Campton collects water. The Pemigewasset comes down the middle and the Mad River, the Beebe River, West Branch Brook and Bog Brook all deliver into it inside the town line — the whole of Campton drains to the Merrimack, and this stretch of valley has been described as one of the most flood-prone areas in the state. Spring runoff, yes. Also ice jams. Also September. Getting water off your lot here starts with knowing where it goes next.
Fifty-two square miles, four named tributaries, one river taking all of it. The flooding is not theoretical: Tropical Storm Irene in September 2011 caused substantial erosion and property damage along the Pemi, and the corridor’s own management plan lists damage to bridges, culverts, dikes and railroad beds as the recurring pattern — from winter ice jams as much as from April melt. There is a dam on the Mad River right at the junction of Routes 175 and 49. Downstream the gauge has logged better than ten minor flood-stage events in a decade. None of that is a reason to panic about a house lot. It is a reason to size a culvert for the event instead of for the average.
The corridor holds real floodplain, and floodplain has a job. The Pemigewasset Wildlife Management Area here takes in better than two miles of river frontage, a one-acre island, and roughly 33 acres of floodplain forest growing on silt the river keeps re-depositing — rich ground, precisely because it goes under. Every town along the Pemi carries a floodplain ordinance, which is what lets property owners buy FEMA flood insurance at all, and FEMA has been reissuing the maps for this corridor. So before we pipe anything we find out which zone you are in. Filling a flood storage area to dry out a yard hands the problem to your neighbor, and usually back to you, two storms later.
Here is the wrinkle specific to Campton: with no municipal sewer anywhere in town, your drainage plan and your septic system are competing for the same dirt. A leach field wants unsaturated soil and clean separation above seasonal high water. A dry well wants to put a roof’s worth of water into the ground. Put those two in the wrong relationship and you get a wet cellar or a failing field, sometimes both. Along the river the septic has to stay 125 feet back from the ordinary high water mark, so on a narrow riverfront lot the drainage has to work around a fixed point. We sketch both before we dig either.
Find out which flood zone your Campton lot is in, and whether your dirt is outwash or till, before you buy a single drainage product. On sand the answer is put the water in the ground; on till the answer is intercept it uphill. Guessing wrong costs the whole install.
We walk it wet if we possibly can. A Campton lot in late August tells you very little. The same lot in a March thaw, or the morning after two inches of rain, tells you everything — where water crosses onto the property, what path it takes, where it stalls, whether the road ditch is quietly aimed at your foundation. The fix belongs at the top of that path. Fighting water at the foundation wall is the expensive way to lose.
Curtain drains go in three to four feet down, perforated pipe bedded in washed stone and wrapped in fabric, running across the slope to daylight. On the sandy glacial outwash down in the valley an infiltration trench or a dry well will swallow roof water and never complain, provided there is clean separation above the seasonal high water table. On till and shallow-to-bedrock ground it simply fills up, and the answer is interception uphill instead. A test pit settles which one you have in about an hour.
Culverts get sized for melt and for the ice-jam event, not for a summer shower, and every outlet gets a stone apron so it doesn’t scour a trench for itself. The cheapest tool on the list is still regrading. A surprising number of wet cellars in this town are wet because somebody graded a yard toward the house decades ago and nobody has touched it since. Six inches of fall in the first ten feet fixes more basements than any pipe we install.
Curtain and French drains in Campton run $2,000–$8,000 depending on length, depth and how far it is to daylight; regrading, swales and re-piping downspouts usually come in under that. Culverts are priced per site once we have seen what they have to carry. Infiltration trenches and dry wells are quoted after a test pit proves the ground will take water. Flat quote.
On the sandy outwash down in the valley, very well. It needs clean vertical separation between the bottom of the system and the seasonal high water table, and it should take roof water only. On till or shallow-to-bedrock ground it fills and backs up. One test pit answers the question, and it costs less than installing the wrong thing.
Uphill, then at the grade against the house. Most wet cellars here are taking water off the slope behind them or straight out of the road ditch, and intercepting it with a curtain drain up the hill beats fighting it at the wall. After that we check whether the yard falls toward the building, which surprisingly often it does.
Probably not, and it is worth finding out before you try. If that corner is mapped floodplain or wetland, filling it runs into the town’s floodplain ordinance and the state wetland rules, and it removes storage the river was using. It also tends to relocate water rather than remove it. We look at the maps first.
For the melt and the ice, not the average storm. The recurring flood damage in this valley is to bridges, culverts and road embankments, and undersized pipe is how that happens one property at a time. We look at the drainage area feeding it and the ditch it interrupts, then go a size up rather than a size down.
It can decide whether the septic survives. Campton has no municipal sewer, so every lot treats its own wastewater, and a leach field needs unsaturated soil to work. Routing roof water or a curtain drain toward the field is a slow way to kill it. We lay the drainage and the septic out together, with the 125-foot river setback as a fixed point.
Free site walks, test pits before quotes, flat pricing, and a crew that knows Lakes Region ground.
Tell us where the property is and what you’re trying to do. We’ll walk the site, talk it through, and give you a straight, flat quote.
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