7.40 WATER POLLUTION CONTROL (SOIL EROSION)
While this section addresses soil erosion on all projects, Construction Manual 10.30 addresses the additional requirements of a storm water discharge permit. Coverage under the Iowa Department of Natural Resources permit is required for all construction activities which disturb more than 1 acre. The Construction & Materials Bureau obtains coverage for projects where the Iowa DOT is the Contracting Authority.
The primary objective is to control soil erosion and sedimentation caused by soil erosion during construction with reasonable and economical construction practices.
While the contract documents indicate locations of sediment control devices (silt fence, ditch checks, and silt basins), their actual location should be verified in the field by the contractor and project engineer in order to fit existing conditions and the contractor’s sequencing and schedule.
The erosion and sediment control devices should not be limited to those which are included in the contract documents. The project engineer should authorize adding any device that will be most effective in controlling erosion.
The primary method for temporary erosion control is stabilizing crop seeding, fertilizing, and mulching.
Stabilizing crop seeding requires seedbed preparation as described in Specification 2601.03, B, 4, a and covering and compacting as described in Specification 2601.03, C, 3.
Where possible, the installation of silt fence or other sediment controls as perimeter control and for ditch checks should be installed prior to any soil disturbing activities occurring on the project.
7.41 CONTRACTOR REQUIREMENTS
The contractor's responsibility is to ensure that soil erosion is minimized and to prevent eroded soil from leaving the construction project onto adjacent property or entering a waterbody. Timely installation of sediment control devices, such as silt fence and ditch checks, will help to prevent this damage from occurring. The most effective erosion control practice is stabilized crop seeding which shall be done as the grading progresses. This may require the erosion control contractor to mobilize and seed more than once.
The contractor's Erosion Control Implementation Plan (ECIP) is the contractor’s schedule (sequence and timing of operations) and proposed method for accomplishing the required erosion control. For projects regulated by a NPDES storm water permit, the ECIP must be submitted to the project engineer prior to the Preconstruction Conference and be accepted before commencing work.
The contractor's ECIP should include information such as that shown in the ECIP Worksheet (Appendix 7-1). Updates to the ECIP may be included on the ECIP Worksheet or the ECIP Update Checklist (Appendix 7-2). Copies of both documents are available at https://iowadot.gov/construction_materials/Earthwork-and-erosion-control
If the temporary erosion control is to be performed by a subcontractor, the subcontractor should be involved in developing the work plan, but the plan should be submitted by the Prime contractor.
On projects regulated by a NPDES storm water permit, the contractor is required to submit an amended Pollution Prevention Plan site map. This marked-up map is required to show the erosion and sediment control work performed. The contractor is required to submit this prior to payment for corresponding work items from Specifications Sections 2601 and 2602. Additionally, it shall be submitted no later than one week after completion of such work items. This time requirement is to comply with the storm water permit. The marked-up map shall be legible and show status of onsite controls (such as control type, installation/maintenance/removal activities, date of work, etc.). They may be completed by the prime contractor or erosion control subcontractor. Depending on the project and amount of work completed over time, the marked-up map might show all work since the start of the project, or if it becomes too cluttered with removal and maintenance mark-ups, the map may have to be restarted. However, it should show the current status of controls onsite for the contract and not just the controls that were installed over the last week. Plan views from the D/E/K sheets or the R-sheets may be used as a basis for the amended site map. Examples of marked-up plan sheets are provided in Appendix 7-3. For DOT projects, amended site maps should be uploaded to DocExpress in the Pay Items drawer (Amended PPP site map document type). For local agency projects, amended site maps should be uploaded to DocExpress in the Environmental drawer.
The prime contractor is required to designate a Water Pollution Control Manager (WPCM) for projects that are regulated by a NPDES storm water permit. Specifications Section 2602 provides a list of the WPCM’s responsibilities. One of the responsibilities is that the WPCM visit the project on a frequent basis and in no instance less than once per week during construction activities. The WPCM must be an Erosion Control Technician (ECT) or be current with Erosion & Sediment Control (ESC) Basics training. Information on the training and certification program is provided in Construction Manual 7.43.
Damage due to siltation on private property shall be corrected by the contractor with no expense to the contracting authority.
7.42 MOBILIZATION FOR EROSION CONTROL
Mobilization for Erosion Control is applied to projects according to Standard Specifications 2602.03, L. For additional clarification, a flowchart showing when Mobilization for Erosion Control applies to a project is provided in Appendix 7-4. Payment for mobilization would apply to any contract items from Standard Specification Sections 2601 or 2602 (excluding mowing, debris pick-up, monitoring well, or removal items). Payment for Mobilization for Erosion Control also does not apply to watering since Section 2601 already provides for payment for Mobilization for Watering.
When erosion control items are incidental, there is no payment for erosion control mobilizations.
Correcting deficient work, fixing damage caused by carelessness or adding work that should have or could have been installed during an earlier mobilization wouldn’t warrant payment for mobilization.
If a contractor will have separate mobilizations for different crews performing different items of work, this should be indicated in the ECIP or the ECIP updates.
The specifications provide a deduction if the contractor does not mobilize within 72 hours of written order or if the work is not completed within 7 calendar days of written order. There is another deduct referenced in Article 2602.03, E when the contractor does not initiate stabilization measures as required by the NPDES storm water permit. These two different deducts should not be applied for the same days for the same work area and items.
Mobilizations for emergency erosion control should be ordered when there is a serious and urgent nature which is beyond normal maintenance of controls.
To determine if a situation warrants an emergency versus regular mobilization, review the location and the weather forecast. For example, the Engineer should order an emergency erosion control mobilization if a site has experienced a major rain event that has shown installed controls at a box culvert outlet are not adequate or have failed and there is another rain event in the immediate forecast.
7.43 EROSION AND SEDIMENT CONTROL TRAINING AND CERTIFICATION PROGRAM
On projects where there is a National Pollutant Discharge Elimination System (NPDES) storm water permit, the Contractor is required to have an Erosion Control Technician (ECT) and an Erosion & Sediment Control (ESC) Basics trained individual. Projects that require NPDES storm water permit will have a Pollution Prevention Plan in the contract documents. The ESC Basics training requirements begin for contracts let on or after October 15, 2013, and ECT requirements begin for contracts let on or after April 15, 2014.
The contractor’s WPCM may fulfill the responsibilities of the ESC Basics trained individual or the ECT (if certified).
Additional information on the program requirements and FAQs is located at:
https://iowadot.gov/construction_materials/earthwork_erosion/ESControl_training
List of ECTs is provided at:
https://iowadot.gov/training/CertTechBook.pdf
This list is updated annually. It may also be updated periodically during the training season.
List of ESC Basics trained individuals is provided at:
https://iowadot.gov/training/ttcp/Erosion-Control-Basic.pdf
This list is updated approximately monthly.
During the course of a project, presence of ESC Basics trained individual should be documented periodically in the inspector’s IDR.