TALK ON WATER | APRIL 2017

THE 6 THINGS YOU NEED TO KNOW ABOUT GRAVEL BAGS 

1. ) Poly Bags, Monofilament Bags…Burlap?

Poly Bags, MonofilamentBags…Burlap, what isthe difference? PolyBags are the mostcommonly available.Typically, Poly Bagsare 14”x 26” empty,and come with variousUV coatings, the best being 2000 hours,(whatever that means).

Monofilament Bags are heavy duty bags whichhave a life expectancy of up to two years, butcost double the price of Poly Bags. They are greatfor long term perimeter protection.

Burlap Bags (old school) tend to belarger in size than Poly Bags, butdegrade fairly quickly.

2.) What’s in your bag? 

What’s in your bag? Gravel Bags, Sand Bags, most of you have heard that sand bags are out and gravelbags are in…but it depends on your application. Sand Bags are effective for keeping water in or out,effectively building a dam. Gravel Bags, on the other hand, are passive BMPs designed to release water at aslower rate and allow sediment to settle out. Controversially 3/4” rock bags do neither and work in a similarway to straw bales, which look substantial, but do little to slow flows effectively.

TALK ON WATER | APRIL 2017

A key consideration is the quality of the material in your bags…

What you don’t want is the Tea Bag effect from your BMPs!

Adding more pollutants because of low grade bag content is not our objective.

3.) How much should a bag weigh? 

How much should a bag weigh? A standard 14”x 26” Poly Bag should weigh approximately 32 lbs. Muchmore than 32 lbs and the bag cannot lay properly and do its job, think stuffed sausage.

7” 

All Gravel bags are not created equal!

TALK ON WATER | APRIL 2017

4.) How high is a typical bag berm? 

A bag laid properly is approximately 3.5” inches high. A bag berm two bags high would then form a 7” tallbag berm.

5.) When should I use bags versus an alternate BMP? 

When should I use bags versus an alternate BMP? There are several good reasons to use a bag berm asopposed to other BMPs. Whenever you need mass, bags are an ideal BMP. When you need to protect ahardscape perimeter, bags are a good option. When you need height, silt fence is a better option. Bags arelabor intensive and costly to install, although affording maximum flexibility.

6.) How many bags should I order? 

How many bags should I order? Poly Bags are slightly less than 1’ in length when laid properly. The key tosuccessfully ordering just the right number of bags is simple.(The length x the number of courses ) + 10% will ensure that you order the right number of bags,e.g. 1000’ perimeter, two bags high, plus 10%. 1000 x 2 = 2000 + 10% = 2200 bags Total.

Note: There are no tails visible when bags are installed properly.