HomeMy WebLinkAbout1981-09-22 OrdinanceI
ORDINANCE NO. 81-3035
ORDINANCE AMENDING SECTION 8.10.24, AREA
REGULATIONS, OF THE ZONING ORDINANCE OF
THE CODE OF ORDINANCES OF IOWA CITY,
IOWA.
SECTION 1. PURPOSE. The purpose of this amendment
Ts to provide a standard to determine the minimum
lot area for a rooming house when located in a
multi -family zone.
SECTION 2. AMENDMENT. Section 8.10.24 of the Code
of Ordinances is hereby amended by adding the
following:
B. For every 330 square feet of total floor
area in a rooming house, the equivalent
minimum amount of lot area required for a
multi -family dwelling unit in the zone in
which the rooming house i;, located shall
be provided.
SECTION 3. REPEALER. All ordinances and parts of
ordinances to conflict with the provision of this
ordinance are hereby repealed.
SECTION 4. SEVERABILITY. If any section,
provision or part of the Ordinance shall be
. adjudged to be invalid or unconstitutional, such
ajudication shall not affect the validity of the
Ordinance as a whole or any section, provision or i
part thereof not adjudged invalid or 1
unconstitutional.
i
SECTION 5. EFFECTIVE DATE. This Ordinance shall j
be in effect after its final passage, approval and
publication as required by law.
Passed and approved this 22nd day of
I September 1981
MAYO
ATTEST:
C 2-&-Y LE
MICROFILMED BY
'JORM MICROLAB
CEDAR RAPIDS -DES 1401NES
IM
It was moved by vpvPra and seconded by Neuhauser
that the Ordinance as read be adopted and upon roll call there were:
AYES: NAYS: ABSENT:
x BALMER
x EROAHL
x LYNCH
x NEUHAUSER
x PERRET
x ROBERTS
x VEVERA
I
First consideration 8/25/81
Vote for passage: Ayes: Roberts, Vevera, Balmer,
Erdahl, Lynch, Neuhauser, Perret. Nays: None.
Second consideration 9/8/81
Vote for passage: Ay—e—si-Tynch, Neunauser, Perret,
Roberts, Vevera, Balmer, Erdahl. Nays: None.
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MICROFILMED DY
JORM MICROLAB
CEDAR RAPIDS•DES MOINES
City of Iowa Ci
MEMORANDUM
Date: September 17, 1981
To: City Council
From: Doug Boothroy, Senior Planner
Re: Amendments to the Zoning Ordinance Regulating Rooming Houses
Two zoning ordinance amendments regarding rooming houses are now being
considered by the Council. One ordinance amends the definition section of the
zoning code to provide consistency with the Housing Code. The other amends the
area regulations of the zoning code, changing the method of determining the
density for development of rooming houses. This latter amendment would improve
the method by which the density regulations are enforced by the use of a
standard based on square footage instead of total population. The present
standard "not more than 30 persons" is difficult to enforce in that head counts
are often inaccurate. Conceivably, higher population densities than permitted
could occur within rooming houses. A structure zoned multi -family could be used
as a rooming house, possibly resulting in higher population density than if it
were used for multi -family purposes. The new ordinance would also regulate a
rooming house at an equivalent density of a multi -family dwelling unit in the
zone in which the rooming house is located.
The amendment to the area regulations is based upon the following assumptions:
1) That rooming houses and multi -family dwelling units should be permitted at an
equivalent density. 2) That population density is better regulated by square
feet of floor area than total number of people per unit permitted. That a
specific amount of floor area would accommodate only a certain number of
occupants as regulated by the Housing Code. 3) That approximately 2.5 people
per dwelling unit can be assumed for multiple family structures notwithstanding
number of bedrooms. 4) That the minimum floor area per occupant, required by
the Housing Code for rooming houses, is a reasonable standard for determining an
equivalency between dwelling unit and rooming house. And, that total floor area
should also include the area within the rooming house used for hallways and
stairwells (approximately 10% of the floor area per floor in a typical rooming
house is used for hallways, etc.). Therefore, a dwelling unit with 2.5 people
is assumed to be equivalent to 330 square feet of floor area in a rooming house.
Based upon the above assumptions, a minimum of 330 square feet of total floor
area in a rooming house is used to determine the minimum amount of lot area
required. For example, in an R3A zone where the density requirement is 1000
square feet of land area per unit, a 6000 square foot lot would permit six
multiple family units or 1980 square feet of total rooming house floor area. A
rooming house would be permitted up to 15 occupants.
Existing rooming houses not meeting the standard would be "grandfathered".
However, this is not the case regarding compliance with the City's Housing Code.
bj3/3
V103
MICROFILMED BY
JORM MICROLAB
CEDAR RAPIDS•DES I40111ES
ORDINANCE NO. 81-3036
ORDINANCE AMENDING SECTION 8.10.3, DEFINITIONS, OF
THE CODE OF ORDINANCES OF IOWA CITY, IOWA.
SECTION I. PURPOSE. The purpose of this amendment
is to amend the—definition section of the zoning
ordinance by adding the following terms: roomer,
rooming house, rooming unit, and dwelling unit.
SECTION II. AMENDMENT. Section 8.10.3A of the
Code of OrdinaFc—esis hereby amended by the
following:
A. Section 8.10.3A.26a of the Code of Ordinances
is hereby amended by deleting said section and
replacing it with the following paragraph:
26a. Dwelling unit/living unit. Any
habitable room or group of adjoining
habitable rooms located within a dwelling
and forming a single unit with facilities
which are used or intended to be used for
living, sleeping, cooking, and eating of
meals.
B. Section 8.10.3A is hereby amended by adding
the following:
26b. Elderly housing. A residential
building(s) containing one or more
dwelling units especially designed for
use and occupancy of any person, married
or single, who is eligible to receive old
age benefits under Title 2 of the Social
Security Act; handicapped within the
meaning of Section 202 of the Housing Act
of 1959, Section 102(5) of the
Development Disability Services and
Facilities Construction Amendments of
1970 or Section 223 of the Social
Security Act; or relocated by
governmental action or disaster.
C. Section 8.10.3A of the Code of Ordinances is
hereby by deleting the following paragraphs:
46. Living unit. The room or rooms occupied
by a family provided that a living unit
must include a kitchen.
47. Lodging house. A dwelling containing not
more than one living unit, where lodging
with or without meals is provided for
compensation to five (5) or more persons,
but not more than thirty (30) persons.
MICROFILMED BY
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CEDAR RAPIDS•DES MOINES
a._
D• Section 8.10.3A is hereby amended by adding
the following paragraphs:
66. Roomer. An occupant of a rooming house
or rooming unit who is not a member of
the family of the rooming house operator.
A roomer shall also mean an occupant of a
dwelling unit who is not a member of the
family occupying the dwelling unit.
66a. Rooming house/lodging house. Any
dwelling, or that part of any dwelling,
containing one or more rooming units, in
which space is let by the owner or
operator to three (3) or more roomers.
Occupants of units specifically
designated as dwelling units within a
rooming house shall not be included in
the roomer count.
66b. Rooming unit. Any habitable room or
group of adjoining habitable rooms
forming a single unit with facilities
which are used, or intended to be used,
primarily for living and sleeping, but
not for cooking or eating of meals.
SECTION III. REPEALER. All ordinances and parts
of ordinances in conflict with the provision of
this ordinance are hereby repealed.
SECTION IV. SEVERABILITY. If any section,
provision or part of the Ordinance shall be
adjudged to be invalid or unconstitutional, such
ajudication shall not affect the
Ordinance validity of the
as a whole or any section, provision or
part thereof not adjudged inva
tutional. lid or unconsti-
SECTION V. EFFECTIVE DATE. This Ordinance shall
be in effect after its final passage, approval and
publication as required by law.
Passed and approved this 22nd day of September, 1981
7 �
ATTEST:
CIT CLEf�
MICROFILMED BY
JORM MICROLAB
CEDAR RAPIDS -DES MOINES
Received ?. Ap?;
By a Legal Departr:;; l
/Ya4
It was moved by Perret and seconded by Vevera
that the Ordinance as read e adopted and upon roll cal t ere were:
AYES: NAYS: ABSENT:
x BALMER
x ERDAHL
x LYNCH
x NEUHAUSER
x PERRET
x ROBERTS
x VEVERA
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Moved by Perret, seconded by Vevera that the rule
requiring that ordinances must be considered and
voted on for passage at two Council meetings
prior to the meeting at which it is to be finally
passed be suspended, that the first and second
consideration and vote be waived, and that the
ordinance be voted upon for final passage at this
time. Affirmative roll call vote unanimous, 7/0,
all Councilmembers present.
i
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IYo�
MICROFILMED BY
`JORM MICRO_ LAB
CEDAR RAPIDS -DES MOINES
\
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It was moved by and seconded by /
that the Ordinance,as read be adopted and upon roll call there were:
AYES: NAYS: ABSENT:
BALMER
ERDAHL
LYNCH
— NEUHAUSER
— PERRET
_ ROBERTS
VEVERA
First consideration 8/25/81
Vote for passage: Aye's: Perret, Roberts, Vevera,
Balmer, Erdahl, Lynch, Neuhauser. Nays: None.
Second consideration 9/8/
Vote for passage: Ayes: r ynch, Neuhauser,
Perret; Roberts, Vevera, Balmer. Nays: None.
j MICROFILMED BY
,JORM MICROLAB
CEDAR RAPIDS -DES MOINES
i
(ieceived A Approved
`yrne Legal Degarfinent
i
ORDINANCE NO.
ORDINANCE AMENDING SECTION 8.10.3, DEFINITIONS, OF
`SHE OF ORDINANCES OF IOWA CITY, IOWA.
SE ION I. PURPOSE. The purpose of /he
amendment
is t amend the definition section zoning
ordin ce by adding the following t roomer,
roomin house, rooming unit, and dwe ing unit.
j SECTION I . AMENDMENT. Section .10.3 of the Code
i
of Ordinan s is hereby amended the following:
A. Section 8.10.3 26a of t Code of Ordinances
is hereb amended by de ting said section and
replacing it with the f llowing paragraph:
26a. Dwel ing un t/living unit. Any
habitab a roo or group of adjoining
habitab roo located within a dwelling
and form g a single unit with facilities
which are s d or intended to be used for
living, sl ing, cooking, and eating of
meals.
B. Section 8.10.3 is reby amended by adding the
following:
26b. Elder y hous g. A residential
buildi g(s) cont ining one or more
dwell' g units es cially designed for
use a d occupancy o any person, married
or s'ngle, who is eli ible to receive old
age enefits under Ti e 2 of the Social
Sec rity Act; handic ped within the
me ning of Section 202 o the Housing Act
of 1959, Section 1 (5) of the
D velopment Disability ervices and
F cilities Construction endments of
970 or Section 223 of the Social
ecurity Act; or rel ated by
governmental action or disaste
C. Sec ion 8.10.3 of the Code of Ordin ces is
her by by deleting the following paragr h:
46. Living unit. The room or rooms occ ied
by a family provided that a living it
must include a kitchen.
D. Section 8.10.3 is hereby amended by adding the
following paragraphs:
66. Roomer. An occupant of a rooming house
or rooming unit who is not a member of
MICROFILMED BY
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the family of the rooming house operator.
A roomer shall also mean an occupant of a
dwelling unit who is not a member of the
family occupying the dwelling unit.
66a. Rooming house/lodging house. Any
dwelling, or that part of any dwelling,
containing one or more rooming units, in
which space is let by the owner or
operator to three (3) or more homers.
Occupants of units spe fically
signated as dwelling units / ithin a
r ming house shall not be 'hcluded in
the roomer count.
f
66b. Roo 'ng unit. Any habi able room or
group of adjoining h itable rooms
forming a single unit ith facilities
which ar used, or in nded to be used,
primarily for living nd sleeping, but
not for coo ing or ea ng of meals.
SECTION III. REPEALER. All ordinances and parts
of ordinances in confl t ith the provision of
this ordinance are hereby ealed.
SECTION IV. SEVERABILIT If any section,
provision or part of the Ordinance shall be
adjudged to be invali or u onstitutional, such
ajudication shall no or
he validity of the
Ordinance as a whole or any se tion, provision or
part thereof not judged inv id or unconsti-
tutional.
SECTION V. EFFEC IVE DATE. This 0 dinance shall
be in effect aft r its final passage, approval and
publication as r quired by law.
Passed and appilved this
ATTEST:
j MICROFILMED BY
'JORM MICROLAB
CEDAR RAPIDS -DES NOINES
MAYOR
Received i Approved
By The legal Drpartmenf
eon*-✓ �'-ef-'P /
/94*,o
_19
7
ORDINANCE NO. 76-2807
AN ORDINANCE REGULATING THE RATE OF DISCHARGE OF STORM WATER RUNOFF:
SPECIFYING CRITERIA FOR DETERMINING RUNOFF RATES: ESTABLISHING DEVELOP-
MENT STANDARDS FOR THE CONSTRUCTION OF RUNOFF CONTROL FACILITIES: AND
SETTING FORTH PROCEDURES FOR THE ADMINISTRATION THEREOF.
SECTION I. PURPOSE.- It is the purpose of this ordinance to establish
maximum rates for the discharge of storm waters into the various watercourses
of the City for the purpose of promoting the health, safety and general welfare of
the papulation by minimizing or eliminating dangers of flooding to life and
property.
It is further the intent of this ordinance that runoff control devices be
provided as areas of land are developed or redeveloped for urban use. It is not
the intent -of this ordinance to utilize areas for the sole purpose of storing or
detaining excess storm water, but to permit such areas to be used for other
compatible urban uses as well.
SECTION II. DEFINITIONS.
A. Storm Water Runoff. Water that results from precipitation which is not
absorbed by soil or plant material.
B. Natural Drainage. Water which flows by gravity in channels formed by
the surface topography of the earth prior to changes made by the efforts of man.
C. Excess Storm Water. That portion of storm water runoff which exceeds
the transportation capacity of storm sewers or natural drainage channels serving
a specific watershed.
D. Excess Storm Water Passage. A channel formed in the ground surface to
carry storm water runoff through a specific area.
E. Storm Water Runoff Release Rate. The rate at which storm water runoff
is released from dominant to servient land.
F. Storm Water Storage Area. An area designated to temporarily accumulate
excess storm water.
G. Tributary Watershed. The entire catchment area that contributes storm
water runoff to a given point.
H. Dry Bottom Storm Water Storage Area. A facility that is designed to
be normally -dry and which accumulates excess storm water only during periods when
the restricted storm water runoff release rate is less than the storm water inflow
rate.
I. Wet Bottom Storm Water Storage Area. A facility that contains a body of
water,and which accumulates excess storm water during periods when the restricted
storm water runoff release rate is less than the storm water inflow rate.
a. Control Structure. A facility constructed to regulate the volume of
storm water runoff that is conveyed during a specific length of time.
lWY
MICROFILMED BY
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CEDAR RAPIDS -DES MOINES
Vi_
Ordinance No. 7b-2
page 2
K. Positive Gravity Outlet. A term used to describe the drainage of an
area in a manner that will ensure complete removal of all surface water by means
of natural gravity.
L. Safe Storm Water Drainage Capacity. The quantity of storm water runoff
that can be transported within a channel,passage, conduit, tube, duct, or com-
bination thereof in such a manner that the elevation of the water. does not rise _
sufficiently above the level of the adjacent ground surface so as to cause
damage to structures or facilities located thereon.
M. Low Flow. The transport or flow of a normal or usual volume of storm
water as opposed to a high or peak volume which would utilize overflow facilities.
17. City. The City of Iowa City, Johnson County, State of Iowa.
0. Director of Public Works. The Director of Public Works or his/her
designate.
SECTION III. REGULATIONS. I The Department of Public Works of the City of
Iowa City, Iowa, shall develop and establish written policies, procedures,
criteria and regulations concerning the inspection, determination and approval
of the standards for the construction and/or development of storm water manage-
ment structures.
Such rules and regulations shall be adopted by resolution by the City Council.
SECTION IV. ADMINISTRATION.
A. Prior to the construction of any storm water control structure or orm
water deten facility on the construction or development site, the d oper
shall obtain a b ding permit. No such permit shall be issued unt' the following
documents have been itted to the Director of Public Works a approved:
i� 1. Plans and prow methods for the preve on and,control of
soil erosion.
O.
2. Plans, specifications and culations for the control of
storm water runoff as required this ordin a and any rules and regula-
tions promulgated by the D' tor.
WB. No building its for habitable structures shall be sued for any
1. development or re elopment not complying with this ordinance.
` C. y decision of the Director shall be pursuant to written specifi -
tion ad regulations as adopted by the City Council.
SECTION V. ADMINISTRATIVE REVIEW. Any person affected by any decision of
the Director which has been given in connection with the enforcement of any
provision of this ordinance ray request, and shall be granted, a hearing on the
matter before the Housing Appeals Board, provided that such person shall file in
the office of the Director a written petition requesting such hearing and setting
forth a brief statement of the grounds therefore. Upon receipt of such petition,
the Director shall set a time and place for such hearing and shall give the
petitioner written notice thereof. At such hearing, the petitioner shall be given
an opportunity to be heard and to show why such decision should be modifi-d or
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Paye 3
withdrawn. The hearing shall be commenced not later than thirty (30) days after
the date on which the petition was filed.
After such hearing, the Housing Appeals Board shall sustain, modify or with-
draw the decision of the Director, depending upon its findings. The proceedings
at such hearing, including the findings, and decision of the Housing Appeals
poard, shall be summarized, reduced in writing and entered as a matter of public
record in the office of the Director. Such record shall also include a copy of -
every notice or order issued in connection with the matter. No hearing shall be
valid unless a majority of the Board is present and no decision at a hearing
shall be valid and binding unless reached by a majority of the whole Board.
Following the decision of the Housing Appeals Board, all parties shall be notified
of the decision by delivery to them of a copy of such decision by personal service
or by certified mail, return receipt requested. Any person aggrieved by the deci-
sion of the Housing Appeals Board may seek relief therefrom in any court of
competent jurisdiction, as provided in the laws of this State. An appeal pursuant
to this section shall not stay the effect of the Director's order unless so
ordered by the Housing Appeals Board.
SECTION VI. APPLICATION. This ordinance shall apply to any residential
development comprising a gross aggregate area of two (2) acres or more or to any
commercial, industrial, institutional, governmental, utility or other development.
or redevelopment comprising a gross aggregate area of one (1) acre or more. The
gross aggregate shall include streets and other dedicated lands.
SECTION VII. EMERGENCY. Notwithstanding any other provisions of this
ordinance, whenever in the judgment of the Director of Public Works a condition
occurs in a storm water. storage area. that creates a dangerous and imminent health
and safety hazard, the Director shall order such action as shall be effective
immediately or in the time and manner prescribed in the order itself.
SECTION VIII. GENERAL REQUIREMENTS.
A. Storm Water Release Rate. The controlled release rate of storm water
runoff shall not exceed the existing safe storm water drainage capacity of the
downstream system as determined by the Director. The release rate shall be the
average value computed with excess storm water representing 50% of the available
storage volume.
Such release rate shall be computed as a direct ratio of the area of the
tributary watershed and shall not exceed 0.15 cubic feet per second per acre
drained.
Where a proposed development contains only a portion of a watershed or
portions of several watersheds, 'storage requirements shall
be based upon the proportion of the area being developed as compared to the entire
watershed tributary to the proposed storage area.
Where it can be demonstrated by the Developer that a higher storm water
release rate will not be contrary to the purpose and intent of this ordinance and
where such proposed release rate will not adversely affect properties in the down-
stream portion of the watershed, the Director may permit such release rate to be
used as deemed appropriate.
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Ordinance No. 76-28
Page 4
B. P.xcnss Storm Water Passage.
1. An excess storm water passage shall be provided for all storm
water storage areas. Such passage shall have capacity to convey through
the proposed development the excess storm water from the tributary water-
shed. The capacity of such excess storm water passage shall be constructed
in such a.manner as to transport the peak rate of runoff from a 100 year
return frequency storm assuming all storm sewers are inoperative, all upstream
areas are fully developed in accordance with the City's current land use
plan, and that antecedent rainfall has saturated the tributary watershed.
2. No buildings or structures shall be constructed within such
passage, however, streets, parking lots, playgrounds, park areas, pedestrian
walkways, utility easements and other open space uses shall be considered
compatible uses. In the event such passageway is reshaped or its capacity to
transport excess storm water otherwise restricted, the Director shall notify
the agency, party or parties causing said restriction to remove the same,
and set a Keasonable time for its removal. If said presons refuse to or are
unable to comply with said order, the Director shall cause said restrictions
removed at the expense of said persons.
3. Where a proposed development contains existing natural drainage,
appropriate land planning shall be undertaken to preserve said natural drainage
as part of the excess storm water passage. '
known atb "E VFC%76, Chou> M4604
C. Determination of Stora a Caoacit . The volume of required storm water
storage shall be calculated on the basis the runoff from 100 year return
frequency storm. Such calculation shal be made in accordance with the hydro -
graph method of analysis
"96P, or other method approved by the Director. The applicable storm water
.runoff release rate shall be considered when calculating the required storm water
storage capacity.
D. Compensating Storage. in the event the orderly and reasonable develop-
ment of an area requires the storage of excess storm water to be located elsewhere,
compensating storage (the storage of an equal volume of excess storm water) may
be provided at an alternative location provided, however, that the feasibility and
details of storm water control shall be approved by the Director.
E. Easements. Easements which cover excess storm water passages, storm
water storage areas and other control structures shall be granted to the City for
the purpose of repair, alteration or to insure their.proper operation, however,
the City shall reserve the right not to accept such easement or any portion
thereof.
SECTION IX. DRY BOTTOM STORM WATER STORAGE AREAS.
A. Design Criteria.
1. Primary and Secondary Uses. Dry bottom storm water storage areas
shall be designed to serve a secondary purpose for recreation, open space,,
parking lot, or similar type of use that will not be adversely affected by
occasional intermittent flooding.
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Ordinance No. 7 6-7-k07
Page 5
2. Drain System. A system of drains shall be provided to transport
low flow storm water runoff through storage areas. Such drainage systems
shall have a positive gravity outlet to a natural passage or storm drain
with adequate capacity as described in Section VIII, subsection B.
Multiple outlets from a storm water storage area are to be avoided
if the outlets are designed to be less than four (4) inches in diameter.
3. Storage Duration. The combination of storage of excess storm water
runoff from a 100 year return frequency storm and the allowable release
rate shall not result in a storage duration in excess of forty-eight (48)
hours.
4. Grades. Where turf areas are used for the bottom of dry bottom
storage areas, the minimum grades for such areas shall be two (2) pnrcent
(5C units horizontal to 1 unit vertical). Maximum side slopes for turf
shall be twenty-five (25) percent (4 units horizontal to 1 unit vertical).
Storage area side slopes shall follow the natural land contours in order to
minimize the amount of earth work necessary to create the.storage facility.
S. Brosion Control. Erosion control measures consisting of mulch,
hydro -seeding, nurse crops, sod installation or other approved means shall
be utilized to control soil movement within and -around the storage basin.
Energy dissipating devices or stilling basins shall be provided to
ensure that downstream soil erosion is alleviated and the regime of the down-
stream drainage facility is not disturbed.
6. Control Structures. Control structures shall be designed as simple
as possible and shall not require manual adjustments for normal operation.
Control structures shall be designed to maintain a relatively uniform flow
independent of storm water storage volume. Inlet structures shall be
constructed in such a manner to prevent high velocity flow, to provide for
the interception of trash and debris and for soil erosion control. Inlets
shall be designed to eliminate turbulent flow conditions during any portion
of the storm water storage cycle.
Overflows for each storm water storage area shall be provided in
the event a storm in excess of the design capacity occurs. Such overflows
shall be constructed to function without specific attention and shall become
part of the excess storm water passage.
SECTION X. WET BOTTOM STORM WATER STORAGE AREAS.
A. Design Criteria. Wet bottom storm water storage areas shall be designed
in accordance with the design criteria governing the construction of dry bottom
storm water storage areas, except for drains as required by Section IX.A.2.
The following additional regulations shall apply:
1. Construction. The water surface area shall not exceed 1/10 of
the tributary watershed. Minimum normal water depth, shall be four (4) feet.
If fish are to be used to keep the pond clean, at least 1/4 of the pond
area shall have a minimum depth of ten (10) feet.
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Page 6
Facilities shall be provided to lower the pond elevation by
gravity flow for cleaning purposes and land/water interface maintenance.
Protection of the land/water interface shall be provided to alleviate soil
erosion due to wave action.
2. Control Structures. Control structures for storm water release
shall operate at their maximum rate with only minor increases in the water
surface level.
3. Stagnation Control. Measures shall be included in the design to
prevent pond stagnation. Such measures may include fountain aeration or
other approved means to ensure aerobic pond conditions.
4. Determination of Storage Capacity. When calculating the storage
capacity of wet bottom storage areas, only the volume available to store
excess storm water shall be considered. Permanent water storage does not
constitute control of excess storm water runoff.
SECTION XI. MISCELLANEOUS STORM WATER STORAGE AREAS.
A. Paved Surfaces. Paved surfaces, including automobile parking lots in
proposed storm water storage areas shall have minimum grades of one (1) percent
(100 units horizontal to one (1) unit vertical) and shall be limited to storage
depths of one and one-half (1-1/2) feet maximum. Pavement base design and construc-
tion shall be accomplished in such a manner as to prevent damage from flooding.
Control structures in paved areas shall be accessible for maintena::ce and clean-
ing. The use of vortex control facilities at inlets to ensure that the maximum
allowable release rates are being developed shall be required as necessary.
Where parking areas are used to store storm water, the areas of greatest
depth shall be restricted to the more remote, least used areas of the parking
facility.
B. Rooftop Surfaces. Rooftop storage of excess storm water shall be designed
with permanent -type control inlets and parapet walls to contain excess storm water.
Adequate structural roof design shall be provided to ensure that roof deflection
does not occur which could cause roof failure. Overflow areas shall be provided
to ensure that the weight of stored storm water will never exceed the structural
capacity of the roof.
C. Underground Storage. Underground storm water storage facilities shall
be designed for easy access to accommodate the removal of accumulated sediment.
Such facilities shall be provided with positive gravity outlets.
SECTION XII. CONTROL IN EXCESS OF REQUIREMENTS -
Provision of Control Exceeding Requirements. In the event storm water
runoff control can be provided in excess of the requirements of this ordinance
and the benefit of such additional control would accrue to the City of Iowa City
at large, the City may provide public participation in the increased cost c'_
the control of storm water runoff in proportion to the additional benefits
received.
MICROFILMED BY
'JORM MICROLAB
CEDAR RAPIDS -DES I401NES
i'-
Ordinance No.
Page 7 -- —
SECTION XIII. REPEALER. All ordinances or parts of ordinances in conflict
with the provisions of this ordinance are hereby repealed.
SECTION XIV. SEVERABILITY CLAUSE. If any section, provision or part of
the ordinance shall be ajdudged to be invalid or unconstitutional, such adjudi-
cation shall not affect the validity of the Ordinance as a whole or any section, ;
Provision or part thereof not adjudged invalid or unconstitutional.
SECTION XV. EFFECTIVE DATE. This ordinance shall be in effect after its
final Massage, approval and publication as required by law. ,
deProsse Perret
It was moved by and seconded by
that the ordinance be finally adopted, and upon roll call there were:
ALES: NAYS: ABSENT:
x Balmer
y deProsse
x Foster
X Neuhauser
x Perret
x Selzer
x Vevera
ATTEST: 7a.
city Clerk
Mayor
First Consideration 8/24/76
Vote for passage: Neuhauser, Vevera, deProsse, Foster: Aye.
Selzer, Balmer: Nay.
Perret: Absent.
Second Consideration
/31/76
Vote for passage: Foster, Neuhauser, Perret, Vevera, deProsse:
Selzer, Balmer: 11Nay. None absent
Date of Publication �¢plewtUer 30t/Q7lP
Passed and approved this 7th day of September , 1976.
MICROFILMED BY
'JORM MICRO_ LAB
CEDAR RAPIDS -DES MOINES
Aye
ORDINANCE NO. 76-2816
AN ORDINANCE A_W"MiNG ORDIIC-iVCE N0, 76-2807 R'rDCH REGULATES THE
RATE OF DISaWRE OF STORM IQAT-rR RUNOFF BY E_NACPING A NEIL EFF=-
TIVE DATE OF SAID ORDINANCE AND REPEALING SECTION XV OF ORDINANCE
NO. 76-2807.
SECTION I. PURPOSE. The purpose of this ordinance is to amend Ordinance
No. 76-2807 which regulates the rate of discharge of storm water runoff by enacting '
a new effective date for said regulations.
SECTION II. AMNUIIET- Section XV shall now state as follows:
This Ordinance shall became effective on the 6th day of November,
1976.
SFxTION III. REPEALER. Section XV of Ordinance No. 76-2807 is hereby repealed
and all ordinances or parts of ordinances in conflict with the provisions of this
ordinance are hereby repealed.
SECTION IV. EFFrMT& DATE. This Ordinance shall be in effect after its
final passage, approval and publication as required by law.
It was :roved by Balmer and seconded by deProsse
that the Ordinance be finally adopted, and upon roll call there were:
AYES: NAYS:
ABSENT:
x
Balmer
x
deProsse
x
Foster
x
Neuhauser
x
Perret
x
Selzer
x
Vevera
ATTEST:_0,//
L A
e Mayor
City Clerl
First Consideration
It was moved by Balmer and seconded by deProsse that the rule
requiring the Ordinance to be considered and voted on for
passage at two Council meetings prior to the meeting at
Second Consideration
which it is to be finally passed be suspended, the first and
second consideration and vote be waived, and that the Ordi-
nance he voted upon for final passage at this time. Pall call:
Date of Publication
deProsse, Foster, Neuhauser, Perret, Selzer, Vevera, Balmer: Aye
Nays: none. Nation adopted, 7/0.
Passed and approved this 2nd day of November 19 76
,
3117
MICROFILMED BY
JORM MICROLAB
CEDAR RAPIDS -DES MOINES
1"-
CRDINANCE NO. 77 -?i: bb
A )RDiNANCE AMENDING THE ADMINIST ION
AND PROCEDURES AS STATED FORTH IN
ORDINANCE NO. 76-2807 WHICH REGULATED
THE RATE OF DISCHARGE OR STORM WATER RUN-
OFF.
Section 1. Purpose. The purpose of this ordiance is
to clarify and make more specific the administration
of the various regulations and procedures as set
forth in the storm water management ordfnance,Ordi
nance No. 76-2807,
Section 2. Amendment. Section IV of Ordinance No.
76-2807 shall now read as follows:
SECTION IV, ADMINISTRATION,
A. Immediately after preliminary plat appro-
val, preliminary P:A,D, LSRD, or LSNRD
approval, or building permit approval, which-
ever comes first, and in all cases before
site work begins, the developer shall submit
the following documents to the Public Works
Director for approval:
1. Plans and proposed methods for the
prevention and control of soil erosion for
the entire development.
2. Plans, specifications, and all calcula-
tions for the control of storm water runoff
as required by this ordinance and any rules
and regulations promulgated by the Director.
B. The original developer shall be responsible
for the implementation and performance of ero-
sion control measures for the time span from the
start of preliminary grading until sale of lots '
or land to a purchaser. After commencement of
lot or land sales, the actual owner of any lot
or land within a development shall be respon-
sible for the prevention and control of soil
erosion for that parcel of land.
C. No building permits for habitable structures
shall be issued for any development or rede-
velopment not complying with this ordinance.
D. Any decision of the Director shall be pur-
suant to written specifications and regulations
as adopted by the City Council.
Section 3. Repealer. Section IV of Ordinance No.
76-2807 is hereby repealed and any and all ordi-
nances or parts of ordinances in conflict with the
provisions hereof are hereby repealed.
MICROFILMED BY
'JORM MICROLAB
CEDAR RAPIDS -DES 140INES
/ y/s
I
L.,.
Section 4, Severability. I.f any section, provision
or part of the Ordinance shall be adjudged to be
invalid or unconstitutional, such adjudication shall
not affect the validity of the ordinance as a whole
or any section, provision or part thereof not adjud-
ged invalid or unconstitutional.
Section 5. Effective Date, This Ordinance shall
be in effect after its final. passage, approval and
publication as required by law.
Passed and adopted thisl3th day of September, 1977.
J" ibIJAW-ti
NARY C. E HAUSER, MAYOR
ATTEST:
j !
E STOLFUS,,LITY CLERK
e
It was moved by Foster and
seconded by Perret that the Ordi-
nance be adopted, and upon roll call there were:
AYES: NAYS: ABSENT:
x Balmer
_x deProsse
x Foster.
x Neuhauser
x Perret
x Selzer
x Vevera
i
1st consideration8/30/77
Vote for passage: Ayes: Balmer, deProsse, Foster, Neuhauser
Perret, Vevera. Nays: none. Absent: Selzer.
2nd consideration 9/6/77
Vote for passage: Ayes: Foster, Neuhauser, Perret, Selzer,
Vevera, Balmer, deProsse. Nays: none.
Date of Publication
p.ECEIVSD .t +?`_'im-D
gj UM LECAL DEPA.Fi.`1.-.IiT
�i.t..l%...._
MICROFILMED BY
'JORM MICROLAB
CEDAR RAPIDS -DES MOINES
0
-AG
yrs
7
vf:,_
APPENDIX 'A'
B. Calculate the capacity of the drainage system under various
hydraulic conditions or establish an acceptable release rate
(0.15 cfs per acre maximum). Plot the value on the form so
that it forms an overlay of the curves established in
paragraph 7 above.
9. Determine the area between the various frequency curves and
the release rate for an eight (8) hour storm measured in
square inches. Establish the volume of storage contained
in one (1) square inch by multiplying the appropriate value
of quantity and time with conversion factors to produce the
answer in acre feet. Calculate the storage requirement by
multiplying the area between the curves by the conversion
factor to produce acre feet. Record the required volume
of storage in the appropriate column on the hydrologic
studies form for the various frequency storms.
10. These values represent an estimate of the volume that
should be provided to contain excess storm water runoff
from the various return frequency storms. While a rigorous
examination of the method will indicate that it is a con-
servative approach to predicting excess storm water runoff,
it is straight forward and the results are within acceptable
limits.
B. Determination of estimated recurrence.
1. Determine percentage of runoff or use information on com-
posite 'N' value from the hydrologic studies form. Compute
the average runoff and record values on the spaces adjacent
to 'Impervious Average Runoff' in the second column of the
estimated recurrence form.
2. The annual number of events for the Iowa City area and the
recurrence interval were computed from an analysis of rain-
fall events using Ralston @2 records of the U.S. Weather
Bureau. This data could be further refined by using addi-
tional records, however, for this purpose the six (6) year
period should be adequate. The estimated average duration
of the storm was established to match the rainfall inten-
sity vs. duration curves found in Figure A-5.
3. Examination of the proposed control structure used to
regulate the discharge of storm water runoff from a storage
area will have a specific release rate that can be calculated.
The quantity of storm runoff released will vary, depending
on the head available from the excess storm water being
stored. This variation should be minimized and the design
modified so that it becomes as uniform as possible. Divide
the quantity of discharge by the acreage being drained,
this will be expressed as cfs/acre. Within a factor of 0.834
this value is equal to inches/hour. Multiply this value by
MICROFILMED BY
JORM MICROLAB
CEDAR RAPIDS -DES MOINES
ESTIMATED RECURRENCE
VOLUME OF STORM WATER STORAGE
VOLUME (ACRE FT.)
MICROFILMED BY
JORM MICROLAB
CEDAR RAPIDS -DES 1401NES
HOURS TO DRAIN
/Ws,
-.7
AREA
DATE
*EXTRACTED FROM
USWB
RALSTON
#2 1969
THRU 1975
RAINFALL
RECORDS
TOTAL
IMPERVIOUS
ANNUAL
RECURRENCE INTERVAL
ESTIMATED
AVERAGE
AVERAGE
RAINFALL
AVERAGE
NO, OF
AVERAGE
RUNOFF (IN.)
STORAGE
(IN.)
RUNOFF
(IN.)
EVENTS
c
DURATION
RELEASED
REQUIRED
STORMS
CUMULATIVE(HOURS)
VHR.
INCHES AC. FT.
0.0-0.1
0.05 _
22.1
26.0
26.0
0.1 - 0.2
0.15
14.9
18.0
44.0
0.50
0.2 - 0.4
0.30 _
16.3
19.0
63.0
0.50
0.4- 0.6
0.50
10.2
12.0
75.0
0.50
0.6-0.8
0.700.75
_
5.6
7.0
82.0
0.8- 1.0
0.90
5.3
6.2
88.2
1.00
1.0- 1.5
1.25
6.0
7.1
95.3
1.25
1.5-2.0
1.751.50
_
2.05
2.4
97.7
2.0- 3.0
2.50
1.80
2.1
ANNUAL
2.00
3.0- 4.0
3.50
0.13
0.15
(5- 10 YEAR)
2.50
4.0- 5.0
4.50
0.03
0.04
(25-50 YEAR)
3.00
OVER 5.0
5.00
0.01
0.01
(100 YEAR)
4.00
5.00
VOLUME (ACRE FT.)
MICROFILMED BY
JORM MICROLAB
CEDAR RAPIDS -DES 1401NES
HOURS TO DRAIN
/Ws,
-.7
i__
FIGURE A-5
RAINFALL INTENSITY VS.
DURATION (IOWA CITY)
24
OIT N
O p
RAINFALL INTENSITY(
(INCHES PER HOUR)
MICROFILMED BY
JORM MICROLAB
CEDAR RAPIDS -DES I401NES
-.7
the estimated average duration and record the answer
in the appropriate space in column 7, headed 'Average
Runoff (in.) Released.'
4. Subtract the value recorded in column 7 from the value
recorded in column 2 and place the answer in the appropriate
space in column 8.
5. Convert the figures in column 8 into acre feet by multiply-
ing by the catchment area in acres and dividing by 12.
Record the answer in column 9.
6. Examine the proposed storm water storage basin and calcu-
late the volume of storage being provided vs. the depth
of storage. Determine appropriate values for the storage
elevation and volume"in acre feet to utilizethe total
grid pattern in the lower left hand portion of the form.
Plot specific conditions of the storage facility on this
grid and.connect with a best -fit curve.
7. Review the data contained in column 9 and establish reference
points on the curve for significant storms, e.g. 80%
annual, 5-10 year,. 25-50 year, 100 year: Designate these;
Points on the curve for 'reference.
8. Calculate the hours needed to drain the storage basin
at the release rates established for column 7. Determine
appropriate values to utilize the total grid system in the
lower right portion of the form and plot a curve of best -
fit for these values. Again examine the data in column 9
and establish reference points on this curve for the same
significant storms.
9. These data can be used to establish flood limits for various
storms, determine overflow events, and explain the duration
of storage for various storms. It should be noted that the
majority of storms will require little or no storage, and
that storage will be required for extremely brief periods
following the storm.
/yrs
MICROFILMED BY
'JORM MICROLAB
CEDAR RAPIDS•DES MOINES
MICROFILMED BY
'JORM MICROLAE3
CEDAR RAPIDS•DES' MOINES
4
Revisions to Design Standards for Public Works Improvements
Iowa City, Iowa
Section VII - Storm Sewers Appendix 'B'
Values of N.to be used with Kutter
or Manning Formulas*
Condition
Type of Surface
New
Goo3-Fair
Poor
Cast iron pipe
0.013
0.014
0.015
0.020
Wrought iron pipe
0.013
0.014
0.015
0.016
Brass or glass pipe
0.009
0.010
0.011
0.013
Smooth plastic pipe**
0.010
0.011
0.012
0.013
Riveted spiral steel pipe
0.013
0.015
0.017
0.019
Corrugated metal pipe**
0.020
0.025
0.027
0.030
Concrete pipe
0.013
0.015
0.017
0.020
Vitrified clay pipe
0.013
0.014
0.015
0.018
Common'clay pipe
0,013
0.015
0.017•.0'.020
Asbestos cement pipe**
0.013
0.014
0.016
0.018
Concrete lined channel
0,013
0.014
0.016
0.018
Rubble.lined channel
0.017
0.020
0.025
0.030
Straight earth channel
0.017
0.020
0.023
0.025
Winding earth channel
0.022
0.025
0.028
0.030
Dredged earth channel
0.025
0.027
0,030
0,033
Earth bottom, rubble side
channel
0.028
0.030
0,033
0.035
Clean, straight natural
stream
0,025
0.027
0,030
0.033
Weedy, straight natural
stream
0,030
0.033
0.035
0.040
Winding, clean natural
stream
0,033
0,035
0.040
0,045
Winding, weedy natural
stream
0.035
0.040
0,045
0.050
IfIls
j MICROFILMED BY
'JORM MICROLAB
CEDAR RAPIDS -DES MOINES
�l
Condition
.Type of Surface New Good 'Fair Poor
Sluggish, large natural
stream 0.050 0.060 0.070 0.080
Sluggish, weedy natrual
stream 0.075 0.100 0.125 0.150
"Adapted from Handbook of Applied Hydraulics by C. v. Davis,
Table compiled by x. tnd
. Horto
.'
"Values from manufacturer's recommended design factors.
i MICROFILMED BY
'JORM MICROLAB
'CEDAR RAPIDS -DES MOINES
I F
MICROFILMED By
'JORM MICROLAB
CEDAR RAPIDS•DES�MOINES
Revisions to Design Standards for Public Works Improvements
Iowa City, Iowa
Section VII - Storm Sewers Appendix 'C'
Acceptable storage of excess storm water runoff may be accomplished
in numerous ways. Each of these methods should be examined to pro-
vide the specific project with the maximum advantage, least cost of
construction and minimum of inconvenience.
To aid in the design of acceptable measures for reducing and
delaying urban storm runoff in Iowa City the following grouping
of methods and accompanying advantage and disadvantage list has
been excerpted from the Soil Conservation Service Technical
Release No 55. These methods are listed to provide a point of
reference for investigating alternative means of compliance with
the Iowa City Storm Water Control Ordinance.
The disadvantages of each control method are listed for the primary
purpose of providing both the design and review engineer with data
to investigate each control measure used, and develop an acceptable
solution for each potential difficulty. In all of these recommended
measures, the matter of economic construction should be stressed.
Economics in construction does not mean the use of insufficient
materials or reduced quality, but additional investigation of
alternatives is required to determine the most efficient and
acceptable use of the materials and resources available on the
construction site.
Methods used to control runoff in urbanizing areas reduce the
volume and/or the rate of storm water runoff. The effectiveness
of any control method depends upon the availability of potential
storage, the inflow rate and the outflow rate. Because a great
variety of methods can be used to control peak storm water
flow, each method suggested should be evaluated for both effective-
ness and acceptability for the given project. Effective and accep-
table measures for reduction of peak runoff rates are, of course,
not limited to those listed.
The details for the construction of each method suggested are
most important. These details should be carefully examined to
ensure that greater problems are not created by the construction
of a control device than are solved.
/4//S
MICROFILMED BY
JORM MICROLAB
CEDAR RAPIDS -DES MOINES
MEASURES FOR REDUCING AND DELAYING URBAN STORM RUNOFF
AREA REDUCING RUNOFF DELAYING RUNOFF
Large flat roof 1. Cistern storage 1. Ponding on roof by constricted
2. Pool or fountain storage downspouts
2. Increasing roof roughness
a. rippled roof
b. gravelled roof
Parking lots 1. Porous pavement
2. Concrete vaults and cisterns
beneath parking lots in high
value areas
3. Vegetated ponding areas around
parking lots
4. Gravel trenches
Residential 1. Contoured -landscape
2. Ground -water recharge
a. perforated pipe
b. gravel (sand)
c. trench
d. porous pipe
e. dry wells
3. Vegetated depressions
MICROFILMED BY
'JORM MICROLAB
CEDAR RAPIDS -DES MOINES
1. Grassy strips on parking lots
2. Grassed waterways draining:.
parking lot
3. Ponding and detention measures
for inpervious areas
a. depressions
b, basins
1. Reservoir or detention'basin
2. Planting a high delaying grass
(high roughness)
3. Grassy gutters or channels
4. Increased length of travel of
runoff by means.of gutters,
diversions, etc.'
i
ADVANTAGES AND DISADVANTAGES OF MEASURES FOR REDUCING AND DELAYING RUNOFF
MEASURE
A, Cisterns and covered ponds 1
E. Surface pond storage
i (usually residential,
commercial and industrial
areas)
C. Ponding on roof by con-
stricted downspouts
D. Increased roof roughness
1. rippled roof
2, gravel on roof
2
3
ADVANTAGES
Water may, be used for:
a, fire protection
b. watering lawns
c. industrial processes
d. cooling purposes
Reduce runoff while only
occupying small area
Land or space above cistern
may be used for other purposes
1. Controls large drainage areas
with low release
2. Aesthetically pleasing
3. Possible recreational benefits
a. boating
b. ice skating
c. fishing
d. swimming
4. Aquatic life habitat
S. Increases land value of
adjoining property
1. Runoff delay
2. Cooling effect for building
a. water on roof
b. circulation. through
1. Runoff delay and some re-
duction (detention in
ripples or gravel)
i MICROFILMED BY
'JORM MICRO_ LAB
-CEDAR RAPIDS -DES MOINES
1.
2.
3.
4.
5.
1.
2.
3.
4.
S.
6.
1.
2.
3.
4.
DISADVANTAGES
Expensive to install
Cost required may be restrictive
if the cistern must accept water
from large drainage areas
Requires expensive cleaning and
maintenance
Restricted access
Reduced available space in
basements for other uses.
Requires advance land planning
Possible pollution from storm
water and siltation
Must be deep enough (+10') to
support fish life to prevent
mosquito breeding
May have excessive algal blooms
resulting in eutrophication
Maintenance problems with land/
water interface
Potential liability
Nigher structural loadings or
greater flexure under loads(r^
Clogging of constricted inlel�
requiring maintenance
Freezing during winter (expansio
Potential for leakage of roof
(water damage)
1. Somewhat higher structural
loadings
2. Higher potential for leaks
4X
1
MEASURE ADVANTAGES DISADVANTAGES
E. Grassed channel and vegetated 1. Runoff delay 1. Requires use of some land
strips 2. Some runoff reduction area for vegetated strips
(infiltration recharge) 2. Grassed areas must be mowed
3. Aesthetically pleasing or cut periodically (main -
P. Ponding and detention
measures on impervious
pavement
1. basins
" 2. constricted inlets
G. Dry reservoir or detention
basin
H. Ground -water recharge
1. perforated pipe or
hose
2. french drain
3. porous pipe
4. dry well
I. Routing flow over lawn
s�
F
i MICROFILMED BY
JORM MICROLAB
.CEDAR RAPIDS•DES'MOINES
depressions in poorly graded
areas
3. Potential for ice build-up
a. flowers
tenance costs)
b. trees
3.
Increased difficulty of cleaning
1.
Runoff delay
1.
i
Somewhat restricted movement_of
2.
Runoff reduction
,
vehicle "'
2.
Interferes with normal use
during heavy runoff periods
3.
Depressions collect dirt and
debris requiring extra main-
tenance. i
1.
Runoff delay
1.
Advance land planning is
2.
Recreation benefits -baseball
necessary,
football, etc., if land is
2.
Maintenance costs
i
provided
a. Mowing grass'
3.
Aesthetically.pleasing
b. Herbicides
4.
Could control large drainage
c. Cleaning periodically
areas with low release
(silt removal)
3.
May require underdrain system
4.
Siltation
1.
Runoff reduction (infiltra-
1.
Clogging of pores or perforated
2.
tion)
Ground -water recharge with
2.
pipe j
Initial expense of installatiO
relatively clean water
(materials) S
3.
May supply water to garden or
3.
Monitoring of water quality, if
dry areas
required could prove expensive
4.
Little evaporation loss
1.
Runoff delay
1.
Possible erosion or scour,
2.
Increased infiltration
which requires added expense
3.
Easy to accomplish
2.
Standing water on lawn in
i MICROFILMED BY
JORM MICROLAB
.CEDAR RAPIDS•DES'MOINES
depressions in poorly graded
areas
3. Potential for ice build-up
Appendix 'D'
MICROFILMED BY
'JORM MICROLAB
CEDAR RAPIDS-DES-140INES
r\
REVISIONS TO DESIGN STANDARDS FOR PUBLIC: WORKS IMPROVEMENTS
IOWA CITY, IOWA
SECTION _7rr — STORM SEWERS APPENDIX
755
to
0
0
745tF
0
752.9
BEST FIT UNIFORM GRADE
4'/350' = 1.14%-1
EXISTING GRADE
TYPICAL STORM 0
DRAIN SYSTEM •
n
rr
F LOW 0
4—WATER MAIN ±
W/5' COVER
0 100 150 200 250 300 350
STREET GRADE - ALLOWING EXCESS FLOW
TO REMAIN IN STREET CHANNEL
+1790/ I - r ♦3.000/. I
755
751.5
HIGH POINT 748.0
752.4
c
d
h
0
750
EXISTING GRADE ±l' -O" HEAD FOR
n
STORM DRAIN
ti
SURCHARGE -
0
-FLOW
n
0
h WATER MAIN
q
N W/5' COVER
a
74 5
N
y
0
50 100 150 200 250 300
350
REVERSE STREET GRADE - REQUIRING EXCESS
FLOW TO SURCHARGE STORM DRAINAGE SYSTEM
9 TEMPORARILY STORE IN THE STREET
THESE REVERSE
GRADES SHOULD BE CREATED TO EXAGGERATE THE NATURAL VARIATIONS
IN THE
EXISTING
TOPOGRAPHY AND MINIMIZE THE EFFECT ON ROADWAY RIDE. LOCAL
STREETS
WILL
GENERALLY NOT BE AFFECTED BY CHANGES OF 3% TO 5% IF
PROPER
VERTICAL
CURVES ARE CONSTRUCTED.
/T/S
MICROFILMED BY
'DORM MICROLAB
CEOAR RAPIDS -DES MOINES
LAND PLAN
PROPOSED SUBDIVISION
(POOR EXAMPLE)
/V/.Il
MICROFILMED BY
JORM MICROLAB
CEDAR RAPIDS -DES 140RIES
LAND PLAN
PROPOSED SUBDIVISION
(GOOD EXAMPLE)
101/
MICROFILMED BY
JORM MICROLAB
CEDAR RAPIDS•DES MOINES
Appendix 'E'
MICROFILMED BY
' JORM MICROLAB
CEDAR RAPIDS•DES MOINES
— Ic
F
V=
•IB
I
I I I r---- A
STORM SEWER STORM SEWER
AT INTERSECTION PARALLEL AT STREET
I I W I I
1 I ¢I I B
- 4 I N I I
C C
J
I
I WI I
a
STORM SEWER
PERPENDICULAR TO STREET
NOTES;
I. FLOWS ALLOWED- TO PROCEED AROUND COR-
NER TO SUMP AWAY FROM INTERSECTION
2. FLOWS NOT ALLOWED TO CROSS INTER-
SECTION
3. DISTANCE BETWEEN MANHOLES NOT TO
EXCEED 400 FEET
4. NO INLETS BETWEEN PTR IN RADIUS
S. M - MANHOLE
G - GRATE INLET OR INLET MANHOLE
C - CURB INLET
CURB INLET SIDEWALK
PROPERTY
ROADWAY LINE --
I I
SECTION B - B
CURB INLETS LOCATED TO KEEP TWO
12 FOOT LANES FREE OF WATER IN
A 5 YEAR STORM.
SECTION A - A
GRATE INLETS LOCATED TO KEEP ONE
12 FOOT LANE FREE OF WATER IN A
5 YEAR STORM.
MICROFILMED BY
`JORM MICROLAB
CEDAR RAPIDS -DES MOINES
MIT
,l
REVISIONS TO DF --,GN
STANDARDS FOR
PUBI_i�;
WORKS IMPROVEMENTS
IOWA CITY, IOWA
SECTION IZZ — STORM
SEWERS
APPENDIX 'E'
PIPE LAID
PARALLEL TO THE STREET
C
C
I
SHALL NOT
LIE UNDER PAVING.
I I
1 1
I
� W
� W
0.5°/ MIN. _ - I
1
I I
I
I
_ _ LOCAL
STREET D
G
_ _
•IB
I
I I I r---- A
STORM SEWER STORM SEWER
AT INTERSECTION PARALLEL AT STREET
I I W I I
1 I ¢I I B
- 4 I N I I
C C
J
I
I WI I
a
STORM SEWER
PERPENDICULAR TO STREET
NOTES;
I. FLOWS ALLOWED- TO PROCEED AROUND COR-
NER TO SUMP AWAY FROM INTERSECTION
2. FLOWS NOT ALLOWED TO CROSS INTER-
SECTION
3. DISTANCE BETWEEN MANHOLES NOT TO
EXCEED 400 FEET
4. NO INLETS BETWEEN PTR IN RADIUS
S. M - MANHOLE
G - GRATE INLET OR INLET MANHOLE
C - CURB INLET
CURB INLET SIDEWALK
PROPERTY
ROADWAY LINE --
I I
SECTION B - B
CURB INLETS LOCATED TO KEEP TWO
12 FOOT LANES FREE OF WATER IN
A 5 YEAR STORM.
SECTION A - A
GRATE INLETS LOCATED TO KEEP ONE
12 FOOT LANE FREE OF WATER IN A
5 YEAR STORM.
MICROFILMED BY
`JORM MICROLAB
CEDAR RAPIDS -DES MOINES
MIT
,l
I I
CURB c = N w 0\7
2 w
UA 2
w A
A a f
0
x
1 1 \\0
o x
m o --y
m
O o 0
o Z
TYPICAL STREET —CURB
GRATE INLET
CURB INLET FRAME, REVERSIBLE GRATE CURB INLET FRAME, REVERSIBLE GRATE
B CURB BOX TO BE NEENAH R-3063 B CURB BOX TO BE NEENAH R-3067
OR APPROVED 'EQUAL OR. APPROVED EQUAL
GRADE GRADE
BEHIND BEHIND
CURB CURB
STREET STREET
GRADE GRADE
�•• GROUT FRAME °'•'
n 2,-0„ o. TO WALL 2•-0" o,
DIA. •o INSIDE •o ••
WAILS TO BE 6" _
e °• POURED CONCRETE "o• C
o o = , ', • OR PRECAST RE- iv r
INFORCED CON-
CRETE SECTIONS-
"4
ECTIONS "4 BARS Pm% -C
•� VERT. B HORI
3"MIN. COVER
12" Ix 12" lu
3" SAND CUSHION -
SECTION A -A
MICROFILMED BY
JORM MICROLAB
CEDAR RAPIDS -DES 1401NES
CURB INLET FRAME,
REVERSIBLE GRATE &
CURB BOX TO BE
NEENAH R-3065 OR
APPROVED EQUAL
STREET GRADE
GROUT FRAME TO
SPACER RING OR
MANHOLE WALL
CEMENT MORTAR JOINTS
WITH RUBBER GASKET
AS SHOWN OR COLD BI-
TUMINOUS COMPOUND
JOINTS MADE IN SAME
MANNER AS SEWER PIPE
JOINTS WITH 6" STRIP°
MASTIC PAINT AROUND .o
OUTSIDE OF JOINT
p.
'•0 4' DIA. FOR 24° f
0 0
N
r ;o
z
vn, i
SECTIO
MICROFILMED BY
'JORM MICROLAB
CEDAR RAPIDS -DES MOINES
TYPICAL STREET INLET MANHOLE
GRADE BEHIND CURB,
BRICK OR CONCRETE AS REQUIRED
,'. o,••a; TO MAX. OF 4" TO MEET STREET
GRADE LINE. 24"MAX. HEIGHT
OF SPACER RINGS, IN-
'%': , :e; .;':e'••:•'"•••';;o.• CLUDING C.I. CURB
..•o' 2-0MIN. •e•.•:.'°.• :.°... .
.p• • • • 0 INLET FRAME.
FLAT TOP :o
�� STEPS TO BE SPACED AT 12" '.•D
o MIN. TO I6" MAX. FOR STEP
..o DETAIL SEE APPENDIX 'G�. •.o
:e STEPS ARE NOT REQUIRED o;, j
'i.. IF MANHOLE IS THAN 3
b FEET IN DEPTH. '••D' 48" PRECAST CON-
CRETE SECTIONS CON-
FORMING TO A.S.T.M.
SPECIFICATION C-75
• S DIA. FOR OVER 24" PIPE fl
SLOPE I" TO 10"
N A - A
IT
r
TYPICAL PEDESTRIAN TYPICAL REAR
MALL INLET YARD INLET
FRAME B GRATE TO BE BEEHIVE GRATE TO BE NEENAH
NEENAH R-2300 OR AP- R-4340 A OR R-4340 B WITH
PROVED EOUAL C.I. FRAME OR APPROVED EQUAL
04 BARSA 12"C: C.
HORIZ. B VERT..PAVING GRADE`
M MIIkL COVER, 1 . I
MICROFILMED BY
JORM MICROLAB
CEDAR RAPIDS -DES MOINES
WE
GROUT FRAME
TO WALL
MICROFILMED BY
JORM MICROLAB
CEDAR RAPIDS -DES MOINES
VARIABLE LENGTH VARIABLE LENGTH
I
1
I
A
I
I
1
I
I
I
I
I
A
o
3
I
1 >
I
1 , I
NEENAH R-4670 OR
R-4781 GRATE WITH
TYPICAL ALLEY INLET NEENAH R-4899 FRAME
OR APPROVED EQUAL
PAVEMENT
_ •� '4 BARS@ 12rr C.•C. G•
'0 VERT. 8 HOR12. d
0 .O 3" MIN. COVER '^. u•
N •' �• '. �n w.r
SECTION A - A
j MICROFILMED BY
`JORM MICROLAB
CEDAR RAPIDS -DES MOINES
iris
a
F
•O
4
1J
Irr
p:
v'
Pe
VARIABLE LENGTH
_I
SECTION A - A
j MICROFILMED BY
`JORM MICROLAB
CEDAR RAPIDS -DES MOINES
iris
a
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I n.[ .r uu e• cun.
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JORM MICROLAB
CEDAR RAPIDS -DES 1401NES
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CEDAR RAPIDS -DES MOINES I I
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�7 TAPERED INLET
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Date: August 18, 1981
To: Neal Berlin and City /Council
From: Chuck Schmadeke G'J:
Re: Storm Water Detention - Ty'n Cae Addition, Parts 1 & 2
Storm water detention for Ty'n Cae Addition, Parts 1 & 2, was designed and
constructed in 1977 and was one of the first facilities built after adoption of
the Storm Water Management Ordinance. Also, to date, it is the only private
facility serving a residential subdivision built along a major creek channel.
The facility was constructed according to requirements of the Storm Water
Management Ordinance and consists of a dam to restrict the flow of the main
channel, an outlet pipe sized to release 0.15 cfs/acre from the total upstream
watershed during a 100 year storm (100 cfs), a storage basin sufficient in size
to contain the excess runoff from Ty'n Cae Addition, Parts 1 & 2, and an overflow
spillway to transport peak runoff from the total watershed.
Section 2.2 of the Design Standards for Public Works Improvements (Section
b. VII - revised) sets forth design parameters for the situation in which main
�t channel flow passes through a subdivision. Section 2.2, in part, is stated as
follows:
r
"Where storm water storage facilities have the potential to contain the
}, runoff from the total tributary watershed they must be constructed to
contain the main channel flow and restrict the flow of all of the storm
water runoff as opposed to only the runoff from that portion of the
watershed containing the project under consideration. Storage volumes
should be calculated to contain only the runoff from the project site,
however, the release rate must be calculated at 0.15 cfs/acre from the
total tributary catchment. Overflow spillway requirements must be
designed to transport peak storm runoff, as stated in Section 2.1, from the
entire tributary watershed under the existing conditions. Future upstream
storage will not be allowed for purpose of design reductions."
The purpose of Section 2.2 of the Design Standards is to have storm water
storage facilities located on the main channel whenever possible. The benefits
of this situation are as follows:
1. Larger pipes can be used in the discharge structure thereby reducing
clogging.
2. If the topography of the area near the channel is relatively flat, a
greenbelt will be provided along a channel by the storage basin. (See
drawing A.)
There are, however, some disadvantages associated with Section 2.2 if the
upstream drainage area is undeveloped. They are:
1. Unacceptable amounts of sedimentation accumulate in the storage basin from
erosion of agricultural land upstream.
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MICROFILMED DY
'JORM MICROLAB
CEDAR RAPIDS -DES MOINES
1-11, 2 1�
2. Since natural runoff even during a two year storm exceeds the 0.15
cfs/acre, the storage basin will reach capacity frequently. The
property owners in Ty'n Cae Addition, Parts 1 & 2, claim that the
storage facility has reached maximum level four or five time this
summer.
The Public Works Department recommends modifying the Design Standards for
Public Works Improvements (Section VII - Revised) to allow off channel
storage if it is anticipated that sedimentation will be a problem, and to
allow consideration for future upstream storage when designing spillways.
The intent of considering future upstream storage is to allow the
construction of a spillway that will restrict flows in such a manner as to
simulate the future fully developed condition in the storage basin. In
other words, this aspect will not fully utilize the storage basin except
during the 100 year storm. (See drawings B and C.) As additional areas
develop and additional storage is provided upstream, the exit channel can
be gradually filled in to insure that the required storage is maintained.
When the total upstream tributary watershed is fully developed, the exit
channel will be completely filled in.
The following modifications to the Design Standards for Public Works
Improvements (Section VII - Revised) are recommended:
Chan a the first paragraph of Section 2_2 to read:
"Where stormwater storage facilities have the potential to contain
the runoff from the total tributary watershed they must be
constructed to contain the main channel flow and restrict the flow of
all of the stormwater runoff as opposed to only the runoff from that
portion of the watershed containing the project under consideration,
unless it can be demonstrated that sedimentation will be excessive.
Storage volumes should be calculated to contain only the runoff from
the project site; however, the release rate must be calculated at
0.15 cfs per acre from the total tributary catchment. Overflow
spillway requirements must be designed to transport peak storm
runoff, as stated in Section 2.1, from the entire tributary watershed
under the existing conditions."
Add the following Section 3.8:
When stormwater facilities are constructed to contain main channel
flow, the exit channel shall consist of a special weir to allow for
future modification to reduce flow and to prevent erosion. The exit
channel and weir must be deisgned to provide storage volumes that
would exist if the facility were built off of the main channel. For
design purposes, the exit channel and weir shall be considered part
of the spillway.
On the matter of the Ty'n Cae subdivision, the developer has agreed to
reconstruct the spillway to comply with the proposed changes in the
ordinance. The additional work will involve regrading the storage basin
MICROFILMED BY
JORM MICROLAB
CEDAR RAPIDS -DES MOIRES
L'.
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3
to provide positive drainage to the creek channel and construction of an
exit channel at the spillway.
It is important that owners of stormwater detention facilities provide
routine maintenance so that the facilities function properly. The storage
basin and spillway should be mowed frequently to reduce sedimentation and
insure adequate drainage. Debris should be removed from the spillway and
outlet pipe to guarantee proper flow conditions.
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JORM MICROLAB
CEDAR RAPIDS -DES 140INES
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