling. Pilot or demonstration testing may be used to gain operational experience or primacy agency acceptance, as discussed in the following sections.

Microbiological challenge tests are not recommended during pilot studies because inactivation efficiency in a pilot system may not be indicative of full scale performance. However, UV reactor validation bioassays could be conducted as part of a full scale UV Disinfection Guidance Manual J 1 June 2003 Proposal Draft Appendix J. Pilot Scale and Demonstration Scale Testing UV Disinfection Guidance Manual J 2 June 2003 demonstration test if on site testing is planned. Appendix C presents a detailed discussion of UV reactor performance validation.

Because UV disinfection is a relatively new drinking water treatment technology in the United States, State regulatory agency acceptance may depend in part on the confidence in the technology gained through pilot and demonstration scale studies. Identifying previous studies of similar scope that provide background and precedents may also be helpful in gaining acceptance of its planned use ( see, for example, et al. Mackey 2001).

If a utility chooses to or is required to conduct pilot or demonstration tests, the primacy agency should understand the objective( s) of the test( s) and the methodologies used. It is recommended that the primacy agency be contacted before testing and involved throughout the pilot and/ or demonstration testing. Identifying and resolving State regulatory agency concerns when planning testing can help produce a more useful dataset. Additionally, it may be helpful to include the State in interim briefings on progress and results, and to give them a final report after completing the testing.

J. 1.1 Water Quality Impacts Extensive data have been generated from pilot scale testing on waters of low to moderate hardness and iron content ( Mackey et al. 2001, Mackey and Cushing 2003). At total hardness and calcium levels below 140 mg/ L and low iron ( less than 0.1 mg/ L), standard cleaning protocols and wiper frequencies ( one sweep every 15 minutes to an hour) were more than adequate to deal with the impact of sleeve fouling at all sites tested. At sites with hardness or iron in the feed water that exceed these levels, it may be advantageous to evaluate fouling rates on a site specific or worst case basis via pilot or demonstration testing to identify how best to keep the sleeves clean.

J. 1.2 Lamp Fouling Factors for Large Systems In UV reactor design, a lamp aging factor of 0.7 is commonly used, as discussed in section <IP_ADDRESS> of the Manual. For larger systems, it may be economical to pilot or demonstration test lamp aging to provide data for selecting lamp aging and low dose alarm design factors that will best balance operational costs ( how many hours one wants to be able to operate a lamp before replacing it) with capital costs ( the size of the system needed based on end of lamp life). Lamp aging factors may also be obtained from a certified lamp age testing program performed by equipment or lamp manufacturers. A lower lamp aging factor means the utility will have less frequent lamp replacements, but may require a larger system to ensure compliance at all times.

J. 1.3 Gaining Operational Experience Due to the small number of U. S. drinking water UV installations, very few United States operators have experience with UV disinfection systems. It may be beneficial for a facility's Proposal Draft Appendix J. Pilot Scale and Demonstration Scale Testing UV Disinfection Guidance Manual J 3 June 2003 staff to obtain operational experience with UV disinfection systems prior to selecting and implementing UV disinfection. If a utility staff becomes familiar with the operational aspects of UV disinfection, that staff will be able to provide feedback input on the UV installation design. In addition, operational experience can help facility managers to determine the staffing/ training needs and help maintenance staff understand and plan for the maintenance needs of the system ( e. g., time to change lamps and calibrate UV intensity sensors and perform manual cleaning).

On site testing is site specific depends on the needs and preferences of the utility. Methods by which facility staff can gain operational experience ( besides on site testing) include: site visits and partnerships with systems already using UV disinfection; conversations and visits with manufacturers and attendance of seminars; and on site training programs ( a detailed discussion of training programs is provided in section 5.7.2).

J. 2 Pilot Versus Demonstration Scale Testing Table J. 1 presents a comparison of the advantages and disadvantages associated with pilot scale and demonstration scale testing. Pilot scale testing involves operating a smaller version of a full sized UV disinfection reactor. It may or may not include all the components of the full sized system. Demonstration scale testing is essentially pilot testing of a full scale UV disinfection reactor.

Table J. 1 Comparison of Pilot and Demonstration Testing Testing Method Advantages Disadvantages Pilot scale   Smaller footprint needed for UV reactors   Less expensive installation and operation   Operators gain O& M experience   High flexibility in placement of equipment   Lesser volumes of water to dispose   Design conditions for UV disinfection systems may not scaleup to full scale systems   In rare cases it may be advisable to use pilot scale treatment process equipment ( filters, clarifiers, etc.) to simulate operational conditions ( e. g., upstream ozone process)

Demonstration Scale   Confidence in long term operation of the UV unit due to the representative scale at which results are obtained   Scale up factors need not be developed   Operators gain operations and maintenance experience on a fullscale system.   Approval from the primacy agency may be required to conduct a demonstration study   Demonstration setups are not as flexible as pilot studies for operational experimentation   Installation and operation more expensive than pilot scale   Greater volumes of water to dispose.

Proposal Draft Appendix J. Pilot Scale and Demonstration Scale Testing UV Disinfection Guidance Manual J 4 June 2003 J. 3 Documenting the Test Reactor For a given test, should the properties of the components that may influence the final outcome of the test should be identified and recorded. That record may later be used to confirm that key components of installed UV reactors match those of the systems tested. Table J. 2 lists the components of a UV disinfection system that should be documented and compared between testing and the final design.

Table J. 2 Key Components Associated with UV Reactor Pilot Scale and Demonstration Scale Testing Test Components to Document Operational Experience Controls, alarms, cleaning mechanisms, operation, maintenance. Fouling Assessment Lamps, sleeves, ballasts, power settings, UV intensity sensor windows, flow velocity. Head loss Assessment ( demonstration scale only) Reactor and wetted components, inlet/ outlet conditions. Ballast Performance Lamps, sleeves, ballast, power settings, operation. Cleaning Mechanism Performance Lamps, sleeves, ballasts, power settings, ballast operation, UV intensity sensor windows ( if wiper used), cleaning mechanism, cleaning solutions, wiper maintenance and operation. Lamp Aging/ Failure Lamps, sleeves, ballasts, power settings, ballast operation, cleaning mechanism, cleaning solutions, wiper maintenance and operation. Sleeve Breakage Sleeves, cleaning mechanisms, flow velocity, water hammer. Controls/ Alarms Lamps, sleeves, ballasts, UV intensity sensors, cleaning mechanisms, controls, operation.

J. 4 Testing Objectives Pilot/ demonstration testing may be used to gain information on a specific UV reactor, a specific water treatment plant ( WTP) site, or a combination of the two. Common test objectives include the following topics:

  The long term performance and failure modes of the lamps   The efficacy of cleaning mechanisms for lamp sleeves and UV intensity sensor windows   The stability of UV intensity and UVT monitors Proposal Draft Appendix J. Pilot Scale and Demonstration Scale Testing UV Disinfection Guidance Manual J 5 June 2003   The reliability of controls and alarm systems   The ease of lamp and UV intensity sensor replacement, the use of reference sensors, and the maintenance of cleaning devices and solutions   The rate of fouling on lamp sleeves and UV intensity sensor windows   The most appropriate cleaning method   The head loss across the reactor at various flow rates ( demonstration scale only)

  The impact on other unit operations at the WTP The information obtained during pilot and demonstration testing should be applicable to the final UV disinfection system installed at the WTP. Accordingly, the equipment tested should be representative of the UV disinfection system that will be installed. Specific elements of a pilot/ demo scale system that should be identical include the UV intensity sensors, lamp and sleeve type, power system, cleaning system, cleaning frequency, and water quality. For example, lamp aging data on a 3 kW 25 cm medium pressure ( MP) lamp driven by an electromagnetic ballast cannot be used to predict the aging expected with a 10 kW 50 cm MP lamp driven by a transformer.

J. 5 Testing Protocols This section describes the major elements and benefits of a range of pilot and demonstration testing protocols to investigate sleeve fouling and cleaning, lamp aging, head loss and alarms and controls.

J. 5.1 Assessing Fouling A fouling assessment can be conducted to answer the following questions:

  How fast do the lamps foul?

  How does water quality affect fouling?

  What lamp fouling factor should be specified?

W   hat lamp cleaning interval is required?

W   hat sleeve replacement interval is required?

H   ow do lamp/ reactor configurations affect fouling?

Is   fouling of the UV intensity sensor window( s) significant and how should it be addressed?

Proposal Draft Appendix J. Pilot Scale and Demonstration Scale Testing UV Disinfection Guidance Manual J 6 June 2003 Fouling may occur on the inner and outer surfaces of the lamp sleeves, the internal surfaces of the reactor, and UV intensity sensor windows. Lamp sleeve fouling may have an impact d to on of d for assessing sleeve fouling similar to that employed by Lin et al. ( 1999b), new lamp can be placed inside the fouled sleeve and ignited. Ultraviolet absorbance at 254 nanom chemical cleaning should restore the sleeve A254 to very near that of a new, clean leeve. If not, manually clean the inside of the sleeve and measure A254. If it is still low, the sleeve s a fouling, care should be taken to ensure that the results scalep to full scale applications. Some differences in system geometry may lead to erroneous conclus leeve f e UV intensity sensor windows, clean the sensor monitoring indows with phosphoric or citric acid at varying time intervals and record the change in sensor reading .5.2 Evaluating Cleaning Systems ethods can be performed to answer the following uestions:

Does a particular cleaning protocol work for the UV reactor application? on dose delivery and cleaning requirements. Sensor window fouling may have an important impact on assessing dose delivery ( e. g., the sensor will not be able to accurately measure lamp intensity). Fouling on the wetted surfaces of a UV reactor has been attribute precipitation of compounds whose solubility decreases as temperature increases, precipitati compounds with low solubility, and deposition of particles by gravity settling and turbulenceinduced impaction ( Lin et al. 1999a). More detailed discussion on fouling is provided in sections <IP_ADDRESS> and A. 4.1.4.

In one metho a eters ( A254) is measured by a calibrated radiometer and compared to a similar measurement made using a new, clean sleeve. The ratio of these two measurements ( UV light passing through the fouled sleeve to that passing through the new sleeve) is the lamp sleevefouling factor.

Manual, s material has likely degraded. If A254 cannot be recovered, further testing may be used to identify a proper sleeve replacement interval. The lamp sleeve fouling factor can be plotted a function of time. Worst case results can be analyzed to determine cleaning requirements and fouling factors for design purposes.

When assessing lamp sleeve u ions based on pilot data alone. For instance, in parallel flow reactors, fouling has been found to be uneven along the length of the lamps ( Lin et al. 1999a). If the lamp and lamp s geometry ( e. g., length or diameter) of the pilot unit is very different from the full scale system, the fouling that will occur in the full scale plant may be markedly different from expectations based on pilot scale data. The lamp lengths will be very different and end effects may be more pronounced ( i. e., the blackened lamp ends of an aged lamp will comprise a greater percentage o the total length of the lamp).

To assess fouling on th w s. It is expected that the rate of fouling on the lamps will be greater than the rate of fouling on the sensor windows due to elevated lamp temperature.

J An evaluation of system cleaning m q

Proposal Draft Appendix J. Pilot Scale and Demonstration Scale Testing UV Disinfection Guidance Manual J 7 June 2003   What is the long term effectiveness of the cleaning method?

  What cleaning frequency is required for each method considered?

nts that accumu te on the lamp sleeves and UV intensity sensor windows. Lamp sleeve cleaning method ning), ipers g .5.2.1 Assessing Lamp Sleeve Cleaning Protocols mp sleeves, and the sults b lowest r at the minimum flow rate and operate the lamps at maxim ith systems using mechanical or physicochemical wipers, an unwiped sleeve se this ata to optimize the cleaning frequency. Sensor windows should be manually cleaned before measur heduled sleeve cleaning cycle, remove the lamp sleeves and assess the sleeve A254 for low pressure ( LP) lamps and absorbance from 20 hen manual, chemical cleaning is recommended, remove the sleeves and measure the sleeve A254 before and after cleaning the outer surfaces. If the new sleeve transm ntify .5.2.2 Assessing UV Intensity Sensor Window Cleaning Protocols actor e cond maxim leaning Various cleaning methods can be used to periodically remove the foula la s include off line chemical cleaning ( OCC) ( off line manual or mechanized clea on line mechanical cleaning ( OMC) ( e. g., brushes or rings), and on line physicochemical w ( acid solution in a wiper collar). Sensor window cleaning methods also include manual cleanin and mechanical wipers.

J A sleeve cleaning assessment should be performed on at least four la e used to identify a sleeve fouling design factor for sizing the UV reactor based on the re individual sleeve fouling factor observed. This will help ensure proper dose delivery for the entire life of the sleeve. One method for assessing lamp sleeve cleaning needs is detailed below:

Pass water through the reacto um power. W can be used as a control to verify that fouling is occurring. The manufacturer's recommendations regarding the maintenance of the cleaning device should be followed.

Record the UV intensity sensor readings before and after the cleaning cycle and u d ements to ensure only lamp sleeve fouling is affecting the sensor values. If possible, check all UV intensity sensor readings with a reference sensor.

At regular time intervals and immediately prior to the sc 0  400 nm for MP. The non destructive method of Lin et al. ( 1999b) may be used as discussed in section J. 5.1.

After 6 months, or w ittance is not restored by the cleaning, it is likely that the sleeve material has fouled internally or permanently degraded. Further monitoring and testing may be necessary to ide the proper sleeve replacement interval.

J To assess fouling of the UV intensity sensor window, one alternative is to operate the under th itions suggested in section J. 5.2.1 ( i. e., minimum water flow rate, re um lamp power). After 6 months, or a time interval suggested by the manufacturer, a chemical cleaning of the monitoring sensor window could be performed. Alternatively, c Proposal Draft Appendix J. Pilot Scale and Demonstration Scale Testing UV Disinfection Guidance Manual J 8 June 2003 could be performed when the sensor reading falls to a minimum value suggested by the manufacturer. The A254 of the window should be measured before and after cleaning. A sensor window cleaning frequency can then be estimated as discussed in section <IP_ADDRESS>.

J. 5.3 Assessing Head Loss ld be performed for demonstration scale ( full scale) systems verify that head loss constraints at the final install station will not be exceeded. Head loss data from pi ion J. 1: Head loss assessments shou to lot scale units should not be used to estimate head loss in a full scale system.

The head loss,   H, through a UV reactor may be calculated according to Equat g Kv2 Equation J. 1 H 2 =

where = Head loss coefficient ( unitless) for the UV reactor = Water velocity ( m/ s) through the reactor , the UV unit can be installed with strumentation to measure pressure loss across the reactor ( including baffles and specialized inlet/ ou res due to um and ma imum flow rates, these measured head loss values can be plotted as a function of the square J. 5.4 amp Aging and Failure e conducted to answer the following questions:

e?

?

ds of hours. The germicidal output of the lam will decline during this period ( Phillips 1983). In MP systems, UV lamp aging can also result i

K v g = Gravitational constant ( 9.8 m/ s2)

To assess head loss through a UV reactor in tlet piping). Since the head loss coefficient will be higher at lower temperatu decreased water viscosity, it may be desirable, if feasible, to measure head loss at the lowest water temperature expected at the UV reactor installation to assess the worst case condition.

If head loss is measured at various flow rates through the reactor, including the minim x of the calculated water velocity through the reactor to determine a head loss coefficient.

L A lamp aging evaluation can b   What is the actual operating lamp life?

  How does lamp output degrade over tim   What lamp aging factor should be specified The service life of a UV lamp extends for thousan p n a change in the spectral output over time. With polychromatic ( MP) UV lamps, lower wavelengths will likely decline at a faster rate than will higher wavelengths. The rate and manner in which a lamp ages is lamp and operation specific. A detailed discussion of lamp Proposal Draft Appendix J. Pilot Scale and Demonstration Scale Testing UV Disinfection Guidance Manual J 9 June 2003 aging is presented in section A. 3.1.6. Lamp output will decrease over time as a function of lamp hours in operation, the number of on/ off cycles, and the power applied per unit ( lamp) length.

La the mp aging tests should be designed to assess the reduction and variance in lamp germicidal output over time under defined worst case operating conditions. Lamp age testing may us igned e batch, lamp assembly, electrical haracteristics of the ballasts, heat transfer from the lamps to the water, and operation of the lamps.

clude electrical power delivered to the ballast, electrical power delivered to the lamp, and water temperature. If UV intensity sensors alone monito radation of the lamp assembly, including electrodes and seals, and any darkening of the lamp   any fouling on the internal surfaces of the lamp sleeves;

ballast operation ( e. g., power setting), heat transfer ( e. g., lamp sleeves), and environment ( water measured using one of the following: a radiometer ter   rkening on the lamp). y be

n be used to identify operational sues and provide operational guidance. The output of the lamps measured under fixed operati and e either a pilot/ demonstration scale UV reactor installed at a WTP or a test bed des to emulate the reactor ( i. e., identical power supply). It is strongly recommended that all tests b done with the lamps housed in the sleeves and powered by the ballasts that will be used in the final application. It is best if the lamp sleeves are maintained free of external foulant during aging tests, in a manner similar to that of the final application.

Factors to consider in designing the test( s) include lamp c Since lamps will be manufactured in batches, it is recommended that lamps from several different lots be evaluated. During demonstration and pilot scale testing, the lamps should be operated in a manner and in an environment that reflects conditions expected when the UV disinfection system is installed at a WTP.

Parameters to monitor over time in r lamp output, it is recommended that the A254 of the water also be measured.

During testing, it is recommended that the following analyses be considered:

  Visually inspect the lamps at regular intervals to document any visible deg envelope;

Document   Measure the germicidal output of the lamp under fixed conditions of temperature and transmission).   One measurement should be made with the lamps aged 100 hours (" new").   The germicidal output may be equipped with a germicidal filter; a reference UV intensity sensor or radiome from 200 to 400 nm; or by bioassay. The output from various positions along the lamp may be measured based on visual inspection ( i. e., the pattern of da   If lamp power is variable, lamp output as a function of lamp power setting ma measured. Assess the output from lamps of different lots.

Pilot/ demo scale test data and visual inspections ca is ng conditions can be plotted over time and fit to provide mean expected performance prediction intervals ( e. g., 90th, 95th, and 99th percentiles) to estimate the range of performance in Proposal Draft Appendix J. Pilot Scale and Demonstration Scale Testing UV Disinfection Guidance Manual J 10 June 2003 lamp intensity at different lamp ages. In a robust system, all the lamps will age in a similar manner. If lamps age differently than expected, the results will affect dose delivery and UV intensity sensor measurements. This data can be used to assess a proper end of lamp life.

J. 5.5 valuating Controls and Alarms ls and alarms should be conducted to verify their erformance and to gain familiarity with alarm/ control response procedures. A test plan is typicall educing ts, or ified .6 References and E. R. Blatchley. 1999a. Inorganic fouling at Quartz: Water interfaces in ultraviolet photoreactors   I Chemical characterization. Wat. Res. 33, no 15:

Lin, L. S., C. T. Johnston, and E. R. Blatchley. 1999b. Inorganic fouling at Quartz: Water interfaces in ultraviolet photoreactors   II Temporal and spatial distribution. Wat. Res. 33,

Mackey , and G. F. Crozes. 2001. Practical aspects of UV disinfection. Denver, CO: AWWA Research Foundation and AWWA.

Mackey Bridging pilot scale testing to full scale design of UV disinfection systems. Denver, CO: AWWA Research Foundation Phillips rces and application of ultraviolet radiation. Academic Press: New York. E An evaluation of the UV reactor contro p y organized prior to testing, describing the control function to be tested, the test procedure, and the expected response. Faults may be induced or simulated. Low dose conditions may be simulated by reducing lamp power, increasing the A254 of the water, r or increasing flow beyond the validation limits of the reactor, turning off lamps or ballas disconnecting sensors. Valve failure, high temperature, and ground fault interrupts may be induced or simulated. Simulating faults may require disconnecting components of the UV disinfection system or using modified electronics. Accordingly, qualified personnel as ident by the manufacturer of the UV disinfection system should undertake these simulations. All operational functions can be verified, including startup and shutdown sequences and cleaning cycles. Dose pacing if used, may be verified by monitoring lamp power settings and dose compliance as flow rate, A254, and lamp output are varied.

J Lin, L. S., C. T. Johnston,

3321 3329.

no 15: 3330 3338.

, E. D., R. S. Cushing , E. D. and R. S. Cushing. Publication anticipated in 2003.

and AWWA.

, R. 1983. Sou Proposal Draft


[Federal Register: May 3, 2010 (Volume 75, Number 84)]
[Proposed Rules]
[Page 23194-23196]
[DOCID:fr03my10-9]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2010-0458; Directorate Identifier 2010-CE-023-AD]
RIN 2120-AA64

Airworthiness Directives; GROB-WERKE GMBH & CO KG Models G102
ASTIR CS and G102 STANDARD ASTIR III Gliders

AGENCY: Federal Aviation Administration (FAA), Department of
Transportation (DOT).

ACTION: Notice of proposed rulemaking (NPRM).

-----------------------------------------------------------------------

SUMMARY: We propose to adopt a new airworthiness directive (AD) for the
products listed above. This proposed AD results from mandatory
continuing airworthiness information (MCAI) originated by an aviation
authority of another country to identify and correct an unsafe
condition on an aviation product. The MCAI describes the unsafe
condition as:

    During an annual inspection, a water ballast hose connector was
found disconnected from the fuselage wall of an Astir CS.
    The investigation has shown that the hose-fuselage connection
bonding has been degraded over years of service.
    This condition, if not corrected, could lead to the following
consequences:

--The water contained in the wing tanks could run down into the
fuselage and fuselage tail which could cause a displacement of the
sailplane centre of gravity and consequently may lead to the loss of
the sailplane controllability, or/and
--The loosened hose may jam the flight controls (push rods) and
consequently may lead to the loss of the sailplane controllability.

The proposed AD would require actions that are intended to address the
unsafe condition described in the MCAI.

DATES: We must receive comments on this proposed AD by June 17, 2010.

ADDRESSES: You may send comments by any of the following methods:
     Federal eRulemaking Portal: Go to http://
www.regulations.gov. Follow the instructions for submitting comments.
     Fax:<PHONE_NUMBER>.
     Mail: U.S. Department of Transportation, Docket
Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New
Jersey Avenue, SE., Washington, DC 20590.
     Hand Delivery: U.S. Department of Transportation, Docket
Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New
Jersey Avenue, SE., Washington, DC 20590, between 9 a.m. and 5 p.m.,
Monday through Friday, except Federal holidays.

Examining the AD Docket

    You may examine the AD docket on the Internet at http://
www.regulations.gov; or in person at the Docket Management Facility
between 9 a.m. and 5 p.m., Monday through Friday, except Federal
holidays. The AD docket contains this proposed AD, the regulatory
evaluation, any comments received, and other information. The street
address for the Docket Office (telephone<PHONE_NUMBER>) is in the
ADDRESSES section. Comments will be available in the AD docket shortly
after receipt.

FOR FURTHER INFORMATION CONTACT: Greg Davison, Aerospace Engineer, FAA,
Small Airplane Directorate, 901 Locust, Room 301, Kansas City, Missouri
64106; telephone:<PHONE_NUMBER>; fax:<PHONE_NUMBER>.

SUPPLEMENTARY INFORMATION:

Comments Invited

    We invite you to send any written relevant data, views, or
arguments about this proposed AD. Send your comments to an address
listed under the ADDRESSES section. Include ``Docket No. FAA-2010-0458;
Directorate Identifier 2010-CE-023-AD'' at the beginning of your
comments. We specifically invite comments on the overall regulatory,
economic, environmental, and energy aspects of this proposed AD. We
will consider all comments received by the closing date and may amend
this proposed AD because of those comments.
    We will post all comments we receive, without change, to http://
www.regulations.gov, including any personal information you provide. We
will also post a report summarizing each substantive verbal contact we
receive about this proposed AD.

Discussion

    The European Aviation Safety Agency (EASA), which is the Technical
Agent for the Member States of the European Community, has issued EASA
AD No.: 2010-0053R1, dated April 14, 2010 (referred to after this as
``the MCAI''), to correct an unsafe condition for the specified
products. The MCAI states:

    During an annual inspection, a water ballast hose connector was
found disconnected from the fuselage wall of an Astir CS.
    The investigation has shown that the hose-fuselage connection
bonding has been degraded over years of service.
    This condition, if not corrected, could lead to the following
consequences:

--The water contained in the wing tanks could run down into the
fuselage and fuselage tail which could cause a displacement of the
sailplane centre of gravity and consequently may lead to the loss of
the sailplane controllability, or/and
--The loosened hose may jam the flight controls (push rods) and
consequently may lead to the loss of the sailplane controllability.

    For the reason stated above, the original issue of this AD
required the inspection of the waterballast system hose-fuselage
connections and the accomplishment of the relevant corrective
actions (repair) as necessary.
    This AD is revised to clarify the purpose of the insertion of
the repetitive inspection in the Aircraft Maintenance Programme and
to refer to a more appropriate scheduled maintenance review for the
insertion of the repetitive inspection in the Aircraft Maintenance
Programme.

You may obtain further information by examining the MCAI in the AD
docket.

Relevant Service Information

    GROB Aircraft AG has issued Grob Aircraft Service Bulletin No. MSB-
GROB-003, dated October 21, 2009. The actions described in this service
information are intended to correct the unsafe condition identified in
the MCAI.

FAA's Determination and Requirements of the Proposed AD

    This product has been approved by the aviation authority of another
country, and is approved for operation in the United States. Pursuant
to our bilateral agreement with this State of Design Authority, they
have notified us of the unsafe condition described in the MCAI and
service information referenced above. We are proposing this AD because
we evaluated all information and determined the unsafe condition exists
and is likely to exist or develop on other products of the same type
design.

Differences Between This Proposed AD and the MCAI or Service
Information

    We have reviewed the MCAI and related service information and, in
general, agree with their substance. But we might have found it
necessary to use different words from those in the MCAI to ensure the
AD is clear for U.S. operators and is enforceable. In making these
changes, we do not intend to differ substantively from the information
provided in the MCAI and related service information.
    We might also have proposed different actions in this AD from those
in the MCAI in order to follow FAA policies. Any such differences are
highlighted in a Note within the proposed AD.

Costs of Compliance

    We estimate that this proposed AD will affect 113 products of U.S.
registry. We also estimate that it would take about 1 work-hour per
product to comply with the basic requirements of this proposed AD. The
average labor rate is $85 per work-hour.
    Based on these figures, we estimate the cost of the proposed AD on
U.S. operators to be $9,605, or $85 per product.
    In addition, we estimate that any necessary follow-on actions would
take about 1 work-hour and require parts costing $5, for a cost of $90
per product. We have no way of determining the number of products that
may need these actions.

Authority for This Rulemaking

    Title 49 of the United States Code specifies the FAA's authority to
issue rules on aviation safety. Subtitle I, section 106, describes the
authority of the FAA Administrator. ``Subtitle VII: Aviation
Programs,'' describes in more detail the scope of the Agency's
authority.
    We are issuing this rulemaking under the authority described in
``Subtitle VII, Part A, Subpart III, Section 44701: General
requirements.'' Under that section, Congress charges the FAA with
promoting safe flight of civil aircraft in air commerce by prescribing
regulations for practices, methods, and procedures the Administrator
finds necessary for safety in air commerce. This regulation is within
the scope of that authority because it addresses an unsafe condition
that is likely to exist or develop on products identified in this
rulemaking action.

Regulatory Findings

    We determined that this proposed AD would not have federalism
implications under Executive Order 13132. This proposed AD would not
have a substantial direct effect on the States, on the relationship
between the national Government and the States, or on the distribution
of power and responsibilities among the various levels of government.
    For the reasons discussed above, I certify this proposed
regulation:
    1. Is not a ``significant regulatory action'' under Executive Order
12866;
    2. Is not a ``significant rule'' under the DOT Regulatory Policies
and Procedures (44 FR 11034, February 26, 1979); and
    3. Will not have a significant economic impact, positive or
negative, on a substantial number of small entities under the criteria
of the Regulatory Flexibility Act.
    We prepared a regulatory evaluation of the estimated costs to
comply with this proposed AD and placed it in the AD docket.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Incorporation by
reference, Safety.

The Proposed Amendment

    Accordingly, under the authority delegated to me by the
Administrator, the FAA proposes to amend 14 CFR part 39 as follows:

PART 39--AIRWORTHINESS DIRECTIVES

    1. The authority citation for part 39 continues to read as follows:

    Authority:  49 U.S.C. 106(g), 40113, 44701.

Sec.  39.13  [Amended]

    2. The FAA amends Sec.  39.13 by adding the following new AD:

GROB-WERKE GMBH & CO KG: Docket No. FAA-2010-0458; Directorate
Identifier 2010-CE-023-AD.

Comments Due Date

    (a) We must receive comments by June 17, 2010.

Affected ADs

    (b) None.

Applicability

    (c) This AD applies to Models G102 ASTIR CS and G102 STANDARD
ASTIR III gliders, all serial numbers, that are:
    (1) Certificated in any category; and
    (2) Have water ballast equipment installed (the water ballast
equipment could have been included as part of an option).

Subject

    (d) Air Transport Association of America (ATA) Code 41: Water
Ballast.

Reason

    (e) The mandatory continuing airworthiness information (MCAI)
states:
    During an annual inspection, a water ballast hose connector was
found disconnected from the fuselage wall of an Astir CS.
    The investigation has shown that the hose-fuselage connection
bonding has been degraded over years of service.
    This condition, if not corrected, could lead to the following
consequences:

--The water contained in the wing tanks could run down into the
fuselage and

fuselage tail which could cause a displacement of the sailplane
centre of gravity and consequently may lead to the loss of the
sailplane controllability, or/and
--The loosened hose may jam the flight controls (push rods) and
consequently may lead to the loss of the sailplane controllability.

    For the reason stated above, the original issue of this AD
required the inspection of the waterballast system hose-fuselage
connections and the accomplishment of the relevant corrective
actions (repair) as necessary.
    This AD is revised to clarify the purpose of the insertion of
the repetitive inspection in the Aircraft Maintenance Programme and
to refer to a more appropriate scheduled maintenance review for the
insertion of the repetitive inspection in the Aircraft Maintenance
Programme.

Actions and Compliance

    (f) Unless already done, do the following actions:
    (1) Within 30 days after the effective date of this AD and
repetitively thereafter at intervals not to exceed 12 months,
inspect the bonding between the water ballast system hose connectors
and the fuselage wall connectors for correct and tight connection
following paragraph 1.8 of Grob Aircraft Service Bulletin No. MSB-
GROB-003, dated October 21, 2009.
    (2) If, during any inspection required by paragraphs (f)(1) of
this AD, any weak bonding is found, before further flight, repair
the connection between the water ballast system hose connectors and
the fuselage wall connectors following the instructions of paragraph
1.8 of Grob Aircraft Service Bulletin No. MSB-GROB-003, dated
October 21, 2009.
    (3) After the effective date of this AD, when installing a water
ballast system on any affected sailplane, ensure that the water
ballast system hose connectors and the fuselage wall connector are
properly and tightly bonded.
    (4) Within 30 days after the effective date of this AD, insert
the following scheduled maintenance task into the FAA-approved
aircraft maintenance program: ``During each annual inspection and
without exceeding a 12-month interval, inspect the bonding between
the water ballast system hose connectors and the fuselage wall
connectors for correct and tight connection. Repair any incorrect or
loose connection.''

FAA AD Differences

    Note: This AD differs from the MCAI and/or service information
as follows: No differences.

Other FAA AD Provisions

    (g) The following provisions also apply to this AD:
    (1) Alternative Methods of Compliance (AMOCs): The Manager,
Standards Office, FAA, has the authority to approve AMOCs for this
AD, if requested using the procedures found in 14 CFR 39.19. Send
information to ATTN: Greg Davison, Aerospace Engineer, FAA, Small
Airplane Directorate, 901 Locust, Room 301, Kansas City, Missouri
64106; telephone:<PHONE_NUMBER>; fax:<PHONE_NUMBER>. Before using
any approved AMOC on any airplane to which the AMOC applies, notify
your appropriate principal inspector (PI) in the FAA Flight
Standards District Office (FSDO), or lacking a PI, your local FSDO.
    (2) Airworthy Product: For any requirement in this AD to obtain
corrective actions from a manufacturer or other source, use these
actions if they are FAA-approved. Corrective actions are considered
FAA-approved if they are approved by the State of Design Authority
(or their delegated agent). You are required to assure the product
is airworthy before it is returned to service.
    (3) Reporting Requirements: For any reporting requirement in
this AD, under the provisions of the Paperwork Reduction Act (44
U.S.C. 3501 et seq.), the Office of Management and Budget (OMB) has
approved the information collection requirements and has assigned
OMB Control Number 2120-0056.

Related Information

    (h) Refer to MCAI European Aviation Safety Agency AD No.: 2010-
0053R1, dated April 14, 2010; and Grob Aircraft Service Bulletin No.
MSB-GROB-003, dated October 21, 2009, for related information.

    Issued in Kansas City, Missouri, on April 22, 2010.
James E. Jackson,
Acting Manager, Small Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 2010-9954 Filed 4-30-10; 8:45 am]
BILLING CODE 4910-13-P