The attached tabulation provides field test data covering the Buzzard Point and Potomac River station installations. The entire Buzzard Point station and the first two units at the Potomac River station are now being used for peaking service only. That is, they are now used mostly for the purpose of generating electricity at times of the highest demands on the system, which since 1942 have occurred in the summer.

Our oldest station-Benning-is in the District of Columbia and has been principally a peaking operation for many years. Its boiler equipment consists of 4 oil-fired 200-pound boilers, 4 coal-fired 200-pound stoker boilers, 12 coal-fired 400-pound stoker boilers with mechanical cinder collectors, and 2 pulverized coal-fired boilers with electrostatic precipitators.

Senator TYDINGS. This is the Benning station you are referring to? Mr. CADWALLADER. Yes, sir; that is the Benning station.

Senator TYDINGS. I noted in the last exhibit to your statement, where you have the Benning station, you listed tons of coal burned and percentage of sulfur, and then you have No. 2 oil gallons and No. 6 oil gallons. What is No. 6 oil gallons and what is No. 2 oil gallons? What does that mean?

Mr. CADWALLADER. We use No. 2, which is residential type heating oil, for lighting off our pulverized coal burners. You will find the same thing indicated in the tabulations for all of our stations; whereever we use pulverized coal, we have to use No. 2 oil to light the boilers off.

Senator TYDINGS. I notice in the other stations you just have No. 2 oil gallons, but in your Benning station, you have No. 6 oil gallons, too. What is the significance of that?

Mr. CADWALLADER. Yes, sir. These four oil-fired, 200-pound boilers referred to are fired with No. 6 oil.

Senator TYDINGS. Why would they be fired with No. 6, rather than No. 2 like the rest?

Mr. CADWALLADER. The No. 2 oil is a high grade oil which is much more expensive than No. 6. The No. 6 we use actually for generating electricity in peaking service at Benning.

The No. 2 oil in the various stations where we burn pulverized coal is used only when we are lighting off a boiler, and as soon as we have established our coal fires, then the No. 2 oil is cut off.

Senator TYDINGS. So you actually use No. 6 oil in the same way you use coal as far as Benning is concerned?

Mr. CADWALLADER. Yes, sir; that is correct.

Senator TYDINGS. What is the difference in the sulfur content between No. 2 and No. 6?

Mr. CADWALLADER. No. 2 oil runs about one-half of 1 percent sulfur. Senator TYDINGS. About 0.5?

Mr. CADWALLADER. About 0.5, yes sir. And No. 6, as now available on the market, runs about 3.5 percent-312 percent. Now, of course, these No. 6 oils are in the process of being converted, we hope, to 1 percent sulfur.

Senator TYDINGS. Excuse the interruption. Please continue.

Mr. CADWALLADER. It is important to emphasize that the Benning and Buzzard Point stations in the District of Columbia and two of the

tive units at the Potomac River station in Alexandria are in peaking service only. Therefore, their highest generation is during the summertime, which is Pepco's peak load season due to air-conditioning requirements.

This means that their contribution to the overall air pollution problem in the District of Columbia is greatest during the summertime, which is when the polluting effect of the winter heating load of Government, business, and private dwellings is the least. This relationship is helpful in avoiding peaks of pollution from the combined effect of the city's heating load and Pepco's generating facilities. Attached is a tabulation giving, by month, for the years 1965 and 1966, the coal and fuel oil burned at each of Pepco's generating stations. Also given is the percent sulfur in the coal. It will be noted that the average sulfur contents are in the low to medium range. For the Benning, Buzzard Point and Potomac River stations, they are—

Of the total coal consumed on the Pepco system in 1965 and 1966, only 28 percent and 32.3 percent, respectively, was burned in the District of Columbia and nearby Virginia. The remainder was burned at plants remote from the District area.

The attachment referred to appears on page 702.)

POTOMAC ELECTRIC POWER Co., WASHINGTON, D.C.

Senator TYDINGS. Mr. Cadwallader, before I start the questioning about the statement, we will take a 3-minute recess.

Mr. CADWALLADER. I would like to add just one more statement. While it did not include the cost of Pepco's air pollution control activities in the preprints for this hearing, I would like to do it now for the record. I will be glad to confirm this in writing.

For its five existing generating stations, Pepco has invested $9 million in air pollution control equipment. Approximately $4 million of this was expended on the Benning and Buzzard Point Stations in the District and the Potomac River Station in Alexandria.

Senator TYDINGS. Over what period of time is this?

Mr. CADWALLADER. From 1933, which was when we originally started to install this type of equipment. The remaining $5 million was expended on the Dickerson and Chalk Point Stations in Maryland. Senator TYDINGS. What is your overall investment?

Mr. CADWALLADER. Five and four-$9 million overall to date. We expect to invest an additional $6 million in air pollution control equipment for the proposed new generating station at Morgantown, Md. These costs are capital costs only and do not include the operating and maintenance costs, which we will be glad to furnish, if you like. Senator TYDINGS. We will take a 3-minute recess. (Whereupon, there was a short recess.)

Senator TYDINGS. We will reconvene the hearing.
Have you completed your testimony, Mr. Cadwallader?
Mr. CADWALLADER. Yes, sir.

Senator TYDINGS. I notice that you have an exhibit entitled "Dust Collector Test Data, Potomac Electric Power Co., Washington, D.C." You have the Buzzard Point Station and the Potomac River Station. I presume you could get me the same material for the Benning and Dickerson Stations, and Chalk Point Station, could you not?

Mr. CADWALLADER. Yes, sir. We have much of that data in our files

now.

Senator TYDINGS. I would appreciate it if you would send it so we can include it in the record.

Mr. CADWALLADER. Yes, sir.

(The information requested may be found on p. 711.)

Senator TYDINGS. Would you explain just what that means when you say, "Boiler output, pounds steam/hour" and "Coal burned, tons/hour," "Gas volume through collector," and so forth? Explain just what that means.

Mr. CADWALLADER. I will try to do that. The efficiency of a dust collector is associated with the gas volume, the volume of flue gases going through it. Now, these flue gases carry along ash particles, and in an electrostatic precipitator, as the volume velocity, that is feet per second going through, decreases, the efficiency increases.

Now, this gas velocity is affected by gas temperature because as the temperature increases the volume increases.

The draft loss referred to is important to mechanical collectors because a mechanical collector depends upon throwing out the ash particles by applying a whirling motion to them. So that, in effect, we have two different pieces of equipment here, the mechanical and electrostatic collector, which operate on different principles.