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We ride at dawn!  Well, if there’s multiple sites to get to before the sun sets at any rate.  

But before we get on the road, let’s look at why we’re headed out in the first place.  The short answer?  Because the National Pollutant Discharge Elimination System (NPDES) permit program and/or the individual State General Permit for the Discharge of Stormwater (for either Industrial or Construction activities) dictate that we must.

The NPDES permit program, created in 1972 by the Clean Water Act (CWA), helps address water pollution by regulating point sources that discharge pollutants to waters of the United States. Under the CWA, EPA authorizes the NPDES permit program to state, tribal, and territorial governments, enabling them to perform many of the permitting, administrative, and enforcement aspects of the NPDES program. Currently 47 states and one territory are authorized to implement the NPDES program.

This post largely covers stormwater inspections under the Construction General Permit(s) (CGP), although the inspection requirements under the Industrial General Permit(s) are similar.  However, an industrial site will have more constituents of concern with the potential to impact the stormwater system onsite and/or downstream, depending on the industrial activities being undertaken on a given site location, and as such have additional monitoring requirements that are not included in the CGP. 

With the CGP, the primary pollutant we’re concerned with is sediment.  Without proper erosion and sediment controls in place, a heavy rainstorm can cause significant issues both on the construction site and in downstream sites and water courses.  An Erosion and Sediment Control (ESC) Plan will have been created as a part of the Stormwater Pollution Prevention Plan (SWPPP) prepared for every site that is covered by the NPDES or State CGP, which lays out the controls necessary for the site to prevent pollutants from being discharged from the site.  That’s where the stormwater inspector comes in.    

Under the NPDES or State CGP, regular stormwater inspections are required, generally on a weekly basis.  Some states, such as New York, require bi-weekly inspections for sites with greater than 5 acres of exposed soils; and others, such as CT and PA, require additional rain event inspections after each storm creating a discharge. 

Ok, so now we’ve made it to a site that is under construction.  Our first responsibility is to confirm that the proposed ESCs and best management practices (BMPs) specified in the SWPPP have been installed, and installed correctly.  Typical ESCs/BMPs required onsite include, but are not limited to the following:

• Perimeter controls – silt fence, hay bales, mulch berms, wattles/coir logs
• Construction Entrance tracking pad(s)
• Inlet protection of catch basins – silt sacks, filter fabric, wattles
• Check dams or temporary swales
• Temporary sediment traps
• Waste management areas (i.e. concrete washout pits)

During a regular weekly inspection, we look at the condition of the existing controls, and note where maintenance is required or if a control has failed.  As the stormwater inspector, we don’t control or direct the construction on the site, but we help to identify where issues have arisen, or may arise, hopefully before a discharge occurs and/or it becomes an issue with the Town, State, or EPA.  Silt fence and wattle gets run over, or wind damaged, and of course can fail under the stress of stormwater flow.  If, and when, a given BMP fails, we identify what and where the failure has occurred, and if necessary, make recommendations for changes or additional BMPs that can be installed to prevent a future failure.  For example, installing a double row of silt fence at the downgradient perimeter of the site; or additional wattle or hay bale rows along the contours of a steep slope. 

The goal is to keep the sediment on the site, to prevent pollutants from entering any streams and ponds downstream. Typically, the first controls installed on a site will be the perimeter (silt fence/hay bales/berms/etc) and temporary sediment traps, which are engineered based on the topography of a site and the downstream features.  Controlling the surface flow on and offsite is imperative to controlling the sediment discharge.  Sediment traps are engineered to collect onsite stormwater and allow for sediment to settle out before the water is discharged from the site.  Most sediment traps are completed as permanent stormwater basins. 

As construction continues and paved roads or parking areas are installed, silt sacks in catch basin/storm drains and regular sweeping keeps the sediment out of the pipes and stormwater basins.  Ultimately the best sediment control is to cover the exposed soils with vegetation.  Obviously not area can be seeded constantly, but inactive areas that are scheduled for a later phase of construction should at minimum have a temporary cover, whether that be vegetation or a hay cover with tackifier for those areas that are likely to become active in a shorter time period.  Temporary cover of exposed inactive areas is especially important in the winter months where the ground surface freezes and rain and/or snow melt cannot infiltrate. 

Aside from sediment, there are other pollutants we look out for during a weekly inspection.  A big offender is concrete rinseate.  A designated concrete washout area is required for collecting all rinsteate when the concrete trucks are done pouring a foundation or sidewalk, etc.   It seems incongruous that pouring a sidewalk is ok, but rinsing the chutes out onto the ground is not.  However, that liquid rinseate is very caustic and can infiltrate and leach into the soil and groundwater if not managed appropriately. 

Construction means heavy equipment; and heavy equipment needs fuel.  Generally, there are above ground fuel tanks located onsite that are visually inspected for evidence of spills or leaks.  If an oil spill or staining is identified, the construction manager/client is notified immediately to clean the area up, as additional spill reporting may be required. 

The last thing we do before leaving a given site is check in with the onsite construction manager and let them know our findings, which will be subsequently written up and distributed electronically.  The written reports are generally required within 24hrs, however, if there’s a big storm coming, that 24hrs may be too late for the crews to complete any repairs necessary to prevent an unwanted discharge!  Communication is key! 

At this point we also leave the previous week’s inspection form and updated construction map in the appropriate binder onsite and note if any updates are needed to contact information, etc, within the SWPPP itself or in the posted signage onsite. 

And then we’re off to the next site to do it all over again!

Author:  Jane Smith
Professional Engineer