Preventing Roof Water from Becoming Storm Runoff

Clean rainwater flowing from the roofs of our homes and other buildings is a precious resource that is more often than not directed as quickly as possible into streets and storm drains to become contaminated runoff capable of polluting streams and aggravating flooding conditions. The prudent property steward will manage rainfall as the treasured commodity that it is—retaining on site as much of it as possible.

Whether you happen to be obtaining your domestic water from a community distribution system or from a private well, infiltrating the rain that falls on your roof directly into the soil is a good way to make sure it helps recharge the groundwater stored in the aquifer—banking it for future use.

Better yet, rain barrels provide a means of intercepting, storing, and dispensing a share of the precipitation from your downspouts before it is discharged into the ground. Water from rain barrels can be drained to hydrate garden plants, rinse the patio, wash the dog, or, in the event of an emergency, fill the need for non-potable uses that include bathing and flushing toilets. For potable applications such as cooking, drinking, and brushing teeth, roof water must first be filtered and disinfected.

Rain barrel layout for a 1,200-square-foot house. — Rain barrels collect and save clean roof water for later use. For every one inch of precipitation, the roof on a house or other building with a footprint of just 1,200 square feet sheds enough to fill about fourteen 55-gallon drums. Live in a home supplied by a well? That’s over 700 gallons of soft water available as you need it, such as during a power outage when the pump won’t operate.

Here at susquehannawildlife.net headquarters, our goal is “no net runoff” from our little urban parcel. We use three rain barrels to catch discharge from the spouting system, then direct the overflow into three different management configurations.

RAIN GARDEN

Commercial Rain Barrel — Precipitation from the downspout is captured in this commercially produced rain barrel. The overflow is directed into the black corrugated pipe…

Gravel Beds in Rain Garden — The gravel beds diffuse energy produced not only by water rushing from the barrel’s overflow, but from sheet runoff entering the garden from the driveway and neighboring street.

STOCK TANK PLANTER

Planter Receiving Overflow from Rain Barrel — This home-brew rain barrel was fabricated from a 55-gallon drum originally used to ship and store car wash soap. We scrubbed it out, then plumbed it up with the overflow feeding a 100-gallon stock tank fashioned into a planter. The drain from the planter sometimes discharges a trickle of water into a porous area of the pavement where it soon percolates into the ground. In this “container rain garden”, we grow wildflowers, sedges, rushes, and warm-season grasses.

THE GARDEN POND/POOLS

Pond/Pool Receiving Overflow from Rain Barrel — Here’s another rain barrel made from a soap drum. This one discharges its overflow into the upper pool of our garden pond.

Overflow from Upper Pool Fills Lower Pool (Sump) — …into the lower pool (bottom right). The lower pool consists of a 100-gallon stock tank sunk below grade level and surrounded by rock. Throughout the summer, a pump located in this “sump” circulates water to a spring-like feature in the upper pool. During a downpour, the lower pool will overflow into the encircling boulders, the level often rising half a foot or more above the top rim of the stock tank flooding the cap stones before receding as the excess water slowly infiltrates down through the gravelly soils. It’s a self-automated, hassle-free water change that helps keep our pools and their inhabitants healthy.

Rain Barrel Overflow Management — Our garden pond stormwater management system keeps the pools topped off and the aquatic ecosystem thriving.

Why not give roof water management a try on your property? It’s a great project for exercising your ingenuity and creativity while doing something truly beneficial for the watershed within which you reside. Best of all, it’s really not that expensive to get started.

Container Rain Garden — A virtuous goal in a wasteful world.

June 5, 2023June 8, 2023

The Value of Water

Are you worried about your well running dry this summer? Are you wondering if your public water supply is going to implement use restrictions in coming months? If we do suddenly enter a wet spell again, are you concerned about losing valuable rainfall to flooding? A sensible person should be curious about these issues, but here in the Lower Susquehanna River Watershed, we tend to take for granted the water we use on a daily basis.

This Wednesday, June 7, you can learn more about the numerous measures we can take, both individually and as a community, to recharge our aquifers while at the same time improving water quality and wildlife habitat in and around our streams and rivers. From 5:30 to 8:00 P.M., the Chiques Creek Watershed Alliance will be hosting its annual Watershed Expo at the Manheim Farm Show grounds adjacent to the Manheim Central High School in Lancaster County. According to the organization’s web page, more than twenty organizations will be there with displays featuring conservation, aquatic wildlife, stream restoration, Honey Bees, and much more. There will be games and custom-made fish-print t-shirts for the youngsters, plus music to relax by for those a little older. Look for rain barrel painting and a rain barrel giveaway. And you’ll like this—admission and ice cream are free. Vendors including food trucks will be onsite preparing fare for sale.

And there’s much more.

To help recharge groundwater supplies, you can learn how to infiltrate stormwater from your downspouts, parking area, or driveway…

Urban Runoff — Does your local stream flood every time there’s a downpour, then sometimes dry up during the heat of summer? Has this problem gotten worse over the years? If so, you may be in big trouble during a drought. Loss of base flow in a stream or river is a sure sign of depleted groundwater levels in at least a portion of its drainage basin. Landowners, both public and private, in such a watershed need to start infiltrating stormwater into the ground instead of allowing it to become surface runoff.

Rain Garden Model — You can direct the stormwater from your downspout, parking area, or driveway into a rain garden to help recharge the aquifer that supplies your private or public well and nearby natural springs. Displays including this model provided by Rapho Township show you how.

…there will be a tour of a comprehensive stream and floodplain rehabilitation project in Manheim Memorial Park adjacent to the fair grounds…

Legacy Sediments — Have you seen banks like these on your local stream? On waterways throughout the Lower Susquehanna River Watershed, mill dams have trapped accumulations of sediments that eroded from farm fields prior to the implementation of soil conservation practices. These legacy sediments channelize creeks and disconnect them from their now buried floodplains. During storms, water that would have been absorbed by the floodplain is now displaced into areas of higher ground not historically inundated by a similar event.

Adjacent to the Manheim Farm Show grounds, the Chiques Creek Stream Restoration Project in Manheim Memorial Park has reconnected the waterway to its historic floodplain by removing a dam and the legacy sediments that accumulated behind it.

Legacy Sediments Removed — Chiques Creek in Manheim following removal of hundreds of truck loads of legacy sediments. High water can again be absorbed by the wetlands and riparian forest of the floodplain surrounding this segment of stream. There are no incised banks creating an unnatural channel or crumbling away to pollute downstream waters with nutrients and sediment. Projects similar to this are critical to improving water quality in both the Susquehanna River and Chesapeake Bay. Closer to home, they can help municipalities meet their stormwater management (MS4) requirements.

Bank-full Bench — Mark Metzler of Rettew Associates guides a tour of the Chiques Creek rehabilitation. Here, cross vanes, stone structures that provide grade control along the stream’s course, were installed to gently steer the center of the channel away from existing structures. Cross vanes manipulate the velocity of the creek’s flow across its breadth to dissipate potentially erosive energy and more precisely direct the deposition of gravel and sediment.

…and a highlight of the evening will be using an electrofishing apparatus to collect a sample of the fish now populating the rehabilitated segment of stream…

…so don’t miss it. We can hardly wait to see you there!

The 2023 Watershed Expo is part of Lancaster Conservancy Water Week.

April 28, 2023May 28, 2023

How Much Rainwater Runs Off Your Roof During a Storm?

During the spare time you have on a rainy day like today, you may have asked yourself, “Just how much water do people collect with those rain barrels they have attached to their downspouts?” That’s a good question. Let’s do a little math to figure it out.

First, we need to determine the area of the roof in square feet. There’s no need to climb up there and measure angles, etc. After all, we’re not ordering shingles—we’re trying to figure out the surface area upon which rain will fall vertically and be collected. For our estimate, knowing the footprint of the building under roof will suffice. We’ll use a very common footprint as an example—1,200 square feet.

40′ x 30′ = 1,200 sq. ft.

By dividing the area of the roof by 12, we can calculate the volume of water in cubic feet that is drained by the spouting for each inch of rainfall…

1,200 ÷ 12 = 100 cu. ft. per inch of rainfall

Next, we multiply the volume of water in cubic feet by 7.48 to convert it to gallons per inch of rainfall…

100 x 7.48 = 748 gallons per inch of rainfall

That’s a lot of water. Just one inch of rain could easily fill more than a single rain barrel on a downspout. Many homemade rain barrels are fabricated using recycled 55-gallon drums. Commercially manufactured ones are usually smaller. Therefore, we can safely say that in the case of a building with a footprint of 1,200 square feet, an array of at least 14 rain barrels is required to collect and save just one inch of rainfall. Wow!

Why send that roof water down the street, down the drain, down the creek, or into the neighbors property? Wouldn’t it be better to catch it for use around the garden? At the very least, shouldn’t we be infiltrating all the water we can into the ground to recharge the aquifer? Why contribute to flooding when you and I are gonna need that water some day? Remember, the ocean doesn’t need the excess runoff—it’s already full.