HomeMy Public PortalAboutResolution 07-97 Amending 6-97A Relating to Storm water Best ManagementRESOLUTION NO.7-97, AMENDING RESOLUTION NO. 6-97A
Resolution No. 6-97A is amended to read as follows:
A RESOLUTION OF THE CITY COUNCIL OF THE CITY OF McCALL, IDAHO,
RELATING TO THE APPROVAL OF THE USE BY THE CITY ENGINEER OF THE
HANDBOOK OF VALLEY COUNTY STORMWATER BEST MANAGEMENT PRACTICES.
WHEREAS:
1. The Council previously adopted Ordinance 712 as an amendment to Title 3 of the
McCall City Code authorizing the City Engineer to consult concerning and to
enforce best management practices with respect to storm and meltwater drainage;
and
2. The joint consultative process among interested parties, including both Valley
County and the City of McCall has resulted in the drafting of the Handbook of
Valley County Stormwater Best Management Practices; and
3. It appears that Valley County and the State Division of Environmental Quality
have approved the use of such Handbook;
4. It appears that in deference to the jurisdiction of Council the Commissioners did
not adopt certain pages of such Handbook which relate to the planning
jurisdiction of the City of McCall,
BE IT RESOLVED by the Mayor and Council of the City of McCall that:
Section 1. The Handbook of Valley County Stormwater Best Management Practices
and the attached McCall Supplemental Stormwater Management Policy are
approved for the use of the City Engineer in the administration of Titles 2 and 3 of
the McCall City Code respecting drainage concerns arising in connection with
those Titles.
Section 2. Council requests Valley County to include this Supplemental Policy in the
copies of the Handbook distributed by it, inserted in correct numerical position,
and Council will advise Valley County of any changes made in accord with
paragraph 3 below.
Section 3. In the event that such Handbook or Supplemental Policy, or either of them,
is ever revised in accord with its terms, such revision(s) shall be returned to
Council for similar approval.
Passed and approved August 14, 1997.
William M. Killen,
Mayor
ATTEST:
ames H. Henderson,
City Clerk
RESOLUTION NO. -97 A.
A RESOLUTION OF THE CITY COUNCIL OF THE CITY OF McCALL, IDAHO,
RELATING TO THE APPROVAL OF THE USE BY THE CITY
ENGINEER OF THE HANDBOOK OF VALLEY COUNTY
STORMWATER BEST MANAGEMENT PRACTICES.
WHEREAS:
1. The Council previously adopted Ordinance 712 as an amendment to Title 3 of the
McCall City Code authorizing the City Engineer to consult concerning and to
enforce best management practices with respect to storm and meltwater drainage;
and
2. The joint consultative process among interested parties, including both Valley
County and the City of McCa11 has resulted in the drafting of the Handbook of
Valley County Stormwater Best Management Practices; and
3. It appears that Valley County and the State Division of Environmental Quality have
approved the use of such Handbook;
BE IT RESOLVED by the Mayor and Council of the City of McCall that:
Section 1. The Handbook of Valley County Stormwater Best Management Practices. is
approved for the use of the City Engineer in the administration of Titles 2 and 3 of
the McCa11 City Code respecting drainage concerns arising in connection with those
Titles.
Section 2. In the event that such Handbook is ever revised in accord with its terms, such
revision(s) shall be returned to Council for similar approval.
Passed and approved June 26, 1997.
William M. Killen,
Mayor
A1'1'J ST:
ames H. Henderson,
City Clerk
3.4 Policy as Adopted by the City of McCall
Increased land development within the City of McCall and the City of McCall impact
area has given rise to a concern for proper stormwater management. Development of
rural lands often results in increased velocity and volume of stormwater runoff and
erosion within the drainage basin. Land development generally increases the area of
impervious surfaces (such as roads, sidewalks, parking lots and roof tops) within a
drainage basin. Increased impervious surfaces within a basin cause reduced infiltration
and decreased travel time which combine to significantly increase peak discharge and
total runoff volumes. Both the quantity and quality of stormwater generated by urban
development must be addressed. Without regulation, as urban areas develop, natural
drainages often are constricted and sometimes eliminated.
Stormwater management practices in McCall must accomplish two major goals:
(1) Maintain or reduce present off -site discharge rates to the extent possible through
control of runoff from an improved site.
(2) Reduce pollutant loads associated with stormwater discharges to Payette Lake and
the Payette River to the extent possible through use of Best Management Practices (see
Chapter 4 and Chapter 5).
This policy section has been prepared to provide consistent guidance to meet the
goal of the minimizing developmental impacts on the surrounding environment and
to control stormwater runoff. The City of McCall recognizes that special
circumstances may arise which warrant the consideration of alternatives not specifically
identified in this Handbook. The City of McCall reserves the right to impose, or entertain
from an applicant, alternative means, measures or technologies that may be more
appropriate for the accomplishment of the goal. The City of McCall's decision in such
matters is final.
Storm Drainage System
McCall's storm drainage system consists mainly of unimproved borrow ditches with
culverts at roadway crossings. There is a limited sub -surface storm drain system located
in the downtown area (2nd Street area).
Stormwater runoff from impervious areas typically enters the borrow ditches, where
runoff either percolates into the ground, evaporates or flows down borrow ditches to
discharge points at natural drainages. The natural drainages transport the water to either
Payette Lake or the Payette River with the only means of treatment being the natural
processes of biofiltration, percolation and evaporation occurring between the point of
impact and point of discharge.
Infiltration is limited to certain higher elevation areas and only during approximately four
months out of the year. The lack of infiltration in the McCall area is due to high
groundwater, frozen soils, and heavy snow. Compounding this problem even further, is
the fact that the primary runoff events occur when rain falls on snow in the spring when
the ground is still frozen.
It is imperative that storm drainage conveyance and detention facilities be designed to
address the circumstances described in the previous paragraph. The guidelines specified
in this document are conservative in that they disregard infiltration in the calculations to
estimate peak runoff. This is accomplished by applying conservatism to the factors that
will effect infiltration in the determination of peak runoff estimates. Methods for
estimating peak runoff are discussed in detail in Appendix D-2. On -site area topography
must be evaluated by topography mapping (available either from the City of McCall
Community Development Department, or a field generated topography map) with
contour intervals of 2 feet or less.
Stormwater Planning & BMP Requirements
Any individual or group wishing to perform development on property within the City of
McCall or the City of McCall impact area, which involves land disturbance are required
to submit a Stormwater Application (page 3-9) and a Stormwater Management Plan
which satisfies the requirements described in Section 3.1 entitled: Stormwater
Management Plan Checklist. Table 3.4-1 list automatic exemptions to requirements in
this policy section.
The information required to be submitted varies depending on the size of the project site
and/or the amount of land to be disturbed during the improvement(s) (Table 3.4-2). The
following is a description of the BMP's required for various sizes of land development
projects:
• Projects with less than 2 acres of total site area or less than 5,000 square feet of
proposed impervious surface will be required to submit to the City Engineer for
review and comment, a Stormwater Management Plan which addresses: Section A -
Basin Characteristics, Section B - Erosion and Sediment Control and Section F -
Operation and Maintenance Plan, of the Stormwater Management Plan Checklist
(Section 3.1).
• Projects with 2 to 5 acres of total site area or from 5,000 to 15,000 square feet of
impervious surface proposed will be required to submit, a Stormwater
Management Plan prepared by a Professional Engineer licensed in the State of Idaho.
Projects which fall under this category are required to address: Section A - Basin
Characteristics; Section B - Erosion and Sediment Control; Section C - Conveyance
System; Section D - First Flush Storm Treatment; and Section F - Operation and
Maintenance Plan, of the Stormwater Management Plan Checklist (Section 3.1).
• Projects with greater than 5 acres of total site area or greater than 15,000 square
feet of proposed impervious surface will be required to submit, a Stormwater
Management Report prepared by a Professional Engineer licensed in the State of
Idaho. This Report will be required to address all sections of the Stormwater
Management Plan Checklist (Section 3.1).
Development which will cause discharge directly to a surface water body and containing
greater than five acres of disturbed area or is from an industrial use (listed in Appendix
A) may be covered under the National Pollution Discharge Elimination System (NPDES)
permit. To receive more information on completing or applying for a NPDES permit
contact the United States Environmental Protection Agency, Region Ten Stormwater
Division. A copy of the permit, when required, shall be submitted to the City Engineer.
A Storm Water Management Report, composed of the following information, must
be submitted to the McCall City Engineer for review:
1. One copy of a signed Stormwater Application (page 3-9).
2. Three copies of the Stormwater Management Plan (based on section 3.1).
3. The engineer shall submit to the City Engineer, nomagraphs, tables, charts
or
calculations used to size pipes, inlets ditches or swales for runoff, Q, as
determined from the Rational Method.
It is strongly recommended that a preliminary submittal be made to the City
Engineer for review of concepts and to determine general compliance with the
City's requirements.
Note: Land improvement activities which: involve the installation of new
stormwater conveyance pipes or ditches; involve the alteration of existing
stormwater conveyance systems; or will significantly alter existing drainage
patterns will be required to address Section C - Conveyance System, of the
Stormwater Management Plan Checklist in addition to the sections specified
for the project based on site area or proposed impervious surface.
feet
STORMWATER APPLICATION
City of McCALL
Fill in all information. Submit one copy of signed application and three copies of
Stormwater Management Plan to the City Engineer.
1. Project Name:
Location:
2. Owner's Name:
Street: City:
State: Zip Code: Phone:
3. Project Description:
a. Total property area, in acres.
b. Proposed impervious surface (asphalt, rooftop, concrete sidewalk, etc.) in square
c. Describe existing vegetation present on site.
d. Start date of construction.
e. Estimated length of time to complete improvements.
4. Three Stormwater Management Plans attached? Yes
No
5. Circle the sections of the Stormwater Management Plan Checklist (section 3.1) which are
applicable to project. A BCDEF
6. Party responsible for operation and maintenance of project, including maintenance of
temporary and permanent Best Management Practices:
Name
Date
Title Signature
Address Daytime Phone After Hours Phone
Do not write below this line.
The submitted Stormwater Management Report (Stormwater Application and Stormwater
Management Plan) is:
Approved:
Not Approved:
Approved, with conditions:
By The City of McCALL
Representative
Signature Title
Date
Table 3.4-1. Exemptions: The following activities are automatically exempt from the
permit requirements of this Ordinance.
(1)
Activities that constitute normal and accepted farming activities.
(2)
Routine maintenance of existing public roads, private roads, driveways, trails where
work is limited to the travelway and no cut or fill slopes are created and no drainage
features are created or modified.
(3)
Road construction which proceeds in compliance with an is restricted by the Idaho
Forest Practice Act, Chapter 13, Idaho Code.
(4)
Logging road construction and routine maintenance, and logging activity under a valid
Forest Practice Act Notification.
(5)
Stream channel alterations which proceed under the terms of a permit issued by Idaho
Department of Water Resources pursuant to Title 42, Chapter 38, Idaho Code, provided
(6)
Cemetery graves.
(7)
Drilling of wells under the terms of a permit issued by the Department of Water
(8)
In any 12-month period, an excavation of less than 50 cubic yards of loose material
which: a) is less than two feet in depth; or b) which does not create a slope greater than
(9)
In any 12-month period, a fill less than one foot in depth placed on natural terrain with
a slope flatter than five horizontal to one vertical (5:1), or a fill less than three feet in
depth and not intended to support roadways, driveways, or structures, which does not
exceed 50 cubic yards on any one lot and does not obstruct a stream, drainage course,
or surface waters. In no case shall this exemption be combined with item 8 of this
Section in a manner which would result in a cut and fill exceeding 50 cubic yards of
(10)
Installation, repair, replacement, or maintenance of septic system provided septic
p
permit requirements for BMPs are implemented.
(11)
Work related directly to vegetable and flower gardens, orchards, lawns, or similar
(12)
Land clearing and similar activities which occur as part of an emergency situation
involving wild fire, danger to life or property, substantial fire hazards, or other public
safety hazards as determined by the County, or during the period covered by an
(13)
Site projects that disturb an area that is less than 500 square feet.
(14)
Excavation of test holes for soil testing activities that are completed within a seven day
time frame; provided that no access roads will be created for test hole excavation and
that the total excavation is less than 50 cubic yards.
Table 3.4-2. The following information further describes, in chart form, the
requirements for submittals.
Requirement
Application
Plan addressing Sections A, B
and C of the Stormwater
Management Plan Checklist
Plan addressing Sections A, B,
C, D and F of the Stormwater
Management Plan Checklist
Plan addressing Sections A, B,
C, D, E, and F of the Stormwater
Management Plan Checklist
Temporary BMP's
Permanent BMP's
Detention of 1st flush storm(2
year design storm frequency)
Detention of increased runoff
caused by project
Plan addressing Section C of the
Stormwater Management Plan
Checklist in addition to sections
required for project based on
size
Total Area
All
All
2 to 5 acres
greater than 5 acres
All
greater than 5 acres
2 acres and greater
greater than 5 acres
Proposed impervious surface
All
All
5,000 to 15,000 s.f.
greater than 15,000 s.f. to
infinity
All
greater than 15,000 s f
5,000 s.f. and greater
15,000 s.f. and greater
Any land improvement project which involves the
installation or modification of a storm water conveyance
(pipe or ditch)
METHODS USED FOR HYDROLOGICAL ANALYSIS
Many hydrologic methods are available for the estimation of pre- and post -development
runoff. These guidelines identify acceptable methods which provide a level of uniformity
for storm drainage practices within McCall and assist the City Engineer in review of
report submittals. The two methods available under these guidelines are the Rational
Method and a simplified SCS Runoff Curve Number Method. Descriptions of both
methods with examples of their use for a typical land development project are contained
in Appendix D-2. Table 3.4-3 defmes the minimum required design storm frequency
that must be used in the design of conveyance systems. Table 3.4-4 defmes the
minimum required design storm frequency that must be used in the design of detention
systems.
TABLE 3.4-3. Minimum design storm frequency for conveyance systems.
Stormwater conveyance systems shall be designed using the ten year design
storm frequency, with the following exceptions:
Land Use Zone Design Storm Frequency
Any drainage crossing a roadway 25
Slopes in excess of 12% 25
Major structures, such as bridges 100
Where an existing, primary storm conveyance runs through a property
(a primary storm conveyance is defined as a channel, ditch, or pipe with
a drainage area 10 acres or larger). 100
Where an existing, secondary storm conveyance runs through a property
(a secondary storm conveyance is defined as a channel, ditch or pipe with
a drainage area from 3 to 10 acres) 25
Note: The minimum pipe size that will be accepted by the City of
McCall for new conveyances will be 15"
TABLE 3.4-4. Minimum design storm frequency for detention systems.
All land improvement activities which contain from
2 to 5 acres of total site area or from 5,000 to
15,000 s.f. of proposed impervious surface must detain the 2 year design storm
All land improvement activities which
on -site, the increase
contain greater than 5 acres of total
is estimated will be
site area or greater than 15,000 s.f.
the proposed project
of proposed impervious surface
must detain,
in runoff that
caused by
for the ten year storm
Note: Emergency spillways must be designed for the 100 year design storm. For
design information, specifications, and details refer to Chapter 5.