Reissued General Permit (PASPGP-4) Affects Linear Projects in Pennsylvania

Posted on July 19, 2011 by Paul A. Kanouff

On July 1, 2011 the U.S. Army Corps of Engineers (Corps) issued the Pennsylvania Special Programmatic General Permit-4 (PASPGP-4) which replaces the expired PASPGP-3.  The PASPGP is a federal Clean Water Act, Section 404 permit which can be authorized by the Pennsylvania Department of Environmental Protection (DEP) and county conservation districts for minor activities in wetlands, streams, rivers, and other waters without additional review by the Corps.  For the most part, the PASPGP-4 is a continuation of the PASPGP-3 but there are some key changes that will impact linear projects.  Although the changes were mainly aimed at the rapidly growing natural gas industry in Pennsylvania, they will affect all linear projects ranging from sewer and water pipelines to electrical, cable, and telephone lines.  The changes affecting linear projects are summarized in this posting.

One aspect of the PASPGP-4 which was the focus of a lot of debate was the definition of Single and Complete Projects.  The definition of a single and complete linear project still refers to each crossing of a separate water body.  However, the PASPGP-4 makes a distinction between the overall project and a single and complete project.  The overall project includes all regulated activities that are reasonably related and necessary to accomplish the project purpose.  Applicants must supply the locations for the start and end points along with the proposed crossings and the total cumulative impacts needed to accomplish the overall project.  Therefore, although a linear project may contain more than one single and complete project, the total cumulative impacts needed to accomplish the overall project must be disclosed.  The cumulative impacts (meaning the sum total of all of the crossings) for the overall project will then be used to determine the category of activity.  Therefore, if the cumulative impact for the overall project is greater than 1 acre of jurisdictional waters or 250 linear feet of streams, then the overall project will be a Category III activity and will be reviewed by the Corps.  However, the cumulative impacts are only used to determine the category level of the activity.  They are not used to determine whether the project is eligible for authorization under the PASPGP-4.  The project will still be eligible under a PASPGP-4 as long as the impacts for each single crossing are less than 1 acre of jurisdictional waters or 250 linear feet of streams.  Therefore, this process has not changed.

The PASPGP-4 includes clarification on the calculation of linear footage of stream impact.  The linear footage of stream impact is now to be measured from the top of bank to the top of the opposite bank and from the upstream to downstream limits of work.  The linear footage of stream impact will be the greater of these two measurements.  Therefore, the right-of-way (ROW) will typically be used to determine the linear footage of stream impacts for pipeline projects.

Through the PASPGP-4, the Corps has established two triggers which can automatically push a project into a Category III review.  The first trigger involves threatened and endangered species.  If the PNDI for a project identifies a conflict with a federally listed species or includes avoidance measures from the U.S. Fish and Wildlife Service (USFWS), the project will be considered a Category III activity and must be reviewed by the Corps.  The second trigger involves interstate projects.  Projects which will be located in Pennsylvania and another state will also be considered a Category III activity and must be reviewed by the Corps.

There was one major change to the PASPGP-4 that was included in the draft version of the general permit that was not included in the final version.  The Corps was expected to lower activities authorized as Waiver 2 (25 PA Code § 105.12(a)(2) Waiver 2) from a Category III activity to a Category 1 activity.  Waiver 2 is for water obstructions in a stream or floodway with a drainage area of 100 acres or less.  This waiver applies only to the DEP and not to the Corps.  Since these activities are still Category III, they must be reviewed by the Corps to obtain federal authorization for the project.

Lastly, projects which were authorized by the PASPGP-3 have been reauthorized by the PASPGP-4 provided the permit for the project had not expired by June 30, 2011.  For most projects, the new expiration date for the reauthorized PASPGP-3 will be tied to any applicable PADEP Chapter 105 applications such as a General Permit or Joint Permit.

If you have any questions regarding the requirements of the PASPGP-4 or any other aspects of the permitting requirements for linear projects in Pennsylvania, please contact Paul Kanouff at pkanouff@cecinc.com or 800-899-3610.

Filed under: Civil/Site, Ecological Services, Environmental, Water Resources | Tagged: , , , | Leave a Comment »

Avoiding Failures and Performance Issues with Mechanically Stabilized Earth (MSE) Walls and Slopes

Posted on August 10, 2010 by Douglas M. Clark, P.E.

Over the past 20 years, the use of mechanically stabilized earth (MSE) walls and slopes has become very common in a large number of construction applications in the U.S. and around the world.  The technology used to build these structures is really quite simple:  reinforcing, typically metal or synthetic grids or sheets, are layered in with compacted soils, adding shear strength and allowing the soils to stand at progressively steeper angles.  Wall faces are typically constructed using concrete panels, split-face masonry blocks, or even vegetation that primarily provides erosion control and aesthetics. The faces provide little if any structural support to the retained soils.

The relatively low cost of MSE structures have made them quite prevalent in transportation and site development projects, and have also led to their use for waste management and environmental remediation projects.  MSE walls can often be constructed for less than half the cost of comparable concrete or steel structures.  This cost advantage increases as the height of the structure increases. This reduced cost has enabled the development of increasingly marginal projects, and pushed the limits of the technology, literally, to new “heights”.  For example, several recent airport expansion projects in the U.S. have utilized MSE wall and slopes well in excess of 100 feet tall.

However, this lower cost and increased use of the technology has come at a price.  While there are no specific published numbers available, the failure rate of these structures has been estimated by some to be as high as 5% to 7%, with 2% likely being a low-end estimate.  “Failure” in this case encompasses not only large-scale collapse or movement, but also settlement and performance issues.  In any case, the number of MSE walls and slopes exhibiting problems is alarmingly high for an engineered structure, and the cost to repair these problems can be many times the original construction cost.

So why do these failures occur?  Over the past 10 years, CEC has been involved with the specification, design, construction monitoring, and failure investigation of a number of MSE walls and slopes.  Published evaluations on MSE wall failures are also quite numerous.  Many studies have shown that, particularly in the private site development sector, engineering site layout, surface and subsurface drainage features, geotechnical engineering evaluations, and construction monitoring are often inadequate.  CEC’s experience investigating failures has identified a number of construction errors that have led to performance issues.  One re-occurring construction factor leading to failure is inadequate backfill compaction when clayey soils are used in the wall construction.

The published studies and our experience also indicate that the contracting methods used for both design and construction of MSE walls and slopes may be contributing to the high failure rate.  Most MSE walls are designed and constructed using a design-build contract where the contractor provides the detailed wall design and constructs the wall.  This process results in highly competitive “cut-throat” bidding among vendors, encourages overly optimistic design assumptions, and often hampers communication and review by the design team.  This process often places numerous risks unknowingly back on the owner.

How can you protect yourself and reduce the risk of failure for MSE walls and slopes on your project?  First, hire civil and geotechnical engineers with experience in the investigation, design, and specification of these structures and ensure that their services are carried through into construction.  If a design-build process is used, a detailed wall layout and performance specification must be prepared listing all wall design, testing, and construction requirements.  Full-time, on-site construction monitoring should be provided by either the wall designer or geotechnical engineer to ensure that the proper testing and site inspections are done. The contractor should not provide the construction monitoring services.   Finally, hire a contractor with experience and certification in MSE construction.

If you have any questions about the use, specification, design, or construction of MSE wall and slopes and how they may impact an upcoming project, contact Douglas Clark, P.E. (dclark@cecinc.com) or Jeffrey Woodcock, P.E. (jwoodcock@cecinc.com) at 800-365-2324.

Filed under: Civil/Site | Tagged: , | Leave a Comment »

Navigating Muddy Waters – New Effluent Limitation Guidelines Will Impact 21,000 Construction Sites Annually

Posted on January 19, 2010 by Beth Chesson, CPESC, CPSWQ

On November 23, 2009, EPA released the final Construction & Development Effluent Limit Guidelines (C&D ELG).  The final C&D ELG will impact all construction sites disturbing more than one acre by imposing non-numeric effluent limitations.  More importantly, the C&D ELG will impose numeric effluent limits for the first time on all construction disturbing more than 10 acres within approximately 4 years.  Most construction sites will need to use Passive Treatment Systems (PTS) to achieve those limits rather than the typical erosion and sediment control measures currently in use.  EPA estimates as many as 21,000 construction sites annually would need to meet those numeric limit standards.

 In the past, sediment control practices have generally been designed based upon a rule of thumb.  Many states rely on 1800 ft3/acre of drainage (or disturbed acre), which doesn’t take into consideration the discharge quality.  In fact, a sediment control measure can have an 80% settling efficiency and still produce a turbid (muddy) discharge.  With this in mind, EPA has been struggling since early 2000 to establish a C&D ELG, with prodding from environmental groups. 

 In November 2008, EPA published a draft C&D ELG that set the ELG (turbidity) at 13 Nephelometric Turbidity Units (NTUs) for sites that disturbed 30 acres or more, were located in areas of the country with high rainfall intensity, and located on soils that had at least 10% clay.  That incredibly low turbidity limit (13 NTUs) severely limited the stormwater treatment options to Active Treatment Systems (ATS) that, simply put, look and function like small waste water treatment plants.  EPA requested public comment on the draft rule and requested additional data on the cost benefit analysis, treatment feasibility, and other components.  Concerns mounted as those affected began questioning the draft rule, particularly the feasibility of achieving the 13 NTU discharge standard. 

 EPA published the final C&D ELG in November 2009 with major revisions based on the comments received.  EPA chose to greatly simplify the rule and increase the numeric standard.  Below is a summary of the final rule: 

  • All construction projects must install best practicable control technologies.
  • Sediment basins and other impoundments must be dewatered from the surface.
  • The ELG has been set at 280 NTUs.  This limit is a daily maximum average, based upon sampling for storms up to the 2 yr, 24 hr storm.  Discharges from storm events greater than the 2 yr, 24 hr are not required to meet the ELG.
  • Discharges from construction sites must meet an effluent limitation guideline as follows:
    • Within 18 months of the effective date of the rule (August 2011), sites disturbing 20 acres or more must meet the ELG.
    • Within 4 years of the effective date of the rule, sites disturbing 10 acres or more must meet the ELG.
    • For both scenarios above, the size limitations apply to “larger common plans of development” like subdivisions with multiple small lots.

 Each state will need to marry the final C&D ELG with their existing monitoring plans, which will be a huge task.  Additionally, EPA has noted that as each state’s construction stormwater permit comes up for renewal, these requirements must be inserted.  EPA is the permitting authority in four states.  Their general permit is due to expire in June 2011 and will be reissued with the ELG requirements in it at that time.  Interestingly, North Carolina’s permit was in the midst of renewal when the ELG rule was finalized, and EPA only allowed their permit to be renewed for 18 months (through August 2011).  After that date, the reissued permit must include the ELG requirements.

 As indicated earlier in this blog, PTS will generally be required to meet the numeric standard of 280 NTUs.  A PTS incorporates a flocculant with a standard construction site practice.  An example of a PTS is a jute-lined ditch that has been impregnated with polyacrylamide (PAM).   Design components that must be considered include mixing zones and settling zones.  At this point, we don’t have design tools that dictate the amount flocculant to be used on a site.  Flocculants and soils must be matched (not every flocculant works on every soil), and the applications tweaked in the field for peak performance.  Then the flocculant must be reapplied after rain events.

You can expect to have the ELG requirements inserted into the permit language if your state’s permit expires before August 2011.  If, however, your permit was reissued before the rule was finalized and without the ELG language in it, EPA could administratively open the permit to have the language inserted into it.  I suspect that between June 2011 (when EPA’s Construction General Stormwater permit expires) and August 2011 (the deadline to begin implementing the ELG) some permits may be administratively opened.  That option is certainly possible.

 If you have any questions about the C&D ELG, how it may impact an upcoming project, and how you can meet the numeric standard, contact Beth Chesson, CPESC, CPSWQ at bchesson@cecinc.com or 615-333-7797.

Filed under: Civil/Site, Waste Management, Water Resources | Tagged: , , | Leave a Comment »

Follow

Get every new post delivered to your Inbox.