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Churches - A Big Stormwater Footprint

Posted June 12, 2014 @ 8:01am | by Earth Wizards

Churches - A Big Stormwater Footprint

Large Buildings and Large Infrequently Used Parking Lots

Church properties provide a great opportunity for sustainable landscape practices to be used. With a large building footprint creating enormous amounts of runoff any available green space should be considered for capturing, or minimally filtering, stormwater.  This can be done with rain gardens/bioswales, underground stormwater storage chambers and/or rainwater harvesting systems (large of course) and permeable pavements in the people-traffic areas. 

Another big ticket, is the parking lot.  Churches have a unique scenario of needing a lot of parking space - infrequently.  Most of the time when you drive by a church during a weekday there's a few cars, once a week things are fairly full and then wow the big events, packed. How does a designer design for this? Historically parking lot designs are done with those big events in mind but rethinking this scenario is vital for the health of our watersheds.  What about sizing the pavement for the often used circumstance based on say a 6 month analysis and then using alternative pavements for the higher use needs. These areas are often referred to as overflow parking and various alternative pavement types, such as a turfstone, or a grid structure filled with soil and turf, could be used.  Of course instituting capture facilities like rain gardens planted with native plants where any stormwater off the parking lot drains towards is a smart thing to do.

Approaching a stormwater mitigation retrofit (or new construction) should start with a purpose in mind, say a 5-year, 24-hour rain event which in Minneapolis/St. Paul currently is 3.5" of rain.  Factoring that runoff from impervious areas and knowing the subsoils then helps to define things. Certainly poor infiltrating soils will cause bigger expenses so being realistic is important.  Even minimally thinking about filtering runoff using most importanly native plants is doing something rather than nothing.

One last consideration and budget-friendly is to think of decreasing pavement with sharing resources. Why not partner with potential neighboring properties that need parking during the week but not on the weekends? Cities are becoming less structured with parking codes because this issue of stormwater quality requires property owners to take big steps towards change.  Plus with more intense rain events, city stormwater infrastructure is over-burdened and the impact on our waterways extreme.

 
 

Greening up your driveway

Posted May 1, 2014 @ 3:08pm | by Earth Wizards

Greening up your driveway

Driveways are conduits for runoff.  Not only do our impervious driveways shed stormwater but often portions of our home, garage and even lawns direct runoff onto the driveway. Hence, why the driveway becomes an ideal design feature to rethink how it's constructed.

Generally there are three methods of thought in making a driveway more "green."  

  1. Decrease the extent of pavement,
  2. Reroute stormwater from the driveway to available green space for a rain garden or native-planted filter strip (one of my favorite methods as it provides habitat), and
  3. Make the pavement permeable, pervious, porous - somewhat interchangeable terms depending upon the surface type used.

Starting with decreasing pavement surface, think about where your car tires actually go. Oftentimes we think the driveway needs to extend all the way along the house to the back of the garage or for it to be three cars wide the full length of the driveway. Consideration of the vehicle's path will help determine what really needs to be a solid hard surface, what can be a secondary pavement type (both turfstone, a grid structure or concrete runners can work well) and then green space of course.

Rerouting can entail contouring the surface if slopes are relatively slight or installing a diverter structure, such as a trench drain.  In Minnesota, contouring can be tricky as winter conditions need to also be considered.  When we're snowbankless that's one thing but take 2014 winter's deluge and that means overflows need to be working well to prevent major ice dams.  Here are two examples of driveways showing a contour versus a steeper slope necessitating a trench drain (also see the main photo of this blog).

Lastly, most expensive but sometimes the most appropriate, are permeable pavements.  In order of the photos are; porous asphalt, porous concrete, permeable pavers, permeable stonework (not generally recommended for driveways but great for patios).

Keep in mind the entire surface doesn't need to be permeable.  Setting a design goal, such as a 2" rain event capture, helps to determine how much of your driveway surface needs to be permeable (that means less cost, less maintenance and less of a carbon footprint with material export/import). I hope this helps in considering what approach may work best for you and feel free to give us a call or email if you'd like us to visit and provide some options for you. Thanks for rethinking your driveway.

 
Filed Under: Paving | Permalink
 

Concrete, Blacktop or What?

Posted April 1, 2014 @ 7:33am | by Earth Wizards

Concrete, Blacktop or What?

How do I choose a driveway surface?

 This is a great question and requires additional information before deciding on the product or products that are right for you and your situation. There are a number of factors to consider when choosing a driveway surface, so lets go through them.

1) Cost

Obviously cost is a big consideration in your decision. Don’t make the mistake of going with the lowest price simply because it is the lowest price. There is usually a reason for the lesser price. Just like anything, “you get what you pay for”. At the same time, the most expensive may not mean better quality either. Do your research and find out who is a quality contractor and get multiple quotes.

2) Existing soil type

This is probably the single most important and often overlooked item in the decision making process. What soil type is in the driveway area? Sand, loam and clay are common soils in the upper Midwest and react differently during the freeze/thaw cycles. Sand is very forgiving, provides good drainage and doesn’t require extra excavation. Clay retains moisture and can move greatly as it expands and contracts during freeze/thaw. If you are in a green/grey clay soil that is wet, you can expect to pay more to have additional excavation, additional base material and possibly stabilization fabric installed. It is critical to have a stable base course for the driveway surface to have a long lasting driveway. This may not be an issue in other parts of the country.

3) Appearance

This is your preference. There are more choices than ever and it’s really exciting! Asphalt, concrete, trap rock, gravel, runners, flag stone or even grass (grass is planted inside a turf stone or plastic which supports the vehicle weight and doesn’t flatten out). How about a combination of two or more of those?

4) Usage

In other words, will there be heavy loads or frequent vehicles using the driveway on a regular basis? This is often not considered in choosing the driveway surface.
 

 
Filed Under: Paving | Permalink
 
 
 

I have already recommended you! Our consultant, Shelly, was extremely knowledgeable. She explained (the process) in technical detail. She is the reason I chose Earth Wizards over the other 5 bidders. Installation crew was terrific and exceeded my expectations.

- Don P.
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