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State Water Resources Control Board Releases Draft General Construction Permit – Proposes Incorporation of Numeric Effluent Limits, Action Levels and Hydromodification Control Requirements

By: Mary Lynn K. Coffee

On March 2, 2007 the State Water Resources Control Board ("State Board") released for public review the much anticipated Preliminary Draft General Construction Permit, which is up for reissuance by the State Board this year.   The General Construction Permit applies to virtually all construction activities that result in soil disturbance of one acre or more.


Two Public workshops on the draft permit have been scheduled:  April 17, 2007 in Rancho Cucamonga and April 20, 2007 in Sacraments.  Written comments on the draft Permit are due April 27, 2007.  Further information about the date and location of the workshops, and the submittal of comments on the Draft General Construction Permit is posted on the State Board website. 


This Draft General Construction Permit ("Permit") makes a number of significant changes from the prior version of the General Construction Permit (Order 99-08-DWQ), including the incorporation of numeric effluent limits and action levels for certain pollutants, advanced or active treatment requirements or strict grading limitations for most southern California sites, and expanded monitoring and reporting requirements.


If adopted as proposed, construction activities will be more complex and expensive.  In addition, meeting the numeric limits and complying with the action levels may require advanced treatment technologies that are not widely used or available at this time.  While a number of the changes proposed in the Draft General Construction Permit are an outgrowth of the June 2006 Blue Ribbon Panel Report on the Feasibility of Incorporating Numeric Effluent Limits Into Storm Water Permits, these changes are being implemented without first addressing the precursor studies and other recommendations that the Storm Water Blue Ribbon Panel determined should be completed before proceeding with its guidance regarding numeric effluent limits, numeric action levels or Advanced or Active treatment.


Other significant changes to the permit include provisions requiring public review of Stormwater Pollution Prevention Plans (SWPPPs), prescriptive BMPs requirements, and new post-development "hydromodification control" requirements. 


The most potentially significant provisions of the Permit for the development industry include:


Ø      Numeric Effluent Limitations ("NELs") for pH apply to all sites and will become effective 18 months after Permit adoption.  Exceedances of NELs must be reported to the Storm Water Annual Reporting Module ("SWARM") and could trigger an enforcement action.  End-of-pipe NELs for pH will particularly present compliance issues for projects using construction materials like concrete that impact the pH of runoff.  The NELs will likely, depending on soil characteristics and other factors, require that neutralization methods be employed to comply with the relevant effluent limit.  These NELs raise particular concerns for redevelopment and infill projects where there is little room onsite for neutralization ponds prior to runoff entering into a storm drain.  These NELs are premature in light of Blue Ribbon Panel Report recommendations.


Ø      NELs for sites using active treatment systems are established for acute and chronic toxicity, turbidity (10 NTU which is as clear as green tea), and pH.  These NELs raise the same concerns as those noted for pH, and, in addition raise concerns related to eliminating all sediment loads and toxicity, whether natural or introduced, from discharges, regardless of background sediment levels in receiving waters. 


Ø      Action Levels ("ALs") for pH, turbidity (500 NTU) and Total Petroleum Hydrocarbons (15 mg/L) ("TPH") are established.  Exceedances of ALs must be reported to SWARM and trigger the responsibility to implement additional BMPs, conduct additional monitoring, including receiving water monitoring, and in some instances, submit additional information to the applicable Regional Board.  Since baseline levels of sediment are not taken into account in setting the ALs, turbidity action levels will be problematic for construction within the alluvial watershed systems predominant in southern and central California, which are naturally very turbid. Therefore, expect modification of grading activities and/or greater use of expensive advanced treatment BMPs to control sediment in runoff from sites during grading.  TPH action levels may require new measures such as offsite equipment maintenance and fueling, and offsite storage of hydrocarbon products.  In addition, reporting of AL exceedances, as mandated by the Permit, results in creation of an evidentiary record that enables third-party citizen suits.


Ø      Expanded monitoring and inspection requirements, including development and implementation of a Construction Site Monitoring Program ("CSMP") prior to the commencement of construction activities.  The CSMP is to be a part of the SWPPP, but it is required to contain elements that go beyond SWPPP requirements.  The CSMP is required to address compliance with NELs and ALs, including the implementation of effluent monitoring and receiving water monitoring requirements at medium and high risk construction sites.  Under the current General Construction Permit (Order 99-08-DWQ), only limited monitoring is required in specific instances, such as when the discharge at issue is directly to a waterbody that is impaired for sediment, or when there is reason to suspect that a BMP failure resulted in the discharge of invisible pollutants. 


Ø      Adoption of a three-tiered, risk-based system for permitting of discharges which categorizes discharges as low, medium or high risk based on a number of factors, including the proximity to receiving waters, area of the site to be cleared and/or graded, whether grading will take place during the wet season, the erosivity of the site and the runoff potential of construction site soils.  Discharges that are determined to be "low risk" are exempted from certain Permit requirements, including ALs and NELs and certain monitoring requirements.  However, based on the soils characteristics that trigger medium and high risk permitting requirements and controls, Flow Sciences has concluded that all sites in Southern California are likely to be medium and high risk sites.  Medium and high risk sties must meet special SWPPP requirements, comply with NELs and ALs, and must conduct greatly expanded sampling and monitoring of both discharges and receiving waters.


Ø      If exposed soils will contain more than 10% particle sizes smaller than .02 mm, the Permit requires implementation of an Advanced or Active Treatment System ("ATS"), or the implementation of a suite of specific source control requirements, including: limiting the area of active construction to 5 acres at one time, providing 100% soil cover for all acres of inactive construction year-round, and providing vegetated buffer strips at all times between the active construction area and any water bodies.  If an ATS is implemented, NELs for pH, turbidity and toxicity will apply to the discharge, as well as additional monitoring requirements.  The RWQCB must approve the ATS system, and the ATS system must have a very large capacity—it must provide treatment for 1.5 x the 10-yr, 24-hr storm event, with a 48 hour discharge period.  At the end of 48 hours, the same capacity must be available again for treatment, requiring upsizing.  According to research conducted into advanced treatment technologies, ATS technologies are not widely available for implementation at this time, but will be mandated for implementation.  These provisions do not comply with Blue Ribbon Report recommendations.


Ø      Requires development of a Rain Event Action Plan ("REAP") for all sites for each likely (30% or greater chance of precipitation) rain event.  The plan must protect all exposed portions of the site within 48 hours of the likely rain event.  The document must be tailored for each rain event, based on site conditions and expected weather conditions.


Ø      The permit identified certain prescriptive BMPs that must be implemented:

·       Soil cover for all inactive areas (inactive is defined as un-worked for 14 days)

·       all active areas must be stabilized from all erosive forces (wind and water)

·       Sediment controls are required for slopes, toe, top, face and at grade breaks according to specified formulas

·       Drain inlet protection is required year round

·       Daily street sweeping is required

·       all stockpiles must be covered and bermed


Ø      Two years from Permit adoption, SWPPP preparers must have attended a State Board sponsored or approved training course on the development of SWPPPs.  Engineers must certify that the SWPPP contains the properly chosen BMPs given planned construction, anticipated site conditions, and anticipated weather conditions.


Ø      All SWPPPs must be provided for 90-day public review period.  During that time, the RWQCB can deny coverage under the Permit, or demand changes and/or public hearings before coverage is granted.  In addition, citizens can review the SWPPPs and arguably could take action for SWPPP inadequacies that they believe exist. Monitoring results must also be included in the SWPPP, potentially creating a "ready-made" litigation record for citizen suits.


Ø      With respect to hydromodification, the Permit requires that post-development runoff volume "approximates" the pre-project runoff volume for areas covered with impervious surfaces.  In addition, depending on project size, additional requirements with respect to preservation of drainage divides and maximizing time of concentration will apply.  Notably, the accompanying Fact Sheet provides that the State Board intends to phase hydromodification control measures into its regulatory program "over time, with a yet to be determined triage process to determine which projects require them."  Fact Sheet for Water Quality Order 2007-XX-DWQ, p. 20.  The dual regulation of hydromodification in local MS4 Permits and the General Construction Permit raises concerns regarding compliance with a multiplicity of conflicting standards.  Post-construction hydromodification control is also inappropriate for inclusion in an industrial construction discharge permit, and is best addressed at the planning, not the construction phase.  The SWRCB has stated that these requirements appear in the Permit because they want to regulate developing areas that have MS4 systems currently serving less than 100,000.  These areas are not subject to MS4 Permit regulation.


Mary Lynn K. Coffee is a partner in Nossaman's Irvine office.  She has extensive experience in compliance with, and permitting and approvals for development projects under local, state and federal resource protection laws, including the federal Clean Water Act (Sections 401, 402 and 404), the California Porter-Cologne Water Quality Act and the state streambed alteration provisions of the California Fish and Game Code.  In this role, she has particular expertise in the development of construction and post-construction surface water quality compliance programs for existing and new real estate developments.  She can be reached at (949) 833-7800 or

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