Wednesday, June 1, 2011

The 3 R's of Sustainable Site Design

I think just about everyone knows the 3 R's - "Reduce, Reuse, Recycle".  My 6 yr old has been known to recite it on occasion, and to his credit he understands at least the basics of it.  Recycling certainly gets the most air time and for the most part I think everyone associates the 3 R's with trash.  Reducing often requires some sacrifice which most of us don't like and in our expendable society reuse is more often than not ignored.  Recycling our trash is admirable and we should all do our best to do this very simple green task.  But I believe that the 3 R's have merit beyond just our consumables.  As a civil engineer and site designer I started thinking about how Reduce, Reuse, Recycle could be applied to what I do the most - site design.  Here is what I came up with - the 3 R's of Sustainable Site Design.

Reduce is probably the most impactful of the 3 R's - after all it is listed first.  The more we can reduce (consumption, development, etc) the less we will need to reuse and recycle.  This applies to development and construction projects as well.  If we first reduce, then we spend less time, money and energy trying to reuse, recycle, control etc.  In the early phases of our site designs we, as design professionals need to be thinking about how we can reduce:

  • Impervious area - Almost always when we develop a previous undeveloped site (more on that below) we increase the impervious surface area.  By replacing pervious areas (grass, forest, brush etc) with impervious area (asphalt, concrete, roofs etc) we increase stormwater runoff, reduce groundwater recharge, increase surface temperatures and create a host of other problems.  If we first focus on REDUCING impervious area we can reduce the amount of work it takes to counteract these effects.
  • Disturbance - Land disturbance damages the soil ecosystems, destroys vegetation, alters stormwater patterns and pollutes runoff.  Some of these affects can be remedied or counteracted, but if we first REDUCE the area disturbed we can reduce the impact as well. 
  • Runoff - Both of the items listed above contribute to increased stormwater runoff, so the first line of defense it to reduce impervious area and land disturbance.  But you can only reduce those so much and still develop and build, but you can still focus additional attention on reducing runoff.  Many stormwater ordinances and practitioners still focus solely on flow rate reduction and not volume reduction.  To reduce the impact on groundwater resources, erosion and the hydrologic cycle we need to also REDUCE runoff volumes to at or below pre-development levels. 
If we are to assume that reduce has the most impact judging by its place in the 3 R's then we can also assume that reuse has the second greatest opportunity for impact - which I believe is true.  In many ways reuse and recycle are interchangeable, but here we are going to consider that reuse does not require re-manufacturing, processing etc.  Can we apply this to site design?  I think so and here's how we can - reuse:
  • Development sites - REUSING previously developed sites is one of the best ways to limit the environmental degradation caused by the development process.  In addition to preserving a green field site that would be used for your project you are also able to take advantage of existing infrastructure and hopefully limit the impact associated with transportation to a more remote site.
  • Natural features - The natural features of a site; topography, water features, vegetation, etc have been refined over time in a way that is difficult or impossible to replicate.  Rather than working against these natural features we should concentrate on REUSING them for the benefit of the site.  This could include improving and reusing an existing wetland for stormwater management or using existing tree canopy to shade buildings and hardscapes. 
  • Artificial features - As with natural features its often possible and beneficial to REUSE any existing artificial features on the site.  If there is an existing farm pond, road or parking lot on site, try to REUSE those features rather than demolishing them and starting over.  Doing this eliminates demolition waste and saves on raw materials and labor associated with rebuilding them.
Last and maybe least (depending on your viewpoint!) of the 3 R's is recycle.  Recycling is certainly important, it can reduce raw material consumption, energy use and landfill space among other benefits.  It's also one of the easiest and most visible green things that you can do.  There are a lot of things you can do as a designer that the general public won't understand or appreciate but people can relate to recycling and that can propel more people to act sustainably.  So beyond our trash, what can we as site designers recycle?
  • Stormwater - Traditional/conventional civil engineering wisdom was/is to get stormwater off site as quickly and efficiently as possible.  But why not RECYCLE it?  Stormwater can be captured and RECYCLED for gray water in buildings, irrigation, fire protection or habitat creation and restoration.  
  • Materials - There are a myriad of opportunities for RECYCLED materials use in site development.  Recycled asphalt pavement, fly ash replacement in concrete and recycled rubber and plastic appurtenances are just a few of the products that can be specified and used in the site development process. By doing this we are encouraging recycling of materials and reducing raw material extraction and energy.
  • Waste - Almost all site development projects require some sort of demolition or clearing.  Rather than hauling off this waste we should consider the opportunities for RECYCLING that waste on site.  For example, demolished concrete can be used as aggregate base for paved surfaces, cleared trees can be chipped/mulched on site and used for erosion control or landscaping and demolished asphalt can be RECYCLED into new asphalt surfaces.
I am sure that are points that I missed here so please send your ideas my way if you have any thing to add.  Ultimately, I think that the 3 R's are a good example that going green and creating more sustainable spaces doesn't have to be complicated.  In engineering school the most important thing that they teach you is how to break down a problem into simple parts - and that's what the Reduce, Reuse, Recycle mantra helps us do.  And if you're not a civil engineer or site design professional hopefully you can use the 3 R's to make your life and work more sustainable.

Friday, May 27, 2011

Sustainable Site Planning Basics

One of the most important and effective ways to create sustainable designs is taking a collaborative approach.  Ideally all of the project stakeholders (owner, architect, engineers, contractors, etc) are brought together before design begins and the design process can be a completely collaborative process where all parties are able to provide valuable input based on their expertise. The reality, however, is that this rarely happens, especially on smaller scale projects. In my experience the typical process involves the owner hiring an architect who later hires the engineers and finally the contractor is brought on board late in design or after the design is completed. Often the architect creates preliminary designs for the project including site layout, building location and orientation, elevations, floor plans etc. Sometimes this occurs with little or no input from the engineers. When the engineer comes on board the opportunity for collaboration and changes to the design is diminished. However, I realize there a lot of reasons that the process can evolve this way and I understand that it will continue to work that way on many projects.

After years of trying to shoehorn LID and green practices into site layouts created by architects I decided that providing some framework for creating sustainable site designs was the best approach to take. In doing that I created a presentation that I take on the road to architects. This post is that presentation in distilled form. The intent of both the presentation and this post is to provide architects and other design professionals with a toolbox for sustainable site planning and therefore facilitate better site designs. Below I have included 7 brief topics on sustainable site design.

What is a sustainable site plan?
My definition - "A site plan that has the least environmental impact while still meeting the client's project goals." It's not sustainable if it only parks half the cars that the project needs and costs twice as much as budgeted. Just like any other design it has to be framed within the typical project parameters, but it also includes consideration of the environmental impacts.

Site Selection
Site selection can have a significant impact on the environmental impact of a project site. Some specific paramters to consider when selecting a site include:
  • Avoid flood plains - continued development in natural flood plain areas has contributed to increased flooding, decreased flooding and increased soil loss.
  • Provide buffers for bodies of water - Development around bodies of water such as streams and wetlands should be limited and include buffers of undisturbed areas of 50'-100' or more.
  • Avoid greenfields - greyfields and brownfields are often less expensive to develop, place less stress on infrastructure and limit the environmental impact of developing previously undeveloped sites.
  • Transportation - the impact that transportation of people and goods to a site has can be significant. Try to select sites that encourage the use of public and non-motorized transportation.
Site/Building Layout
The simple act of proper building orientation can create energy savings of up to 25%. As little as 8 degrees of rotation can have an impact. Consider the following when siting and orienting buildings.

  • Elongate the plan on the east/west axis
  • Maximize north and south exposure for daylighting
  • Minimize east and west facing windows
  • Orient most populated areas to the north and south
The above items are good general guidelines but keep in mind that extreme climates may warrant different practices. For instance in extremely cold climates limiting windows on the north side may create energy savings that outweigh the benefits of the daylighting that they provide.

Impervious Surfaces
Increasing the imperviousness of a site can have a tremendous effect on the water cycle. Impervious surfaces limit groundwater recharge, increase pollutant loads and runoff and create a heat island effect.    Its important to limit the impervious areas on site to the minimum. Doing this often improves the aesthetic of the site, reduces the environmental impact and saves money.  Below are some things to consider in order to reduce site imperviousness.
  • Minimize parking areas
    • Zoning code minimum or less
    • Incorporate compact car spaces when possible
    • Reduce lane sizes
  • Provide plantings in and around parking areas
  • Implement Green Roofs
  • Implement pervious paving options
    • Pervious pavement/asphalt
    • Pervious concrete
    • Permeable pavers
    • Grasspave systems
Grading Considerations
The environmental impacts of mass grading a development or building site is often overlooked.  Site grading destroys the natural ecosystem present within the soil.  This ecosystem provides systems to break down pollutants, provide nutrients for biota, support insect and animal life and numerous other benefits.  It takes many years for the soil to recover from mass grading and sometimes it never does.  There is also the temporary or permanent impact of soil erosion which pollutes waterways and washes valuable soil off site.  Whenever possible we should try to limit grading operations to the distances beyond constructed items as shown below.

  • < 10 feet beyond surface walkways, patios, surface parking, and utilities
  • < 40 feet beyond the building perimeter
  • < 15 feet beyond primary roadway curbs
  • < 25 feet beyond constructed areas with permeable surfaces (pervious paving, stormwater  detention, and playing fields)
Stormwater Management
Stormwater runoff is one of the most significant environmental impacts of a developed site. But it also provides one of the greatest opportunities for sustainable design.  All of the items listed above help to limit the amount and speed of stormwater leaving the property and also contribute to improving the water quality as well.   However, developing a site can significantly alter the hydrologic cycle for the property and surrounding area.  Steps can and should be taken to maintain the pre-development hydrology or even to improve it.  Many municipal regulations require that the post-development runoff rate does not exceed the pre-development rate, but do not address runoff quantity.  These regulations are largely flood control based and do not address groundwater recharge and the hydrologic cycle.  The Low Impact Development techniques shown below can be used to mimic the pre-development hydrology.
  • Raingardens/Bioretention
    • 6"-12" deep
    • 8%-10% of site area
    • <1/2 acre drainage area
    • up to 2 acres possible
    • landscape islands
    • 4'-10'+ between parking rows
    • 8'-10' for double loaded rows
  • Wetlands
    • 6"-12" deep
    • large drainage areas (often > 25 acres)
    • minimum 6”-18” permanent pool depth
    • excellent water quality control
    • provides wildlife habitat
  • Grass swales/infiltration trenches
    • up to 5 acres drainage areas
    • 1%-4% slopes
    • low maintenance
    • improves stormwater quality
  • Green roofs
    • well suited for urban and ultra urban areas
    • intensive and extensive types
    • < 20% roof slope
    • improves stormwater quality
    • intercepts and stores rainfall (up to 50%)
    Landscape Design
    Landscape design is often ignored in the initial planning stages and is tacked on at the end of the project.  This is unfortunate and discounts the many benefits that proper landscape design can have beyond aesthetics.  On the other hand, improper landscape design can have significant negative effects such as excessive potable water use and erosion.  Listed below are a number of items to consider during the site planning phase and throughout the design process.

    • Limit potable water use
      • Use Native Species
      • Place landscape areas to receive runoff
      • Use captured rainwater
    • Shade large hardscapes
    • Shade buildings in summer, allow sunlight in during winter 
    • Place and design landscape areas to filter and clean stormwater
    • Raingardens in parking areas
    • Bioretention rather than retention ponds
    Below are some excellent resources for additional and supporting information about sustainable sites.

    1. The Sustainable Sites Initiative
    2. The United States Green Building Council
    3. Portland Sustainable Stormwater Management Program
    4. US EPA 
        1. Stormwater management
        2. LID Techniques
    5. The Center for Watershed Protection
    6. Prince Georges County Maryland - Division of Environmental Protection
    Slides from my Sustainable Site Planning Basics Presentation

    All of the techniques listed above are just items to consider when performing site planning.  As you can see the items impact the architect, civil engineer, MEP engineers, contractor and owners.  Ultimately, the best way to produce sustainable site plans is to get the entire design and construction team together early and often in the development process.  

    Wednesday, May 11, 2011

    Go Green - Without Compromise?!

    Do you always have to compromise something to Go Green?  I think this is a critical question that determines how we frame the discussion surrounding sustainability.  More often than not, the perception is that we have to give up this or that for the sake of the planet or "Going Green".  Contrary to that, my opinion is that you CAN go green without compromise.

    Don't get me wrong, often it's appropriate and necessary to compromise for the greater health of the planet.  But more often than not, the green decision involves less compromise than the alternative; but we must understand that there are different types of compromise. We tend to be a culture of immediacy - what effects me and my immediate space, time, family etc. right now. Going green without compromise requires that we view and discuss the bigger picture.  We must get beyond the first cost, right now thinking and consider the long term costs and impacts of what we are doing.  It's also important to focus on what is important and relevant to you, your client, your business etc.  Its always best to do as much as you can, but start by focusing on what makes sense and provides a real benefit rather than a compromise.  Here are some examples.

    • I am working with a hospitality management group on a hotel seeking LEED certification.  This group develops and manages its properties. One of their most significant ongoing costs is energy and water. In working toward their LEED certification and sustainability goals we chose to focus first on energy and water efficiency because it reduces their costs and risk.  We also pursued other green building goals, but we always focused on what made sense for the hotel guests, staff and owners.  By doing that they are able to benefit without compromising by going green.
    • The Chesapeake Bay Foundation is a group whose mission is to protect and preserve the Chesapeake Bay Watershed.  They do this primarily through research, education and advocacy.  In 2001 the foundation constructed a new headquarters facility that received LEED Platinum Certification.  The foundation uses the facility to demonstrate its commitment and to educate the public.  Rather than simply building a structure to house their offices the Chesapeake Bay Foundation created an effective tool for the work that they do.  No compromise - just green!  If they had built a less green building they would have compromised this opportunity.    
    • The Coca-Cola Company uses tremendous amounts of water when manufacturing and bottling their beverages around the world.  Many of their operations are in parts of the world where access to clean water is a problem for locals.  Recognizing this inequity and the impact that they were having on the environment, Coca-Cola initiated a water stewardship campaign to reduce their water use and return clean water to the environment.  Coca-Cola also has other sustainability initiatives that are important and effective, but water use is one of the most important areas that is relevant to their business and provides benefit to their bottom line and the communities that they work in.
    In order for going green to be truly sustainable we must focus on the benefits rather than the compromises.  Doing business without regard for the long term environmental and social impacts of our work is not sustainable.  Nor is ignoring the impact on the bottom line in the name of the environment.  We must find this balance by encouraging people and businesses to do what they can, educating them about the long term costs and effects of not going green and by pointing out the win-win rather than the compromises.

    Monday, April 18, 2011

    Civil Engineering Tip - Go Play in the Rain!

    My latest bit of unsolicited advice for civil engineers and other land development professionals is simple - Go Play in the Rain. Or if you feel you have gotten too old (never!) to play in the rain, at least get out and watch it.  The typical human tendency is to stay inside when it rains, and going out to check on the site of your proposed, ongoing or completed construction project is probably one of the last things that you want to do, but it can be a tremendous learning experience.

    With current technology including more precise surveys, aerial photography, GPS, GIS, you name it, it has become increasingly easier to design projects without spending any real time on the site.  And more often than not when the project is done, the only time we go to visit the site is if there's a problem.  I confess that I used to fall into this trap as well.  But lately whenever we get a significant rainfall (0.5"-1" or more-which seems to be happening with greater frequency - but that's for another blog post) I try to make an effort to check out some of my projects and other areas that have stormwater challenges.  My wife finds this behavior quite amusing, but it has provided me some insight on stormwater design and basic hydrology that I couldn't get from the digital information that I have.  Here are some of the rather simple but powerful insights that I have gained from standing in the rain looking like an idiot:
    • Lawns and other areas that we often consider pervious aren't - It's common practice to assign lower curve numbers or runoff coefficients to lawn and/or grassed areas, which is a reasonable assumption to make.  However, I think that more often than not these areas create more runoff than we give them credit for.  One only has to stand in the rain in a residential subdivision watching the runoff from lawns to realize that while these areas are certainly not as impervious as pavement or roofs, they certainly produce significant runoff.
    • Topographical surveys miss a lot - Topographical surveys are an essential part of the design and planning process and are a great tool for determining runoff patterns, but they can't replace some time on the site, especially in the rain.  A few minutes in the rain will usually reveal small nuances in the topography and runoff patterns that even a good topographical survey will miss.  And those nuances can have a major impact on the stormwater performance of your site.
    • Better pay attention to your erosion controls - In my experience erosion controls are usually compliance based and not performance based.  That is to say that they are designed and installed to the minimum standard required by law and to keep from being fined.  Unfortunately, the result of this is often under performing erosion controls and a quick visit to the site during a heavy rain will reveal this.     
    • Detention ponds rarely (never?) mimic pre-development hydrology - Have you ever watched the discharge from a detention pond during and after a rainfall event?  It almost never resembles the pre-development hydrology.  Most detention ponds are designed to meet municipal standards for discharge, which usually focus on flood control and do nothing else to match pre-development hydrology.  Never is this more clear than when you watch the discharge from a pond during and after a storm.
    These are all simple points that can be easily overlooked from the comfort of your desk.  And while I think most engineers inherently know these things, I believe that it's worth while to get out in the rain and see it for yourself first hand.  So go ahead, be an idiot like me and go play in the rain!

      Monday, February 28, 2011

      The Truth about LEED

      You may have already heard, but there's a lawsuit pending against the USGBC. The plaintiffs claim that they are losing customers because USGBC's false advertisements mislead the consumer into believing that obtaining LEED certification incorporates construction techniques that achieve energy-efficiency.”  If you're looking for an article that jumps on that train, you're in the wrong place.  I think this lawsuit is seriously misguided, and draws attention away from all of the positive consequences of the USGBC's work. 

      The truth is that LEED is flawed and imperfect, but I don't think that the USGBC ever claimed it was perfect or the end all of green buildings.  What the USGBC did/does say is that they want LEED to encourage market transformation, which I think they have already achieved.  I have been involved with the USGBC and LEED on several levels and here is what I know and believe about LEED.  
      1. It has created AWARENESS - I don't think that there is any doubt that LEED and the USGBC have brought widespread awareness to green buildings.  Does a building have to be LEED certified to be green - of course not.  Nor does certification guarantee that a building is more green than another which is not, but it does carry weight.  They may call it LEEDS, but in general LEED has brought more visibility to the green building market than anything else I can think of.  And that's a positive thing - the more we can get people talking and thinking about green buildings and sustainability, the better off we are.
      2. It has generated INVOLVEMENT - The USGBC and LEED have brought individuals and groups to the green building table that would not have participated in the absence of LEED.  Whether they like it or not most design and construction professionals have recognized that LEED is here to stay and as a result have jumped on board.  They might not be enthusiastic about green buildings at first, but  becoming involved usually allows them to see the value and sense in green building.
      3. It has provided a framework for EDUCATION - The USGBC in and of itself has done a tremendous job of educating the building and design industry about sustainable design and green buildings.  But even beyond that, the LEED rating system provides a great framework for others to use in educating.  I believe strongly in education as advocacy, and I have found that we can use LEED as a tool to educate others about what can be done to make our built environment more sustainable and green.
      4. It encourages INTEGRATED DESIGN - I think that most professionals would agree that an integrated approach to design and construction is best.  However, that doesn't mean that it's standard practice.  In my experience the goal of LEED certification forces the project team to come together earlier and more often than in projects that aren't seeking certification.  When project team members collaborate early and often it almost always results in a better project than when each of the team members operates independently.
      5. It generates BETTER BUILDINGS  - Hopefully, I won't be next on the list of lawsuits for saying this, but I believe that LEED has generated better buildings.  Design teams and owners seeking LEED certification have been accused of "point chasing" and I can attest that it does happen.  However, what I've often found is that there are good practices that are implemented for the sake of LEED that would not otherwise been done, which can result in better buildings.  On projects that I am involved with I try to encourage the team to pursue points and practices that have some value beyond LEED, but in some cases points are pursued only to achieve certification.  And although that bothers me a little, what I have come to realize is, if it makes for a better building then the motivation for doing it doesn't make it a bad thing.
      The USGBC and LEED are always changing and improving and I think that each iteration of the LEED system brings improvements with it.  However, it will always be imperfect and we need to be careful to not let perfect be the enemy of good.  I believe that the USGBC has transformed the market for the better and while there is always room for improvement, the TRUTH is that the building industry is better because of it.

        Wednesday, January 19, 2011

        Am I a green hypocrite?

        Am I a green hypocrite? I might be... This is something that I struggle with quite regularly.  I consider my self an environmentally responsible individual and sustainability is a core tenant of the business that I founded.  With just about every decision that I make, or at least the major ones, I try to consider the environmental consequences of that decision and action.  However, I'd be lying if I said that I always made the environmental choice.  Most of the time there is probably a good reason for that, but sometimes its really just a matter of preference.  Does that make me a green hypocrite?  I hope not, but I will leave that for someone else to decide.  Here are some of my green and not so green decisions - am I a green hypocrite?

        1. Morning coffee - This is a basic decision that most of us make every day.  Its a small thing but it can have environmental implications nonetheless.  I rarely get coffee to go in disposal cups which are very resource and waste intensive so this decision is - green!  But at my office I have a one cup at a time coffee maker that I use, which may save water but also has more packaging and waste - not green.
        2. Cars - Neither my wife or I drive a hybrid or an electric.  But our lifestyle doesn't require us to drive a great deal and we don't drive gas guzzlers. My guess is that we have a smaller transportation carbon footprint than most Americans, but probably more than most Europeans.  not green.
        3. House - I live in a spec house that was built in 2004, so it isn't the most energy efficient home around.  I have replaced all of my incandescent bulbs with CFLs - I think that I have tried every brand and variation of CFL available! I have also installed low flow fixtures in the bathrooms and kitchen, painted with zero voc paint and use green cleaners, but it is still far from what I would consider a green house.  We plan to build in the future, at which point I intend it to be very green, but we aren't there yet - not green.
        4. Business - Sustainability is a core tenant of my business model.  I try to operate my business both internally and externally as sustainably as I can.  I have a green procurement policy - I purchase 100% recycled office products whenever they are available, I limit my printing, I buy energy star electronics etc.  I also try to design as sustainably as I can within the projects constraints and goals. As a civil engineer some of my projects contribute to the environmental damage resulting from development, but I do my best to reduce that impact.  All in all I think that I can reasonably call my business - Green!
        5. Personal habits - This is one area that we have the most control over in terms of sustainability, and the little things that you do (or don't do) can have an impact.  I do my best to recycle everything that I can, turn off the lights when I leave the room, buy environmentally preferable products, unplug electronics, etc. But I do have some less than green habits though - I prefer soda from a can, I eat meat with most meals and I drink a lot of sports drinks from small plastic bottles.  All in all though, I would consider my personal habits - Green!
        6. Children -  I have three children so some people would automatically say that's not sustainable because it's more than the replacement birth rate (birth rate to replace yourself), but I think that might be a little extreme.  I try to teach my children to be environmentally responsible in their actions and decisions and I am amazed how much my 6yr old already does it (my other two are younger so the jury's still out). On the other hand, they have a lot of "things" which I realize is wasteful and resource intensive.  Hopefully, they will learn to be responsible stewards of our planet, but only time will tell - draw.
        So by my analysis my house and cars are not green, my coffee and kids are a draw and my business and personal habits are green.  Does that make me a green hypocrite - I would love to hear your comments with opinions about whether you and/or I are green hypocrites! I may or may not agree with you, but after agonizing over this for some time here is what I have come to find.  You can't do everything! That may sound like a self justification or a cop out, but I believe it.  I think that we do sustainability and the environment a disservice when we discount the little things that people do because some of the other things they do aren't green.  We should be encouraging people to do what they can and not discourage them because they're not green enough.  Many people each doing a little can be much more effective than a few doing a lot.  Personally I plan to keep on trying to do more so that I can start calling all of the above GREEN!

        Tuesday, January 4, 2011

        The Most Overlooked Green Site Practice

        As design engineers I believe that our tendency is to focus on post construction stormwater controls and best management practices. This is natural and to some degree warranted- after all we are usually hired to design a finished product and how it gets constructed is often left to the contractor. Couple that with the fact that the insurance companies and attorneys are always advising design professionals that "we are not responsible, in any way, for the means, methods, sequence, procedures, techniques, scheduling of construction" and it is understandable that the focus is on post construction stormwater management. However, because of that I think Erosion Prevention and Sediment Controls (EPSC) during construction are often overlooked as a green site design and planning technique. Give your erosion prevention and sediment controls a little love!

        It might not be sexy but EPSCs or lack thereof can have a tremendous environmental impact. According to the EPA a typical, unmanaged construction site can lose approximately 35-45 tons or soil per acre in one year. By comparison, forest or farm land will lose 1 ton or less per acre over the same time period. Left unmanaged that soil can travel downstream and clog natural and man-made waterways, affect water supplies, damage aquatic life, and otherwise adversely impact adjacent property owners and waterways. In addition, bare soil can increase runoff velocities resulting in further erosion on site and downstream, increase runoff volumes causing flooding and reducing groundwater recharge and increase water temperatures negatively impacting aquatic species. Beyond that, if you ever want to upset the neighbor of one of your construction sites try dumping some dirty water or sediment on their property - it will definitely get their attention!

        If you are applying LID (Low Impact Development) techniques to your site, it becomes even more critical to pay attention to the erosion and sediment controls. I have experienced this on some of the first LID projects that I designed and I saw otherwise good LID designs perform poorly because the contractor did not properly install and maintain erosion controls. With traditional stormwater controls much of the flow is directed to catch basins and pipes where it is easy to manage sediment and control flows. However, when the post construction design relies on vegetative practices such as swales and raingardens it is critical to prevent erosion rather than just control sediment. And it is equally important to make sure that infiltration practices don't become clogged and compacted during construction which can negatively impact their post construction performance. Many times these items are overlooked because LID techniques are new to the design and construction team.

        So what can you do? Of course it is very site specific and you may have little or no control over construction phase activities, but there are some very basic tenants that you can apply that will do wonders for your erosion and sediment controls during construction.
        1. Disturb as little area as possible - the most basic thing that you can do to reduce soil erosion and sediment loss is to limit the amount of area that you disturb. You can do this by getting involved early in the planning process and working with the architect or planner to locate the building and infrastructure and being mindful of the natural slopes and general topography.
        2. Phase your grading operations - the common practice on most sites, especially smaller ones, is for the excavator to come in at the begging of the project, strip all of the topsoil in disturbed areas and grade the whole site to sub-grade. Much or all of the site is then left disturbed for the life of the construction project. By phasing the grading operations you can limit the amount of time the land is disturbed and therefore limit the amount of time that it can erode.
        3. Reduce slope gradients and lengths - steep and long slopes erode exponentially more than shorter flatter slopes. Try to keep slopes to 4:1 or less and less than 40' long. If slopes are steeper and/or longer they should be terraced, furrowed, serrated or stepped.
        4. Establish vegetation on disturbed areas - the best way to limit erosion and control sediment is to get vegetation established. A good stand of grass will beat silt fence any day. Here is a case where the color green really means something - a brown construction site will not perform as well as a green one! Unfortunately, the vegetation is often put off until the completion of the project rather than using it during construction to control erosion.
        5. Maintenance, maintenance, maintenance - don't wait for erosion controls to fail or for the local of state authorities to come calling before cleaning and maintaining erosion controls. Its always easier to maintain than it is to fix it once it gets out of hand.
        The five techniques above are really just a sampling of what can be done to help prevent erosion and sediment loss, but I think that the key points are to be mindful of it in the design phase, stay on top of it and establish vegetation early. Traditionally the focus has been more on sediment control, yet it should be on erosion prevention. Doing that will limit environmental impact and improve the post construction performance of stormwater controls.