About ten years ago, in 2011, I did my first Rain Barrel Workshop. At this workshop, we discussed using low-impact development in new development and changing how stormwater management systems are sized, managed, and maintained from a regional perspective. We then made and customized Rain Barrels using recycled containers.
Most recently, on April 26, 2022, I presented a workshop to Carbon County, Pennsylvania residents through the Carbon County Environmental Education Center. (See presentation) This discussion focused on the individual homeowner's effort to "Get Back to Zero." "Get Back to Zero" means achieving no-change in your home's pre-development and post-development amount of runoff.
Since Carbon County is a rural area, most rural lots are over one acre and either forested or meadow in nature. However, many urban areas have large impervious areas with little green space due to their history as old mining towns.
This blog post is our effort to develop a guide with respect to runoff for the average rural homeowner and to provide resources for urban citizens and for those who may be looking at rainwater harvesting systems. We'll use Pennsylvania as our case study.
- 1% of the annual rainfall is 114,500 gallons per acre per year in Pennsylvania.
- A 1000 square foot home generates approximately 26,182 gallons per year of runoff, excluding the driveway.
- Simpler Terms: 1 inch of rainfall on a 1000 square foot roof is over 600 gallons of water per rain event. Assuming a rain barrel has a volume of 80 gallons, this would require about 8 rain barrels for each 1 inch rain event, but if the barrels are 50 gallons you would need 12 rain barrels (So rain barrels may not be the single solution in all cases).
- Pennsylvania receives about 42 inches of rainfall per year.
- In forested areas, the annual portion of the streamflow that is groundwater is over 60%. This explains why the stream is cold and has water when it does not rain.
- About 80% of Pennsylvanian rain events are less than 1 inch.
How will Climate Change impact Pennsylvania in the future? – likely, Pennsylvania will get more rainfall per year, but less in the summer months and more in the fall and spring. (Recommended reading on "Climate Change" at the bottom of the page)
If we could turn back the clock and modify the initial development to provide a two-story home rather than a one-story home, use a smaller driveway footprint, add some rain barrels, and use a more native landscape approach to vegetation and lawn, the annual rate of runoff would be 18% of the annual flow, which is only a 280% increase.
If the project added overland flow with biofiltration areas, i.e., part of your lawn stays wet longer and bioretention structures, we are at a 6% annual flow, which is only a 40% increase in the annual runoff. In the presentation example, getting back to zero required the reuse of this water for flushing toilets and then recharging the water through the use of septic systems and installing a "green roof" system to store and evapotranspiration the remaining water.
Since getting back to zero for an existing home by remodeling and retrofitting does not make financial sense and would likely be very difficult to implement, it may make sense with respect to Urban Stormwater Redesign. We can take some basic steps to reduce our "Stormwater Footprint."
The KnowYourH20 team advocates that you "Get Informed" before developing and implementing an action plan in order to have the most effective and cost effective solution.
Go outside during a heavy rainstorm and observe where and how water enters and leaves your property. Where are the ins and outs, and what is occurring?
Aside: When I did this, I discovered that a lot of water came from an up-gradient homeowner on one side of my home. I had several downspouts that were clogged and overflowing. My sump pump would turn on nearly immediately, and most of the water ran down the edge of my driveway, along my foundation, and water went from my roof to my foundation drains. No wonder I had a very wet basement and occasional basement flooding. I did not know, and I am a hydrogeologist! (A scientist that studies the Earth with expertise in water and hydrology – flowing water and groundwater).
Fix obvious problems and then make additional observations.
From your observations, what are your problems, and how or where are they interconnected, such as downspouts to foundation drains and a wet or damp basement.
1. Clean and fix the gutters and determine if an area of the home needs a gutter. Add gutter guards or other structures to prevent debris from entering the gutters.
2. Disconnect the gutters to foundational drains and redirect to landscape areas to reduce concentrated flows to spread the water.
3. For concentrated flows onto the property, you may want to consider installing a surface swale that can be filled with rock that can be used as a walkway and hardscape feature. It may appear as a small stream during a rain event that diverts the water to an infiltration area, bioretention structure, water feature, or something that works for your setting.
4. Sketch your property for an overview and study your options.
Here are some online resources to learn more about stormwater management. (Courses can be used for continuing education as well as credits for professionals)
Consider the relatively inexpensive things first such as:
1. Reducing the amount of "European Lawn"
2. Adding rain barrels
3. Disconnecting downspouts
4. Clean gutters
5. Repair and stabilize areas of the property that are eroded
6. Redirect runoff to green spaces
7. Use stormwater for landscape irrigation
8. Review your options (rain garden, tree planting, native grasses, convert impervious areas to porous areas), cistern, and other landscape and gardening features
9. And do not forget about the hidden gem - avoid adding pavement when it is not needed.
If your plan includes rainwater harvesting for agricultural, animal, or human uses, rooftop rainwater harvesting has become increasingly popular to provide off-grid high-quality drinking water. Rainwater can also be used for gardening, livestock, irrigation, etc. The most common materials used to capture and store rainwater are tile, metal sheets, and plastics. Before using the water, we recommend that the system be flushed, and the water tested.
After your plan has been implemented, in part or full, go back and reevaluate how it is working.
It took me over four years to fully implement my plan, which includes:
Year 1 - Rain barrels
Year 2 - Implementing surface swales and a small water feature
Year 3 - Disconnecting downspouts and redirecting to landscape features, including native grasses and fruit trees
Year 4 - Added a larger water feature with surface gravel swales that act like walkways.