Reg2Col.DOT - Virginia Register of Regulations - Commonwealth of ...

TITLE 4. CONSERVATION AND NATURAL RESOURCES VIRGINIA SOIL AND WATER CONSERVATION BOARD Proposed Regulation Title of Regulation: 4VAC50-20. Impounding Structure Regulations(amending
4VAC50-20-20 through 4VAC50-20-90, 4VAC50-20-150 through 4VAC50-20-180,
4VAC50-20-200 through 4VAC50-20-240, 4VAC50-20-260 through 4VAC50-20-320;
adding 4VAC50-20-52, 4VAC50-20-54, 4VAC50-20-58, 4VAC50-20-105, 4VAC50-20-
125, 4VAC50-20-155, 4VAC50-20-165, 4VAC50-20-175, 4VAC50-20-177, 4VAC50-20-
330, 4VAC50-20-340, 4VAC50-20-350, 4VAC50-20-360, 4VAC50-20-370, 4VAC50-20-
380, 4VAC50-20-390, 4VAC50-20-400; repealing 4VAC50-20-100, 4VAC50-20-110,
4VAC50-20-120, 4VAC50-20-130, 4VAC50-20-140, 4VAC50-20-250). Statutory Authority: §10.1-605 of the Code of Virginia. Public Hearing Information: October 4, 2007 - 7 p.m. - Roanoke City Council Chambers, Noel C. Taylor
Municipal Building, 215 Church Avenue Southwest, Roanoke, VA 24011 October 9, 2007 - 7 p.m. - Hampton City Hall, 22 Lincoln Street, 8th
Floor, Hampton, VA 23669 October 10, 2007 - 7 p.m. - Henrico County Government Complex Board Room,
4301 East Parham Road, Richmond, VA 23228 October 11, 2007 - 7 p.m. - Augusta County Government Center, 18
Government Center Lane, Verona, VA 24482 October 16, 2007 - 7 p.m. - City of Manassas Council Chambers, 9027 Center
Street, Manassas, VA 20110 Public Comments: Public comments may be submitted until 5 p.m. on October
19, 2007. Agency Contact: David C. Dowling, Policy, Planning, and Budget Director,
Department of Conservation and Recreation, 203 Governor Street, Suite 302,
Richmond, VA 23219, telephone (804) 786-2291, FAX (804) 786-6141, or email
david.dowling@dcr.virginia.gov. Basis: The Virginia Dam Safety Act (§10.1-604 et seq. of the Code of
Virginia) ensures public safety through the proper and safe design,
construction, operation, and maintenance of impounding structures in the
Commonwealth. This is accomplished through the effective administration of
the Virginia Dam Safety Program (program). Authority for the program rests
with the Virginia Soil and Water Conservation Board (board) and it is
administered on behalf of the board by the Department of Conservation and
Recreation's Division of Dam Safety and Floodplain Management. The program
focuses on enhancing public safety through bringing all impounding
structures of regulated size under Regular Operation and Maintenance
Certificates. Pursuant to §10.1-605, the board is directed to promulgate regulations for
impounding structures. Purpose: As there have been no regulatory changes made to the impounding
structure regulations since the late 1980's except to update the definition
of regulated dams to conform it with the 2001 legislative change in
definition (Chapter 92 (SB1166) of the 2001 Virginia Acts of Assembly), it
was determined that this body of regulations required a substantive review
and potential revisions. Since the 1980's, public safety concerns have
evolved and engineering and technology and methodologies have advanced.
These events have resulted in the need to consider amendments to the
regulations. Further with the significant revisions made to the Virginia
Dam Safety Act during the 2006 legislative session (Chapter 30 (HB597) of
the 2006 Virginia Acts of Assembly) it is necessary to update the
regulations to reflect those revised and enhanced powers and authorities.
It has also been determined that the administration and implementation of
the Dam Safety Program could be improved through regulatory updates and
that the intent and procedures embodied within the regulations could be
clarified for the regulated community's and the public's benefit. For the purposes outlined above and most importantly for the purpose of
protecting the safety and welfare of the public and their property from the
impacts of a dam failure, this regulatory action amends the Virginia Soil
and Water Conservation Board's Impounding Structure Regulations to: 1. Revise the dam hazard potential classification system; 2. Specify that spillway design requirements are applicable to all state
regulated dams; 3. Modify the spillway design requirements to enhance public safety and
reduce subjectivity; 4. Allow for the potential reduction of the spillway design flood
requirement through an incremental damage assessment for all qualified
dams; 5. Establish dam break inundation zone mapping requirements; 6. Expand emergency action plan requirements for High and Significant
Hazard Potential dams and emergency preparedness plan requirements for Low
Hazard Potential dams; 7. Establish permit application fees for the administration of the Dam
Safety Program that will create a stream of revenue sufficient to support
an additional dam safety engineer; 8. Remove the forms that are incorporated by reference and move reporting
standards into the regulations; 9. Create new definitions or modify current definitions; 10. Reorganize, clarify, and expand sections related to permitting
procedures; and 11. Update sections related to inspections, enforcement, and unsafe
conditions. Making these key modifications to the regulations will result in a Dam
Safety Program that will be better able to protect the public's safety,
treat all dam owners similarly and fairly in accordance with the
regulations, increase awareness of dams and their potential impacts within
local governments and their citizens, and help improve the administration
of the program to the benefit of the public. The implementation of the
criteria established in this regulation should minimize dam failure and the
potential significant impacts associated with such a failure. It should also be noted that many of these impounding structures also have
environmental benefits in that they serve as sediment retention basins thus
improving water quality. However, alternatively, the failure of such an
impounding structure may result in significant downstream environmental
damages should the sediment be released. Substance: Key provisions of this regulatory action include the following: 1. A revision of the dam classification system from four categories (Class
I, II, III, and IV) to three hazard classifications (High, Significant,
and Low). This will conform the classification categories to those used by
federal agencies and many states. Functionally, the change will primarily
involve grouping Class III and Class IV dams together into the Low
category. Currently the Class IV dams do not have to have an engineer, an
inspection, or an Emergency Action Plan (EAP). It was determined that all
dams should be regulated similarly for dam safety purposes. 2. A specification that the Spillway Design Flood requirements (Table 1)
are applicable to all dams not just "new" (post July 1982) dams. In
addition, Table 1 is revised to: a. Reflect the revised dam classifications. b. Update spillway design requirements to enhance public safety and to
move towards federal standards. c. Eliminate spillway design flood ranges that may result in
inconsistency in application. d. Require that the spillway of all High hazard dams be engineered to
pass the full Probable Maximum Flood. e. Specify minimum thresholds for incremental damage assessment. It was
determined that for the purposes of public safety that all dams should be
regulated in accordance with standardized spillway design requirements
and evaluation procedures. 3. The creation of a new section that allows for the potential reduction
of the spillway design flood requirement through an incremental damage
assessment for those dams meeting the specified administrative
requirements. This would now be applicable to all eligible dams where
previously it was only available to dams constructed prior to July 1982.
Additionally, it is specified that the spillway design flood shall not be
reduced below the minimum threshold values as determined by Table 1. In
consultation with the technical advisory committee, it was determined that
the incremental damage assessment should be made available to all dam
owners to see if a reduction in the required Spillway Design flood (SDF)
could be considered where the breach of a dam would not significantly
worsen downstream flooding. It was determined that a minimum threshold be
established below which the SDF could not be reduced to set out a baseline
that adequately protects public safety. 4. The creation of a new section that sets out dam break inundation zone
mapping requirements. In consultation with the TAC, it was determined that
both for hazard potential classification determination for all dams and
for Emergency Action Plans for High and Significant dams that a dam break
inundation zone map should be required. The map will specify the areas
that might be inundated during both a sunny day failure and a probable
maximum flood (PMF) failure in order to demonstrate the levels where
failure of the dam does not further constitute a hazard to downstream life
or property. The areas to be impacted during a break should be the areas
of focus for emergency warnings and evacuations. 5. A specification that for each Operation and Maintenance certificate
(Regular or Conditional) issued, the impounding structure owner shall send
a copy of the certificate to the appropriate local government(s) with
planning and zoning responsibilities. As downstream development approved
by