Notes from Site Visit at 

CPS Energy’s Calaveras Power Station on October 29, 2008 

EPA conducted a site visit at CPS Energy’s Calaveras Power Station located in San Antonio, TX 

on Wednesday, October 29, 2008 to learn about the operations at the plant, specifically the FGD 

wastewater handling system. Table 1, located at the end of this memorandum, identifies the site 

visit participants. Plant process flow diagrams are included as an attachment to this 

memorandum. 

This memorandum describes the information collected during the site visit and the pre-site visit 

phone call, which was held on October 7, 2008. 

Background on Steam Electric Detailed Study and Introductory Remarks 

EPA provided background on the steam electric detailed study, highlighting the current focus on 

wastewaters from coal-fired facilities, specifically ash handling, FGD wastewaters, and coal pile 

runoff. EPA stated that the purpose of the study is to determine whether revisions to the current 

effluent guidelines for the industry are warranted. 

EPA stated that the purpose of the visit is to learn more about the plant’s operations, specifically 

the operation of the FGD scrubber systems and the FGD wastewater handling systems. 

Company Overview 

 CPS Energy is municipally owned, but also has a Board of Directors. Fourteen 

percent of revenues from the company go back to the city. 

 CPS Energy operates both the JK Spruce and Deely power plants, which are 

located adjacent to each other on Calavaras Lake. The entire site, including both 

plants, covers 6,600 acres, of which the lake occupies 3,600 acres. 

 Both plants operate under one NPDES permit and have one common intake. Each 

plant operates its own water treatment plant. 

 The Calaveras Power Station consists of three plants, the Sommers Plant (2 gasfired units), the Deely Plant (2 coal-fired units) and the Spruce Plant (1 existing 

and one under construction coal-fired units). 

 A study conducted on Calavaras Lake analyzed mercury and other metals in the 

water column, sediment, and fish tissue, as well as in the intake water (San 

Antonio River). There was no analysis specifically of the plant effluent. Lowlevel analytical methods were used for the analyses. 

 Recently, CPS Energy replaced their ESPs on the Deely units with baghouses due 

to issues with opacity. After the change to baghouses, the opacity decreased from 

10% to 0.4%. Personnel stated that the ESP at Deely was old and difficult to keep 

within their opacity limits, and the baghouse reduces labor. 
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Plant Overview – JK Spruce 

 Spruce has one coal-fired generating unit, and is currently installing a second unit. 

Unit 1 has a capacity of 550 MW and was built in 1992. Unit 2, with a capacity 

of 750 MW, is under construction and is expected to be online in 2010. The table 

below contains some general information for each generating unit. 

Unit 

Installation 

Date 

Net 

Capacity 

(MW) 

Particulate 

Control NOx Control SO2 Control 

1 1992 550 Baghouses No SCR Wet FGD in original 

design (1992) 

2 2010 

(expected) 

750 Baghouses SCR will be 

installed with 

unit 

Wet FGD in original 

design (2010) 

 Spruce burns Powder River Basin coal. The sulfur content of the coal typically 

ranges from 0.3 to 0.4% sulfur. The chlorine content of the coal is 0.01% 

chlorine. Spruce obtains about 95% of their coal from one supplier. 

 Coal is received by rail, transferred to the coal pile, and stored in day silos. The 

on-site coal pile covers approximately 40 acres. 

 Runoff from the coal pile is captured in a runoff pond, which is pumped through a 

clarifier where polymer is added prior to discharge to the Calavaras Lake intake 

canal. The runoff pond is tested for TSS, oil and grease, and pH. At the request 

of EPA, site personnel measured the pH of the runoff pond and found it was 8.3 

S.U. 

 Spruce operates a dry fly ash handling system and has done so for over 10 years. 

The dry fly ash is stored in a silo and sold for use off site in cement 

manufacturing. Fly ash is transferred off site 3 to 4 times per week. 

 Spruce operates a dry bottom ash handling system for Unit 1 (Unit 2 is planned to 

use a dry system as well). Spruce personnel stated that the bottom ash is collected 

in a water bath collection trough at the bottom of the boiler and a drag chain 

moves along the trough pulling the bottom ash out of the boiler. Bottom ash is 

dropped in a pile in an outdoor bunker. Water draining from the pile is collected 

in a sump and pumped to the SRH pond. The bottom ash is trucked by the 3rd

party distributor. 

 

 Spruce personnel stated that Unit 1 does not have a SCR system, but Unit 2 is 

planned to be installed with a SCR system. Spruce expects to operate the systems 

year round. At this point, Spruce does not expect any change in their ability to 

reuse water, but is investigating if there is anything they should anticipate. 

 Spruce operates an on-site landfill and has historically landfilled solids from the 

operation. For the past 15 years, only economizer ash and some solids from the 

Sludge/Recycle/Holding (SRH) pond have been landfilled. The landfill is 
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currently used to temporarily store small quantities of ash prior to being recycled 

off site. The landfill is lined with no leachate collection. Landfill runoff goes to a 

separate landfill runoff pond which discharges to Calavaras Lake through internal 

outfall 013, combining into final outfall 007 to the lake. Spruce personnel 

indicated that they test the landfill runoff for TSS, oil and grease, and selenium 

every six months. 

FGD System and Wastewater Handling (JK Spruce) 

 Spruce operates a limestone, natural oxidation FGD scrubber system on Unit 1. 

Unit 1 has three individual absorber vessels, two that are in operation at any one 

time and one spare. Each of the absorber vessels at Spruce has three spray levels, 

each operated by a separate recirculation pump. A process flow diagram for the 

FGD system is included as an attachment to this memorandum. 

 Personnel noted that calcium sulfite may be produced with the natural oxidation 

system if the operation is not working correctly, and this has happened on 

occasion (typically after an outage). 

 Plant personnel stated that they are planning to convert Unit 1 to a limestone, 

forced oxidation FGD scrubber system at the next outage (expected Spring 2009) 

to improve SO2 removal, which is currently at about 84% removal, to 95% 

removal. Personnel do not expect any difference in the gypsum byproduct. 

 Spruce is installing a single tower limestone, forced oxidation FGD scrubber 

system on Unit 2. A one tower design is the current industry practice, and it is 

better from an operability and reliability standpoint. 

 Makeup water for the scrubber comes from Calaveras Lake. Spruce personnel 

stated there are no particular issues or treatment of the lake water needed prior to 

reuse. 

 Gypsum is produced from Unit 1, and goes through a 3rd party distributor for sale, 

primarily for use in cement manufacturing. There is no limit on chlorides when 

used in cement. A small amount of gypsum was previously sold for wallboard 

manufacturing, although not any longer. The chlorides limit for use as wallboard 

is <100 ppm. The gypsum product is not currently utilized for wall board. 

Spruce does not landfill any of the gypsum. 

 Spruce does not wash the gypsum to remove chlorides. The plant is equipped 

with sprays on the vacuum drum filter, but they have not used them. They would 

only be used when marketing the gypsum as wallboard. The wash water flow 

would be 30 gpm, and would be transferred to the thickener and then to the 

reclaim tank. 

 Spruce does not add any additives to the scrubber to improve the efficiency of the 

SO2 removal in the scrubber. 
Page 4 

 Spruce personnel estimated that the solids concentration in the scrubbers is 

approximately 14-15% (by weight). Absorber pH is maintained near 5.5 S.U. 

 Spruce personnel stated that the chlorides concentration in the scrubbers is 

between 8,000 and 10,000 ppm. The scrubber manufacturer, ABB, allows 

chlorides to range from 15,000 ppm to 20,000 ppm; however, Spruce has found 

that lower chlorides results in better gypsum production. Scrubber wastewater is 

purged when chlorides reach 10,000 ppm. 

 Spruce personnel stated that the blowdown from the scrubbers is typically 

continuous. The blowdown is transferred to the thickener feed tanks and then to 

the thickeners for solids dewatering. 

 Spruce personnel stated that the overflow from the thickeners is transferred to the 

reclaim tank. From the reclaim tank, the FGD wastewater can be transferred back 

to the scrubber, to the ball mills, or to the SRH pond. Personnel indicated that 

wastewater is discharged to the SRH pond about every three weeks for 6 to 8 

hours. The SRH pond is made up of a north and south pond, which are used 

alternately. 

 Spruce personnel stated that the underflow from the thickeners (approximately 35 

percent solids) is transferred to the filter feed hold tank. The tank feeds the rotary 

vacuum filters, which dewaters the gypsum. The gypsum is conveyed 

approximately one mile to the stackout location where it is loaded onto trucks. 

The filtrate from the vacuum drum filters is transferred to the thickeners about 95-

99 percent of the time; if necessary, it will be sent to the SRH pond. 

 From the SRH pond, the water is treated through a clarifier at 120 gpm where 

polymer is added. Effluent from the clarifier is discharged to the Calaveras Lake 

intake canal. Currently, discharge is periodic. Spruce is installing a new set of 

clarifiers for Unit 2 that will each operate at 400 gpm and can be operated in 

series or in parallel. Spruce personnel expect daily discharge once Unit 2 is 

operating. 

 Spruce personnel stated that they monitor Se, Cu, and Fe in their clarifier effluent. 

Selenium is typically below 0.1 ppm (the plant permit limit is 0.2 ppm). Cu and 

Fe are only monitored when metal cleaning operations are occurring. 

Deely Plant 

 The Deely plant has two coal-fired generating units. Neither unit is currently 

equipped with FGD scrubbers; but scrubbers are planned and budgeted for both 

units. Plant personnel are considering installation of limestone forced oxidation 

systems, but are also evaluating the use of “dry” scrubbers. The capital cost for a 

wet scrubber is more than a dry scrubber, but CPS Energy personnel stated that 

the lifecycle costs for wet and dry FGD systems are comparable. 

 Deely Unit 1 will be equipped with a SCR in 2011. The SCRs are planned to be 

operated year round. 
Page 5 

 Deely operates a dry fly ash handling system. The dry fly ash is stored in a silo 

and sold for use off site in cement manufacturing. 

 Deely did not perform a wet to dry fly ash handling conversion because the plant 

has never wet sluiced their fly ash. In the first few years of operation, the fly ash 

was ponded until a market for the ash could be developed. Fly ash has always 

been transported from the ESP hoppers to the silos with air. 

 Deely operates a wet bottom ash handling system for Units 1 and 2. The plant has 

two bottom ash ponds. As one pond fills with ash, the sluice water is discharged 

to the second pond while ash is removed from the first pond. Deely typically 

switches ponds about every 6 months. Ash sluice water is recycled back to the 

plant; Deely also has the option to discharge the water to Calaveras Lake if 

needed. The bottom ash pond discharges to the lake periodically (approximately 

weekly) due to insufficient surge volume in the system, or when draining a pond 

to remove ash. Constructing additional surge volume capacity would be needed 

to eliminate all discharge from the bottom ash pond. 

 Plant personnel stated that they have considered retrofitting Deely to use dry 

bottom ash handling; however, they do not anticipate switching to submerged 

scaper conveyor ash handling due to the expense and installation constraints, and 

no serious study has been performed. 

 CPS Energy personnel stated that they can’t reuse the sluice water as scrubber 

makeup water; they would need to treat the sluice water to remove carbon so they 

would not contaminate the gypsum produced by the system. 
Page 6 

Table 1. Site Visit Attendees 

Name Organization (Representing) Telephone E-mail Mario Alvarez CPS Energy (210) 353-5818 maalvarez@cpsenergySamuel Helmle CPS Energy (210) 353-5580 sfhelmle@cpsenergy.cJeff Kruse CPS Energy (210) 353-3839 jjkruse@cpsenergy.com Erik Meyers CPS Energy (210) 353-3955 ekmyers@cpsenergy.coKim Stoker CPS Energy (210) 353-2929 krstoker@cpsenergy.coGregg Tieken CPS Energy (210) 353-2158 grtieken@cpsenergy.coRudy Martinez CPS Energy (210) 353-3979 rumartinez@cps energyRon Jordan EPA/Office of Water (202) 566-1003 jordan.ronald@epa.gov Deb Bartram ERG (Contractor to EPA) (703) 633-1669 deborah.bartram@erg.c
Attachment 

CPS ENERGY PROCESS FLOW DIAGRAMS