HEALTH SAFEGUARDS IN THE PARKS

By H. B. Hommon,
Senior Sanitary Engineer,
U. S. Public Health Service.

Water pumped from the 4,300-foot well in Mesa Verde National Park, Colorado, has a temperature of 110 degrees Fahrenheit. It has the taste of dissolved iron, and there is a slight odor of hydrogen sulphide. Taste, odor, and heat are removed by discharging the water over a cooling and aerating tower, treating with lime, settling in a tank, and filtering through a rapid sand filter. The water then is cool and palatable.

On the South Rim of Grand Canyon National Park, Arizona, where scarcity of water several years ago necessitated hauling it 100 miles in tank cars at the almost unheard of price of more than $3 per 1,000 gallons, "industrial" water is now manufactured at 35 cents per 1,000 gallons. This water, used exclusively for such purposes as generating steam in railroad locomotives, flushing toilets, and irrigating lawns, is made by reclaiming sewage whose disposal previously was something of a problem in itself.

And what becomes of the millions of tin containers that bring into Yosemite National Park, California, a large amount of the food consumed by the half million visitors there each year? The cans are pressed into bales, thus reducing their volume about 90 per cent, and are then used to fill borrow pits or are otherwise buried. This prevents creation of unsightly and fly-breeding dumps. The same practice is followed in other parks.

MESA VERDE WATER PLANT.

Visitors to the national parks and monuments have little, and frequently, no conception of the work that goes on behind the scenery to provide safeguards for protection of their health. It's all accomplished under supervision of the U. S. Public Health Service. The effectiveness of the program can be readily measured when it is explained that since its inauguration in 1921, only three cases of typhoid fever have been reported in the national parks and monuments west of the Mississippi River. The sources of infection of those three cases have never been determined, so it seems reasonable to conclude that they may have originated outside the parks.

There is no place in any national park or monument where untreated sewage is discharged into a stream or lake. Where there is only a small volume of sewage the general practice is to settle it in a tank and either discharge the effluent into covered channels in porous sub-soil, or into open ditches or ponds in isolated places, or to filter it through sand. For the larger volumes produced in such areas as Yosemite Valley, and the South and North Rims of Grand Canyon, complete treatment and disinfection of the sewage is required, and it has been necessary in each case to design a plant to meet local conditions. Although it is used exclusively for industrial purposes, the effluent from the plant at the South Rim of the Grand Canyon now meets the U. S. Public Health Service bacteriological standards for water supplies used for drinking and culinary purposes on common carriers in interstate traffic. This plant produces approximately 165,000 gallons of water daily during the summer. To preclude any possibility of making cross-connections between the fresh-water piping system and the reclaimed sewage-water pipe lines, the latter are covered with vitrified pipe, have a lower pressure than the fresh-water lines, and the outlets are painted red and posted with warning signs.

At the North Rim of Grand Canyon, and in Zion, Mount Rainier, Yellowstone, and some of the other national parks and monuments, the sewage is settled, then disinfected if necessary, and sprayed over natural ground surfaces in places where there is practically no runoff to streams. This is a practical, economical and inexpensive method of sewage disposal which can be used wherever local conditions are favorable.

A sewage treatment plant of unusual design was constructed at the headquarters area in Rocky Mountain National Park, Colorado, to meet severe local conditions. The sub-soil is impervious, there is a small volume of sewage, sub-zero weather prevails over long periods, and a high degree of treatment is required. The unusual feature of the plant, which consists of a septic tank and sand filter, is the building over the filter. This building has glass on the side exposed to the sun, to prevent freezing of the filter in winter. The filter, warmed by the sun, has operated without serious trouble from freezing even when the temperature has been 28 degrees Fahrenheit below zero.

In cases where developed areas in national parks and monuments are adjacent to lakes or rivers, the problems of sewage disposal become involved with many practical considerations. At the Hemenway Wash development in Boulder Dam National Recreational Area, Nevada, the lodge, cabins, and campground are being constructed just above the high water level of Lake Mead. It was not considered advisable to discharge even highly purified sewage into the lake. The only alternative was to pump it to a treatment plant located where there would be no interference with present or future developments. The plant and pumping station were recently completed and are now in operation.

SPRAYING TREATED SEWAGE.

The most difficult problem of sewage disposal was in Yosemite. A treatment plant constructed in 1921 became so badly overloaded and was so obsolete by 1930 that it caused a serious odor nuisance and had to be replaced. The lower end of the valley where it was necessary to locate the new plant, is very narrow, and the site selected was adjacent to the Merced River, less than 100 yards from two main highways and a bridle path. Many people believed that sewage could not be treated in this area without an odor or other nuisance. The plant would have to fulfill the following requirements: it must not be prominently in view from roads and trails on the floor of the valley or the trails along the canyon walls; it must not produce odors or noise; and the effluent, which had to be discharged into the Merced River, must not contaminate the water or kill fish. A modern treatment plant using mechanical equipment and requiring a minimum amount of space was designed to treat the estimated maximum sewage flow of 1,200,000 gallons daily. It has been in successful operation since 1931 without complaints of any nature.

In Carlsbad Caverns National Park, New Mexico, it is necessary to pump sewage from comfort stations, and liquid wastes from the lunch room, 750 feet underground, into the sewer system on the surface. Sewage pumps are generally designed to lift sewage around 150 feet. Solids in the liquid wastes from the caverns are reduced to a very small size, by comminutors, so that the pumps can handle this waste without stoppage.

Before public health work was undertaken in these recreational areas on an organized basis, it was the general practice to haul garbage and refuse to places just outside the developed areas and pile it on the ground. Many of these garbage dumps covered several acres, and all of them were a serious nuisance. This was prior to the days of extensive public campgrounds, when practically all garbage and refuse came from the kitchens of hotels and lodges, and contained a high percentage of water. The commercial incinerators were built to burn fairly dry garbage and refuse, so it was necessary to design one suitable for handling wet garbage. Eighteen incinerators of this type are now in operation. The fly problem at these plants is solved by placing water pipes in combustion chambers and using the heated water for washing the garbage cans, trucks and platforms. In areas where incinerators have not been installed the practice is to dump garbage into trenches and cover it daily with earth.

The beginning of public health work in national parks and monuments can be traced to the late Stephen T. Mather, first Director of the National Park Service. In the late summer of 1920, he requested the U. S. Public Health Service to detail a sanitary engineer to investigate water supplies, sewage disposal, and general sanitary conditions in some of the western national parks. The writer was given this assignment, and arrived in Sequoia National Park, California, in September of that year. The general sanitary conditions there, as they pertained to cleanliness of campgrounds and buildings, were satisfatory. The water supplies were from springs which were apparently not seriously contaminated. There were no comfort stations. Garbage and refuse were hauled to a dump.

General Grant National Park, adjoining, was next visited, and then Yosemite, followed by Yellowstone, in Wyoming. In General Grant, now a part of the Kings Canyon National Park, sanitary conditions were about the same as in Sequoia. In Yosemite, raw sewage was being discharged into the Merced River; and in Yellowstone, untreated sewage from the hotels, lodges, stores, and residences flowed directly into streams. Some of the water supplies in Yellowstone and Yosemite were either contaminated or subject to potential contamination.

The superintendents of these four parks were, of course, aware of the conditions, but they were handicapped by lack of funds. There was no trained personnel. The report to the Surgeon General included a recommendation that a sanitary engineer from the Public Health Service be detailed for temporary duty with the Park Service. Mr. Mather then requested that such an assignment be made. The detail was given to the writer, in May, 1921, when he was placed in charge of Interstate Sanitary Districts 5 and 6, with headquarters in San Francisco. Inspections were made that summer in all of the western national parks.

Since only two of the parks had resident engineers, it was necessary for the Public Health Service engineers to prepare plans sand cost estimates for the sanitary utilities most urgently needed. The Congress was fairly liberal with appropriations, and within a very few years allotments were made regularly for additional employes, for water-works, and development of campgrounds. The number of visitors to the national parks and monuments increased at a rapid rate from year to year, and additional areas were added to the System, but adequate sanitary facilities have been provided to meet these increased demands.

From 1921 to 1932 the cooperation of the Public Health Service, as represented by the San Francisco office, extended to all national parks, including those in Alaska and Hawaii. In 1932 the country was divided into eastern and western divisions. The western office was given the territory west of the Mississippi River, except that Hot Springs National Park, Arkansas, was placed under the eastern division, with headquarters in Interstate Sanitary District No. 2, in Washington, D. C. This arrangement is still in effect.

The National Park Service, cooperating closely with the Public Health Service, has made every effort to provide complete protection for the health of park personnel and the millions of people who visit the parks and monuments each year.