January 13

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A Contractor’s Guide to Proper Stormwater Drainage

Stormwater runoff is the leading cause of water pollution. As stormwater travels across the ground it picks up everything in its path: garbage, chemicals, vehicle fluids. If you can name it and it’s found on the ground, it’s contributed to water pollution on some level.

As concern for runoff water pollution grows new regulations evolve to help keep it in check. As a contractor, it’s your responsibility to ensure the systems you build, meet these expectations.

Stormwater dain

Are your stormwater drainage systems up to the challenge?

If you have doubts, this is the article for you. Read on to learn how you can help save Mother Earth.

What is an MS4? 

MS4 is a creative acronym standing for Municipal Separate Storm Sewer System. It’s a plumbing network designed to collect stormwater runoff. MS4s consist of ditches, underground pipes, retention basins, and roadside inlets.  

The acronym uses the word “separate” because MS4s are independent of traditional sewer systems. Keeping the two systems apart helps keep runoff clean so it can get released back into the ecosystem.

Rural locations aren’t required to be a part of the MS4 program, but urban areas are growing. As urbanization and awareness of water pollution spread, so to will the demand for MS4s. 

How Does This Effect Me? 

The Clean Water Act states you must have a special permit to empty pollutants into a body of water through a point source. It’s called a National Pollutant Discharge Elimination System (NPDES) permit. 

Most construction sites in MS4 areas need an NPDES permit because of the pollution produced during construction. It’s often the job of the site’s general contractor to obtain the permit. 

You usually need a permit when your activities will disturb one or more acres of land. You may also need a permit if the site drains into a local sewer system. 

This EPA guide explains how to obtain a permit

Do I Need a Stormwater Pollution Prevention Plan (SWPPP)? 

An SWPPP outlines all the ways you intend to keep your site compliant. 

In most cases, the EPA or state authorities require an SWPPP for construction sites. Even if they don’t it’s a good idea to have one. Regulators have a more favorable outlook on contractors who have an SWPPP when there is a discharge of pollutants. 

You can develop your own or hire someone to write a plan for you. 

Many prefer writing their SWPPP themselves because no one else knows their site better. Others prefer having an experienced SWPPP author write their plan because they have a better understanding of the requirements. 

How Can I Manage Stormwater Runoff? 

There are many methods you can use to control your stormwater runoff at a construction site. Procedures used to manage runoff are called Best Management Practices or BMPs. 

Compost-Based Methods

Compost helps control runoff in a variety of ways. Benefits of using compost-based methods include:

  • Ability to retain high volumes of water.
  • Retention of pollutants improving downstream water quality
  • Decomposes nutrients and hydrocarbons trapped inside the compost
  • Improvement of soil structure and nutrient content

Use Compost blankets for erosion control. Compost filter berms and filter socks are better suited for sediment control. 

Detention Ponds and Basins

You can channel runoff to detention ponds or basins instead of downstream water sources like rivers.

Detention ponds act like temporary holding tanks for stormwater runoff until it’s safe to release. Basins hold water until it can soak through the soil. In either case, you’ll need a stormwater drainage system to direct the flow of water to your pond or basin. 

In construction, there are three main types:

Extended Detention Ponds

Water stays in an extended detention pond until pollutants settle on the bottom.

Later, you can reintroduce the water back into the ecosystem at a controlled rate. Doing so reduces flooding and helps cut down on water pollution. 

Wet Ponds

Wet ponds hold runoff until the next rain when new stormwater fills the pond. It’s a more or less automated system so you have no control over when the water gets evacuated.

This means pollutants may not have enough time to settle before it’s released. 

Infiltration Basins

Infiltration basins are shallow, man-made ponds that allow runoff to permeate the soil. As the water soaks through the ground, pollutants get filtered out. The water then makes its way to underground water sources where it rejoins the ecosystem.

Do not use infiltration basins in areas with:

  • A lot of groundwater near the surface of the permeation area
  • Compressed soil
  • Excessive amounts of sediment in the stormwater
  • Clay soil

Infiltration basins in these locations may result in flooding because the water can’t absorb fast enough. 

What About Residential Drainage Systems?

Residential drainage system graphic

 

You don’t usually need permits for residential drainage systems. This is because residential environments have far less potential for pollution.  

Still, it’s important to ensure runoff can make it to an outlet that reduces water pollution before it reaches a downstream water source. The water also needs a place to go so that it doesn’t damage structures or landscaping. 

Outlets for residential draining systems include: 

  • Culverts
  • Retaining ponds
  • Curbsides
  • Ditches
  • Permeable ground

No matter the outlet, you’ll need to use piping to convey excess water where it needs to go.

Using PVC Pipe for Stormwater Drainage 

Pipe made of PVC is cheap and easy to work with. This makes it ideal for both construction zone and residential drainage systems.

In both cases, it’s best to install the pipes underground. Doing so keeps the pipes out of the way and helps to keep it out of sight.

Follow these steps to install a PVC pipe for your drainage system. 

1. Mark the drainage path where the pipes will lay. 

Use construction marker spray to mark the path for your drainage system. In a residential system, the path starts from a downspout and leads to the outlet. Starting points in a construction zone vary depending on the project but also end at the outlet. 

2. Dig a trench for the pipes. 

Use a trencher set to your desired depth to dig a trench. For residential systems, 16 inches is ideal. Start at the outlet where the drainage system will end and follow the markings to the start. 

3. Smooth out the bottom of the trench. 

Remove any rocks and roots along the bottom of the trench. A smooth trench bottom will help you avoid damage to the pipes during installation and after. 

4. Dig a shallow hole at the outlet end of the trench. 

The hole should remain the same depth as the trench itself, but you need to widen it to just over twice the width. For a 16 inch trench, the hole needs to be about 36 inches in diameter. 

5. Attach a downspout adapter if necessary. 

A downspout adapter is necessary for residential use. At construction sites, you may or may not need one depending on your drainage system. The important thing is that the water has a way to enter the system and make it’s way to the outlet. 

6. Cut the pipes to length. 

Based on your marked path, cut the PVC pipes to length. The last length of pipe needs to extend about six inches into the hole you dug at the end of the trench. 

Especially when working with pipes underground and in other tight spaces an inside pipe cutter is your best friend.

Pipe cutters with guides help you make true cuts with quick efficiency. Flush cuts give you more space to work with when you apply PVC cement and help prevent leaks down the road.

These tools are versatile.

They make it possible to cut piping below floor level or in a ceiling. They’re excellent for use around swimming pools and they make replacing closet flanges easy. You can even use them to cut through pipes encased in concrete or soil.

It’s also safer to use than other cutting methods because it stays inside the pipe during and after each cut. 

Just remember that not all interior pipe cutters are not created equal. This review will guide you in choosing the best cutter for your business

7. Connect the pipes. 

Join the pipes with PVC cement as normal. Don’t forget to hold the pipes in place for 15 seconds after application to ensure a firm hold. 

8. Fill in the hole. 

Use gravel to fill in the hole and cover the end of the pipe. Spread the gravel evenly with a shovel. The gravel will help filter out contaminants before runoff reaches the outlet. 

8. Fill in the trench. 

Use dirt to fill in the rest of the trench. Don’t forget to pack down the earth surrounding the pipe to keep it in place.

Need a Tool That’s a Cut Above the Rest? 

As a contractor, you need professional quality tools that won’t let you down. That’s why Tigerfish Tools designed the EzyGrind Inside Pipe Cutter.

The EzyGrind tool is the fastest cutter on the market and comes in two sizes:

The diamond blade can stand up to concrete and makes easy work of cutting through PVC, HDPE and ABS pipes. Both sizes come with a guide wheel for accuracy and safety.

Whether you’re working with stormwater drainage or interior plumbing, this is the right tool for you.

Please contact us anytime, if you have questions about what we offer!


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Stormwater Drainage


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