No increase in temperature "from background levels to a degree known to be unfavorable for salmon development" should take place in the river.

Dissolved oxygen within the spawning gravel of the river bottom was not to fall below 7 ppm.

Chemical concentrations in the Sacramento were not to exceed :

0.05 ppm for Mercaptans,

1.00 ppm for crude sulfate soaps,

1.00 ppm for fatty acids,

0.2 ppm for resin acids.

Effluent concentrations in the river were not to exceed 10 of the TLm (median tolerance limit) of the most susceptible resident salmon species or the minimum concentration having “a significantly deleterious effect on the survival, quality and hatching of their eggs."

The available oxygen in the Sacramento over and above that required for the propagation and growth of the normal aquatic population was determined, and Kimberly-Clark was allowed to use one-half parts per million of this excess. If it had been feasible to situate the operations below all spawning beds at some downstream point along the central stretches of the river, such strict conditions would not have been needed. The Benthic Biological Section of the State of California's "Sacramento River Water Pollution Survey," issued in 1962, had reported that these "middle reaches were relatively unproductive of bottom life." Such a location, however, would have been away from the lumber operations and other sources of wood supply. It became, therefore, a question of economics: Would the cost of operating the pollution abatement facilities necessary for this sector be offset by the yearly savings resulting from the use of the wood slabs and trim now being wasted?

Thus, we had the tremendous advantage that all firms have which build a new plant. We knew what was needed at this location. We had complete freedom in design and layout. We knew what was technically available and economically practical in abatement facilities, so we could "count the cost." In other words, we were able to decide whether we could afford to build a house for this particular climate. This, I repeat, is a tremendous advantage over those who have built houses in the past but who have seen the pollution climate change rapidly over a space of a relatively few years.

"The cost of pollution abatement is a cost of doing business."

So said J. R. Kimberly, President of Kimberly-Clark Corporation to corporate management several years ago; so said James Quigley of the Department of Health, Education and Welfare at the Chamber of Commerce meeting in Washington last December; and the truth of this statement is becoming appreciated across the length and breadth of this nation. Like all costs of doing business, however, it must be of a magnitude compatible with the enterprise of which it is an integral part.

This cost will not be the same at all installations. It will vary with local conditions just as other costs of doing business vary-costs of raw material, power costs, transportation costs, marketing costs, and the costs of local and state taxes.

The magnitude of this cost of pollution abatement is not usually appreciated by the general public. Capital costs for just this part of our installation at Anderson were in excess of $2,000,000. Operating costs for the first year were over $400,000, or expressing total costs of the effluent system in another way: The operating cost of the effluent treatment plant was approximately 5-3⁄4¢ per pound of BOD removed. This, of course, includes costs during the initial and often trying start-up period and so is higher than projected for regular operation. Nevertheless, we expect the cost of operation to approximate a quarter of a million dollars annually when operations are stabilized--an outof-pocket cost upon which there is no dollar return.

But, getting back to the factors which made possible the Shasta project, one further advantage must not be overlooked or discounted. That is the advantage of progressive maturity in the field-new techniques characterized by an increasing efficiency and expanded ingenuity. This maturity in the field is characterized by—

Extensive surveys made by the Institute of Paper Chemistry to establish the biological conditions of the river prior to the construction of the mill,

Investigations conducted by the National Council for Stream Improvement concerning the effect of this specific type of pulp and paper mill effluent upon salmon and salmon eggs,

The original design of the system and recommendations made by Roy F. Weston, Inc.,

The statistical analysis of seasonal variation in the dissolved oxygen content of the Sacramento as made by the Quality Control experts,

The application of information and experience gained from existing installations by the Kimberly-Clark Research and Engineering Division.

The technical know-how of pollution abatement, the state of the art, and the practicality of operation have advanced more in the last decade than in the entire century preceding it. Many problems still remain to be solved-some of which are mentioned later but the fact remains that things considered to be only hopeful thinking twenty years ago can be done and are being done today and will be done more efficiently and more extensively in the future. This then is the general background of the Kimberly-Clark enterprise at Anderson.

I. OPERATING FACILITIES AND EFFLUENT TREATMENT LAYOUT

The kraft pulp mill includes a continuous digester rated at 150 tons per day. All of the pulp is bleached, C-E-CIO2-H-CIO2, optional peroxide. The unbleached permanganate target is 19 to 22 and the bleached brightness target is 88 to 90. depending upon the grade. A high density tower stores bleached pulp for the paper mill, and the balance is fluff-dried, baled and sold as market pulp. In addition a mechanical groundwood-from-chips operation currently produces 30 to 40 tons per day of peroxide bleached groundwood pulp for the paper mill.

The paper mill includes a 189'' wire width Fourdrinier machine, with machine roll coater and off-machine coater. The rated capacity of the mill is 180 tons per day of a wide range of Kimberly-Clark printing paper grades, in roll and sheet form.

Fresh water for the integrated pulp and paper operation is taken from seven. 1,500 gpm-rated wells, depth 500 to 600 ft.

The 64 acre mill site is about two miles south of Anderson, California, and about the same distance west of the Sacramento River. It adjoins the largest of the three Kimberly-Clark California Lumber Division sawmills.

The main elements of the pulp and paper mill liquid waste treatment system are located at the north side of the mill site, occupying about 7-% acres for the treatment area proper. Other essential stations include:

(1) A storm sewer pumping station, on mill grounds.

(2) A storage lagoon (also on mill grounds) of 20 acres gross area, and 51 million gallons capacity to hold the final effluent before discharge. This U-Shaped pond is located about one-half mile west of the treatment area, and a flow-pH monitoring station adjoins it.

(3) Effluent distribtuor system at the river, with remotely positioned flow control valve.

(4) a 40 acre pasture for spray disposal of surplus secondary sludge.

(5) A land-fill site for disposal of primary sludge and other solid wastes from the mill.

To accommodate the supporting operations, listed in 3, 4 and 5 above, Kimberly-Clark purchased over 1,000 acres of farm land, located two to five road miles from the mill, and bordering the Sacramento. It is not now expected that all or even the majority of this land will be used for effluent disposal. It rep resented, however, the first of the "safety features" which characterize this development.

A. General

II. PROCESS AND EQUIPMENT DETAILS

The photograph, Figure 1, shows the main portion of the Anderson mill effluent plant. The line flowsheet, Figure 2, identifies the several major components in locations corresponding to the photograph. Five separate underground sewer systems carry waste waters from the pump and paper mills to the effluent plant. By designing the treatment system simultaneously with the design of the production units, it was possible to separate process waters of different compositions. This simplifies the treatment in a way that is not possible in an older mill.

At the lower left is a package unit sanitary sewerage plant (SSP) rated at 28,000 gal./day, and based on the "total oxidation" activated sludge process, with terminal chlorination. Sanitary wastes from the mill, which now employs 330 people, are treated independently of the industrial wastes.

B. Primary waste treatment

To the right of the SSP in Figure 2 is the main pumping station for those waste waters requiring primary treatment. Three sewers terminate here: (1) Special floor drain system (SFD), serving the "critical" kraft pulp mill areas digester, calciner-causticizer, evaporators.

(2) Regular floor drain system (RFD), serving all other areas, including kraft dryer, groundwood mill, paper mill, and utilities.

(3) Special storm sewers (SSS). (Diverting certain storm sewer waters to the effluent plant was one of several post start-up changes. This one was to protect Anderson Creek, a low-flow tributary of the Sacramento River.)

Adjoining the primary pumping station is a special storage basin (BLB) for strong wastes, another of the safety features of the effluent plant. The BLB can be used to intercept and to store up to 50,000 gal. of any abnormal discharges such as black liquor spills.

The primary pumping station includes coarse bar screens, a 6,000 gal./min. vertical centrifugal pump for the main flow, a 1,700 gal./min. pump for the BLB, and related interceptor valving and level control equipment. The main flow. which currently averages 2,700 gal./min. is delivered to the primary control basin (PCB), which provides the needed smoothing out of the flow and solids concentration before going to the primary clarified. (The general design data for these vessels, as well as the others in the system, are tabulated in Table A.)

The primary clarifier (PC) was designed for a feed rate of 27.9 gal./hr./sq. ft. (670 gal./day/sq. ft.) with settleable solids removal better than 90%. Sus

pended solids removal was expected to be 80% of the 5,900 lb. per day infeed, without the use of chemical clarification aids. The design provided for a net flow of approximately 40 gal./min. of underflow sludge at 1% dry solids. The clarified overflow goes to a division box (DB), where it mixes with other mill waste waters prior to secondary treatment.

The filter building (FB) houses a two-stage, belt-type rotary vacuum filter, six ft. diameter by five ft. face and the following auxiliary equipment:

(1) Primary sludge pumps, one 220 gal./min. vertical centrifugal, and one 150 gal./min. double diaphragm, in parallel. These operate with flooded suctions, and are sized to allow 25% to 75% sludge recirculation to the 20 ft. diameter x 6 ft. deep concentric feed well of the primary clarifier.

(2) Sludge flocculator, flash-mix type, 2 min. design retention, with hydrated lime and ferric chloride additive systems.

(3) "Packaged" vacuum system including filtrate receiver, 150 gal./min. filtrate pump, and 344 cfm vacuum pump.

(4) Filter cake transport system, including a screw conveyor and a recently installed elevator, which delivers 15%-33% consistency sludge to a dump truck. Under normal operating conditions, the filter manufacturer predicted a sludge thickening rate of 3.2 lb. dry solids/hr./sq. ft., indicating that the filter would not have to be run 24 hrs./day to handle the design loading of 5,100 lb. of dry sludge solids (5,100 lbs. included chemicals added for filtration).

Due to start-up difficulties in the pulp and paper mill, the entire primary treatment system has been subjected to actual solids loadings which for certain periods have reached six times design. These abnormal conditions required several field changes in both equipment and operating procedures, some of which are described in a later section of this paper. (One such item is the temporary primary sludge storage lagoon (PSS), which can be seen just to the rightsouth of the primary clarifier, in Figure 1.)

C. Secondary waste treatment

In the center foreground of Figure 2 is the division box, where waste waters from three main sources are blended prior to secondary treatment:

(1) Overflow from the primary clarifier (PC), including filtrate from the sludge filter. Flow range 1,500 to 4,500 gpm, average actual flow 2,700 gpm. (2) Surplus clarified water from the paper mill white water settler, about 800 gpm, plus 300 gpm decker water from the groundwood mill.

(3) Kraft bleachery white waters, including kraft mill condensates treated in the odor abatement system, totaling about 3,800 gpm.

Flows 2 and 3 were assumed to have settleable solids contents equivalent to that of a primary clarifier effluent. This again permitted efficiencies in treatment facilities which would be difficult to achieve in an older mill served by a common

sewer.

Prior to arrival at the effluent plant, the kraft bleachery white waters are used to reduce odor levels in certain kraft mill exhaust gases and condensates. In the course of this treatment, limestone is added to maintain the pH of the mixed waters at the division box in the range of 6.5 to 8.0. To supplement this separate pH control systems are provided for the addition of milk of lime, caustic soda, or sulfuric acid as required.

The effluent control station, of which the division box is a part, houses most of the instrumentation, and also provides laboratory facilities. At this station, a 10,000 gal./min. capacity vertical centrifugal pump moves the raw secondary waste waters to either of two holding basins (HB-1, north; HB-2, south). Because of the large flow and relatively low storage capacity of the division box and process sewers, a 6,000 gal./min. pump is provided for standby service. While a single 2,000,000 gal. capacity holding basin might have been adequate for storage of raw secondary waste waters, two of them were provided as another safety feature. (Subsequent events showed this to be a wise decision). The basins are piped in parallel, and a 1,450 gal./min. pump is available for transferring the contents of one basin to the other, or to the primary pumping station. Ordinarily, one HB is kept empty, providing about 4 hr. of emergency storage at the current average flow rate of 7,600 gal./min.

Flow from the "on-stream" HB to the aeration basin (AB) is by gravity, and a pH recorder is installed in this line. The aeration basin is equipped with four independent towers, with a two-speed turbine (50/25 HP drive motor) and a 1,175 SCFM rated positive-displacement blower (50 HP motor) on each. Aeration is by turbine-supplemented sparge ring, the mixed liquor being kept at