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    Construction Site

    Stormwater runoff from construction sites is a major contributor to urban runoff pollution. Pollutants from construction sites include sediment trackout, concrete washouts, vehicle fluids, paints, solvents, sealants, trash, fertilizer, pesticides, and sediment.   Pollutant-laden stormwater runoff from construction sites may adversely impact the desert environment and clog drainage systems resulting in downstream flooding. 

    The purpose of the Construction General Permit (CGP) Notice of Intent (NOI), issued by the Arizona Department of Environmental Quality (ADEQ), is to reduce stormwater pollution originating from construction sites.  A CGP NOI must be obtained for the following construction sites:

    • Sites larger than one acre or
    • Sites that will disturb less than one acre and are part of a common plan of development that will disturb one or more acres. 

     
    Pima County assists construction operators in maintaining compliance with both the CGP and local ordinances, as required by the Clean Water Act and Pima County’s Municipal Separate Storm Sewer System Permit.  These activities include reviewing design plans to verify they meet stormwater regulations and inspecting construction sites to ensure control measures are installed and maintained effectively.

     

    Plan and Develop Control Measures for Construction Site Activities

    Each control measure has a specific function to maintain stormwater quality: reducing erosion, reducing runoff, controlling sediment and preventing the discharge of pollutants.  Thorough employee training is necessary to ensure that control measures are installed and maintained properly.  Carefully schedule construction activities and the installation of control measures to limit soil disturbance and the potential for stormwater pollution.  The ADOT Erosion and Pollution Control Manual,  CALTRANS Construction Site BMP Manual, and AASHTO Construction Stormwater Field Guide provide guidance on the uses, limitations, design considerations and, maintenance needs of control measures.

    Erosion control measures

    These control measures act to stabilize the soil preventing it from moving across and off your site.

    • Preserving existing vegetationVegetation PreservationHydroseeding
    • Mini benches
    • Mulch cover
    • Seeding
    • Geotextile
    • Soil binders
    • Crown Ditch        

    Runoff control measures

    These control measures act to slow water down as it moves across and off your site.

    • Earth dikes    Inlet erosion protectionsOutlet erosion control protection
    • Cut to fill slope transitions 
    • Rock outlet protection
    • Erosion protection at structures
    • Slope drains
    • Check dams

    Sediment control measures

    These control measures reduce the movement of sediment around and off your site.

    • Sediment control bermPerimeter Control WattleTrack out pad
    • Sediment basin
    • Sediment wattle/log
    • Storm drain protection
    • Curb inlet protection
    • Stabilized site entrance
    • Compost sock
    • Rock and sediment berms

     

    Good housekeeping control measures

    These control measures prevent the contamination of and by construction materials

    • Vehicle cleaning without the use of soap, solvents, or steam
    • On site vehicle fueling in a designated area with clean up supplies readily available
    • When maintaining vehicles follow spill prevention practices
    • Street sweeping
    • Store materials in covered areas off the ground
    • Provide secondary containment for liquids that are 1.5 times the volume of all containers within it
    • Strictly follow the Port-a-johnSecondary Containmentrecommended usage instructions
    • Protect stockpiles from run-on and run-off
    • Stake down portable toilets on level surfaces away from drainage ways
    • Close dumpster lids at end of day and during rain events

    Obtain a CGP NOI from ADEQ

    To obtain a CGP NOI, apply by registering for a free myDEQ Account and then apply for a CCP NOI.  A Stormwater Pollution Prevention Plan (SWPPP) that meets the requirements of the CGP must be developed to receive a Certificate of Authorization.

    While completing the application ADEQ's 2013 CGP or EPA's website for construction general permits may be useful references.  The EPA also provides a guide for developing a site specific SWPPPPimaMaps may be used to prepare the general map and site map (PimaMaps Quick Start Guide).  Application fees range from $250 to $500.

    If your construction site disturbs less than 5 acres and has a rainfall erosivity factor less than 5, the site may be eligible for an Erosivity Waiver. EPA Rainfall Erosivity Factor Calculator determines if the site could be eligible. The waiver fee is $750.  The Erosivity waiver is time sensitive; if the project continues beyond the dates specified in the waiver certification, the operator must obtain CGP coverage. 

     

    Manage Your Construction Site for Clean Stormwater

    Keep a current SWPPP on-site whenever construction or support activities are actively underway.  The SWPPP should identify the stormwater team, construction schedule, summary of potential pollutants, control measures to prevent discharges, records of inspections, maintenance actions, and corrective actions. 

    Stormwater management is an adaptive process and the SWPPP is a living document.  Revise the SWPPP and site map as necessary during the permit coverage to reflect current site condition.  Update the SWPPP within 7 days whenever there is a change in design, construction, operation, or maintenance at your site; or a change to the stormwater team. 

    Perform routine inspections to ensure the SWPPP is being implemented correctly and effectively.  Additional inspections prior to storm events are advantageous to managing stormwater runoff and associated pollutants.  Conduct inspections using the ADEQ CGP Inspection Form, the Pima County Inspection Form, or an alternative form that documents all the information required by the CGP.  During the inspection you should:Construciton Site
    • Ensure all structural control measures are installed according to the specifications in the SWPPP and are functioning as intended.
    • Assess the effectiveness of good housekeeping practices and pollution prevention procedures
    • Observe conditions across the site for evidence of erosion and discharge of pollutants.
    If a deficiency is observed during the inspection, evaluate the cause of the problem and potential solutions.  Implement corrective measures within seven days and update the SWPPP as necessary to reflect current conditions.

    The AASHTO Maintenance Stormwater Field Guide provides a quick reference for inspection, control measure maintenance and common operational practices.

    Local Ordinances

    In addition to the CGP, construction sites within Pima County must also adhere to both Pima County Code (PCC) and the Arizona Revised Statutes (ARS).    Ensure that your construction site is meeting the following ordinances:
    • Rubbish, trash, weeds, filth, debris, and dilapidated buildings have been removed (PCC § 7.33.020)
    • An environmental nuisance, if present, has been abated (PCC § 7.45.020)
    • Construction in a drainage way or floodplain allows stormwater conveyance (PCC § 10.44.030.N)
    • Grading and alteration within a regulatory floodplain or sheet flood zone minimizes the loss of soil through erosion or stormwater flow (PCC § 16.42.030.A)
    • The construction site does not cause excessive amounts of dust (PCC § 17.16.050)
    • Drainage control systems prevent or reduce erosion (PCC § 18.81.040.H)
    • Right-of-way is maintained during grading in a neat and clean manner (PCC § 18.81.040.L)
    • Off-site activity, if any, is conducted  in accordance with a temporary use permit (PCC § 18.93.040)
    • Used oil is not disposed on land or applied as dust suppressant (ARS 49-801, 803, 811, 812)

    Terminate CGP Coverage

    To terminate CGP coverage, submit a Notice of Termination (NOT) using myDEQ. Before terminating CGP coverage one of several conditions must be met: 

    Final Site Stabilization Options

    1. All soil disturbing activities at the site have been completed; and all construction debris and temporary control measures have been removed; and either a. and/or b. is met:
      1. Vegetative cover on all unpaved areas has a density of 70% of the preconstruction native background vegetation cover
      2. Equivalent permanent stabilization measures (such as the use of riprap, gabions, gravel, or geotextiles) have been employed
    2. For individual lots in residential construction; temporary stabilization has been completed on a lot and the homeowner has been informed of the need for final stabilization.
    3. For construction on agricultural land, the disturbed areas have been returned to preconstruction agricultural use.

    Site Stabilization Alternatives Options

    1. Sites with additional retention capacity must meet the following conditions:
      1. Sites have a retention capacity that meets or exceeds the 100 year/ 2 hour storm event
      2. The nearest receiving water is ephemeral and not within 2.5 miles of a perennial or intermittent water body.
      3. All stormwater generated by disturbed areas of the site, is directed to one or more retention basins
      4. The operator complies with good housekeeping measures
      5. The operator maintains the capacity of the retention basins
      6. The operator determines temporary and final stabilization requirements for the site to reduce or minimize the discharge of sediment and other pollutants
    2. Sites returned to pre-construction discharge conditions must meet the following conditions:
      1. The operator must demonstrate that stormwater discharge from the site’s pre- and post- construction activities is equal or less than in volume and pollutant load from disturbed areas, as calculated by an Arizona registered professional engineer, geologist or landscape architect
      2. Site is not located within 2.5 miles of an impaired or Outstanding Arizona Water.

    Other Conditions for Terminating CGP Coverage

    1. Another permitted operator assuming control over the site.
    2. Coverage under another AZPDES permit.
    3. Construction activity under the original NOI was never initiated and plans have been abandoned.