Answering nature's call: how to solve the problem of wastewater treatment.

It is a beautiful day--the sun is out and the air is fresh and clean. The serenity of nature saturates the moment until a helicopter appears up the valley chopping the peace and blowing that moment away. Underneath the chopper, tethered, is a 55-gallon drum swinging its way to the nearest sewage plant. It is an icon to the lengths we take to keep backcountry areas unspoiled, yet in doing so, spoil them.

Leaving the city also means leaving the comforts of home. One of those comforts is not thinking about what happens after you flush, or at least not being burdened with the challenges of properly taking care of your waste. No matter how outback and off the beaten path, the challenges of wastewater treatment are many. One of the most basic is keeping our pristine areas looking that way, which is becoming more difficult as the same number of parks and camps attempts to accommodate the ever-increasing number of visitors.

Old, tired and out of the way pretty much addresses the state of wastewater infrastructure at some parks. Pipe, pumps and plants built decades ago are now at the end of their design lives and being pressured to perform more than ever. Some of these systems fail to meet the challenge. Other parks are meeting the challenge by transforming their wastewater systems into models of "green" infrastructure.

Engineered wetlands have been tailored for a camp in the north country of Minnesota. Parks in the state of Washington are developing wastewater systems that incorporate reuse of treated wastewater. And, at an extreme, some other parks are resorting to advanced "membrane" sewage plants to meet stringent discharge limits. In most cases, three issues are at the core: the need to improve aging infrastructure, the capacity to handle increasing wastewater flows, and the ability to comply with stringent discharge limits.

Core Issues

The need to address aging infrastructure has resulted in some notable projects across the country. At Glacier National Park, Mont., a 27 year-old treatment plant had insufficient capacity, while at Everglades National Park, Fla., the wastewater system was outdated and unable to meet future regulatory requirements. The treatment system at the Park at Wind Cave in South Dakota was undersized and poorly located. Mt. Pisgah Park in North Carolina was out of compliance and received a violation notice.

Addressing these "deferred maintenance" projects has been an ongoing concern of the National Park Service and steps are being taken to catalog, prioritize and correct them. State park systems are in need of help as well. Washington State has budgeted $17 million for wastewater and stormwater projects at its parks. More than 20 of their parks will have projects aimed at replacing and or improving their infrastructure. And the problem has continued to trickle to the local level--taken as a whole, these examples are indicative of the aging wastewater infrastructure in every type of park.

Wastewater flows at parks are related to the number of visitors--the more people that visit, the more the bathrooms are used. And as the number of campers and tourists increase, particularly with the oncoming retirement of baby-boomers, parks and camps are struggling to manage the related increases in wastewater flows. Not only are comfort stations and RV sites being upgraded, but so are the pipes and pumps that service them.

Along with aging infrastructure and increase in flows, parks and camps are charged with "meeting applicable federal and state regulations." This seemingly simple requirement has significant ramifications. As an example, a small sewage plant servicing a campground may have to comply with one or all of the following:

* National Environmental Policy Act

* Clean Water Act

* Endangered Species Act of 1973

* Wild and Scenic Rivers Act

* Floodplain Management Executive Order

* Protection of Wetlands Executive Order

* National Historic Preservation Act

Probably the most significant regulation with respect to wastewater treatment is the Clean Water Act, which governs the discharge of pollutants into the nation's waterways. Its requirements to keep waters fishable and swimable and to maintain downstream water quality results in stringent discharge limits. The discharge of nutrients, like phosphorus and nitrogen, are strictly limited. Regulations aside, as stations to nature, it is paramount that parks and camps are designed to protect the environment as well as provide access to it, limiting human impact and leaving no trace on the ground or in the water. The challenges in doing so, however, are numerous and present constraints not normally encountered by engineers.

"Engineering in a park environment can be surprisingly challenging," agrees Nathan Epling, a public health specialist engineer with the National Park Service. "There are many stakeholders involved with all aspects of a project and sensitivity levels are high--from biologists protecting threatened species to visitors protecting the special places they remember from childhood. It is important to honestly consider these challenges and meet them with sound and innovative engineering solutions as they will be the most effective and sustainable."

Challenges

Wastewater treatment is rarely a cookbook exercise. And, while there are always those with a special "black box" technology that is sure to be the cure, designing a wastewater treatment system for remote parks or sections of parks is a special order each time. Being remote is the primary challenge at many public parks as well as the primary appeal.

At its extremes, waste is transported back out of the outback by raft, pony, truck or helicopter. This approach however, is not sustainable and in areas where there are a large number of visitors, this approach is simply not viable. In these cases, waste needs to be effectively handled on-site.

On-site treatment in remote areas can range from basic septic systems to the complex type of sewage plants found in cities. One thing is common, regardless--reliable electricity is necessary to operate pumps, blowers and other equipment necessary to do the job. This is a challenge because being off-road means being off-grid, where reliable electricity is seldom available. As a result, remote systems need to be designed with electrical failure in mind, so that when the lights go out, the wastewater doesn't go out as well.

Another challenge is the constant variation in flows. Most engineered systems tend to operate best when conditions are the same every day. Given a "steady state," a system can be optimized and left alone. Due to rushes of seasonal and weekly traffic at parks, treatment systems hardly ever experience such a state of steadiness, which makes achieving a consistent level of treatment a challenge.

"Design and implementation of wastewater treatment systems for park settings present a unique set of challenges;' says Martin Hildebrand, president of Nelson Environmental. "Main attractions to parks often include recreational opportunities in pristine natural water bodies. To maintain the recreational quality of these water bodies, nutrient removal for surface water discharge is becoming an increasingly important factor. Treatment plants in a park setting must also be able to accomodate massive seasonal flows and peaking factors (often 10:1 high to low flow ratios) without being upset or producing odors."

In addition, most sites have periods of the year in which they are closed and systems are shut down. This need to routinely start up and shut down is particularly troublesome for biological treatment systems that rely on a critical mass of bacterial activity to remove pollutants in wastewater.

While each system design has its challenges, operation of on-site systems is no walk in the park either. Far be it from "set and forget," personnel already tasked with meeting the needs and neediness of visitors, are responsible for the proper functioning of these systems. And, suffice it to say, there are other jobs at a park more enjoyable than cleaning out a lift station or measuring the level of sludge in a septic tank.

Operation and technical issues aside, probably the most significant challenge at any public park is simply getting the money and doing the paperwork to get a new or improved system. Before even thinking of getting a contractor on-site, a detailed environmental impact statement must be developed that thoroughly addresses all aspects of a project.

Completion of the necessary reports and forms does not ensure that the project will be funded any time soon. As typical, adequately addressing infrastructure needs often takes a backseat behind preferred initiatives and other crises of the day. And the result, the parks infrastructure too often becomes old, tired and out of the way.

Trends

There are a number of trends surfacing in the wastewater industry that are influencing how parks and camps are responding to the challenges they face. One trend is an emphasis on using natural systems to provide "green" solutions. Engineered wetlands are leading the charge here and are proving to be important tools for wastewater treatment at remote sites.

Another trend is the use of sophisticated membrane bio-reactors (MBR) to meet tight effluent limits with a small footprint. Other trends include a focus on re-using treated wastewater and using equipment from the "decentralized" or "on-site" wastewater market that services cluster developments in suburban and exurban communities.

Case Studies

Natural Systems

Coincidently enough, natural systems can be employed to meet the challenge of answering nature's call while out in nature. The use of wetland systems for wastewater treatment has long been in practice. However, in the past decade, a "4th generation" of wetland systems has evolved that incorporates engineering practices commonly used in sewage plant design.

Natural treatment technologies exploit the natural mechanisms of bacteria so that they remove pollutants from wastewater and are easily integrated into the surrounding environment. Paired with soil infiltration, natural treatment systems are proving a low-impact approach to treat and dispose of wastewater on site.

At the Northern Tier High Adventure Base located in northern Minnesota near the Boundary Waters Canoe Area, a sub-surface flow wetland system was constructed to replace the undersized package plant. The mulch-insulated system is designed for year-round use and constructed to operate under severe freezing conditions. Of particular note is the use of an innovative drip-tube aeration system that provides uniform oxygen throughout the wetland that ensures consistent performance through the seasons.

The Indian Creek Nature Center outside of Cedar Rapids, Iowa, installed natural wetland treatment system to replace a malfunctioning septic tank and drainfield. The system is designed to treat sewage from the low-flow toilets at the center, which can have more than 1,500 visitors on a given day.

The two-stage system uses both subsurface and free surface wetlands to reduce the concentrations of organics and solids that are ultimately discharged to the Cedar River. The use of the wetland treatment system is consistent with other innovative environmental technologies used at the center, which includes solar panels and compact fluorescent lighting.

Membranes

MBR systems use membrane technology to separate solids from a liquid. They are similar in use to reverse osmosis units and are commonly used in advanced sewage plants. In recent years, numerous MBR suppliers have entered into the market increasing competition and reducing equipment costs. One issue often sited with membrane systems is the care and cost required in maintaining the membrane filters.

A membrane system is in use at the Everglades National Park facilities. The site is located in a large mangrove that is considered to be the largest in the Western Hemisphere. A budget of $4.1 million was approved in 2002 to improve the Flamingo wastewater system that is designed to treat 90,000 gallons per day, and meet the stringent discharge limits set by the Florida Department of the Environmental Protection. For this facility, an extremely low phosphorus concentration of 0.1 mg/l was set as an effluent limit.

Far from the mangrove swamps of Florida, high in the Canadian Rockies another membrane system was installed by Parks Canada for the community of Field, British Columbia. This system, too, was installed to meet high treatment levels expected by Parks Canada.

Others

Many parks and camps use septic tanks and drainfields to meet their wastewater treatment and disposal needs. The tanks remove solids and scum and must be periodically pumped by "honey wagons." Historically, after the tanks, the wastewater is discharged to drainfields and allowed to seep into the soil. Recent practice has underscored the need to provide additional pre-treatment between the tanks and fields to reduce organic loading.

Excessive loading of organics to drainfields can result in clogging and in wastewater being exposed to the environment. Also, alternative approaches to disposal of the treated wastewater are being used like drip irrigation.

A case in point is the Otter Creek Campground and Restaurant in Virginia. This campground has incorporated an aerobic treatment unit (ATU) to provide treatment of the septic tank effluent. The ATU is designed to provide aeration and surfaces where bacteria can attach for the removal of pollutants. A drip irrigation system has also been designed that uses the same technologies found in large-scale agricultural facilities. The use of drip irrigation has allowed the park to use difficult areas that could not be used with traditional drainfield areas.

Re-use of wastewater is already being practiced on a large scale in Florida and drier parts of the west coast. Re-use is now being considered in wastewater projects at parks. Fort Flagler and Blake Island State Parks in Washington are currently considering integrating the capacity to reuse treated wastewater. Along with plans to upgrade wastewater treatment system, Watertown National Park in south Alberta incorporates golf course irrigation by treated wastewater in its plans.

Conclusion

Parks and camps have unique challenges with respect to how they manage the impact of visitors. As these same parks and camps experience more visitors, innovative and advanced wastewater treatment systems are being engineered to address the particular needs of each site. Trends and advances experienced as a whole in the wastewater treatment industry are being integrated into these remote facilities that are proving to protect nature from nature's call. And with this, some comfort is provided--comfort that the environment we visit is, after all, protected from our visit.

RELATED ARTICLE: Flushing out trends in portable toilets.

By Bob Barton

We've all had experience with portable toilets at some point in our lives. These services meet the basic needs for restrooms when large crowds are around or there are no permanent facilities available. But while the basic portable toilet is an economical way to fill the need, it is not ideal for all uses. The portable restroom industry is now branching out with a huge selection of alternatives.

Wheelchair-accessible portable restrooms can be ideal for areas where there are families with young children. The extra space in these provides room for a parent helping even two or three children. And where government regulations require it you can rent a fully ADA-compliant restroom that is even larger.

A step up from the basic portable is a restroom with a flushing toilet. These look the same on the outside, but offer a more experience on the inside. These restrooms sometimes even contain a sink for hand washing instead of the waterless hand sanitizer found in the more basic models.

At the top of the scale are restroom trailers. These restrooms on wheels are just like a permanent restroom, offering separate men's and women s facilities, heat, air conditioning and sinks with hot water. They come in different sizes and a variety of heavy-duty models for large public events, as well as deluxe versions for smaller private parties. The deluxe trailers are just like a restroom in a fine restaurant or hotel.

Managers should consider a number of factors when planning how many portable restrooms may be needed at an event. The number of people who will use the facilities, the length of the event and whether or not food and beverages will be served all affect the quantity of restrooms that will be used. For example, many park and recreation planners forget that at an event like a Little League game, there are parents and other spectators in addition to the players and coaches.

Also remember that a basic portable restroom is good for about 120 uses before it needs to be serviced. Flushing restrooms have a smaller capacity due to their need for fresh water. Servicing the restrooms more frequently will reduce the number you need.

While it sounds like a dizzying array of decisions, professional portable restroom companies are experts in this area and will be glad to help determine the best option for any facility or budget. Look for suppliers who are members of the Portable Sanitation Association International, which ensures its members provide a high quality of service (www. psai.org).