"They paved paradise ...".

"... And put up a parking lot." Joni Mitchell first penned the lament forty years ago, with Counting Crows covering it for a new generation thirty years later. But until our cars fold into a suitcase like George Jetson's, we need a place to safely store, load, and unload them everywhere we want to stop. Parking lots are "necessary evils," but they don't have to be troublesome. In fact, when they're designed and built right, people won't even notice them. I've long said that camps are like small cities, with all of the responsibilities to serve their guests that a municipality has for its citizens: Clean, inviting water supply, effective sewage treatment and disposal, reliable power and communications, and safe, maintainable roads and pathways. Moreover, it's arguably tougher for camps because although they have all of those needs, finding the funds and knowledge to meet "non-program" requirements can be next to impossible.

Often, there's a drive to make new facilities multi-use in order to get the most bang for every buck, and this can bring a boatload of other troubles when the original reason for the project becomes overshadowed and even forgotten. One great example is space for parking vehicles. Stormwater and environmental regulations can make a simple "parking lot" project seem like building a skyscraper. This month, we're going to look at some of the issues surrounding parking areas at camp, and how they can be handled unobtrusively and without paying a platinum premium for it.

How Much Is Enough?

The "We need parking!" cry goes out almost like clockwork. Whether it's staff training or camper drop-off or pick-up, it seems that traffic jams and folks parking in bad places create headaches. But how bad, really, is the problem? Obviously, if it's been like this for years and you've managed, the perception is that it's not too bad. However, if first-year camper parents are grousing to themselves about it, maybe they won't be second-year parents. If you decide to do something about the situation, the first thing that your engineer will ask is "How much parking do you need?" If you've never specifically counted the cars and traffic during the troublesome events, that will be a really, really hard question to answer. So collecting data is the key to ensuring that the parking area is neither too big (which costs more than it needs to), nor too small.

The traffic count can be done a couple of different ways. The most low-tech method is to simply count the parked vehicles at regular intervals during the event (drop off, pick up, community fireworks, whatever). If your camp has a single entrance and exit, then the greeter at the gate can operate a little hand-held counter like USA Bluebook item AD-33770 (about $12). If traffic is a bit heavier or lasts more than a couple of hours, you might consider renting a mechanical system. Your local municipality or district state department of transportation might even have one that you can borrow. It counts vehicle passes by pressing a switch when cars drive over an air tube lying in the road and works really well over a fairly long period of time. The catch here is that someone needs to read the instrument at the end of the traffic-generating event, because it won't do much good to know how many vehicles came and left all summer if you're simply trying to size a parking lot. Once you know how many vehicles (and what kind!) you need to accommodate at one time, you're at the starting point to decide how big an area you'll need and what shape it needs to take.

Dimensions and Geometry

Although almost everyone has parked a car, most folks don't give the event a second thought unless there was trouble, like banging doors into each other, no room to maneuver, loading or unloading, or sloppy, goopy muck. Here are some dimensions that will get you in the ballpark. Generally speaking, parking spaces for common passenger vehicles are 9'--10' wide and 18'--20' long. Remember that "accessible spaces" (which are required by federal law even for private facilities) need extra width to accommodate lifts, wheelchairs, and maneuver space. Two way traffic aisles typically need at least 18' for safe travel, and this dimension is really pushing the safety envelope when you think about excited children running between cars and loading/unloading luggage. That 18' is a great number though for one-way, slanted parking. I'm a huge fan of this arrangement because it channels vehicle traffic and when working properly is much safer than the alternative. That said, one-way, diagonal parking can create a nightmare for other drivers and pedestrians by a single wrong-way driver. Clear signage and courteous parking attendants will prevent most of the problems.

Finally, understand that since cars don't (usually) bend in the middle, parking lot layout has to include the total turning radius of the vehicle's trailing wheel in a turn. You may be surprised to know that the inside rear wheel path of a typical passenger vehicle in its tightest turn is a 15' radius (30' diameter!) circle. So for a car to successfully make a U-turn, it needs at least 30' of clear space on the inside of the turn. Vans take more space, vehicles with trailers more yet, and obviously busses require a bunch more.

The other design element that plays a big role in how well your parking lot works is its slope. A steeper slope will make the water drain away faster, but makes loading, unloading, and walking more difficult. Obviously, the converse is also true: flatter slopes make movement for people easier, but draining storm-water slower. In general, the minimum slope in any directions for an asphalt lot should be V4" per foot (2.08 percent). At the same time, that is the maximum slope in any direction for a handicap parking space. If your lot is gravel or soil, the slope should be increased to facilitate drainage. Handicap parking areas will require special attention because the maximum slope requirements mentioned previously will still apply. Yep. That's right. The very flat slopes for a handicap parking area are ideal for creating puddles.

Stormwater/Runoff

The next thing that you'll probably want to think about is what happens to the rainwater and snow melt that accumulates on this parking area. You'll want the water off your parking and driving surfaces as quickly as possible, and snow melt to stay off. Properly sloped, ditches, swales, and pipes collect and convey the flow away from your facility. These, too, must have the correct geometry and slope to convey a volume of water associated with different storm intensities. And those properties are all affected by the type of covering or lining where the water will flow. Steep slopes will tend to erode, so big rocks (called "riprap") often line the bottom of channels. Since slower flow is deeper than it would be otherwise, the ditch has to be constructed deeper. Side slopes greater than two (horizontal) to one (vertical) are difficult and dangerous to mow, so flatter side slopes are generally preferred over steeper ones. Finally, drainage ditches should have a flat bottom about 2' wide for maintenance.

Permitting

Federal regulations under the National Pollutant Discharge Elimination System (NPDES) set requirements for the quantity and quality of water running from an improved surface like a parking lot. Water flowing across a parking area tends to "wash" automotive chemicals and lubricants along with salts and deicing materials. Even the nonchemical constituents (like mud and anti-skid) can be quite noxious, damaging the ecology of receiving water courses. Even the temperature of water is managed through the NPDES program. Water cools hot pavement by absorbing the heat and becoming hotter itself. This very warm, oxygen-free water needs to be allowed to cool and re-oxygenate before it is released to a stream, lake, or pond. The most straightforward method to "treat" parking lot "first flush" stormwater is by collecting and storing it for a period of hours or days. During this time, some should soak into the earth, and the rest should be allowed to bleed off slowly to the receiving water course.

And if all that weren't enough, a parking area that exceeds one acre (210' x 210') may require an earth disturbance permit under the same regulations (or a state version of them). This is to ensure that there is a workable plan to control sedimentation and erosion while the bare earth is most susceptible to rutting and wash-outs.

Finally, there are probably local regulations (township or county) that apply to "land developments." You should consult with the local officials well in advance of your project (a year should be enough), to ensure that construction isn't interrupted by upset regulators threatening fines. This delay will cost your organization much more time and money than you would have spent to get the necessary approvals in the first place.

What to Do?

There are some pretty neat innovations that may help reduce how much space is required for the combined parking and stormwater facilities. As mentioned previously, the best thing to do with stormwater is to let it soak into the ground (or "percolate"). Where the soil is deep and receptive, large corrugated plastic chambers (they look like half-pipes) are laid atop beds of 1" stone beneath the parking area proper. The stormwater is directed into these chambers where it soaks into the ground. Infiltrator chambers (www. infiltratorsystems.com) are one such product, and ADS pipe (www.ads-pipe. com/en/product.asp?productID=133) making one similar. Where space is limited and the soils are conducive, this might be just what your facility needs to expand your parking area.

Another interesting approach to parking area topping is reinforced soil or turf. Grasspave[R], by Invisible Structures Corporation (www.invisiblestructures. com/grasspave2.html) is one such product. It uses a plastic grid comprised of interconnected shallow cups to hold a drainage base, topsoil, and grass seed. Mowable and even lightly plowable, automobile wheel loads are distributed by the edges of the cups, which protect the roots of the grass. This approach has the additional benefit of reducing the amount of runoff in the first place, since it's a porous media. The root zone of the turf also contains microbes and organisms which can break down some of the automotive drips and drops, preventing them from becoming water borne and en route to a stream near you. Another product by Invisible Structures is very similar and simply replaces the turf with pea-sized gravel, reducing runoff by absorbing most of the rain that falls on it. This application is an outstanding solution for paths and trails because the installation is very adaptable for wheelchair and ADA access.

Finishing Touches 

There are many of things that can be done to soften, protect and improve the visual effect and the function of your parking spaces. Landscaping is one important addition that's often overlooked. Shade trees help to cool the driving surface, the vehicles and the people walking through. Low shrubs reduce the visual effect of light reflecting from low vehicle components like fender reflectors and headlights. But remember to select appropriate varieties of plantings that fit your site and situation. Beyond soil pH and drought tolerance, remember that roots will tent to spread in search of water, and that can damage or even destroy the pavement surface, particularly asphalt. Remember, too, that snow removal can physically damage landscaping and salt can poison it. A competent landscape architect can help you select plantings that can tolerate most, if not all, of the limitations of your site and operation.

Finally, whether or not you install it, consider lighting. Motion-sensitive, area-specific, low-voltage lighting can provide safe movement through the parking area without blotting out the stars or wasting electricity. Remember that the reason guests visit remote, "wild" areas is to experience something different, yet secure, and they deserve a contribution to their safety.

I do not subscribe to the "Field of Dreams" approach of "If you build it, they will come." Nobody is going to visit your facility just to use your really cool parking lot. Consider designing and designating a parking area, instead of just an area where people put their cars. Because if getting to and from their car is too much of an adventure for your guests, it might just be their only trip to your facility.

RickStryker, P.E., is aprofessional engineer, serving camps and conference centers nationwide with consulting services from site planning and design through general consultations on a wide range of infrastructure issues, including water supply, sewage disposal, and construction administration. He can be reached at 570-828-4004, or by e-mail at [e-mail].