In coordination with other local jurisdictions and industry, Fairfax County is adopting guidelines (PDF) which clarify Section R404, Foundation Walls, of the International Residential Code.

The new guidelines (PDF), effective September 1, 2006, address restraint requirements before placement of fill, curing times for plain concrete, brick ledge parameters and submission requirements for other foundation wall designs.

If you have any questions concerning the guidelines (PDF), please contact Paul Lynch, Director of the Residential Inspections Division at 703-324-1780, TTY 711.

Issue: Application of Section 118-2-1(a) of the Chesapeake Bay Preservation Ordinance (CBPO) for storm sewer or conveyance channel outfall improvements within a RPA with respect to the submittal and Director approval process of a WQIA.

Background: Outfall structures of storm sewer systems and stream bank stabilization measures, among other facilities, are included in the CBPO as “water-dependent development”, which is ‘the development of land or a facility that cannot exist outside of a RPA and must be located within a RPA, either in whole or in part, by reason of the intrinsic nature of its operation’ [CBPO 118-1-6(ff)]. When these structures are proposed to be located within a RPA, approval of a WQIA by the Director is required [CBPO 118-2-1(a) and 118-3-3(a)]. The purpose of the WQIA is to demonstrate that the proposed RPA encroachment is necessary and that impacts are identified, minimized, and mitigated to the maximum extent practicable. The design details of storm sewer system outfalls and conveyance channels must be included in construction plans as defined in Chapter 104 of the County Code. These same details are also to be included in the WQIA, which upon approval, must subsequently be incorporated into the final approved construction plan.

Most all WQIAs for outfall improvement or construction contain similar information and mitigation methods. The clearing limits are restricted around standard storm drainage easements, super silt fence is used during construction, revegetation of disturbed areas with ground covers, and channel stabilization with biostabilization materials or other energy dissipators have been consistently addressed in each WQIA for a storm system outfall within a RPA. In an effort to reduce review and processing time, and eliminate redundant review steps, incorporation of the WQIA directly into the construction plan for review and Director approval is desirable. This will also reduce inadvertent omissions of design details on the construction plans.

Procedures:  Effective immediately, development plans proposing construction of a storm sewer or conveyance channel outfall in a RPA may include the required WQIA within the development construction plan for Director approval. The WQIA is to be incorporated in the overall stormwater management plan, erosion and sediment control plan and landscape plan addressing the required items of CBPO 118-4-3. The assessment shall be labeled on the development plan as ‘Water Quality Impact Assessment Narrative’ and shall:

1. Display the boundaries of the RPA as well as include a description of the source of the RPA boundary, e.g., adopted County map or approved RPA delineation study.
2. Display (on the grading plan) and describe the location and nature of the proposed RPA encroachment and impacts to the RPA (in narrative form), including the area of the clearing and grading (i.e., in square feet).
3. Provide a justification statement for the proposed encroachment and impacts to the RPA.
4. Display and describe the extent and nature of any proposed disturbance or disruption of wetlands.
5. Display and discuss the type and location of proposed best management practices to mitigate the proposed RPA encroachment or adverse impacts.
6. Describe the extent to which the proposed construction will comply with the performance criteria of the CBPO.
7. Describe the runoff in the outfall in terms of flow rate (in cubic feet per second) and velocity (in feet per second) for the 2-year, 2-hour storm event and the 10-year, 2-hour storm event.
8. Describe, quantify and display any erosion protection measures used in the channel, such as rip rap energy dissipaters, or to protect the RPA buffer from degradation due to point discharge or sheet flow discharge.
9. Provide an outfall channel profile, cross-sections (with equal horizontal and vertical scales) and information consistent with Chapter 5 of the latest edition of the Virginia Erosion and Sediment Control Handbook under the ‘Determination of Adequate Channel’ section.

The “Plan Approval Information” chart, Item #8 Water Quality Impact Assessment ‘Required’ box on the plan Cover Sheet shall be marked and the ‘Comment/Sheet No.’ shall contain a note as to which plan sheet contains the narrative statement.

With review and Director approval of the construction plan, approval of the WQIA will be deemed to have been met.

If you have any questions or need additional information, please call Stormwater Specialist at 703-324-1720, TTY 711.

The use of lumber species not native to North America and not listed in the National Design Standard (NDS) has recently become more prevalent in residential construction. Fairfax County does not wish to restrict the use of these species (i.e., ipe, spanish cedar, meranti). However, with the many species on the market today, Land Development Services must regulate their acceptance with the specific requirements listed below.

• The use of lumber species not native to North America shall be limited to decking surface installations only. Their use as structural elements, such as guardrails, joists, beams or rafters, is prohibited.
   
• Upon submission to Building Plan Review, the building plans shall include a report from a testing laboratory recognized in the United States or Canada for the decking surface material. The report shall include the following minimum data for the species proposed in the construction:
  • Allowable bending stress
  • Allowable shear stress
  • Modulus of elasticity
• The submitted building plans shall also include verification of decay and termite resistance of the proposed species from an organization recognized by a federal agency of the United States or Canada.
   
• Labeling and field identification per IBC, Chapter 17, shall also be provided. This is to ensure the specified species is the actual species installed in the field.

If you have any questions regarding the policy outlined here, contact 703-222-0114, TTY 711.

Issue:

New submission requirements associated with recommendation SW-10 of the Infill and Residential Development Study will be effective for all first submission site plans, subdivision plans, rough grading plans, bonded grading plans where the limits of disturbance have not been included in the subdivision plans, public improvement plans, infill plans, and minor site plans that are submitted on or after May 12, 2003. The details of the new requirements which were developed by a committee of private and public professionals are provided in the document entitled "Policy and Procedures for the Evaluation of Downstream Impoundments." The document contains the new submission requirements as well as the role of the design professionals and review staff in implementation.

Background:

Developers and downstream property owners share a common desire to have minimal impact caused by upstream land development activities. Impacts in the form of siltation to downstream properties, especially natural resources, may result in significant liabilities to a developer involving litigation with the affected parties that may take a substantial amount of time and expense to resolve. Certainly the downstream property owner would like to avoid damages resulting in costly resolution as well. The County can provide assistance to both parties by requesting information that identifies and quantifies existing conditions prior to land disturbance. Without definitive measurements of pre-existing conditions, it has been difficult for all parties to reach agreement on downstream damages caused by the land disturbing activities of a developer's project. Neither party is served well in these situations, which have become more frequent as infill development continues in the County. The existence of siltation that occurred prior to development can make the determination of liability even more difficult. Downstream property owners are sometimes left with no remedy for siltation on their properties because they are unable to prove that a particular development caused the siltation. Likewise, developers are unable to quantify the extent of their responsibility.

If you have any questions regarding submission requirements, please call Environmental and Facilities Review Division at 703-324-1720, TTY 711.