Photo Caption: Site Map of planned construction for a municipality

The purpose of construction site runoff control is to reduce pollutants in stormwater runoff from construction activities. The Phase II Final Rule requires the operator of a regulated municipality to "have procedures for site plan review of construction plans that consider potential water quality impacts." The procedures for site plan review generally include identifying key staff to conduct the reviews, developing a system to track plans, developing procedures for consistent plan review, and training staff.

The site plan required by Phase II must address erosion and sediment controls as well as controls for "other waste" at the site. EPA and States generally require construction site operators to develop a stormwater pollution prevention plan, or SWPPP, for their stormwater discharges. A SWPPP is broader in scope than an erosion and sediment control plan or site plan.

Phase II municipalities must develop and implement a construction site runoff control program to address stormwater runoff from construction activities that result in a land disturbance of one acre or greater. Construction activities that disturb an acre or more may pose a significant threat to local waterways based on the large amount of exposed soil. Therefore, implementing proper best management practices (BMPs) can greatly reduce the impacts to receiving waterbodies including streams, rivers, and oceans.

A key aspect of this construction site runoff control program is the review of site plans to ensure they include adequate BMPs to protect water quality. Related activities include a municipal construction inspection program, contractor training, and local ordinances for construction site runoff control.

Stormwater site plans must be reviewed by municipal staff to ensure they address local requirements and protect water quality. Facilitation of a successful program to review stormwater site plans will provide the municipality with the ability to ensure that water quality objectives, erosion and sediment control requirements, and BMP maintenance are adequately considered. Procedures for review of stormwater site plans should include:

• Identifying responsible plan review staff
• Developing a system to track plans
• Developing tools and procedures for consistent plan review
• Training MS4 staff to adequately implement these procedures.

The General Permit for construction activity issued by the state or EPA requires that construction sites disturbing greater than or equal to one acre have a site-specific Stormwater Pollution Prevention Plan (SWPPP) for their stormwater discharges. Municipalities are required to review site plans, which are generally a part of the SWPPP. Some municipalities have chosen to review the entire SWPPP. In any case, municipal plan review staff should be familiar with the components of the SWPPP.

Municipalities are encouraged to identify projects requiring coverage under their state's Construction General Stormwater Permit. One particularly effective way of addressing General Permit coverage is by using a construction project tracking system and requiring the construction site operator to submit proof of Notice of Intent (NOI) submittal to the state or EPA before approving a project. At a minimum, the municipalities should make sure that project applicants are aware of the need to apply for General Permit coverage for projects disturbing greater than one acre.

Developing stormwater site plan review procedures will typically include the following four topics:

Identifying responsible plan review staff
Some municipalities address stormwater site plan review through an existing grading permit application process. The municipality should clearly identify staff responsible for stormwater site plan review and should ensure that there is periodic feedback between the plan review staff and inspection staff to make sure that what is approved on the plans is actually installed and working in the field.

Developing a system to track plans
Most municipalities already have a system in place to track plans that have been submitted for review. This system should also include specifics on the stormwater site plan, such as the size of the site, whether it has a state- or EPA-issued NPDES construction permit, and the review status of the stormwater site plan. The system ideally also should track information on inspection and enforcement actions related to that site and identify the construction site operator.

Developing tools and procedures for consistent plan review
Municipalities should develop tools such as checklists to ensure that staff reviews are consistent and thorough. These checklists should address the ten elements described below, in addition to the common issues and problems found by inspectors at sites.

Training municipal staff
Plan review staff should received training on the local stormwater requirements; EPA/state construction general permit requirements; and stormwater BMP selection, installation, and maintenance. Training is offered from many sources, including the International Erosion Control Association .

Plan review staff should check site plans to ensure they address common, critical elements. The following ten elements of an effective stormwater site plan (adapted from Brown and Caraco, 1997) present a comprehensive approach to addressing construction site runoff. These elements include:

1. Minimize Clearing and Grading

Construction site operators should take all measures possible to avoid clearing/grading stream buffers; forest conservation areas; wetlands, springs and seeps; highly erodible soils; steep slopes; environmental features; and stormwater infiltration areas. In addition, site fingerprinting should be employed and limits of disturbance (LOD) should be mapped, clearly delineated on site with flags and conveyed to personnel.

2. Protect Waterways

Construction site operators should identify waterbodies on site and adjacent to the site. If construction activities occur near a waterbody, clearing/grading activities should be minimal and silt fencing and/or and earthen dikes should be installed.

3. Phase Construction to Limit Soil Exposure

Prior to construction initiation, activities should be broken into phases. Grading activities should be limited to the phase immediately under construction to decrease the time that soil is exposed, which, in turn, decreases the potential for erosion. Additional phases should begin only when the last phase is near completion and preferably exposed soil has been stabilized. Construction scheduling should facilitate installation of erosion and sediment control measures prior to construction start, detail time limits for soil stabilization after grading occurs, and schedule BMP maintenance.

4. Immediately Stabilize Exposed Soils

Exposed soils should be stabilized within two weeks of the onset of exposure. The long-term goal is to establish permanent vegetation after each phase of construction; however, mulch, hydroseeding, or other means of soil coverage may protect exposed soil while facilitating vegetation growth. The stormwater site plan should detail appropriate plant species to be seeded, as well as weather and climactic conditions necessary for germination and successful vegetation establishment.

5. Protect Steep Slopes and Cuts

Cutting and grading of steep slopes (>15 percent) should be avoided wherever possible. If a steep slope exists, all water flowing onto the slope should be redirected with diversions or a slope drain. Silt fence at top and toe of the slope must be anchored well, although this measure may not provide adequate protection by itself. On steep slopes, jute netting and erosion control blankets (geotextiles) should be used in conjunction with seeding or mulching, as seeding alone may not be effective.

6. Install Perimeter Controls to Filter Sediments

Silt fence should be properly installed around the perimeter of the construction site. A fiber roll on the inside (site-facing) of the silt fence works to provide additional filtration. In areas of heavy flows or breech concern, a properly sized earthen dike with a stabilized outlet should be created. In addition, catch basin inlets receiving stormwater flows from the construction site must be protected with adequate inlet controls.

7. Employ Advanced Sediment Settling Controls

Sediment Basins should be created where space is available; however, discharge from basins must be non-turbid. The use of skimmers and multiple cell construction of basins assist in sediment drop-out.

8. Certify and Train Contractors on Stormwater Site Plan Implementation

Contractors and/or construction staff should be trained in erosion and sediment control practices and procedures to effectively install and manage erosion and sediment control features. Meetings and site inspections by municipal staff provide opportunities for discussion of effective BMPs with site staff. Inspectors should make a strong commitment to contractor education to develop a constructive and responsive relationship.

9. Control Waste at the Construction Site

The site plan should describe the type of construction site waste found at the site (such as discarded building materials, concrete truck washout, chemicals, litter, and sanitary waste) and how that waste will be controlled to minimize adverse impacts to water quality. For example, concrete washout and trash storage areas should be clearly labeled on the plan and should be located away from waterbodies and catch basin inlets.

10. Inspect and Maintain BMPs

Each stormwater site plan should clearly describe the construction site operator's BMP inspection and maintenance, including who will inspect the site and how often. Ideally, an example inspection form should be included with the plan. Inspections should occur at a regular interval and should also occur immediately before and after rain events. The plan should also describe how BMPs will be maintained.

Brown and Caraco, 1997, Muddy Water In, Muddy Water Out? From: Watershed Protection Techniques. 2(3): 393-403.