SUSMP Appendix E

Project Features and Potential Impacts to be considered during Project Planning

Features and Potential Impacts to be Considered

Reasons why they must be considered

Identify which RWQCB will have jurisdiction over the project(s). Does the RWQCB have any special requirements?

Requirements may vary by RWQCB. May impact permanent and temporary control requirements.

Identify receiving waters and all other waters that may affect, or may be affected by, the project. Consider aquifers, wells, streams, lakes, reservoirs, wetlands, and waters both fresh and saline. Consider impacts throughout the project lifecycle, including construction, maintenance, and operation.

First step in identifying impacts and potential control measure requirements.

Will construction require work in, above, or directly adjacent to the water bodies listed above?

Could require additional environmental permits/agreements and control measure requirements.

Are any of the receiving waters or watersheds a source for domestic water supplies?

Could require additional environmental permits/agreements and control measure requirements.

Are any sensitive fishery, wildlife, recreational, agricultural, or industrial aquatic resources located in the vicinity of the project?

Could require additional environmental permits/agreements and control measure
requirements.

Are any of the receiving waters impaired (303d listed)? (Discharges to impaired water bodies may be subject to strict numeric water quality standards and prescribed treatment controls.)

Supplemental controls may be required to meet further reduce pollutants, meet numeric water quality standards, waste load allocations or
requirements of an adopted watershed plan.

What is the County’s contribution, expressed as a percentage of total flow, to receiving waters that are impaired or sensitive?"

Used to determine if permanent treatment
controls are required.

What is the unit cost for additional right-of-way should it be needed for treatment controls?

Used to determine if permanent treatment
controls are required.

Will the project increase the potential for downstream erosion by adding impervious surfaces, decreasing the time of concentration, or redirecting flows?

May need to implement detention devices to
prevent damage to off-site streambanks or
channels.

Does the project discharge to lined, engineered drainage facilities or unlined, natural channels?

Consideration for implementing detention devices for streambank protection.

Identify general soil types and vegetation within the project site.

Basic information needed for slope design and slope protection plans.

How difficult will it be to re-establish vegetation following construction?

How long will it take for the new vegetation to establish?

What are the steepest slopes that should be allowed?

What vegetation, if any, should be preserved?

Determine the general climate, annual rainfall, and typical seasonal rainfall patterns for the project area.

Basic information needed for slope design and slope protection plans.

Determine the proposed project slopes, and areas of cut and fill.

Basic information needed for slope design and slope protection plans.

Does the project include contaminated or hazardous soils as identified in the initial site assessment (ISA) and environmental documents?

May impact project construction activities and
deployment of temporary controls during
construction.

Will the contractor’s yard be located within the County’s right-of-way or otherwise be arranged for or provided by the County? If so, what are the potential impacts?

May impact responsibility for, deployment of,
temporary controls during construction.

Do the local regulatory agencies have seasonal construction restrictions?

May impact project construction scheduling and deployment of temporary controls during
construction.

Options for Avoiding or Reducing Potential Impacts During Project Planning

Can the project be relocated or realigned, while upholding safe design standards, to avoid or reduce impacts to receiving waters?

Yes

No

Why

Can structures and bridges be designed or located to reduce work in live streams and minimize construction impacts?

Can the horizontal and vertical alignments be adjusted, without jeopardizing safe design standards, to minimize erosion from slopes by:

Disturbing existing slopes only when necessary?

Minimize cut and fill areas to reduce slope lengths?

Incorporating retaining walls to reduce steepness of slopes or to shorten slopes?

Acquiring right-of-way easements (such as grading easements) to reduce steepness of slopes?

Avoiding soils or formations that will be particularly difficult to re-stabilize?

Providing cut and fill slopes flat enough to allow re-vegetation and limit erosion to pre-construction rates?

Provide benches or terraces on long cut and fill slopes to reduce concentration of flows?

Rounding and shaping slopes to reduce concentrated flow?

Collecting concentrated flows in stabilized drains and channels?

Retaining natural vegetation where feasible?

Can alternative materials or facilities be utilized to reduce future maintenance impacts on water quality (i.e. use of textured concrete in lieu of painted materials)?

Can the project be scheduled or phased to minimize soil-disturbing work during the rainy season?

Can permanent BMPs (especially basins) and conveyance systems be installed early in the construction process to provide additional protection and to possibly utilize them in addressing construction stormwater impacts?