HomeMy WebLinkAboutMINUTES - 01232007 - C.17 TO: BOARD OF SUPERVISORS SE
Contra
V
FROM: CARLOS BALTODANO, DIRECTOR Costa
" .,a
F�, ..;. ¢
BUILDING INSPECTION DEPARTMENT, County
DENNIS BARRY, DIRECTOR
COMMUNITY DEVELOPMENT DEPARTMENT,
MAURICE SHIU, DIRECTOR �•
PUBLIC WORKS DEPARTMENT
DATE: January 23, 2007
SUBJECT: Water Drainage Plans Ordinance
SPECIFIC REQUEST(S)OR RECOMMENDATION(S)&BACKGROUND AND JUSTIFICATION
RECOMMENDATIONS
1. ADOPT Ordinance No. 2007-01, requiring drainage plans and improvements for
certain development projects in the unincorporated area; and ADOPT findings in
support of Ordinance No. 2007-01.
2. DETERMINE that the adoption of the ordinance will not have a significant effect on the
environment, and that it is exempt from the California Environmental Quality Act
(CEQA) under State CEQA guidelines pursuant to Article 5, Section 15061(b)(3);
DIRECT the Community Development Department(CDD)to file a Notice of Exemption
with the County Clerk; and DIRECT the Building Inspection Department t Arrange for
payment of a $25.00 fee to the County Clerk for filing and a $25.00 fe e CDD for
processing of the Notice of Exemption.
t J
CONTINUED ON ATTACHMENT: YES SIGNATURE
RECOMMENDATION OF COUNTY ADMINISTRATOR RECOMMEN ATION OF BOARD COMMITTEE
/APPROVE OTHER
f
SIGNATURE(SP"C'e, AO-ZA�--
ACTION OF BO 70N APPROVED AS RECOMMENDED OTHER
VOTE OF SUPERVISORS
✓/ 1 HEREBY CERTIFY THAT THIS IS A TRUE
UNANIMOUS(ABSENT AND CORRECT COPY OF AN ACTION TAKEN
AYES: NOES: AND ENTERED ON THE MINUTES OF THE
ABSENT: ABSTAIN: BOARD OF SUPERVISORS ON THE DATE
SHOWN.
Contact: Carlos Baltodano (33[5]-1108)
ATTESTED: CL r 'e3 0&V;;1'
cc: Building Inspection John Cullen,Clerk of the Bo4LO&Supervisors
County Administrator and County Administrator
County Counsel
Community Development
Public Works
BY DEPUTY
CB:nr
FISCAL IMPACT
None.
BACKGROUND/REASONS FOR RECOMMENDATIONS
On July 25, 2006, the Board of Supervisors directed the Building Inspection, Community
Development and Public Works Departments to work with County Counsel and the District
II Supervisor to draft ordinance amendments to address the possible impacts from single
family residential building permits on natural or repaired landslide areas.
It had come to the attention of the District II Supervisor that building permits had been
issued for three single family residential additions in the same incorporated area without
consideration of the cumulative impacts of the drainage from these additions on a repaired
landslide. Approving permits for these additions caused the drainage from each lot to be
taken to a previously repaired landslide area. This raised the concern of what would
happen if other properties in the area made similar improvements and did not consider the
impacts by the additional drainage run-off in a repaired landslide or areas with inadequate
existing drainage facilities.
At the request of the Board, the three departments have been meeting to identify ways to
alert staff of unstable soils areas during the review of permits and how future cumulative
impacts from drainage could be tracked over time. After several meetings, it was
determined that it would be more prudent to require drainage plans in order to track the
cumulative drainage impacts on adjacent properties. Construction of drainage
improvements is required if specified in a drainage plan that has been approved by the
County Building Official. Attached is a drainage plan ordinance that adds section 74-6.012
to Title 7 (Building Regulations) of the County Ordinance Code. Also, attached are the
findings of local conditions to justify construction standards.
The Drainage Plan Ordinance describes when the plans are required and specifies the
exact content and information .needed on the plans to be submitted. The basic
requirement is to indicate the location of all proposed natural and man-made drainage
facilities for the storage or conveyance of runoff including drainage swales, ditches,
culverts and berms, sumps, sediment basins, channels, ponds, storm drains and drop
inlets. This will show where and how the water is being conveyed and where it travels
through the site and where it finally is discharged.
The construction of drainage improvements will be required if they are specified in a
drainage plan that has been approved by the County Building Official. The Drainage Plan
Ordinance will require that the drainage plan shall be prepared by a registered civil
engineer if construction is proposed for land where the slope exceeds 20 percent or if the
land is identified by the County Building Official as having a history of unstable soil or
landslide. This determination will be based using the most current USGS seven and one-
half minute quadruple map or other published sources.
Water Drainage Plans Ordinance 2007-01 Page 2 of 2
(Adopt 01/23/07)
ORDINANCE NO. 2007-01
WATER DRAINAGE PLANS
The Contra Costa County Board of Supervisors ordains as follows (omitting the parenthetical
footnotes from the official text of the enacted or amended provisions of the County Ordinance
Code):
SECTION I. SUMMARY. This ordinance adds section 74-6.012 to the County Ordinance
Code to require a drainage plan to be prepared for certain development projects and to require
construction of drainage improvements if the improvements are part of a drainage plan approved
by the County Building Official.
SECTION II. Section 74-6.012 is added to the County Ordinance Code,.to read:
74-6.012 Drainage Plan.
(a) When Required. A drainage plan is required for any building, structure or improvement
that requires a building permit and falls within one of the following categories:
(1) Results in an impervious surface of 1;000 square feet or more.
(2) Involves grading, or removal of vegetation down to bare soil by any method, of
more than 10,000 square feet.
(3) Is subject to local ponding due to soil or topographic conditions.
(4) Is located within a special flood hazard area, as defined in section 82-28.504.
(5) Involves land disturbance or structure placement within 100 feet of the top bank
of any watercourse shown with a blue line on the most current USGS seven and
one-half minute quadrangle map.
(6) Involves construction of 500 square feet or more on land where the slope exceeds
10 percent.
(7) Is located in an area identified by the County Building Official as having a history
of flooding or erosion that may be further aggravated by, or have a harmful effect
on, the construction or adjoining properties.
(b) Contents.
(1) A drainage plan shall include the following site information:
ORDINANCE NO. 2007-01
1
(A) Flow lines of surface and subsurface waters onto and off of the site.
(B) Existing and finished contours, at two-foot intervals.
(C) The location of any existing buildings, structures or improvements on the
property where the work is to be performed and on adjacent lots.
(D) Sufficient information to demonstrate compliance with chapters 816-4 and
816-6.
(E) The location of all existing natural and man-made drainage facilities for
the storage or conveyance of runoff, including drainage swales, ditches,
culverts and berms, sumps, sediment basins, channels, ponds, storm drains
and drop inlets serving the site.
(2) A drainage plan shall include the following drainage information:
(A) The location of all proposed natural and man-made drainage facilities for
the storage or conveyance of runoff, including drainage swales, ditches,
culverts and berms, sumps, sediment basins, channels, ponds, storm drains
and drop inlets.
(B) All surface and subsurface drainage devices,walls, cribbing, dams and
other protective devices to be built with or as a part of the proposed
construction.
(C) Hydraulic calculations that show the flow-carrying capacities of proposed
conveyance devices and justify the estimated runoff of the area served by
any proposed conveyance device.
(D) Discharges and velocities of proposed conveyance devices, and storage
volumes of any sumps, ponds or sediment basins.
(3) Engineered drainage plans. A drainage plan shall be prepared by a registered civil
engineer if construction is proposed for land where the slope exceeds 20 percent
or if the land is identified by the County Building Official, based on the most
current USGS seven and one-half minute quadrangle map or other published
sources, as having a history of unstable soil or landslides. An engineered drainage
plan shall include estimates of existing and increased runoff resulting from
proposed improvements and methods for reducing the velocity of any increased
runoff, in addition to all other.information required by this section.
(4) Geotechnical reports. If a drainage.plan shows that discharge resulting from the
proposed construction will occur over land where the slope exceeds 20 percent or
ORDINANCE NO. 2007-01
2
over land with a history of unstable soils, then a geotechnical report shall also be
prepared.
(c) Procedures. A drainage plan shall be submitted with the building permit application.
Drainage plans shall be neatly and accurately drawn, at an appropriate scale that will
enable ready identification and recognition of submitted information. Drainage plans
shall be prepared in accordance with written standard specifications on file with the
County Building Official. A drainage plan is not considered approved until the County
Building Official approves the plan in writing.
(d) Violations.
(1) The failure to submit a required drainage plan is a violation of this section.
(2) The failure to comply with an approved drainage plan, including the failure to
construct drainage improvements specified in an approved drainage plan, is a
violation of this section. (Ord. 2007-01 §2.)
SECTION III. EFFECTIVE DATE. This ordinance becomes effective 30 days after passage,
and within 15 days after passage shall be published once with the names of supervisors voting for
or against it in the Contra Costa Times, a newspaper published in this County.
PASSED on JANUARY 23 , 2007 ,by the following vote:
AYES: Gioia, Uilkema; Bonilla,
Glover and Piepho
NOES: None
ABSENT: None
ABSTAIN: None
ATTEST: JOHN CULLEN,
Clerk of the Board of SupervisorsL-157oard air
and County Administrator
By: [SEAL]
eputy
TLG:
HA2007\Building lnspection\drainage plan ord-final2.wpd
ORDINANCE NO. 2007-01
3
CONTRA COSTA COUNTY
FINDINGS IN SUPPORT OF ORDINANCE NO. 2007-01
The Board of Supervisors of Contra Costa County, in adopting Ordinance No. 2007-01
regarding water drainage plans and improvements, finds as follows.
1. Soils
Contra Costa County is replete with various soils, many of which are unstable, with clay
loam and alluvial fans being predominant. These soil conditions are moderately to
severely prone to swelling and shrinking, are plastic, and tend to liquefy.
2. Hillside Development
Due to technological engineering advances and scarcity of flat parcels of land, more and
more development is occurring on hillsides. Within Contra Costa County there are
hillside areas that are known to be prone to landslides or can be susceptible to unstable
conditions. As new development creates new driveways, roof tops, and decks, it creates
additional impervious surfaces. In addition, some prior hillside development activities
resulted in oversteepened and improperly sloped or retained older cuts and excavations.
Some of these also contribute to instability.
3. Roads
Throughout Contra Costa County, the topography and development growth has created a
network of older, narrow roads. These roads vary from gravel to asphalt surface and vary
in percent of slope, many exceeding 20 percent. Several of these roads extend up through
the winding passageways in the hills providing access to remote housing subdivisions.
The majority of these roads are private with no established maintenance program. During
inclement weather, these roads are subject to rockslides and mudslides, as well as
downed trees, obstructing all vehicle traffic.
4. Seismicity
Contra Costa County is located in Seismic Risk Zone 4, which is the worst earthquake
area in the United States. Buildings and other structures in Zone 4 can experience major
seismic damage. Contra Costa County is in close proximity to numerous earthquake
faults including the San Andreas Fault and contains all or portions of the Hayward,
Calaveras, Concord, Antioch, Mt. Diablo, and other lesser faults. A 4.1 earthquake with
its epicenter in Concord occurred in 1958, and a 5.4 earthquake with its epicenter also in
Concord occurred in 1955. The Concord and Antioch faults have a potential for a Richter
6 earthquake and the Hayward and Calaveras faults have the potential for a Richter 7
earthquake. Minor tremblers from seismic activity are not uncommon in the area. A
study released in 1990 by the United States Geological Survey says that there is a 67%
chance of another earthquake the size of Loma Prieta during the next 30 years, and that
the quake could strike at any time, including today. Scientists, therefore, believe that an
earthquake of a magnitude 7 or larger is now twice as likely to happen as to not happen.
Earthquakes of the magnitude experienced locally can cause major hillside damage and
landslides.
5. Need for Ordinance
Ordinance No. 2007-01 is necessary to protect the public health, safety and welfare and
to protect public. and private property, because of the conditions described above.
Without proper drainage control, soils become more unstable, and the potential for
landslides increases. Improperly controlled drainage in hillside areas can contribute to
landslides in several ways. When a hillside is saturated, a potential landslide block has
more weight because of the water, which results in a larger driving force. Groundwater
moving through the soil exerts seepage forces that further reduce stability, and the
presence of groundwater reduces the strength of the soil on a potential slide plane.
Improperly controlled surface water runoff can reduce slope stability by infiltrating into
-the near-surface soils at critical locations, and by causing erosion. Where groundwater
emerges at the surface, resulting in a spring or seep, the runoff can cause surficial erosion
that can undermine or oversteepen a slope. Undermining or oversteepening and the
consequent loss of support at the toe of the slope can trigger a landslide. Furthermore,
without proper drainage control, an increase in impervious surfaces results in an increase
in the volume and velocity of runoff, which can result in flooding, erosion and alterations
in natural streams.
The purpose of Ordinance No. 2007-01 is to properly control and route surface water
runoff. Under the ordinance, surface water runoff can be controlled and routed to
existing natural and man-made drainage facilities for the storage or conveyance of runoff,
including drainage swales, ditches, culverts and berms, sumps, sediment basins, channels,
ponds, storm drains and drop inlets, or new improvements can be required, depending on
the conditions of the property where development is proposed. In addition, the ordinance
will allow the tracking and monitoring of projects and of the potential impacts to public
and private property in hillside development.
PROOF OF PUBLICATION
(2015.5 C.C.P.)
STATE OF CALIFORNIA
County of Contra Costa
I am a citizen of the United States and a resident of the
County aforesaid; I am over the age of eighteen years,
and not a party to or interested in the above-entitled
matter.
am the Principal Legal Clerk of the Contra Costa Times,
a newspaper of general circulation, printed and published
at 2640 Shadelands Drive in the City of Walnut Creek,
County of Contra Costa, 94598.
And which newspaper has been adjudged a newspaper of
general circulation by the Superior Court of the County of
Contra Costa, State of California, under the date of
October 22, 1934. Case Number 19764.
The notice, of which the annexed is a printed copy (set in
type not smaller than nonpareil), has been published in
each regular and entire issue of said newspaper and not
in any supplement thereof on the following dates,to-wit:
Jan. 29,
all in the year of 2007
I certify (or declare) under penalty of perjury that the
foregoing is true and correct.
Executed at Waln Greek, California.
On this 31 day o anuary, 2007
...................... ... .....................................................
Signature
Contra Costa Times
P 0 Box 4147
Walnut Creek, CA 94596
(925) 935-2525
Proof of Publication of:
(attached is a copy of the legal advertisement that
published)
ORDINANCE NO.2007-01
WATER DRAINAGE PIANS
The Contra Costa County
Board of Supervisors or-
dains as follows(omitting
the parenthetical foot-
notes from the official
text of the enacted or
amended rvislons of
the County Ordinance
Code):
sECT1oN L summARY.
This ordinance adds sec-
tion 74.6,012 to the Coun-
ty Ordinance Code to re-
quire a drainage plan to
bo prepared for certain
development projects
and to require construc-
tion of drainage improve-
ments if the Improve-
ments are part of a drain-
age plan approved by the
County Building Official,
SECTION if. Section 74-
6.012 is added to the
County Ordinance Code,
to read:
74.6012 Drainage Pian.
(a) When Required. A
drainageplan is required
for any building, struc-
ture or improvement that
requires a building permit
and falls within one of the
following categories:
(1)Results in an Impervi-
ous surface of 1,000
square feet or more.
(2) Involves
gveggetgation
down to bare soil by any
method. of more than
10,000 square feet.
(3) Is subject to local
PPonding due to soil or
topographlc conditions.
(4) is located within a
special flood hazard area,
as defined In section 82-
28.504.
(5)involves land disturb-
ance or structure place-
ment within 100 feet of
the top bank of any wa-
tercourse shown with a
blue line on the most cur-
rent USGS seven and one-
half minute quadrangle
map.
(6) involves construction
of 500 square feet or
more on and
where the
slope exceeds 10 percent.
{7)is located in an area
identified by the County
Building Official as having
a history of flooding or
erasion that may be fur-
ther aggravated by, or
have a harmful effect on,
the construction or ad-
joining properties,
(b)Contents.
(1)A drainage plan shall
include the foflowing site
Information-
(A)Flow fines of surface
and subsurface waters
onto and off of the site.
(8) Existing and finished
contours,at two-foot in-
tervals.
(C) The location of any
existing buildings, struc-
tures or Improvements on
theproperty where the
work is to be performed
and on adjacent lots.
(D)Sufficient information
to demonstrate compli-
ance with chapters 816-4
and 816-6.
(E)The location of all ex-
((sting natural and man-
made drainage facilities
for the storage or convey-
ance of runoff, including
drainage swales,ditches,
culverts and berms,
sumps, sediment basins,
channels, ponds, storm
drains and drop Inlets
serving the site.
(2)A drainage plan shall
Include the following
drainage Information:
(A) The location of all
proposed natural and
man-made drainage fa-
cilities for the storage or
conveyance of runoff,In-
cluding drainage swales
ditches, culverts and
berms, sumps, sediment
basins, channels, ponds,
storm drains and drop In-
lets.
(B) All surface and sub-
surface drainage devices
walls,cribbing,dams and
other protective devices
to be built with or as a
p r t of trhe proposed con-
(C)Hydraulic calculations
that show the flow-
carrying capacities of
vicesoand justify the esti-
mated runoff of the area
served by any proposed
conveyance device.
(D)Discharges and veloc-
Ities of proposed convey-
ance devices, and stor-
age volumes of an
sumps, fonds or sedr
ment bas ns.
(3)Engineered drainage
pians. A drainage plan
shall be prepared by a
registered civil engineer
If construction is pro-
posed for land where the
slope exceeds 20 percent
or if the land Is Identified
by the County Building
Official, based on the
most current USGS seven
and one-half minute
er
guff
quadrangle
sources, as
RavinB a history of unsta-
ble soil or landslides. An
engineered drainage plan
shall Include estimates of
existing and Increased
runoff resulting from pro-
methods for reducing the
velocity of any Increased
runoff, In addition to all
other Information re-
quired by this section.
(4) Geotechnical reports.
If a drainage plan shows
that discharge resulting
from the proposed con-
struction will occur over
land where the slope ex-
ceeds 20 percent or over
land with a history of un-
stable soils, pthen a
also be prepared.ort shall
(c)Procedures.d A drain-
ageplan shall be submit-
ted with the building per-
mit application. Drainage
plans shall be neatly and
accurately drawn, at an
appropriate scale that
wllI enable ready Identifi-
cation and recognition of
submitted Information.
Drainage plans shall be
prepared in accordance
with written standard
specif cations an file with
the County Bullding Offi-
cial. A drainage pian Is
not considered avproved
until the County Building
Official approves the plan
In writing.
(d)Violations.
(1)The failure to submit a
n
uired drainage plan is
a violation of this section.
(2)The failure to comply
with an approved drain-
a�e plan, including the
failure to construct drain-
age improvements s eci-
fled in an approved dprain•
aBe plan,1,a vioiation of
this section. (Ord. 2007-
01§ZJ
SECTION III. EFFECTIVE
DATE.This ordinance be-
comes effective 30 days
after passa e,and within
15 days after passage
shall be published once
with the names of super•
visors voting for or
against It In the Contra
Costa Times, a newspa-
per published in this
County.
PASSED on JANUARY 23,
2007 by the following
vote:
AYES: SUPERVISORS
GIOIA UILKEMA BONILLA.
GLOVkR AND PIKPHO
NOES:NONE
ABSENT,NONE
ABSTAIN:NONE
ATTEST:JOHN CULLEN,
Clerk of the Board of
Supervisors and County
Administrator
MARY PIEPHO
Board Chair
By:EMY SHARP
Legal CCT 7520
Publlsh January 29,2007
PROOF OF PUBLICATION
(2015.5 C.C.P.)
STATE OF CALIFORNIA
County of Contra Costa
I am a citizen of the United States and a resident of the
County aforesaid; I am over the age of eighteen years,
and not a party to or interested in the above-entitled
matter.
I am the Principal Legal Clerk of the Contra Costa Times,
a newspaper of general circulation, printed and published
at 2640 Shadelands Drive in the City of Walnut Creek,
County of Contra Costa, 94598.
And which newspaper has been adjudged a newspaper of
general circulation by the Superior Court of the County of
Contra Costa, State of California, under the date of
October 22, 1934. Case Number 19764.
The notice, of which the annexed is a printed copy(set in
type not smaller than nonpareil), has been published in
each regular and entire issue of said newspaper and not
in any supplement thereof on the following dates,to-wit:
Jan. 29,
all in the year of 2007
I certify (or declare) under penalty of perjury that the
foregoing is true and correct.
Executed at Waln Creek, California.
On this 31 day o anuary , 2007
...................... . . .....................................................
Signature
Contra Costa Times
P O Box 4147
Walnut Creek, CA 94596
(925) 935-2525
Proof of Publication of:
(attached is a copy of the legal advertisement that
published)
"Contra Costa Times To: EShar@cob.cccounty.us
•' Legals" cc:
<cctlegals@cctimes.c Subject: Re: ADOPTION OF ORDINANCE NO. 2007-01
om>
01/24/2007 01:05 PM
Please respond to
cctlegals
THIS E-MAIL CONTAINS PERTINENT INFORIVIATI.ON; PLEASE READ IT
CAREFULLY I.N :I.TS EN7TIRETY.
PLEASE NOTE:,All of our offices will be closed Presidents'Day, 111ondtrv, Hebrrraq 19,
'1007.
Good Afternoon. FYI: I should be able to e-mail the formal confirmation for 2037 by the end of
the week.
If you have any questions regarding the legal notice confirmed below, pleasereference LEGAL
NUNIBER 7610. Only e-mailectlegals(a?cctimes.com regarding Conk a Costa Times, Concord
Transcript, or Contra Costa Sun legal notices.
" :LEGAL SCHEDULE CONFIRMATION
TYPE: In=COlUmn Liner. Classified Section
LEGAL NUMBER: 761.0
PO#: F05508 2038,
Publication: CCT
RLin Date(s): 01/'29
'Legal Acct#: 200 4197
Total Amount: 5387.80
.FOR YOUR INFORMA7TI.ON - Revisions/Cancellations: 1. will need a cancellation request
referencing LEGAL NUI%1BER 7610—or all changes attached in a final draft Microsoft Word
Document — e-mailed to ectlegals(i-itectimes.com by no later than 4 PM tomon•ow, Thurs., 011125.
Otherwise, the wording of.the legal will publish as you e-mailed. Thanks!
Anashia Lloyd
.Legal Advertising Coordinator
(925) 943-8019
(925) 943-8359 — fax
Contra Costa Times
ATTN.- Legal Dept.
P.O. Box 4718
Walnut Creek, CA 94596
cctlegals )cctimes.com
t
L
_.:
LEGAL PUBLICATION REQUISITION
Contra Costa County �-
Y~L.'
r7q�COUTl'�
12
FROM: Clerk of the Board TO: Contra Costa Times
651 Pine St., Room 106 P.O. Box 4718
Pine Street, Martinez 94553 Walnut Creek, CA 94596
E-MAIL: cctlegals a,cctimes.com
FAX No. 925-943-8359
Requested by:
Date: MMZA;k 2007
Phone No.: 9.25-335-1903 Reference No.: 2038
Org.: Sub Object: 2190 Task: SAS Activity:
q
Publication Date (s) JANUARY 2,K, 2007
No. of Pages:
LEGAL PUBLICATION ADOPTION OF ORCINANCE NO. 2007-01
WATER DRAINAGE PLAN
"e-mail"
** Immediately upon expiration of publication, ***
send in one affidavit for each publication in
order that the auditor may be authorized to pay you bill.
Authorized Signature:
Please confirm date of publication and receipt of this fax.
ORDINANCE NO. 2007-01
WATER DRAINAGE PLANS
The Contra Costa County Board of Supervisors ordains as follows (omitting the parenthetical
footnotes from the official text of the enacted or amen_ded provisions of the County Ordinance
Code):
SECTION 1. SUMMA11Y. This ordinance adds section 74-6.012 to the County Ordinance
Code to require a drainage plan to be prepared for certain development projects and to require
construction of drainage.improvements if the improvements are part of a drainage plan approved
by the County :B1.iilding Official.
SECTION 11. Section 74=6.012 is added to the County Ordinance Code, to read:
74-6.012 Drainage Plan.
(a) When Required. A drainage plan is required for any building, structure or improvement
that requires a building permit and falls within one of the following categories:
(1) :Results in an impervious Surface of 1,000 square feet or more.
(2) Involves grading, or removal of vegetation down to bare soil by any method, of
more than 10,000 square feet.
(3) Is subject to local ponding due to soil or topographic conditions.
(4) Is located within a special flood hazard area, as defined in section 82-28.504.
(5) Involves land disturbance or structure placement within 100 feet of the top bank
of any watercourse shown with a blue line on the most current USGS seven and
one-half Minute quadrangle map.
(6) involves construction of 500 square feet or more on land where the slope exceeds
10 percent.
(7) Is located in an area identified by the County Building Official as having a history
of flooding or erosion that may be further aggravated by, or have a harmful effect
on, the construction or adjoining properties.
(b) Contents.
(1) A drainage plan shall include the following site information:•
ORDINANCE NO. 2007-01
1
(A) Flow lines of surface and subsurface waters onto and off of the site.
(B) Existing and finished contours, at two-foot intervals.
(C) T11e location of any existing buildillgS, structures or improvements on the
property where the work is to be performed and on adjacent lots.
(D) Sufficient information to demonstrate compliance with chapters 816-4 and
816-6.
(E) The location of all existing natural and man-made drainage facilities for
the storage or conveyance of runoff, including drainage swale..s, ditches,
culverts and berms, sumps, sediment basins, channels, ponds, storm drains
and drop inlets serving the site.
(2)' A drainage plan shall include the following drainage information:
(A) "Che location of all proposed natural and man-made drainage facilities for
the storage or conveyance of runoff, including drainage swales, ditches,
culverts and berms, sumps, sediment basins, channels, ponds, storm drains
and drop inlets.
(B) All surface and Subsurface drainage devices, walls, cribbing, dams and
other protective devices to be built with or as a part of the proposed
COi1St1-LIC11011.
(C) Hydraulic calculations that show the flow-carrying capacities of proposed
conveyance devices and justify the estimated i-unoff of the area served by
any proposed conveyance device.
(D) Discharges and velocities of proposed conveyance devices, aild storage
volumes of any Sumps, ponds or sediment basins.
(3) :Engineered drainage plans. A drainage plan shall be prepared by a registered civil
engineer if COnStruction is proposed for land where the slope exceeds 20 percent
or if the land is identified by the County .Building Official, based on the most
Current USGS seven and one-half minute quadrangle map or other published
sources, as having a history of unstable soil or landslides. An engineered
drainage plan shall include estimates of existing and increased runoff resulting
fi-on) proposed improvements and methods for reducing the velocity of any
increased runoff, in addition to all other information required by this section.
(4) Geotechnical reports. I.f a drainage plan shows that discharge resulting from the
proposed construction will occur over land where the slope
ORDINANCE NO. 2007-01
exceeds 20 percent or over land with a history of unstable soils,
then a geotechnical report shall also be prepared.
(c) . Procedures. A drainage plan shall be submitted with the building permit application.
Drainage plans shall be neatly and accurately drawn, at an appropriate scale that will
enable ready identification and recognition of submitted information. Drainage plans
shall be prepared in accordance with written standard specifications on file with the
County Building Official. A drainage plan is not considered approved until the County
Building Official approves the plan in writing.
(d) Violations.
(1) The failure to submit a required dfainage plan is a violation of this section.
(2) I'he failure to comply with an approved drainage plan, including the failure to
construct drainage improvements specified in an approved drainage plan, is a
violation of this section. (Ord. 2007-01 $2.)
SECTION III. EF'.FECT..iVE DATE. This ordinance becomes effective 30 days after passage,
and within 15 days after passage shall be published once with the names of supervisors voting
for or against it in the Contra Costa Times, a newspaper published in this County.
PASSED on JANUARY 23, 2007 by the following vote:
AYES: SUPERVISORS GI.OIA, UILKEMA, BONILLA, GLOVER AND PI:.EPH.O
NOES: NONE
ABSENT: NONE
ABSTAIN: NONE
ATTEST: JOHN CULLEN, MARY PIEPHO
Clerk of the Board of Supervisors Board Chair
and County Administrator
By: EMY SHARP
Deputy
ORDINANCE NO. 2007-01.
3