# 1) XcelEnergy·

~ RTsPON-s-iS-i-i:-ijY--NA-ruli-ETM May 18, 2009 Mr. Richard Kinch US Environmental Protection Agency (5306P) 1200 Pennsylvania Avenue, NW Washington, DC 20460 414 Nicollet Mall Minneapolis, Minnesota 55401-1993

Re: Xcel Energy Response to Request for Information relating to Surface Impoundments Under 104 (e) ofthe Comprehensive Environmental Response, Compensation, and Liability Act, 42 U.S.C. 9604(e). Dear M.r.Kinch: Please find enclosed the response from:

- Public Service Company of Colorado (PSCo), a Colorado corporation;

- Northern States Power Company of Minnesota (NSP-M), a Minnesota corporation, and; Northern States Power Company ofWisconsin (NSP-W), aWisconsin corporation; all d/b/a Xcel Energy Inc., related tothe US Environmental Protection Agency's (EPA) "Request for Information" received May 4, 2009 for surface impoundments that are used to manage coal combustion residuals or byproducts at our coal fired generation plants. This response addresses the nine additional facilities Xcel Energy identified in a letter to EPA dated April 17, 2009, specifically:

• NSP-W Bay Front Plant inAshland, Wisconsin
• NSP-M Minnesota Valley Plant in Granite Falls, Minnesota
• PSCo Arapahoe Station in Denver, Colorado
• PSCo Cameo Station in Grand Junction, Colorado
• PSCo Cherokee Station in Denver, Colorado
• PSCo Comanche Station in Pueblo, Colorado
• PSCo Hayden Station in Hayden, Colorado
• PSCo Pawnee Station in Brush, Colorado
• PSCo Valmont Station in Boulder, Colorado We are consolidating and submitting the requested information for the nine facilities as attachments to this letter. The responses are organized by plant to respond to the questions posed inthe US EPA letter.In an effort to assist the agency in its collection of information, we are also providing copies ofthose documents where available, which EPA has identified in/its request for information. We have made every effort to fully respond to EPA's request for information in the very limited amount oftime that was provided to us and despite the ambiguous nature of several ofthe requests. To the best of my knowledge, the information contained inthis response istrue, accurate, and complete, as of this date. Please direct any questions concerning this submittal to my attention atthe address listed below. Sincerely, Terry E. Coss, PE Environmental Director Xcel Energy 414 Nicollet Mall Minneapolis, MN 55401 

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# uc)1 Date

Attachment 1: NSP-W Bay Front Plant Attachment 2: NSP-M Minnesota Valley Plant Attachment 3: PSCo Arapahoe Station Attachment 2: PSCo Cameo Station Attachment 3: PSCo Cherokee Station Attachment 4: PSCo Comanche Generating Plant Attachment 5: PSCo Hayden Station Attachment 6: PSCo Pawnee Station Attachment 7: PSCo Valmont StationUS EPA Request for Information relating to Surface Impoundments Date: May 18,2009 

### Attachment 1: NSP-WBay Front Plant Bay Front Plant is reporting on the following two surface impoundments:

• Surge Basin
• Polishing Pond Notethat the polishing pond is likely beyond the scope of EPA's information request, given its primary purpose is not to store or dispose of coal combustion residuals or byproducts. However, we are including a description ofthis surface impound~ent for purposes of completeness and due to the ambiguous nature of EPA's request. Background: The Bay Front Plant has two settling ponds that are connected in series. Thefirst pond, called the Surge Basin, is the primary settling pond for process waste solids, including ashfines/slag. Thesecond pond, called the Polishing Basin, contains small amounts of process waste due to carry over from the Surge Basin. Surface discharges from the basins are monitored and reported under astate issued NPDESpermit. Flyash and bottom ash produced atthe plant are managed in silos and trucked off-site for beneficial reuse. The Surge Basin will generally accumulate about 2,000cubic feet of process waste annually. The Polishing Basin will accumulate about 90 cubic feet annually. The Surge Pond is typically dredged annually and the polishing pond is dredged as needed. The materials dredged from the ponds are dewatered and trucked off site for beneficial reuse. Response to the USEPAQuestions 1. Relative to the National Inventory of Dams criteria forHigh, Significant, Low orLess-than-Low, please provide thepotential hazard rating foreach management unit and indicate who established the rating, what the basis 

### ofthe rating is, and what federal, orstate agency regulates the unites). If the unites) does not having 

### a rating, please note that fact. 

### The Surge Basin and Polishing Basin have not been rated byany agency under the National Inventory of Dams criteria. Based on the NIDcriteria, the two management units would not meetthe minimum size for aclassification rating.

Pg. 1US EPA Request for Information relating to Surface Impoundments Date: May 18, 2009 Attachment 1: NSP-W Bav Front Plant
2. Whatyear was each management unit commissioned and expanded? The basins were constructed in 1976. 3. Whatmaterials are temporarily orpermanently contained in the unit? Use the fol/owing categories torespond to this question: (1) flyash; (2) bottom ash; (3) boiler slag; (4) flue gas emission control residuals; (5) other. Ifthe management unit contains more than one type ofmaterial, please identify aI/that apply. Also, ifyou identify "other,"please specify the other type of materials that are temporarily orpermanently contained in the unites). The Surge Basin temporarily stores siagfines that are part of the process water treatment atthe plant. The Polishing Basin contains process water and only de-minimis solids, such as slag fines or sediments, that may be carried over Jrom the Surge Basin. 4. Was the management unites) designed by

### a Professional Engineer? Is or was the construction ofthe waste management unites) under the supervision ofa Professional Engineer? Isinspection and monitoring of the safety ofthe waste management unites) under the supervision of

### a Professional Engineer? The two basins were designed and certified by a Professional Engineer in 1976. We were unable to locate any documentation demonstrating that the construction was· under the supervision of a Professional Engineer 5. When did the company last assess orevaluate the safety (i.e., structural integrity) ofthe management unites)? Briefly describe the credentials of those conducting the structural integrity assessment/evaluations. Identify actions taken orplanned byfacility personnel as

### a result ofthese assessments orevaluations. Ifcorrective actions were taken, briefly describe the credentials ofthose performing the corrective actions, whether they were company employees orcontractors. Ifthe company plans an assessment orevaluation in the fqture, when is itexpected to occur? We could not locate records documenting that 

### the pond has been evaluated for structural integrity. NSP-W completed afield study as part of meeting the requirements ofthe State ofWisconsin Administration Code NR 213, "Lhling of industrial Lagoons and Design of Storage Structures". A report issued in 1992, completed by a Professional Engineer, confirmed the storage ponds met or
Pg.2US EPA Request for Information relating to Surface Impoundments Date: May 18, 2009 Attachment 1: NSP-W Bav Front Plant
exceeded the requirements of NR213. A letter is attached from the Wisconsin DNR documenting their review 

### of the 1992 report and agreeing with the findings. 6. When did

## a State or

## a Federal regulatory official last inspect orevaluate the safety (structural integrity) ofthe management unites)? Ifyou are aware of

## aplanned state orfederal inspection orevaluation in the future, when is itexpected to occur? Please identify the Federal or State regulatory agency ordepartment which conducted orisplanning the inspection orevaluation. Please provide 

### a copy ofthe most recent official inspection report orevaluation. Wisconsin does·notrecogniz,e the two 

### basin~ as dams and there have been n6 state orfedera'l inspections recorded related to the structural integrity oftheseinanagement units. To our knowledge there are no State or 

### Fede~al.inspections planned. 7. Have assessments orevaluations, orinspections conducted by State or Federal regulatory officials conducted within thepast year uncovered 

## a safety issuers) with the management unites), and, ifso, describe the actions that have been orare being taken to deal with the issue orissues. Please provide any documentation thatyou have for these actiqns. Not Applicable - Refer to item 6. 8. Whatis the surface area (acres) and total storage capacity ofeach ofthe management units? Whatis the volume ofmaterials currently stored in each ofthe managementunit(s)? Please provide the date that the volume measurement(s) was taken. Please provide the maximum height ofthe management unites). The basis fordetermining maximum height is explained later in this Enclosure. Based on the engineering study completed in 1976, the Surge Basin is an earth embankment with the berm height of 9.5 

### ft. measured from the downstream toe to the embankment crest. The Polishing Basin isan earth embankment with a berm height of 7.5 ft. The surface area and maximum volume (at the embankment crest) of the Surge Basin 

### are 0.15acres 

### and 2,200cubic yards, respectively. The surface area and maximum volume (at the embankment crest) of the Polishing Basin are 0.41 acres and 4,980 cubic yards, respectively.
Pg. 3US EPA Request for Information relating to Surface Impoundments Date: May 18, 2009 Attachment 1: NSP-W Bay Front Plant

9. Please provide 

### abriefhistory ofknown spills orunpermitted releases from the unit within the last tenyears, whether ornot these were reported to State offederal regulatory agencies. Forpurposes ofthis question, please include only releases to surface water orto the land (do not include releases togroundwater). We have found no record of known spills or unpermitted releases from the ponds to surface waters or land during the past 10years. 10.Please identify allcurrent legal owners(s) and operator(s) at the facility. The Bay Front Plant is owned by Northern States Power Company - Wisconsin, a subsidiary ofXcel Energy Inc.

Pg.4US EPA Request for Information relating to Surface Impoundments Date:. May 18, 2009 

### Attachment 2: NSP-MMinnesota Vallev Plant
Minnesota Valley Plant .isreporting on fCl)ur surface impoundments, referred to as Ponds 1,2, 3and 4. Background: The Minnesota Valley Plant is ourrently inactive and has not produced significant amounts of ash for the last 10years. When the plant operates, the fly and bottom ash are combined before being hydraulically transported to afour pond settling system. Thesettling treatment occurs in aseries of three ponds. Thefirst pond in the series has historically alternated between pond 1 or pond 2 (parallel operation). Surface discharges from the ponds are monitored and reported u!nderastate issued NPDESpermit. Forthe past 20years, Pond 1 has served asthe primary storage facility for solids accumulations from the other ponds

.. The combined ash is stored in Pond 1 until it is full. The pond is then dredged as needed to maintain capacity, and then the ash is dewatered.and transported bytruck to adry disposal facility. All ofthe ponds are located below grade on three sides, with the fourth side adjacent to the river being an earth embankment. Pond No.1's west side is acombination of natural material and earthen embankment. Pond 1 currently contains combined ash. Theash has been dry stacked above the top ofthe pond but graded s()that runoff is controlled within the pond. The ponds aresubject to periodic visual inspections by plant personnel. Response to the USEPAQuestions 1. Relative to the National Inventory ofDams criteria forHigh, Significant, Low orLess-than-Low, please provide thepotential hazard rating for each management unitand indicate who established the rating, what the basis of the rating is, and what federal, orstate agency regulates the unites). Ifthe unites) does nothaving 

## arating, please note that fact. 

### None ofthe four ponds noted above have been rated byany agency under the National Inventory of Dams. Based on the NIDcriteria, the four ponds would beclassified as low hazard. 2. Whatyear was each management unit commissioned and expanded?

Pg. 1US EPA Request for Information relating to Surface Impoundments Date: May 18, 2009 Attachment 2: NSP-M Minnesota Vallev Plant
Ponds 1 and 2were put into service as part of a new unit being installed in the early 1950's. Ponds 3 and 4 were added to the site in 1975. 3. What materials 

## are temporarily orpermanently contained in the unit? Use the following categories torespond to this question: (1) flyash; (2) bottom ash; (3) boiler slag; (4) flue gas emission control residuals; (5) other. Ifthe management unit contains more. than one type ofmaterial, please identify all that apply. Also, ifyou identify "other,"please specify the other type of materials that are temporarily orpermanently contained in the unites). A combination offly ash and bottom ash are temporarily deposited in the pond system. The ash that accumulates in the other ponds is transferred, as needed, for temporary storage in Pond 1. As noted above, this first pond is periodically dredged and any material removed is dewatered and trucked off-site for dry disposal. 4. Was the management unit(s) designed by

## a Professional Engineer? Is or was the construction ofthe waste management unit(s) under the supervision 6f

## a Professional Engineer? 

## Is inspection and monitoring of the safety 

### of the waste management unit(s) under the supervision of

### a Professional Engineer? The original ponds were designed as part ofthe original plant design. We were unable to locate any documentation that the plans were prepared and signed by a Professional Engineer. We could not find documentation that the ponds added in the 1970's were designed bya Professional Engineer. A hydtologic analysis ofthe ponds was completed in 1996, but the structural integrity ofthe earth embankments was not addressed. 5. When did the company last assess orevaluate the safety (i.e., structural (ntegrity) ofthe management unit(s)? Briefly describe the credentials of those conducting the structural integrity assessment/evaluations. Identify actions taken orplanned byfacilitypersonnel as a result ofthese assessments orevaluations. Ifcorrective actions were taken, briefly describe the credentials ofthose performing the corrective actions, whether they were company employees orcontractors. Ifthe company plans an assessment orevaluation in the future, when is itexpected to occur? No record of any structural integrity assessment ofthe ponds has been found. Given the low risk of a structural failure, the company

Pg.2US EPA Request for Information relating to Surface Impoundments Date: May 18, 2009 

### Attachment 2: NSP-MMinnesota Vallev Plant
has no current plans to complete astructural assessment in the future. 6. When did

## a State or

## a Federal regulatary afficiallast inspect arevaluate the safety (structural integrity) afthemanagement unites)? Ifyau are aware af 

## aplanned state arfederal inspectian arevaluatian in the future, when is it expected to.accur? Please identify the Federal arState regulatary agency ardepartment which canducted Drisplanning the inspectian or evaluatian. Please provide 

### a capy afthe mast recent afficial inspectian repart ar evaluatian. 

### The Minnesota Department of Natur,alResources, Dam Safety Unit, does not recognize any of the ponds as dams andthere have been no state orfederal inspections recorded related to the structural integrity of these management units. To our knowledge, there are no inspections planned for these management units. \".', '. " , 7. Have assessments qrevall!;ations,or inspectians, Gonauctedby State ar Federal regulatary afficials conqucted within thepastyear uncavered 

## a safety issuers) with thf]man,agern,entunites), and, ifsa, describe the actians that have been arare being takim to.deal with the issue arissues. Please provide any dacumentatian thatyau have farthese actians. 

### NotApplicable
- Referto item 6. 8. Whatis the surface area (acres) and tatal starage capacity afeach afthe management units? Whatis the valume afmaterials currently stared in each afthe management unites)? Please provide the date that the valume measurement(s) was taken. Please provide the maximum height afthe management unites). Thebasis fardetermining maximum height is explained later in this Enclasure. 

### Thefour ponds each haveasurface areaapproximately three quarter of an acre. As noted above, the crest ofthe ponds is at grade except for the sides adjacent to the Minnesota River. The constructed earth embankment height for the ponds is approximately 6

## ft, but adding the natural riverbank, the total height is approximately 15

### ft. from toe of the river to the embankment crest. Approximately half that height is below the river pool elevation during normal conditions. The average depth of Ponds 1.and 2 is approximately 12ft., corresponding to the height of the earth embankment plus the basin formed bythe excavation of natural soils from inside ofthe pond.
Pg. 3US EPA Request for Information relating to Surface Impoundments Date: May 18, 2009 

### Attachment 2: NSP-MMi,nnesotaVallev Plant
The resulting maximum volume of these ponds is estimated at 9acreft (12,000cubic yards) of storage (both solids and water). The depth of Ponds 3and 4are approximately 9ft, resulting in a maximum volume of 7acre-ft (10,800cubic yards) ofstorage (both solids and water). Pond 1 is almost full. Pond 2contains ash amounting to more than half its total volume. The'ashvolume in the other two ponds is less than 25 percent of their total volume. 9. Please provide 

### abrief history 

### ofknown spills orunpermitted releases from the unit within the last tenyears, wh~ther ornot these were reported to State 

### offederal regulatory agencies. Forpurposes 

### ofthis question, please include only releases to surface water orto the land (do not include releases togroundwater). 

### We havefound no record of known spills or unpermitted releases from any of the ponds to surface waters or land during the past 10 years. The ponds have been overtopped during flood events on the Minnesota River in 1997and 2001,which could have resulted in some ash being carried away byfloodwaters. 10. Please identify allcurrent legal owners(s} and operator(s} at the facility. 

### The Minnesota Valley Generating Facility is owned by Northern States Power Company
- Minnesota, asubsidia.ry of Xcel Energy Inc.

Pg.4US EPA Request for Information relating to Surface Impoundments Date: May 18, 2009 

### Attachment 3: PSCo'Arapahoe Station Arapahoe Station is reporting on the following six surface impoundments:

• North Storm Water/Process Water Pond • South Storm Water/Process Water Pond
• South Ash Pond
• Emergency Pond
• Discharge Pond
• Ash Pump Pond Notethat many, if not all of these surface impoundments are likely beyond the scope of EPA's information requestt 

### given their incised/below-grade nature, and/or the fact that their primary purpose is not to store or dispose of coal combustion residuals or byproducts. However, we are including a description of these surface impoundments for purposes of completeness and due to the ambiguous nature of EPA's request. Background: '. ,I 

### Thefirst three ponds listed above were formerly used to settle bottom ash out of the process water. Thewater then flowed through the Emergency Pond and Discharge Pond, mixing with other plant process wastewater prior to discharge in accordance with aState-issued NPDESpermit. In June 2005an ash dewatering system was built eliminating the need for ash settling ponds, and the first three ponds listed above were dredged to remove residual ash and subsequently repurposed. These three ponds now havethe potential to receive process water during plant upsets. The North and South Storm Water Ponds also receive stormwater. The Emergency Pond and the Discharge Pond currently receiveblow-down water from the circulating water system, other process wastewater, and stormwater. TheAsh Pump Pond was never used for ash settling; its name derives from its useto pump makeup water to the bottom ash sluicing system. This pond does occasionally receive small amounts of process water from the ash dewatering system, aswell asstorm water and other plant waste-water streams. Thewater from this pond flows to the Emergency Pond and/or Discharge pond. Inspections of the ponds are conducted daily for normal operation by plant operators and chemists.

Pg. 1US EPA Request for Information relating to Surface Impoundments Date: May 18, 2009 

### Attachment 3: PSCoArapahoe Station

1. Relative to the Nationallnventoty 

### ofDams criteria forHigh, Significant, Low orLess-than-Low, please provide thepotential hazard rating for each management unit and indicate who established the rating, what the basis 

### ofthe rating is, and what federal, orstate agency regulates the unites). If the unites) does not having 

## a rating, please note that fact. 

### All six ponds are incised (below-grade), and none have been rated by any agency under the National Inventory of Dams, norwould we expect them to meetthe minimum threshold for any such rating. 2. Whatyear was each management unit commissioned and expanded? 

### The original plant pond design consisted of one large ash settling pond put into service when the plant became operational in 1950. In about 1965(exact date unknown), five separate and smaller ponds (the North Storm Water 

## IProcess Water Pond, South Storm Water 

## I Process Water Pond, South Ash Pond, Emergency Pond, and Discharge Pond) were constructed and put into service in the area of the original ash-settling pond. TheAsh Pump Pond was constructed and put into service when the plant became operational in 1950. 3. What materials are temporarily orpermanently contained in the unit? Use the following categories to respend to this question: (1) flyash; (2) bottom ash; (3) boiler slag; (4) flue gas emission control residuals; (5) other. Ifthe management unit contains more than one type 

### ofmaterial, please identify all that apply. Also, ifyou identify "other,"please specify the other type 

### of materials that are temporarily orpermanently contained in the unites). 

### Three ponds (the North.Storm Water 

## IProcess Water Pond, South Storm Water 

## IProcess Water Pond, and the South Ash Pond) were formerly used to settle out and temporarily store bottom ash generated atthe facility. These three ponds are no longer used for settling ash, and were dredged to remove bottom ash subsequent to construction of the ash dewatering system. They may now receive water from the Ash Pump Pond. The Emergency Pond and Discharge Pond are no longer used to process ash, but still contain some residual bottom ash from former plant operations. They are now used to settle suspended solids and

Pg.2US EPA Request for Information relating to Surface Impoundments Date: May 18, 2009 Attachment 3: PSCo Arapahoe Station
control water chemistry from other plant wastewater prior to discharge under the NPDES permit. An ash dewatering system is now in use and occasionally process water from that system is discharged to the Ash Pump Pond. 

### 4. Wasthe management unites)designed by

### a Professional Engineer? Is or was (he construction ofthe waste management unite 

### s) under the supervision of

### a Professional Engin~er? Is inspection and monitoring of the safety ofthe waste management unites) under the supervision of

### a Professional Engineer? No plant documentation was· located to demonstrate that the ponds were designed byor construction supervised bya Professional Engineer. 5. When did t/Jecompany last assess brevaluate the safety (i.e., structural integrity) ofthe management,unit(s)? Briefly describe the credentials of those conducting the struc.tu(alintegrity assessment/evaluations. Identify actions taken orplanned byfacility personnel as a result ofthese assessments orevaluations. Ifcorrective actions were taken, briefly describe the credentials ofth.oseperforming tbe corrective actions, whether they were company employees orcontractors. Ifthe company plans an assessment orevaluation in the future, when is itexpected to occur? No record of any structural integrity assessment ofthe ponds was found, norwould we expect such an assessment to have been performed given they are below-grade, incised ponds. There are no plans to evaluate the structural integrity ofthese ponds in the future. 6. When did

## a State or

## a Federal regulatory official last inspect orevaluate the safety (structural integrity) ofthe management unit(s)? Ifyou are aware of

### aplanned state.orfederal inspection orevaluation in the future, when isitexpected to occur? Please identify the Federal or State regulatory agency ordepartment which conducted orisplanning the inspection orevaluation. Please provide 

### a copy ofthe most recent official inspection report orevalu§1tion There have been no state or federal in$pections recorded related to the structural integrity ofthese management units. To the best of
Pg. 3US EPA Request for Information relating·to Surface Impoundments Date: May 18, 2009 

### Attachment 3: PSCoArapahoe Station

our knowledge, there are no inspections planned for these management units. 7. Have assessments orevaluations, orinspections conducted by State or Federal regulatory officials cond~'cted within thepast year uncovered 

### a safety issuers) with the management unites), and, ifso, describe the actions that have been orare b~ing taken to deal with the issue orissues. Please provide any documentation thatyou have for these actions. 

### Not applicable
- refer to item 6. 8. Whatis the surface area (acres) and total storage capacity 

### ofeach 

### of the management units? Whatis the volume 

### ofmaterials currently stored in each 

### of the management unites)? Please provide the date that the volume measurement(s) was taken. Please provide the maximum height 

### of the management unites). Thebasis tor determining maximum height is explained later in this Enclosure. 

### The Emergency Pond is 1.6acres in size, with acapacity of approximately 19,500cubic yards. The pond is entirely below grade, and therefore per Enclosure Ato EPA's letter, novolume or height information is reported

.. The Discharge Pond is 0.86acres in size, with acapacity of approximately 11,800cubic yards. The pond is entirely below grade, and therefore per Enclosure Ato EPA's letter, novolume or height information is reported. The South Storm Water 

## IProcess Water Pond is 0.89acres in size, with acapacity of approximately 22,500cubic yards. The pond is entirely below grade, and therefore per Enclosure Ato EPA's letter, novolume or height information is reported. TheAsh Pump Pond is 0.32acres in size, with acapacity of approximately 5,700cubic ya~ds. The pond is entirely below grade, and therefore per Enclosure Ato EPA's letter, novolume or height information is reported. The South Ash Pond is 0.87aCresin size, with acapacity of approximately 21,800cubic yards. The pond is entirely below grade, and therefore per Enclosure Ato EPA's letter, novolume or height information is reported.

Pg.4

### us EPA Request for Information relating to Surface Impoundments Date: May 18, 2009 

### Attachment 3: PSCoArapahoe Station
The North Storm Water 

## IProcess Water Pond is 1 acre in size, with a capacity of approximately 

### 13,000cubic yards. The pond is entirely below grade, and therefore per Enclosure Ato·EPA's letter, no volume or height information is reported. 9. Please provide 

### a briefhistory 

### ofknown spills orunperri1itted releases from the unit within the last tenyearS, whether ornot these were reported to State 

### offederal regulatory agencies. Forpurposes 

### ofthis question, please include onlyreleases to surface water orto the land (do not include releases togroundwater). 

### We havefound no record 'of known spills or un-permitted releases from the units to surface water orto the land within the past 

### 10 years. 10. Please identify a/lcurrent legal owners(s) and operator(s) at the facility. 

### Arapahoe Station is owned ,by Public Service.Company of Colorado, asubsidiary ofXcel Energy Inc.

Pg, 5US EPA Request for Information relating to Surface Impoundments Date: May 18, 2009 Attachment 3: PSCo Arapahoe Station

Page intentionally blank

Pg.6US EPA Request for Information relating to Surface Impoundments Date: May 18, 2009 

### Attachment 4: PSCoCameo Station
Cameo Station is reporting on the following two surface impoundments:

• Process Water Retention Pond
• Ash Silo Storm Water Retention Pond. Note that these surface impoundments ,arelikely beyond the scope of EPA's information request, given their ircised/below-grade nature, and/or th~ fact that their primary purpose is nqt to store or dispose of coal combustion residuals or byproducts. Hbwever, we are including a description of these surface impoundm~nts for purposes of completeness anddue to the ambiguous nature of EPA's request Background: The Process Water Retention Pond, a below-grade incised pond, is used to control pHfrom the boiler blow down, capture small amounts of ash carried from the floor drains·of the plant, and to hold other plant process wastewater. TheAsh Silo Storm Water Retention Pond was originally aditch next to the railroad right ofway that was dammed at one end to create a pond. This pond captures stormV!'ater runoff and water from the daily wash down ofthe ash silo and surrounding area. The ponds arevisually inspected daily by plant personnel. 1. Relative to the National Inventory 

### ofDams criteria forHigh, Significant, Low orLess-than-Low, please provide thepotential hazard rating for each management unitand indicate who established the rating, what the basis 

### ofthe rating is, and what federal, orstate agency regulates the unit(s). If the unit(s) does nothaving 

### a rating, please note that fact. 

### Neither ofthe two ponds listed a~ove have been rated byany agency under the National Inventory of Dams, nor dowe believe either pond meets the minimum threshold to be rated. 2. Whatyear was each management unitcommissioned and expanded? 

### The date of construction of the ppnds is unknown, but is.believed to coincide with plant construction In 1956. 3. Whatmaterials are temporarily orpermanently contained in the unit? Use the following categories torespond to this question: 

### (1) fly

### ash; (2) bottom
Pg.1US EPA Request for Information relating to Surface Impoundments Date: May 18, 2009 Attachment 4: PSCo Cameo Station
ash; (3) boiler slag; (4) flue gas emission control residuals; (5) other. Ifthe management unit contains more'than one type 

### ofmaterial, please identify all that apply. Also, ifyou identify "other,"please specify the other type 

### of materials that are temporarily orpermanently contained in the unites). The Process Water Retention Pond is used to settle suspended solids and control water chemistry prior to discharge under an NPDES permit. Italso 

## captur~sminor amounts offly ash and bottom ash carried from the floor drains ofthe plant. The Storm Water Retention Pond captures stormwater runoff and water from the daily wash down ofthe ash silo and surrounding area. Itcontains small amounts offly ash and bottom ash from these activities. 4. Was the management unites) designed by

### a Professional Engineer1 Isor was the construction bfthe waste management unites) under the supervision 

### ofa·Professional Engineer? Is inspection and monitoring 

### of the safety 

### of the waste management unites) under the supervision 

### ofa Professional Engineer1 The ponds were designed as part ofthe original plant design. However, no documentation cpold be found to demonstrate that a Professional Engineer certified the design or supervised the construction ofthe ponds. 5. When did the company last assess orevaluate the safety (i.e., structural integrity) 

### of the management unites)? Briefly describe the credentials 

### of those conducting the structural integrity assessment/evaluations. Identify actions taken orplanned byfacility personnel 

### asaresult 

### ofthese assessments orevaluations. Ifcorrective actions were taken, briefly describe the credentials 

### ofthose performing the corrective actions, whether they were company employees orcontractors. Ifthe company plans an assessment orevaluation in the future, when is itexpected to occur1 No record of any structural integrity assessment of the ponds was found. There are no plans to evaluate the structural integrity ofthese ponds in the future, due to their small size and configuration.

Pg. 2US EPA Request for Information relating to Surface Impoundments Date: May 18, 2009 Attachment 4: PSCo Cameo Station

6. When did

## a State or

## a Federal regulatory official last inspect orevaluate the safety (structural integrity) ofthe management unit(s)? Ifyou are aware of

## aplanned state orfederal inspection orevaluation in the future, when 

### is itexpected to occur? Plea~e identify the Federal orState regulatory agency ordepartment which conducted or

### isplanning the inspection orevaluation. Please provide 

## a copy ofthe most recent official inspection report orevaluation. There have been no State or Federal inspections recorded related to the structural integrity 

### ofthese management units. To the best of our knowledge, there are no inspections planned for these management units. 7. Have assessments orevaluations, orinspections conducted by State or Federal regulatory officials conducted within thepastyear uncovered 

## a safety issuers} with the maf}agementunit(s), and, ifso, describe the actions that have been orare being taken to deal with the issue orissues. Please provide any documentation .thatyou have for these actions. Not applicable - refer to item 6. 8. What

### is the surface area (acres) and total storage capacity ofeach ofthe management units? What

### is the volume ofmaterials currently stored in each ofthe management unit(s)? Please provide the date that the volume measurement(s) was taken. Please provide the maximum height ofthe management unit(s). Thebasis fordetermining maximum height 

### is explained later in this Enclosure. The Process Water Retention Pond is 0.3 acres in size, with a capacity of approximately 2,520 cubic yards. The pond isentirely below grade,·and therefore per Enclosure A to EPA's letter, no volume or height information is reported. The Storm Water Retention Pond is 0.05 acres in size, with a capacity of approximately 1,000 cubic yards. The pond is about half-full, primarily water with minor amounts ofsolid material, so the approximate volume stored is 500 CY. The stored volume was visually estimated on May 6, 2009. The maximum height ofthe pond isapproximately 12feet. 9. Please provide 

### abrief history ofknown spills orunpermitted releases from the unit within the last tenyears, whether ornot these were reported to State offederal regulatory agencies. Forpurposes ofthis question,
Pg. 3US EPA Request for Information relating to Surface Impoundments Date: May 18, 2009 Attachment 4: PSCo Cameo Station please include only releases tosurface water orto the land (do not include releases togroundwater). We have found no record of known spills or un-permitted releases from the units to surface 

### wate.r orto the land within the past 10 years. 10.· Please identify allcurrent legal owners(s) and operator(s) at the facility. Cameo Station is owned by Public Service Company of Colorado, a subsidiary of Xcel Energy Inc.

Pg.4

### us EPA Request for Information relating to Surface Impoundments Date: May 18, 2009 

### Attachment 5: PSCoCherokee Station
Cherokee Station is reporting on the following six surface impoundments:

• West Ash Pond
• Center Ash Pond
• EastAsh Pond
• Emergency Spill Pond
• West Polishing Pond
• East Polishing Pond Note that many, if not all of these surface impoundments are likely beyond the scope of EPA's information request, given their incised/below-grade nature, and/or the fact that their primary purpose is not to store or dispose of coal combustion residuals or byprodllcts. However, we are including a description ofthese surface impoundments for purposes of completeness and due to the ambiguous nature of EPA's request. Background Cherokee Station currently collects its sluiced bottom ash in three Ash Ponds. One pond atatime receives asl;l. Ash settles out in each of these Ash Ponds and sluice water overflows to a lift station. This lift station sends a mixture of ash pond water and other plant wastewater through a clarification waste treatment system. 

# Ifthe lift station level gets too high the excess water bypasses the clarifier and flows to the Emergency Spill Pond. This water isthen pumped backthrough the clarifier. Clarified water goes to the Polishing Ponds for pHadjustment prior to discharge in accordance with aState-issued NPDESpermit. Ash is periodically dredged from the ash ponds and transported offsite bytruck for disposal. Inspections of the ponds are conducted for normal operation daily by plant operators and chemists.

1. Re/ative to the National Inventory ofDams criteria forHigh, Significant, Low, orLess-than-Low, please provide thepotential hazard rating for each management unit and indicate who established the rating, what the basis 

### of the rating is, and what federal orstate agency regulates the unit(s)./f the unites)does nothave 

### a rating, please note that fact. 

### The Emergency Spill Pond has adam on the south end that is approximately 8feet high. It has not been rated byany agency under the National Inventory of Dams, norwould we expect itto meet any minimum threshold for rating.
Pg. 1US EPA Request for Information relating to Surface Impoundments Date: May 18, 2009 

### Attachment 5: PSCoCherokee Station

The remaining ponds are incised (below-grade). None have been rated byany agency under the National Inventory of Dams, nor would we expect them to meetthe minimum threshold for any rating. 2. Whatyear was each management unit commissioned and expanded? 

### The three Ash Ponds were constructed and put into service in 1957. Thetwo Polishing Ponds and~theEmergency Spill Pond followed in 1979-1980. 3. What materials are temporarily 

### orpermanently contained in the unit? Use the following categories torespond to thisquestion: (1) flyash; (2) bottom ash: (3) boiler slag; (4) flue gas emission control residuals; (5) other. Ifthe management unit contains more than one type 

### ofmaterial, please identify all that apply. Also, ifyou identify "other,"please specify the other types of materials that

### are temporarily 

### orpermanently contained in the unites). 

### The primary makeup ofthe ash in the three Ash Ponds is sluiced ash, which is mainly bottom a$h. The ponds do contain minor amounts offly ash, boiler slag, and flue gas emission control residuals. These ponds are periodically dredged with waste being transported offsite for proper disposal. The Emergency Spill Pond receives lift station overflow, coal pile runoff and surface storm water runoff. The Emergency Spill Pond is pumped back to the lift station for treatment assoon as possible. Thetwo Polishing Ponds receive treated wastewater from the clarifier for pH adjustment prior to discharge in accordance with the State-issued NPDESpermit. The clarifier is designed to remove solids, but the potential exists for de minimis carry-over of ash particles to the Polishing Ponds. 4. Was the management unites)designed by

### a Professional Engineer? Is

### or was the construction 

### ofthe waste management unites) under the supervision 

### ofa Professional Engineer? Isinspection and monitoring 

### of the safety 

### of the waste management unites) under the supervision 

### ofa Professional Engineer? 

### Thethree Ash Ponds were part of the original plant design, but no documentation can befound showing that aprofessional engineer
Pg.2US EPA Request for Information relating to Surface Impoundments Date: May 18, 2009 

### Attachment 5: PSCoCherok~ Station prepared orsigned the ash pond plan layout, or supervised the construction. As for the other ponds no documentation was found that these ponds were designed byor construction supervised bya professional engineer 5. When did the company last assess 

### orevaluate the safety (i.e., structural integrity) of the management unit(s)? Briefly describe the credentials of those conducting the structural integrity assessments/evaluations: Identify actions taken orplanned byfacility personnel as a result of these assessments 

### orevaluations. Ifcorrective actions were taken, briefly describe the credentials o(tt,ose perf9rming the corrective actions, whether they were company employees 

### orcontractors. Ifthe company plans an assessment 

### orev,aluatiofl In the future, when is itexpected to occur?·

... 

### No record of anystructural integrity assessment ofthe ponds has been found. There are no plans to evaluat~ the structural integrity of these ponds in the future, dueto their size and configuration. 6. When dida State or a Federafregulatory official last inspect or evaluate the safety "structural integrity) 

### ofthe management unites)? Ifyou are aware of aplanned state or federallnspec(ion or evaluation in the future, when is itexpected to occur? Please·identify the Federal 

### orState

.regulatoryagency or department which conducted or isplanning the inspection or evaluation. Please provide a copy of the most recent official inspection report 

### orevaluation. 

### There have been no State or Federal inspections recorded related to the structural integrity of these management units. Tothe best of our knowledge, there are no inspections planned for these management units. 7. Have assessments or evaluations, or inspections conducted by State or Federal regulatory officials conducted within the past year uncovered a safety issue(s) with the management unit(s), and, ifso, describe the actions that have been or are being taken to deal with the issue or issues. Please provide any documentation that you have for these actions. 

### NotApplicable
- Referto item 6.
Pg. 3US EPA Request for Information relating to Surface Impoundments Date: May 18, 2009 

### Attachment 5: PSCoCherokee Station

,

8. What isthe surface area (acre's) and total storage capacity of each ofthe management units? What isthe·volume of material currently stored in each of the management unit(s)~Please provide the date that the volume measurement(s) was taken. Please provide the maximum height ofthe management unit(s). The basis for determining maximum height is explained later inthis Enclosure. 

### TheWest Ash Pond is 0.39acres in size, with acapacity of approximately 12,700cubic yards. The pond is entirely below grade, and therefore per Enclosure Ato EPA's letter, novolume or height information is reported. The Center Ash Pond is 0.48acres in size, with acapacity of approximately 15,600cubic yards. The pond is entirely below grade, and therefore per Enclosure Ato EPA's letter, novolume or height information is reported. The EastAsh Pond is 0.~9acres in size, with acapacity of approximately 12,700cubic yards. The pond is entirely below grade, and therefore per Enclosure Ato EPA's letter, novolume or height information is reported. The Emergency Spill Pond is p.4 acres in size, with acapacity of approximately 7,700cubic ya~ds. Aconcrete dam on the South end is 8feet 4 inches high from toe to crest. Current volume as measured on May 12,2009 is approximately 644cubic yards, and consists primarily ofwater. TheWest Polishing Pond is 1 acre in size, with acapacity of approximately 25,000cubic yards. The pond is entirely below grade, and therefore per Enclosure Ato EPA's letter, novolume or height information is reported. The East Polishing Pond is 1 acre in size, with acapacity of approximately 25,000cubic yards. The pond is entirely below grade, and therefore per Enclosure Ato EPA's letter, novolume or height information is reported. 9. Please provide a brief history of known spills or unpermitted releases from the unit within the last ten years, whether or notthese were reported to State orfederal regulatory agenCies. For purposes ofthis question, please

Pg.4US EPA Request for Information relating to Surface Impoundments Date: May 18, 2009 Attachment 5: PSCo Cherokee Station
include only releases to surface water orto the land (do not include releases to groundwater). We have found no record of known spills or un-permitted releases 

### from the units tosurface water orlo the land within the past 10 years. 10. Please identify all current legal owner(s) and operator(s) atthe facility. Cherokee Station isowned by Public Service Company of Colorado, a subsidiary ofXcel Energy Inc.

Pg. 5US EPA Request for Information relating to Surface Impoundments Date: May 18, 2009 Attachment 5: PSCo Cherokee Station

Page intentionally blank

Pg. 6US EPA Request for Information relating to Surface Impoundments Date: May 18, 2009 

### Attachment 6: PSCoComanche Station
Comanche Station is reporting on five surface impoundments:

• Ash Pond #1
• Ash Pond #2
• Ash Pond #3
• Polishing Pond (#4)
• Ash Disposal Facility (ADF)Stormwater Retention Pond Notethat some of these surface impoundments are likely beyond the scope of EPA's information request, given their incised/below-grade nature, and/or the fact that their primary pur;pose is not to store ordispose of coal combustion residuals or byproducts. However, we are including a description of these surface impoun~ments for purposes of completeness and due to the ambiguous nature of EPA's request. Background: Ponds used atComanche Station are used to manage clarifier underflow (calcium carbonate), bottom ash solids, de minimis amounts ofscrubber solids, and other plant process wastewater. AII.of these ponds are clay lined and are operated under aState-issued NPDESpermit. Comanche also has astorm water retention pond as part of its dry ash disposal facility. Clarifier underflow material is generated as part ofthe water treatment process atComanche Station. The ~alciumcarbonate is hydraulically transported from the clarifiers to As~ Ponds 1 &2to allow for settling of solids and dewatering in preparation for permanent disposal. Deminimis amounts ofscrubber solids are also disposed of in Ash Ponds 1 &2when needed; in these rare cases the material istransported via avacuum truck. Bottom ash generated atComanche! is hydraulically transported to Ash Pond 3 (bottom ash pond) that tempprarily stores the ash until it can be removed. Thefly ash/scrubber solid~ generated at Comanche are managed in aconditioned state and are disposed of in a landfill located on plant property. The landfill has aclay liner and stormwater is collected in a retention pond atthe disposal facility. Pond 4 is a polishing pond that Ponds 1-3 pass through before the water is discharged in accordance with the ~tate-issued NPDESpermit

Pg.1US EPA Request for Information relating to Surface Impoundments Date: May 18, 2009 

### Attachment 6: PSCoComanche Station
TheADF Stormwater Retention Pond c~ptures storm water runoff and associated suspended solids (ash and scrubber solids) from the dry ash landfill. Inspections of the ash ponds are conducted daily by plant operators and chemists for normal operation.

1. Relative to the National Inventory ofDams criteria forHigh, Significant, Low

### orLess-than-Low, please provide thepotential hazard rating foreach management unit and indicate who established the rating, what the basis ofthe rating is, and what federal, oristate agency regulates the unites). If the unites) does not having 

### a rating, please note that fact. 

### All five ponds are incised (below-grade), and none have been rated byany agency under the National Inventory of Dams criteria, nor would we expect them to meet any minimum threshold to be rated. 2. Whatyear was each management unit commissioned and expanded? 

### Ponds 1 - 4were constructed in 1912. TheADF Stormwater Retention Pond was constructed in 1987. 3. What materials are temporarily 

### orpermanently contained in the unit? Use the fol/owing categories to respond

### to this question: (1) flyash; (2) bottom ash; (3) boiler slag; (4) flue gas emission control residuals; (5) other. Ifthe management unit contains more than one type ofmaterial, please identify aI/that apply. Also, ifyou identify "other,"please specify the other type of materials that are temporarily 

### orpermanently contained in the unites). 

### Ponds 1 

### &2containclarifler underflow material and de minimis quantities of emission control residuals from scrubbers. Pond 3temporarily stores bottom ash prior to removal for disposal. Pond 4 contains process water with only de minimis amounts of bottom ash or emission control residuals carried over from Ponds 1, 

### 2,or3. TheADF Stormwater Retention Pond contains stormwater and small amounts ofsediment, fly ash, bottom ash, or emission control residuals carried off from the ash disposal facility bysurface runoff.
Pg. 2US EPA Request for Information relating to Surface Impoundments Date: May 18, 2009 Attachment 6: PSCo Comanche Station

4. Was the management unites)designed by

### a Professional Engineer? Is

### or was the construction 

### of the was~emanagement unites)under the supervision 

### ofa Professional Engineer? Is inspection and monitoring 

### of the safety 

### ofthe waste management unites) under the supervision 

### ofa Professional Engineer? Ash ponds 1 - 4were designed, and construction supervised by a 

### PE in 1973. The ADF Stormwater Retention Pond was designed, and construction supervised 

### by

## a PE in 1987. 5. When did the company last assess 

### orevaluate the safety (i.e., structural integrity) 

### ofthe management u.nft(s)? Briefly describe the credentials 

### of those conducting the 'structural lh{egrityassessmentlevaluations. 'Identify actions taken 

### orplanned byfaGilitypersonnel as

### a result 

### ofthese assessments 

### orevaluations." Ifcorrective actions were taken, briefly describe the credentials ofthose performing the corrective actions, whether they were companyelTJployees 

### orcontractors. Ifthe company plans an assessment 

### orevaliJation in the future, when is itexpected to occur? No records have been located to confirm ifthe ponds at Comanche Station have been evaluated for

## s~ructural integrity. There are no plans currently 

### tb'evaluate the structural integrity of these ponds inthe future, baSed on their design as below-grade, incised ponds. 6. When did

### a State 

### ora Federal regulatory official last inspect 

### or evaluate

, the safety (structural integrity) 

### ofthe management unites)? Ifyou are

aware 

### ofaplanned state 

### or federal inspection 

### or evaluation in the future, when is itexpected to occur? Please identify the Federal 

### orState regulatory agency ordepartinent which conducted 

### orisplanning the inspection 

### or evaluation. Please provide 

## a copy

### ofthe most recent official inspection report 

### orevaluation. There have been no State or Federal inspections recorded related to the structural integrity ofthe Comanche ponds. To the best of our knowledge there are no inspections pl"anned.

Pg. 3US EPA Request for Information relating to Surface Impoundments Date: May 18,2009 

### Attachment 

### 6: PSCoComanche Station

7. Have assessments 

### or evaluations, 

### or inspections conducted by State 

### or Federal regulatory officials conducte,d within thepast year uncovered 

## a safety issue(s) with the management unites), and, ifso, describe the actions that have been 

### or are being !taken to deal with the issue 

### or issues. Please provide any documentation thatyou have forthese actions. 

### Please refer to question 6. 8. Whatis the surface area (acres) and total storage capacity 

### ofeach 

### ofthe management units? What is the volume 

### ofmaterials currently stored in each 

### ofthe management unit(s)? Please provide the date that the volume measurement(s) was taken. Please provide the maximum height 

### ofthe management unites). The basis fordetermining maximum height is explained later in this Enclosure. 

### Ponds 

### 1

- 4are identical in size at 

### 1.6acres and have avolume of 18,700 cubic yards each. The po~ds are entirely below grade, and therefore per Enclosure Ato EPA's letter, novolume or height information is reported. TheADF Storm Water Retention ·Pond capacity is 0.92acres in size with acapacity of 12,700 cubic yards. The pond is entirely below grade, and therefore per Enclosure Ato EPA's letter, novolume or height information is reported. 9. Please provide 

### a briefhistory 

### ofknown spills 

### or unpermitted releases from the unit within the last tenyears, wh,ether

### ornot these were reported to State 

### offederal regulatory agencie$. Forpurposes 

### ofthis question, please include only releases to surface water

### or to the land (do not include releases togroundwater). 

### On April 9, 2007 the pipe from Polishing Pond (#4) going to the river was hit during an excavation. B~1:ween 2000-3000 gallons of process water was released into an excavation area before the flow was stopped and the line was patche4. The collected water was pumped back into the Polishing Pond. We havefound no records of any other known spills or unpermitted releases from the ponds to surface waters or land during the past 

### 10years. 10. Please identify allcurrent legal own~rs(s) andoperator(s) at the facility.

Pg. 4·US EPA Request for Information relating to Surface Impoundments Date: May 18, 2009 

### Attachment 6: PSCoComanche Station Generating Unit Nos. 1 and 2ofthe Comanche Station are owned by Public Service Company of Colorado, asubsidiary of Xcel Energy Inc. Generating Unit No.3 is operated by Public Service Company of Colorado. It isjointly owned by PSCo, Intermountain Rural Electric Association (IREA), and Holy Cross Energy.

Pg. 5US EPA Request for Information relating to Surface Impoundments Date: May 18, 2009 Attachment 6: PSCo Comanche Station

Page intentionally blank

Pg.6US EPA Request for Information relating to Surface Impoundments Date: May 18, 2009 

### Attachment 7: PSCo Hayden Station Hayden Station is reporting on the following six surface impoundments:

• High Quality Skimmer Pond
• High Quality Pond
• Intermediate Quality Pond
• FlyAsh Decant Basin
• Common WetAsh Settling Basin
• Ash Disposal Facility (ADF) Con~ct Storm Water Pond Notethat many, if not all ofthese surfaqe impoundments are likely beyond the scope of EPA's information request, given their incised/below-grade nature, and/or the fact that their primary purpose is not to store or dispose of coal combustion residuals or byproducts. However, we are including a description of these surface impoundments for purposes of completeness and due to the ambiguous nature of EPA's request. Background: Hayden Station collects all coal combu$tion residues for dry on-site disposal. FlyAsh is collected dry and tfansported bytruck to an on-site Ash Disposal Facility (ADF). Bottom ash is dewatered in bins and transported bytruck to an on-site disposal area. Thefacility has three above grade process ponds connected in series that are designed to remove suspended solids and control water chemistry prior to reuse within the faoility (High Quality Skimmer Pond, High Quality Pond and the Intermediate Quality Pond). Excess solids that settle out in the first pond in the series (HQSkimmer Pond), which may include ash particles, are periodically dredged, dewatered and then transported to the on-site ash disposal area. Thefacility also hastwo below grade concrete ash cleanout basins. The smaller basin (FlyAsh Decant Basin) is used for ash silo load-out cleanup water and the larger basin (Common WetAsh Settling Basin) isfor storage ifthe bottom ash dewatering system fails and other ash dewatering needs. These basins are normally empty and are cleaned out following each occurrence. Thefacility also has aContact Storm W;iter Pond that receives stormwater runoff from the ash disposal area. This'pond water istested prior to discharge under a NPDESPermit. The pond is constructed as a basin following natural contours.

Pg. 1US EPA Request for Information relating to Surface Impoundments Date: May 18, 2009

. 

### Attachment 

### 7: PSCo Havden Station
Routine visual inspections of these surface impoundments are conducted by plant personnel.
1. Relative to the National Inventory 

### ofDams criteria forHigh, Significant, Low

### orLess-than-Low, please provide thepotential hazard rating foreach management unitand indicate who established the rating, what the basis 

### ofthe rating is, and what federal, 

### or state agency regulates the unit(s). If the unit(s) does not having 

## a rating, please note that fact. 

### The Intermediate Quality Pond is listed.on the NIDand rated asa Low Hazard Dam. The three process water ponds (High Quality Skimmer Pond, High Quality Pond and the lntermediate Quality Pond) share acommon dam around them and are classified on the State of Colorado, Division ofWater Resources
- Dam Safety Branch's inspection forms as Low Hazard. The State inspects this dam every 6years. Thetwo concrete cleanout basins (FlyAsh Decant Basin and the Common WetAsf:lSettling 

## Basill)a9d the Contact Storm Water Pond atthe ash disposal area have'not been classified, norwould we

.expect them to meetthe minimum threshold for any rating. 2. Whatyear was each management unit commissioned and expanded? 

### The High Quality Skimmer Pond, High Quality Pond and the Intermediate Quality Pond were commissioned in 

### 1975. The FlyAsh Decant Basin and the Common Wet Ash Settling Basin were commissioned in 

### 1992. The contact storm water pond atthe ADFwas commissioned in 

### 1983. This pond is formed bythe working face of the ash disposal cell and the adjacent native hillside. Consequently, the configuration ofthis pond is modified both vertically and horizontally during the course of development ofthe ash disposal area. 3. What materials are temporarily 

### orpermanently contained in the unit? Use the fol/owing categories torespCnd to this question: (1) flyash; (2) bottom ash; (3) boiler slag; (4) flue gas emission control residuals; (5) other. Ifthe management unit contains mortJthan one tYpeofmaterial, please identify al/that apply. Also, ifyou identify "other,"please specify the other type of
Pg. 2US EPA Request for Information relating to Surface Impoundments Date: May 18, 2009 

### Attachment 7: PSCo Havden Station
materials that are temporarily orpermanently contained in the unites). 

### Small amounts of fly ash, bottom ash, and flue gas emission control residues aretemporarily deposit~' in the first pond (High Quality Skimmer Pond) in the series. This pond is periodically dredged and any material removed is dewater~d and sent for disposal. Some fly ash, bottom ash, and flue gas emission control residues may move through the under drains to the High Quality Pond. The Intermediate Quality Pond may contain water that has mixed with fly ash, bottom ash, and flue gas emission control residues in the two previous ponds. The FlyAsh Decant ~,asil1m~ycontain fly ash, bottom ash, and flue gas emission control re~id~~s. The Common Wet'Ash Settling Basin may contain fly ash, bottom ash, and flue gas emission, ~ontrol residues.

'I
. .' ., ... < 

### The Contact Storm Water'Pond'at the ,a~hdisposal area may contain fly ash, bottom ash, and flue gas emission control residues. 4. Was the management unites) designed by

### a Professional Engineer? Is or was'the construction ofthe waste management unite s) under the supervision of

### a Professional Engineer? Is inspection and monitoring of the safety ofthe waste management unites) under the supervision of a Professional Engineer? 

### The High Quality Skimmer Pond, High Quality Pond and the Intermediate Quality Pond were designed bya Professional Engineer (PE). A PEsupervised the construction ofthese three ponds. A PE Dam Engineer from the State of Colorado, Division ofWater Resources
- Dam Safety Branch, inspects the High Quality Skimmer Pond, High Quality Pond and the Intermediate Quality Pond Dam every 6years. A PEdid not design or oversee the construction of the FlyAsh Decant Basin and the Common WetAsh Settling Basin. A PEdid not design or oversee the construction of the Contact Storm Water Pond atthe ash disposal area.

Pg. ~US EPA Request for Information relating to Surface Impoundments Date: May 18, 2009 Attachment 7: PSCo Havden Station

5. When did the company last assess orevaluate the safety (i.e., structural integrity) 

### of the management unit(s)? Briefly describe the credentials 

### of those conducting the structural integrity assessment/evaluations. Identify actions taken orplanned byfacility personnel as a result of these

. assessments orevaluations. Ifcorrective actions were taken, briefly describe the credentials 

### of those performing the corrective actions, whether they were company employees orcontractors. Ifthe company plans an assessment orevaluation in the future, when is itexpected to occur? As. noted in the response to Question 4, the High Quality Skimmer Pond, High Quality Pond and the Intermediate Quality Pond are regularly inspected by a dam safety engineer from the State of Colorado. These structures are also subject to routine operational inspections by plant staff to identify issues that might develop between State inspections. We would not normally perform an independent and redundant sJructuraJsafety or integrity inspection absent a specific concern. The Company has not performed a structural safety inspection of the below-grade Fly Ash Decant Basin, the Common Wet AshSettling Basin, orthe Ash Contact Storm Water Pond. There are no plans to evaluate the structural integrity ofthese ponds in the future. 6. When did

### a State or

### a Federal regulatory official last inspect orevaluate the safety (structural integrity) of the management unites)? Ifyou are aware of aplanned state orfederal inspection orevaluation in the future, when is itexpected to occur? Please identify the Federal orState regulatory agency ordepartment which conducted orisplanning the inspection orevaluation. Please provide 

### a copy

### of the most recent official inspection report orevaluation. The State of Colorado, Division ofWater Resources - Dam Safety Branch inspected the three process water ponds (High Quality Skimmer Pond, High Quality Pond and the Intermediate Quality

. Pond) on May 9,2007. The Dam Engineer is a PE. The State of Colorado Inspection Report is attached. There have been no other State or Federal inspections recorded related to the structural integrity ofthese or the other ponds. To the best of our knowledge there are no future inspections planned at

Pg.4US EPA Request for Information relating to Surface Impoundments Date: May 18, 2009 

### Attachment 7: PSCo Havden Station
this time, other than the six-year recurring Colorado State inspection noted above. 7. Have assessments orevaluations, or inspections conducted by State or Federal regulatory officials conducted within thepastyear uncovered 

### a safety issuers) with the management unites), and, ifso, describe the actions thathave been orare being taken to deal with the issue orissues. Please provide any documentation thatyou have for these actions. 

### There were only minor issues noted on the inspection report including rodent control, '{egetatiQn management and crest grading. Corrective actions have been'completed. Seeattached Weed Control PUl;'chaseOrder #269792,Crest Grading Work Order #

: •. 1' " , :' • 

### 2973887

.. 8. What is the surface area (adres).and tdtal storage capacity 

### ofeach ofthe management units? What

### is

## the volume ofmat/3ria/sburtently stored in .',' ',' 'I each ofthe managemeht unit(s)? Please provide the'date that the volume measurement(s) was taken. Pleaseprovide the maximum height ofthe management unites). Theba~is fordetermining maximum height is explained later in this Enclo'Stir13.,

. 

### The High Quality Skimmer por-d has adesign maximum surface area under 1.0acre and 8,872cubic 'yards ofstorage. The embankment is approximately 19ft. high from toe to crest. As of May7, 2009a visual estimate ofthe volume of ash or other solids in this pond is about 3,000cubic yards. This pond is'currently being dewatered and should becleaned out this summer. The High Quality pond has a'design maximum surface area under 4.5 acres and 65,000cubic yards of storage. The embankment is approximately 15ft. high from toe to crest
..As of May7, 2009a visual estimate ofthe volum.eof a$h or other solids in this pond is about 1,000cubic yards. This pond contains about 7,500cubic yards ofwater, is currently being dewatered and should becleaned out this summer. The Intermediate Quality pond has adesign maximum surface area under 20acres with 442,000cubic yards ofwater storage. The pond is normally maintained ator nearfull capacity. The embankment is approximately 22ft. high from toe to crest. We do not have current information on the volume of ash or other solids in this pond, since the pond is intended for process water storage and treatment and
Pg. 5US EPA Request for Information relating to Surface Impoundments Date: May 18, 2009 

### Attachment 7: PSCo Havden Station
does not receive significant volumes ofsolids. The pond water level is typically maintained ator near capacity. The FlyAsh Decant Basin has adesign maximum surface area under

.0.006acres, and acapacity of 64.5cubic yards. The pond is entirely

below grade, and therefore per Enclosure Ato EPA's letter, no volume or height information is repQrted. The Common WetAsh Settling Basin has adesign maximum surface area under 0.09acres, and acapacity of 474cubic yards. The pond is entirely below grade, and therefore per Enclosure Ato EPA's letter, novolume or height information is reported. The Contact Storm Water Pond atthe ash disposal area has a surface area of under 0.75acres, and acapacity of approximately 5,900cubic yards. The pond is entirely beJowgrade, and therefore per Enclosure Ato EPA's lett$r, novolume or height information is reported. 9. Please provide 

### a brief history ofknown spills orunpermitted releases from the unit within the last tenyears, whether ornot these were reported to State offederal regulatory agencies. Forpurposes ofthis question, please include only releases tosurface water orto the land (do not include releases togroundwatel). 

### We havefound no record of known spills or un-permitted releases from the units to surface water orto the land within the past 10 years. 10. Please identify allcurrent legal owners(s) and operator(s) atthe facility. 

### The Hayden Station is operat~d by Public Service Company of Colorado, which is asubsidiary of Xcel Energy Inc. It isjointly owned by PSCo, PacifiCorp, and Salt River Project.

Pg. 6US EPA Request for Information relating to Surface Impoundments Date: May 18, 2009

. 

### Attachment 8: PSCo Pawnee Station
Pawnee Station'is reporting on the fQllowing six surface impoundments and one ash disposal facility:

• New BO~Qm; Ash Water Recove'iy·Pond • Bottom Ash:Oisposal Pond
• Ash Water Recovery Pohd
• Intermediate Quality (IQ)Water Pond
• Evaporative Pond B
• Evaporative Pond C
• Ash Disposal Facility (ADF) Notethat many, if not all ofthese surface impoundments and the landfill are likely beyond the scope of EPA'sinfprmation request, given their incised/below-grade rlature, and/or.the fact tha,ttheir: primary purpose is not to.store or dispose of coal combustion-residuals or byproducts. However, we are including' a'description ofthem all-for purposes of completeness and dueto the ambiguous nature of EPA's request. Background: 

### ,i
t' "
.. 

### Pawnee Sta.tion is azero discha~ge'facility. Flyash and bottom ash are both coJlected on a,dry basis and are"mar:'keted for avariety of beneficial uses, including concrete. A minor fraction of ash that is not sui,tablefor utilization is disposed of in an on-site la..-dfillthat is constructed entirely below grade. This landfill also receives 'rawwater treatment system clarifier residuals that aretransported by.truck. In 2002,the plant installed adrag-chain to mechanically remove and dewater bottom ash prior to loading on atruck for uti.lization or disposal in the on site dry landfill. Prior to this conversion, bottom ash was sluiced to lined settling ponds. From there itwas periodically dredged and dewatered for disposal in the on-site dry landfill. Thefollowing ponds may come in con~ct with or havethe potential to contain asmall amount of bottom ash fines: "New" Bottom Ash Water Recovery Pond, Bottom Ash Disposal Pond, Ash Water Recovery Pond, Intermediate Quality (IQ) Pond, Evaporative Pond B, and Evaporative Pond C. 

### 1. The "New" Bottom Ash.Water Recovery Pond is used as a holding basin for make upwater to the boiler bottom ash water system. Although the primary function ofthe pond is a reservoir for the boiler bottom ash water system, it contains asmall portion of bottom ash
Pg. 1US EPA Request for Information relating to Surface Impoundments Date: May 18, 2009 

### Attachment 8: PSCo Pawnee Station fines, asthe water is re-circulated through the boiler bottom ash water system. 2. The Bottom Ash Disposal Pond is no longer in service. This pond was asettling pond in which sluiced bottom ash settled out and the water was recovered for re-circulation. After the solids settled in the pond, the overflow drained into the Ash Water Recovery Pond. This pond still contains some residual bottom ash and occasionally receives direct precipitation 3. TheAsh Water Recovery Pond is no longer in service. Itserved as a re-circulation basin for the boiler bottom ash water system after grinding and sluicing of bottom ash. This is abelow grade pond that still contains some residual bottom ash and occasionally receives direct precipitation. 4. The Intermediate Quality (IQ)Water Pond is used to store storm water runoff, high quality pondoverflow, and miscellaneous plant drains. When water resource~ are low, the pond makeup can be supplemented using the water from the boiler bottom ash water system, therefore the pond potentially contains asmall amount of bottom ash. 5. Evaporative Ponds Band Care used to collect wastewater from the brine concentrators and overflow from the IQpond. The primary function ofthe ponds is to collect and evaporate wastewater from the brine concentrators. Athird, idle evaporative pond exists atthe site (Pond A) and had the same function as Ponds Band Cwhen it was in use. However, it has been empty and out of service since about 2004. 6. Pawnee has a landfill, which in past operations has been used to dispose of fly ash and bottom ash (hauled bytruck), and slurry produced from the water treatment clarifier, which is also transported bytruck. Currently, the majority of bottom ash and fly ash are being marketed for beneficial reuse and avery limited amount is being disposed in the landfill. The landfill continues to accept slurry waste from the clarifier. The landfill was formed byan excavation and is fully below grade. Routine visual inspections of the ponds and landfill are conducted by plant or contractor personnel.

Pg.2US EPA Request for Information relating to Surface Impoundments Date: May 18, 2009 

### Attachment 8: PSCo Pawnee Station

1. Relative to the National Inventory ofDams criteria forHigh, Significant, Low

### orLess-than-Low, please provide thepotential hazard rating foreach management unitand indicate who established the rating, what the basis ofthe rating is, and what federal, 

### orstate agency regulates the unit(s). If the unit(s) does not having 

### a rating, please note that fact. 

### The Intermediate Quality Pond and the Evaporation Ponds are listed on the NIDand rated as Low Hazard Dams. The Colorado State Engineers O~ce, Divisions ofWater Resources, regulates the "New" Bottom Ash Water Recovery Pond, IQpond, and Evaporative ponds Band C. The State Engineer has classified the IQ Pond and Evaporative Ponds Band CasClass 3dams. The Engineer's Office has not classified the "New" Bottom Ash Water Recovery Pond orthe Bottom Ash Disposal Pond. TheAsh Water Recovery p'Qn!J 

### and FlyAsh Landfill are below grade, and have not been rated~ 

### by'~nyagency under the National Inventory of Dams, nor dowe believe they would meetthe minimum threshold for any rating. 2. Whatyear was each management unit commissioned and expanded? 

### The Bottom Ash Disposal Pond and Ash Water Recovery Pond were commissioned in 1980; usewas discontinued in 2002. The IQ Pond and Evaporative Ponds Band Cwere commis~ioned in 1980. The "New" Bottom Ash Water Recovery Pond was constructed and commissioned in 2005. The Landfill was constructed in the late 19705and placed into service in 1980. 3. What materials are temporarily 

### orpermanently contained in the unit? Use the following categories torespond to this question: (1) flyash; (2) bottom ash; (3) boiler slag; .(4) flue gas emission control residuals; (5) other. Ifthe management unit contains more than one type ofmaterial, please identify all that apply. Also, ifyou identify "other,"please specify the other type of materials that are temporarily 

### orpermanently contained in the unit(s).

Pg. 3US EPA Request for Information relating to Surface Impoundments Date: May 18, 2009

. Attachment 8: PSCo Pawnee Station

Both the Bottom Ash Disposal Pond and Ash Water Recovery Pond contain bottom ash from prior operations. The amount ofwater retained in these ponds from precipitation is insignificant and, typically evaporates quickly due to the arid climate. Both ponds are no longer in service. The "New" Bottom Ash Water Recovery Pond contains a small amount of bottom ash within the process water managed in this pond. The IQ pond contains a small,amount of bottom ash within the process water managed in this pond. Evaporative Ponds Band C contain plant process wastewater and solids from the wastewater evaporation. 

### Th~seponds also have the remote possibility of containing bottom ash fines from the IQ pond overflow .

.The Landfill contains fly 

### ash, bottom ash, and lime slurry from the

water treatment process. 4. Was the management unites) designed by

### a Professional Engineer? Is or

, was the construction ofthe wa$te management unites) under the supervision of

### a Professional Engineer? Is inspection and monitoring of the safety ofthe waste management unites) under the supervision of

### a Professional Engineer? A Professional Engineer designed all ponds and the landfill. Plant construction records do not indicate that a Professional Engineer supervised construction ofthe original ponds. The "New" Bottom Ash Water Recovery Pond, IQ Pond, and Evaporative Ponds Band C are under the jurisdiction ofthe Colorado State Engineer. 5. When did the company last assess orevaluate the safety (i.e., structural integrity) ofthe management unit(s)? Briefly describe the credentials of those conducting the structural integrity assessment/evaluations. Identify actions taken orplanned byfacilitypersonnel as a result ofthese assessments orevaluations. Ifcorrective actions were taken, briefly describe the credentials ofthose performing the corrective actions, whether they were company employees orcontractors. Ifthe company plans an assessment orevaluation in the future, when is itexpected to
Pg.4US EPA Request for Information relating to Surface Impoundments Date: May 18, 2009 

### Attachment 8: PSCo Pawnee Station
occur? 

### No record of anystructural integrity assessment of the ponds by Company personnel has been found. Structures classified as dams are regularly inspected by a Dam Safety Engineer from the State of Colorado (see response to Question 6 below). Wewould not normally perform an independent and redundant structural safety or integrity inspection absent a specific concern. There are no plans to evaluate the structural integrity of ponds not classified as dams. 6. When did

## a State or

## a Federal re,gulatoryofficial last inspect orevaluate the.safety (structural infegritY) 

### ofthe management unit(s)? Ifyou are aware of

### aplanned state orfederal inspection orevaluation in the future, when is itexpected to occur? Please identify the Federal or State regulatory agency ordepafttfiem whichconducted orisplanning the inspection orevaluation. Please provide 

## acopy ofthe most recent official inspection report orevaluat~on. 

### The State Engineer conducts periOdic inspections of the ponds classified as dams. The last safety evaluation for the IQpond was conducted in 2002 by the Colorado State Engineer. The inspector indicated that this pond should beclassified as aClass ,4

### dam, butwe have received no documentation reclassifying this from aClass 3 pond. The Colorado State.Engineer inspected evaporative ponds A, Band C in December of 2008. At the fifn~ ofthe inspection repairs were being conducted on the liner for C Pond as noted in the report. The Colorado State Engineer has not inspected the "New" Bottom Ash Water Recovery Pond. Based on the normal interval of State inspections, we anticipate the pond will undergo asafety inspection bythe State Engineer in or·around 2010. 7. Have assessments orevaluations, orinspections conducted by State or Federal regulatory officials conducted within thepastyear uncovered 

## a safety issuers) wIth the management unites), and, ifso, describe the actions that have been orare being taken to deal with the issue orissues.
Pg. 5US EPA Request for Information relating to Suliace Impoundments Date: May 18, 2009 

### Attachment 8: PSCo Pawnee Station

Please provide any documentation thatyou have for these actions. 

### During the inspection of Evaporative Ponds A, Band Cin December of 2008,three issues were identified: 1) "No gage rods" was noted in the report. Gage rods were actually present in Ponds Band C, but new rods have sin"ce been installed in these ponds. Pond A is empty and out of service, so no gage rod is necessary. 2) Erosion was noted on the access road between Ponds Aand B. The eroded areas have since been repaired. 3) Damagewas noted on to the liner of Pond C. Seethe attached Work Order

## #2962135documenting the repair to correct this damage. 8. What is the surface area (acres) and total storage capacity ofeach ofthe management units? What is the volume ofmaterials currently stored in each ofthe management unites)? Please provide the date that the volume measurement(s) was taken. Please provide the maximum height ofthe management unites). Thebasis for determining maximum height is explained later in this Enclosure. 

### The "New" Bottom Ash Water Recovery Pond size is 6acres with a total storage capacity of 83,900cubic yards. Current volume is estimated as 52,400cubic yards as measured on May3, 2009, and primarily consists ofwater with minor amounts ofsolid material. Maximum height is 16ft. The Bottom Ash Disposal Pond size is 13acres, and total storage capacity is 403,000cubic yards. Current volume is estimated at 121,000cubic yards, with estimations based on observation of solids accumulated on May3,2009

.. Maximum height is 10ft. TheAsh Water Recovery Pond size is 1 acre, and total storage capacity is.8,100 cubic yards

..The pond is entirely below grade, and therefore per Enclosure Ato EPA's letter, novolume or height information is reported. The IQ Pond size is 3.5acres with atotal storage of 77,400cubic yards. Current volume as measured on May3,2009 is 35,500cubic

,yards, and primarily consists ofwater with minor amounts of solid material. The maximum height is 21 ft.

Pg.6US EPA Request for Information relating to Surface Impoundments Date: May 18, 2009 Attachment 8: PSCo Pawnee Station Evaporative Pond Bsize is 14.8 

### a~reswith atotal storage of 222,200 cubic yards. Volume as measured on May 3,2009 is 114,200 cubic yards, and primarily consists ofwater with minor amounts ofsolid material. The maximum height is 13 ft. Evaporative Pond C size is 10.5 acres with atotal storage of 154,900 cubic yards. Volume as measured on May 3, 2009 is 87,600 cubic yards, and primarily consists ofwater with minor amounts ofsolid material. The maximum height is 13

### ft. The Landfill size is 34 acres with a total storage capacity of 2,176,400 cubic yards. The landfill is entirely below grade, and therefore, per Enclosure A

### to EPA's letter,no volume or height information is reported. I 9. Please provide 

### a briefhistory 

### ofknown spills orunpermitted releases from the unit within the last tenyea~,'Whethei 

### ornot these were reported to State offederal regulatory agenCies. 'Forpurposes ofthis question, please include only releases to'sUrface water orto theland(do not include releases togroundwater). " We have found no record of known spills or un-permitted releases from the management unitS to surface water or to the land within the past 10years. 10. Please identify allcurrent legal owners(s) and operator(s) atthe facility. Pawnee Station is owned by Public Service Company of Colorado, a subsidiary ofXcel Energy.

Pg.7US EPA Request for Information relating to Surface Impoundments Date: May 18, 2009 Attachment 8: PSCo Pawnee Station

Page intentionally blank

Pg. 8US EPA Request for Information relating to Surface Impoundments Date: May 18, 2009 

### Attachment 9: PSCdValmont Station
Valmont Station is reporting on the following three surface impoundments:
• EastAsh Settling Pond
• West Ash Settling Pond • Coal Pile Stormwater Runoff Pond Notethat many, if not all ofthese surfaqe impoundments are likely beyond the scope of EPA's information request, given their incised/below-grade nature, and/or the fact that their primary purpose is not to store or dispose of coal combustion residuals or byproducts. However, we are including a description of these surface impoundments for purposes of completeness and due to the ambiguous nature of EPA's request Background: TheValmont Generating Station collects all coal combustion by-products for off-site utilization or on-site disposaJ in aState approved dry ash landfill. Flyash is collected dry. Bottom ash is hydraulically conveyed to two ash settling ponds which are excavated bi-annually and the ash either utilized or disposed. The outfall of the ash disposal ponds is regulated under the site NPDESpermit and discharges to the plant cooling water reservoir system. The ponds are not permanent ash disposal ponds but rather provide settling and temporary storage of bottom ash. Only one of these ponds istypically active and used atanyone time. Operating practice is to clean out and switch the active pond every year. The Coal Pile Stormwater Runoff Pond has the capability of receiving washdown from the paved area around the ash storage silo. Valmont Station hasthree large reservoirs on site. These are used for raw water storage and plant water cooling/recirculation. The day-to-day pond operations,are monitored bythe Plant Chemist, according to the requirements ofthe NPDESpermit.
1. Relative to the National Inventory 

### ofDams criteria forHigh, Significant, Low

### orLess-than-Low, please provide thepotential hazard rating foreach management unit andindicate who established the rating, what the basis 

### ofthe rating is, and what federal, orstate agency regulates the unites). If the unites) does not having 

### a rating, please note that fact. 

### TheAsh Settling and Stormwater Runoff ponds are incised (belowgrade). Neither has been rated byany agency under the National
Pg. 1US EPA Request for Information relating to Surace Impoundments Date: May 18, 2009 

### Attachment 9: PSCoValmont Station Inventory of Dams (NID), norwould we expect them to meetthe minimum threshold for any rating. 2. Whatyear was each management unit commissioned and expanded? 

### Both Ash Settling Ponds were built in 1964and the Coal Pile Stormwater Runoff Pond was built in 1993. 3. What materials are temporarily orpermanently contained in the unit? 

### Use the following categories to respond to this question: (1) flyash; (2) bottom ash; (3) boiler slag; (4) flue gas emission control residuals; (5) other. Ifthe management unit contains more than one type

### ofmaterial, please identify all that apply. Also, ifyou identify "other,"please specify the.other type of materials that are temporarily orpermanently contained in the unites). 

### The East and West Ash Settling Ponds primarily contain bottom ash but may contain some de minimis amounts of fly ash and/or emission control residue. The Coal Pile Stormwater Runoff Pond primarily contains coal fines, but may also contain some de minim.is amounts of fly ash and/or emission control residue from washdown operations. 4. Wasthe management unites) designed by

### a Professional Engineer? Is or was the construction 

### ofthe waste management unites) under the supervision of a Professional Engineer? Is inspection and monitoring of the safety of the waste management unites) under the supervision of a Professional Engineer? 

### The ponds were designed by Professional Engineers. Wewere unable to locate documentation to confirm whether construction was overseen bya Professional Engineer. 5. When did the company last assess or evaluate the safety (Le., structural integrity) ofthe management unit(s)? Briefly describe the credentials of those conducting the structural integrity assessment/evaluations. Identify actions taken or planned byfacility personnel as a result ofthese assessments or evaluations. Ifcorrective actions were taken, briefly describe'the credentials ofthose performing the corrective actions, whether they were company employees or contractors. Ifthe company plans an assessment or evaluation inthe future, when is itexpected to occu~ .

Pg, .2US EPA Request for Information relating to Surface Impoundments Date: May 18, 2009 

### Attachment 9: PSCoValmont Station
PSCo has not conducted structural integrity evaluations of either the Ash Settling Ponds orthe Coal Pile Stormwater Runoff Ponds because oftheir small'size and at grade construction. 6. When did a State or a Federal regulatory official last inspect or evaluate the safety (structural integrity) ofthe management unit(s)? Ifyou are aware of a planned state orfederal inspection or evaluation in the future, when is itexpected to occur? Please identify the Federal or State regulatory agency or department which con.ducted or is planning the inspection or evaluation. Please provide a copy ofthe most recent official inspection report orevaluation. 

### There have been nostate or Federal inspections recorded related to the structural integrity of these management units. Tothe best of our knowledge, there are n9 state orfederal inspections planned for these manageme9t uni~

... , 7. Have assessments orevaluations, orinspections conducted by State or Federal regulatory officials pon4l.{rfed within thepastyear uncovered 

### a safety issue(s) with the man~,Qer!1(!JfJrunit(s), and, ifso, describe the actions that have been orare being taken to deal with the issue orissues. Please provide any documimtatton thatyou have for these actions. 

### Not applicable
- referto item 6. 8. What is the surface area (acres) and total storage capacity ofeach ofthe management units? What is the volume ofmaterials currently stored in each ofthe management unites)? Please provide the date that the volume measurement(s) was taken. Please provide the maximum height 

### ofthe management unites). Thebasis fordetermining maximum height is explained later in this Enclosure. 

### TheAsh Settling Ponds are each approximately 1 acre in size, with a capacity of about 26,000cubic yards. Both are entirely below grade, and therefore, per Enclosure Ato EPA's letter, novolume or height information is reported. The Coal Pile Stormwater Runoff Pond is approximately 0.14acres in size, and has acapacity of about 670cubic yards. The pond is entirely below grade, and therefore, per Enclosure Ato EPA's letter, novolume or height information is reported.

Pg. 3US EPA Request for Information relating to Surface Impoundments Date: May 18, 2009 Attachment 9: PSCo Valmont Station

9. Please provide 

### abrief history 

### ofknown spills orunpermitted releases from the unit within the last tenyeats, whether ornot these were reported to State 

### offederal regulatory agencies. Forpurposes 

### ofthis question, please include only releases to surface water orto the land (do not include releases togroundwater}. There was one recorded 

### spill from the West Ash Settling Pond on February 14, 2008 that was reported to the State of Colorado and the National Response Center (NRC). About 25 cubic yards of bottom ash slurry was released into the plant cooling water reservoirs. A vacuum truck was used to recover the bottom ash. We have found no record of other known spills or unpermitted releases from any ofthe units to surface water or land within the last

.. ten years. 10. Please identify allcurrent legal owners(s) and operator(s) at the facility. The Valmont Station is owned by Public Service Company of Colorado, asubsidiary ofXcel Energy Inc.

Pg.4

# (lXcelEnergy·
RESPONSIBLE BY NAT IEOctober 12, 2009 Mr. Richard Kinch US Environmental Protection Agency (5306P) 1200 Pennsylvania Avenue, NW Washington, DC 20460 414 Nicollet Mall Minneapolis, MN 55401 1-800-895-4999 xcelenergy.com

Re: Summary Database Results Errors
- Request for Information relating to Surface Impoundments Under 104 (e) ofthe Comprehensive Environmental Response, Compensation, and Liability Act, 42 U.S.C. 9604(e). Dear Mr. Kinch: On May 18, 2009 we submitted responses to the US Environmental Protection Agency (EPA) "Request for Information" received May 4, 2009 pertaining to surface impoundments used to manage coal combustion residuals or byproducts atthe following operating companies:

• Public Service Company of Colorado (PSCo), a Colorado corporation;
• Northern States Power Company of Minnesota (NSP-M), a Minnesota corporation, and:
• Northern States Power Company ofWisconsin (NSP-W), aWisconsin corporation EPA subsequently released a summary ofthe submitted i[1formation to third parties per a FOIA request and has now placed that summary information (Database Results
- PDF) on their website at: http://www.epa.gov/epawaste/nonhaz/industrial/special/fossil/survevs/index.htm A review of the summary table has indicated that itcontains several errors, which are inconsistent with the information we provided on May 18th. Foryour convenience, the inconsistencies are identified separately by operating company inthe three attachments.US EPA Request for Information relating to Surface Impoundments Date: May 18, 2009

To ensure that correct information is utilized bythe EPA, by State agencies, and is made available to the public, we request that the database be updated to reflect the correct information in an expeditious manner. We further request that after correctioh ofthe EPA database and summary posted on the Agency's web site, any organizations or persons that received incorrect information under a FOIA request be notifi~d that corrected information is available. Please direct any questions concerning this submittal to my attention atthe address listed below.

55401 

## 10-/2,- OC1 Date' Sincerely,



# - ~Cs~ ..- I j Terry E. Coss, PE Environmental Director Xcel Energy 414 Nicollet Mall, Minneapolis, MN (612) 330-5596
Attachment 1: Public Service Company of Colorado (PSCo) Attachment 2: Northerh States Power Company of Minnesota (NSP-M) Attachment 3: Northern States Power Company ofWisconsin (NSP-W)

Pg. 2Summary Database Results Errors
- US EPA Request for Information relating to Surface Impoundments Date: October 5, 2009
Attachment 1·: Public Service Company of Colorado (PSCo)
The following errors were identified inthe summary Database Results table pertaining to PSCo facilities:

• Cherokee Station o The Emergency Spill Pond storage capacity should be 5 acre-ft (7,700 CY), not 0acre-ft as shown.

• Hayden Station o The High Quality pond capacity should be 40 acre-ft (65,000 CY), not 1 acre-ft as shown.

• Pawnee Station - o Corrective measures were implemented for the two evaporation ponds, as evidenced by our text and the attachments sent inthe initial response. Therefore, Column 7 should read "Yes", not "No" as shown. o The storage capacity values for the following ponds (listed inthe order shown) are incorrect. Itappears that the "current volume" information submitted was used (incorrectly) to determine the volumes shown, instead of using the "total storage capacity" information also requested and provided in our response. The correct pond capacity numbers that should actually be reported are: • Evaporation Pond C
- 96 acre-ft (154,900 CY)
• New Bottom Ash Water Recovery Pond
- 52 acre-ft (83,900 CY)
• Bottom Ash Disposal Pond
- 250 acre-ft (403,000 CY)
• Evaporation Pond B
- 138 acre-ft (222,200 CY)
• Intermediate Quality (IQ) Water Pond
- 48 acre-ft (77,400 CY)

Pg. 1Summary Database Results Errors
- US EPA Request for Information relating to Surface Impoundments Date: October 5, 2009
Attachment 2: Northern States Power of Minnesota (NSP-M)
The following errors were identified inthe summary Database Results table pertaining to NSP-M facilities:

• Minnesota Valley Generating Plant o Ponds 1 and 2 have a maximum storage volume of 9 acre-ft. instead of 7 acre-ft. shown on column 8

.

• Sherburne County Generating Plant o Pond No.3 (North portion) was put into service in 2004 instead of 1975 as shown in Column 2.

Pg. 1Summary Database Results Errors
- US EPA Request for Information relating to Surface Impoundments Date: October 5, 2009
Attachment 3: Northern States Power Company ofWisconsin (NSP-W)

The following errors were identified inthe summary Database Results table pertaining to NSP-W facilities:

o No errors were noted.

Pg. 1