RV Park & Campground Drainage

Parks get built on the land that drains worst

Look at where campgrounds sit. River bends and lake edges, because that is the view guests pay for. Old pasture and cutover timber, because it was cheap and flat enough. Floodplain margins that could never carry a subdivision. Low ground along a highway with a good billboard sightline. The site selection that makes a park commercially attractive is very often the same one that makes it wet, and no amount of gravel fixes a grade problem baked in at survey.

Then there is how a park is built. Very little of a campground is engineered pavement. Most of it is compacted aggregate, mowed turf and crowned dirt roads, with islands of real hardscape at the bathhouses, the store and the pavilion. A park drains partly like a parking lot, partly like a farm lane and partly like a lawn, all inside a hundred feet of each other — while a 40 ft coach parks on top of it.

The commercial stakes are different too. A campground's revenue is a review score, and mud gets photographed. A pad that holds two inches of water after a Thursday storm becomes a one-star post on Friday and a refund on Saturday, and it stays searchable for years. Meanwhile the people crossing your wet bathhouse apron at 6 a.m. in flip-flops are guests, not trained employees, so a slick apron or a missing grate is a liability exposure rather than a maintenance ticket. And the season fights you: the rain that does the damage falls in the shoulder months, and the only window to fix it is that same window, with a skeleton crew, before reservations land. That is why we push park owners toward one whole-property plan, quoted once and phased over several off-seasons, instead of a scramble every April.

Parks share plenty of DNA with hotels — see resort and hospitality drainage for the amenity side of that argument — but a campground has one thing no hotel does: the guest brings a 30,000 lb vehicle and parks it on your dirt.

Surface by surface: what goes wrong, and what actually fixes it

The honest version of a park's drainage picture, including the parts we do not sell and the parts that belong to somebody else entirely.

The sites themselves — gravel, paved and pull-through

The complaint generator. A pad crowned properly on day one gets rutted by fifth-wheel landing gear, dished by tire tracks, and slowly regraded flat by the loader that redresses it every spring. Then it holds water — usually first at the strip in front of the utility pedestal, where guests step out of the coach and a hose bib drips for six months a year.

The fix depends on the surface. On a gravel site a channel drain is the wrong answer: every load rating we publish assumes full concrete encasement, and a channel bedded in crusher run will float and rack. Fix gravel with grade and a catch basin at the low corner, piped out. On a site with a concrete patio slab or utility pad, a small channel along the slab edge is exactly right and costs almost nothing while the slab is still being formed. Read driveway drainage for the geometry — a pull-through drains like a short driveway with a hookup on it.

Loop roads and the entrance

Loop roads are the park's storm conveyance whether you designed them that way or not. Water runs the wheel tracks, finds the low point, and either crosses the road or stands in it. Crown and roadside swale is the cheapest answer where you have the width and the fall; in a tight loop with sites on both sides you usually do not, and the answer is a trench drain cut across the road at the low point, tied to solid pipe and a basin.

The entrance road and check-in apron deserve their own budget line. Everything heavy that visits crosses that one strip: every coach, every delivery truck, the propane truck, the pumper, fire apparatus on an inspection run. Class C 250 is the floor there, and Class D 400 — a 400 kN test load — is what we spec when the entrance doubles as the emergency lane. It is the one place in a campground where we routinely move people off the stocked catalog and onto quote-only engineered channel.

Bathhouse exteriors: aprons, surrounds and door thresholds

The highest-traffic pedestrian hardscape in the park, and the one most often undersized. Water arrives at a bathhouse from three directions at once: roof runoff off an unguttered eave, walkway grade sloping back toward the doors, and water tracked out by everyone who used a shower. A slab that pitches even slightly toward the threshold puts standing water exactly where wet bare feet are.

What we spec is a small channel across the door approach and along the apron's low edge, terminating in a basin. On an accessible route the grate matters more than the channel: openings limited to 1/2 in. in the direction of travel, elongated slots run perpendicular to the path — read Understanding the ADA before standardizing a grate on a route guests cross with walkers and wheelchairs. Scope note, and we are direct about it: everything inside the bathhouse — shower and restroom floor drains, laundry receptors, trap primers, the vent stack — is plumbing scope, by a licensed plumber, under local code. We sell exterior surface drainage, not interior sanitary or hygienic drainage, and we will not spec our channel into a shower floor.

Pavilion, camp store and pool deck

Small, high-value hardscape where a failure is visible to every guest who walks past. Pavilions collect a large roof area and dump it in four corners onto turf that erodes into a trench; store and office entries are where guests stand still in the rain. Short runs of small channel plus a basin handle these, and the cheapest fix on the property is usually just tying roof leaders into solid pipe rather than letting them splash at grade. The pool deck is its own discipline: a low-profile deck drain along the coping that a bare foot can cross, in a finish that reads as part of the deck rather than as hardware. Design detail lives on the pool deck drainage page — what is worth saying here is that a campground pool deck is also the gathering area and the thing that gets photographed, so do it once in a line built for it rather than improvising with road channel.

Tent loops, turf, dog runs and playgrounds — where subsurface systems are real

Plenty of parks have genuine subsurface drainage, and pretending otherwise helps nobody. A french drain is perforated pipe bedded in washed stone and wrapped in filter fabric, trenched below grade to pull water out of saturated soil rather than off a surface. In a campground they show up under tent pads that never dry out, along the uphill side of a soggy turf loop, under dog runs and playground surfacing, and behind retaining walls on terraced sites. They are contractor-installed work with a trencher and a laser, and we do not sell perforated pipe, stone or fabric. Nothing in our catalog is a french drain and we will not describe it as one.

What we do sell is the layer above and after it: surface collection points that intercept water before it reaches saturated soil, plus the basins, fittings and outlets that carry it away. Make the sequencing argument before you sign a subsurface contract — a system asked to absorb everything the roofs, roads and pads send it silts in and fails years earlier than one that only handles what the surface layer missed. See yard and lawn drainage for how that surface half gets laid out.

The dump station, and everything else that is by others

The dump station is sanitary scope and by others. The inlet, its trap, the rinse hydrant and everything downstream belong to a licensed plumber and your state health department; we claim no products for it. The only thing we touch near one is stormwater on the surrounding approach apron, kept deliberately separate from the sanitary inlet. Same for the downstream half of a park's water: detention and retention ponds, bioswales, underground chambers, water-quality units, oil/water separators and interceptors are civil and specialty scope — downstream, and by others. We sell no pumps, lift stations, septic or treatment equipment, so if a low corner has no gravity outlet, that is a conversation with a civil engineer before it is a conversation about parts.

How water moves across a park, and how to know your system has room

Get the volume roughly right before anybody picks a part number. It is not hard arithmetic and it settles most of the arguments.

Start with what sheds, and be honest about gravel. Roofs and pavement are effectively 100% impervious; turf absorbs until it does not. The one people get wrong is aggregate: a gravel pad six seasons into having coaches parked on it is compacted close to impervious, especially when already wet. Treat mature gravel as pavement in your first pass, not as a soakaway. Every 1,000 sq ft of impervious surface produces about 623 gallons per inch of rain. Sixty sites at 12 ft × 40 ft is 28,800 sq ft — roughly 17,900 gallons per inch — before one foot of loop road or one bathhouse roof is counted. A mile of 20 ft wide loop road adds about 105,600 sq ft, near 65,800 gallons per inch on top of that.

Then convert to rate, because channels and pipes are sized by rate. The number worth memorizing: 1 inch per hour falling on one acre is roughly 1 cubic foot per second, about 449 gallons per minute. A ten-acre park core under a 2 in./hr cell is moving near 20 cfs, close to 9,000 gpm, and it arrives inside twenty minutes.

Then follow it across the ground. Water sheets off roofs and pads, concentrates where two slopes meet, runs the wheel tracks and the swale, and pools at the lowest point it can reach. That low point is where a basin goes; the concentration line — road crossing, apron edge, bathhouse threshold — is where a channel goes. The most common design error we see in parks is a channel set partway down a grade, where water is still moving fast enough to skip the grate, instead of at the toe where it stops.

Then check the outlet, because the outlet is the bottleneck. The channel almost never limits the system; the pipe leaving it does. Solid drain pipe wants consistent fall — 1/8 in. to 1/4 in. per foot — and a 4 in. line asked to carry what a 6 in. line should is the real reason most "clogged" campground drains back up. Put the park's own numbers through our Runoff Calculator, read the method in Sizing for Storms: Estimating Runoff, and match load class to traffic with the Load Class Recommendation Guide.

One park-specific correction to all of it: add sediment to every calculation. A gravel park delivers fines into every inlet, every storm, forever. A system sized perfectly for clean water and given no sediment strategy sits at half capacity by the second season — and the owner blames the product.

Where each part of the catalog earns its keep in a park

Same catalog, very different jobs depending on where you are standing. This is where we have opinions.

Channel, sized to the surface it crosses. Mini (72 in. × 3-1/2 in. wide × 3-1/8 in. deep), Slim and Micro belong on pedestrian concrete — bathhouse aprons, walks, store entries. Spee-D (5-3/4 in. wide, 3-3/4 in. deep) and the 5 in. Pro Series are the workhorses on site slabs and light crossings; the 8 in. and 12 in. Pro Series exist for volume, and you go there before running two channels in parallel. Dura-Slope is for the long dead-flat run with no grade to borrow.

Basins — every low point, and the end of every channel run. Catch basins collect at a point and give you a serviceable cleanout; a run piped blind into a buried tee is a run nobody can maintain. The ladder is real: 9 in. (#900, 9-3/8 in. square, 10-1/8 in. tall) at a leader or small turf dip, 12 in. (#1200) at site corners and walkway ends, 18 in. and 24 in. at loop-road low points. Kits beat loose parts when a park needs a dozen assemblies; round basins and universal outlets cover the odd tie-in.

Risers — the most under-ordered part in this entire vertical. Every spring a loader adds another half inch of gravel and topdressing; after four seasons the rim is buried and gets reported as a wet spot rather than as a drain. Order the riser with the grate: #916 for the 9 in. (7-3/8 in. tall), #1216 for the 12 in., #1816 for the 18 in., the #2418 extension for the 24 in., #101R for a Spee-D basin.

Sediment control — non-optional on a gravel park. The Spee-D strainer coupling (#245) catches fines mid-run; the 9 in. and 12 in. catch basin filters (#900FF, #1200FF), the Filcoten silt bucket (#22515) and the V100 sump kit catch them at the basin. Cheap parts, and the difference between vacuuming an inlet in twenty minutes and jetting a line.

Grates — specified by load and by leaf litter, not by color chip. Take the top from the grate catalog rather than from an application page: channel grates by system, cast iron and ductile iron where coaches cross, galvanized steel in maintenance yards, atrium grates in wooded loops where a flat grate blinds under a season of pine straw, and square or round grates on basins — with decorative grates earning their keep at the entrance monument. On finish, the turf tones are what parks want: Green (#990, #1212, #1812, #2412) and Sand (#999S) read as ground, not as hardware.

Lock the grates down. A public property with overnight guests and no gate loses grates, and coaches break the ones that stay. Spee-D grate screws (#S229), Pro Series channel screws (#829), the 12 in. Pro Series grate security clip (#849), the Dura-Slope ProFit Grate Lock (#DS-122) and the Filcoten anti-vandalism locking device (#32087) cost a rounding error and prevent an open hole on a loop road at 11 p.m.

Discharge and utilities, on the same order. Pop-up emitters release collected water at grade out in the turf and close flush so a mower passes over them; dry wells handle the corner with nowhere to daylight; the drainage fittings are what actually consume install day. And since a park has water, sewer and electric at every site, add valve boxes with covers marked for the service beneath — WATER (#107BCW, #111BCW), SEWER (#107BCS, #111BCS), ELECTRICAL (#112BCE), reclaimed (#111BCR). Standardizing them park-wide saves a tech an hour every time something needs shutting off.

What we would put on a park's order, loop by loop

Typed by the job each line does in a campground, not by brand. Quantities come from a walk of the property, load class comes from what rolls over it, and channel width comes from the calculator.

Phasing it across off-seasons without repricing every year

Product selection is the easy half. The useful half for a park owner is turning a walk of the property into one plan you can execute over three winters.

Send a loop-by-loop list, not a wish list. For each zone: what is there now, the count, and what rolls over it. Photos of one grate per type beat any written description — the part number is usually molded into the underside. We come back within one business day with part numbers, quantities and pricing itemized by phase. Stocked NDS, Stegmeier and Filcoten items ship as ordered; the ACO lines are quote-only and configured per project, so start those weeks before an install window rather than the week of it.

Order the spares now. A 10–15% overage on grates and a couple of risers on the shop shelf turns a two-week work order into a next-morning fix in peak season, and protects the color match because the spares came off the same run.