Planning Commission Packet - 02/03/1981 POOR QUALITY RECORD
PLEASE NOTE: The original paper record has been archived and
put on microfilm. The following document is a copy of the
microfilm record converted back to digital. If you have questions
please contact City of Tigard Records Department.
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AGENDA =`�
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TIGARD PLANNING C0�7MISSION
FEBRUARY 3, 1981 - 7:30 y�.ni. , ;;a,
FOWLER JUNIO'R AIGH - LECTURE ROOM '`I
10865 541 Walnut Street, Tigard
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l. Open Meeting
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2. Roll Cal].
3. Approval of Minutes from Previous Meeting
4. Planning Commission Communication
5. Public Hearing:
A. Staff Report
B. Applicant's Presentation
C. Public Testimony:.
1. Proponent's
2. Opponent's
3. Cross-Examination
D. Staff Recommendation
E. Commission Discussion and Action
5.1 CONDI'PIUNAL USE AND VARIANCE, CU 14-80/V 15-80 (DAVID CHU'RCH 5INGLE
F�12ZY ATTACH�D) NPO #2 '
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5.2 ZONE CHANGE PLANNED DEVELOPMENT, ZCPD 30-80 (GENTLE WOODS PLANNED �
DEVELOPMENT SINGLE FAMILY iJNIT5) NPO #5
5.3 VARTAt�10E, V 1-81 (SCHOLLS FERRY THRIFTWAY SIGN VAR.IANCE) NPO #7 C'
5.4 VAR2ANCE, V 14-80 (SILCO CONSTRUCTION SETBACK VARIANCE) NPO #2 '�
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5.5 CONSID�RATION OF NEIGHBORHO011 PLANNING ORGANIZATTON, NPO #5 MFP�ERSHIP ;
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6. Old Business a
7. New Business: Election of Officers j
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E3. Other Business : Joint me�ting with City Council i
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9. Adjournment
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PUBLIC NOTIC�
TIGARD PLANNING COMPQISSION 3" '
E'EBRUARY 3, 1981 - 7:30 p.m.
FOWLER JUNTOR HIGIi - LECTURE 1200M { '
� 10865 SW Walnut Street, Tigard ;
5, pUBLIC HEARINGS ` '
` 5.1 CONDITIONAL US� APdD VARIANC�, CU 14-30/V 15-80 (DAVID CHURCH SINGLE NPO #2 �
FAMILY ATTACHED)
For a re-hearing of Variance, V 15-80 (a Variance of Condition Number 6
of Minor Land Partition, MLP 20-79. �lso, a Conditional Use, CU 14-80
(to construct a single family attached unit in an R-7 "Single Family
Residential" Zone located at 12533 St�7 Grant (Wash. Co. Tai� Ma� 251 2BB,
� � Tax Lot 1801) . . .
5.2 .ZONE CHANG� PLANNED DEVELOPML�NT, ZCPD 30-80 (G�N'PLE WOnDS PLAI�INED
NPO #�5
DEVELOPMENT SINGL� i P�1II�Y UNITS) ,
A`.mquest by 'Gotter - JaehrTing '1'artnezship �fbr a �reliminary and
General 1'lan Review oi Uentle �aoods i�lanned Development single family
units on 22 lots located at 151�30 S'�V 79th (Wash. Co. Tax Map 2S1 12C,
Tax Lots 1�00 and 130Q)
5.3 VAP.IANCE, V 1-81 �SCHOLLS L'�F1ZY TH�TP'TGaAY SIGN VARIANCE)
NPO #7
� reques� by Howard Williams for an increase in �,he �].lowable sia11 •size }'
located at 12220 SS�I Scholls Eerry Road (Tr7ash. Co. Tax �Iap 1S1 348, ��
Tax Lot 300. ;
NPO #2 t
5.4 VARTANCE, V 1.4-80 (SILCO CON5TRUCTION S�'I'B�1CK VARIANCE) �
2� re-hearing of Variance, V 14-80;ailcq Cons'�'�xuc�tion's 3-ec�u�.st for a ,
Variance in the setback requirements in an N,-4 "Industrial Park" ,
Zone to permit construction of a buildin� located at 9350 S4d T�.gard `�
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Street {Wash. Co. Tax Map 2S1 2AB, Tax Lot 19�1) . r
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5.5 CONSIDERATTON OF NEIGHBO�HOOI3 PLANNII3G ORGA�TIZ�,TION, i]PO #5 MEMBEI2�HTP d
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A request �ro� John S�nets, NPO #5 ChairperSon, for re-activation of �
NPO #5.
JpINT MEETING 49ITH TIGARD CITY COUNCIL DUR:LNG STUDY SES5ION
TO B� PUBLISHED TN TTGARI7 TZMES JANUARY 21., -1981 AND �7�,NU1�1RY 28, 1981`
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MINUTES
TIGARD PLI�NNZNG COMMISSION
February 3, 1g81 - 7:30 p.m.
Fo�vler Junior Tii�h - Zeci;ure Room
10865 S4V Walnut Street, Tigard, OR
Pre�ident Tepedino called the meeting to order at 7:30.
ROI,L:CALL•
Present: Bonn, Helmer, Aer.ron, Kolleas, Moen, Speaker, Tepedino
Absent: I'unls.
Vacant: Qne seat
Staff: Hot�rard, Newtoii
The MINUT�,S of the January 6 meeting were considered, and on motion
by Bann, seconded by Helmer, they tvere approved as submitted. I
CONIMU�IICATIONS: There Lvere no communications to staff requirin6 I
reading at this time. Tlie president read into the record two letters: �
one from John Smets, �ormer chairru�n of NPO 7�5, sLatin� the NPO is nov�
reactivated; an.d the other from 1'at Tiutchins, c.hairman of NPO #1, asking
they be consulted early abou�; any developments in their area. The presi- II
dent also passed to each commiseioner a copy of a lei;ter received by him ,
from Linda Macpherson� Fie1d Representative of the Department of Land I
Conservation and Development in response to his request for statutory '
and judicial citations with respect to Oregon�s planning goals. Tt �vas II
noted that oach commissioner had received a copy of the mayor�s sampling
of opinion on City of Tigard concerns, and tha� some (but not a11)
commissioners had received a complimentary copy of a TriMet book of
schedules.
The president read the usual notice of authority for and procedure I�
to be followed ii1 the mee�tin6. Iioward stated for the benefit of the
audience i;he sclieduled meeting of i:he city council and plannin� commis- ��,
sion would not be held this evening due to the inability of two council i
members to attencl. Tho presi.dent then oponed th� meoting to PUBLIC '
HEARINGS.
5.1 CONDITIONAL USE AND VARIANCE, CU 14-80/V 15-80 (DAVTD
CIiURCH STNC�LE FAMILY ATTACIiED) NPO �2
For a re-hearing of Variance, V 15-SO (a Variance of
Condition Number 6 of Minor Land Partition, MLP 20-79.)
��so, a Conditional Use� CU 1C�-80 (to construct a �ingle
family attached unit in an R-7 "Sing].e I'amily Residentia��'
Zone) located a� 12�33 SW Grant,(Wash. Co. Tax Map 2S1 2Ii�,
Tax Lot i8oi).
Tioward read the STAI'F I��1'ORT, but did not read the twelve condi-
'��.0215 �ugges�Led by staff should the comm3.ssion approva the applicant's
MINUT�S
TIGARD �LANNTNG COMMTSSIQN
February 3, 1981
Page 2
request. He then read two letters received from Mrs. Mona Rosa, owner
o� �z 1800 ('t�e parcel. fronting on Grant Street.) 7.'he first lettor,
da�Eed Docember 8, 1980, amounted to a request fox appeal to the city
r,auncil should �he commission approve the applicant�s reques�t. The
second 7.etter, dated January 30, 1981, explained her present residonce
in New York, her intention to return to Tigard, and her objections
to o�her than single family buildings on the ps`operty behind her house.
T.he APPLICANT�S PR�SENTATION was made by the owner, David Church,
6328 SW Haines Road, Portland. Iie explained what he was requesting,
the present accoss ta the back portion of what was �z a.800, the use of
a portion of his property for parking by the occupants of Mrs. Rosa�s
property. He objec�ed to tho suggested Conditinn 3 callin� for 2y.
feet of pavement in the 29 foot access, and Condition 2 calling for a
considerabl.e footage of fencing.
Thore was na PUBLIC �rESTIMONY.
In CROSS-EXAMINA'rTON ANl� 1�EBUTTAL Moen and Si�oaker asked for i.nfarma-
tion on pas� considerations by and actions taken Wl'�h respect to this
property by the planning commission. This was responded to at length
and in detail by Newton, who illustrated her remarks with a diagram on
the blackboard. Topedino ascertained from staff that this was a de novo
hearing, allowing new testimony and a decision based on considerations
other than those relied on in t.he previous (Novembor 25) hearing.
Speaker inquired about the statements in Mrs. Rosa�s letter with
respect to the distance between her house and the access easement.
Newton and Church responded, indicating setback requirements are satis-
fied.
COMMIS,SIOIV DISCUSSIOPT AND ACTION: Moen, Bonn aild Helmer all
e;cpressed a lack of enthusiasm toward the request. Speaker 3.nquixed
about i;he extent of paving at the 24 foot proposed wid�h, and the devel-
opm�nt, present and prospective, of the surrounding asea. Staff agreed
�t�e area does not fit well in�o the usual lotting patterns, requiring
extensive use of flag lots to provide access to lots partitioned from
much lar�er lots as ori�inally laid out. Kolleas inquired whAt vegeta-
tion exists along the nortli property line.
Tepedino inquired the exact request of the commission, and opined
it �vas a very corizusin� situa�tion. He stated he wa� unpersuaded of the
merits of the request and called fo.r a motion. Moen MOV�D for denial,
seconded by Iierron. Speaker suggest;ed the comm�s�ion should be specific ,
as to the bases for denial, and that the reasons given in tY�e code for a
variance are n�t xeally met in this request. He suggested the commis-
sion exorcise the authority �ranted it in the code to instruct the planning
direc�Gor not to grant a varianae to the 10 foot per lot access req�ire- '4
ment. 'i'opedino revie�ved the requirements for a variance, and felt these
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MINUx�S �
TIGARD PLANNING COMNIISSION �;
k'ebruary 3: 1g81 E;
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requirementu had not been met in this request. Moen thsn �epeated his �;
motio�l for denial of .CU 14-80 arsd V 15-+80, bas:ed on fa9.lure to mee� the +
qualifications for a variauce �pecified in t.he cade, and failure to have ��
adequate access for the density requested. Helmer seconded the motion
�ox denial for the roasons spec:tfied. The motion passed unanimously.
5•2 ZONE CHANGE PLANNED DL+'�I�LOPNENT, ZCPD 30-.80 (G�NTLE WOODS '
PLANNED DEVEZOPI�IENT SINGLE FAMILY UNITS) NPO ��5
p rec�ues� by Gotter-J�ehrling Partnsrship for a Preliminary
and General 2'lan Review of Gentle Woods Planned Deve].opment
�ingle family units on 23 lots located at 15180 SW 79th
(Wash. Co. Tax Map 2S1 12C, Tax Lots 1200 and 1300).
Howard read the STAFF REPORT and RECOMNIENDATIONS, correctin� Findings
of Fact Nos. 7 and 10 to read Z3 lots� instead of 22 as printed.
The A�PLIGAP7T�S PRESENT.ATION was made by Bob Cru2 of David Evans
atid Associates, 200 SW Market St. , Portland. He expressed satisfaction
v11th the staff report and agreement with the conditioizsy and asked �or
approval by t.he commission.
There was no PIIBZTC T�STIMOIJY.
COMMI85ION DISCUSSTON ,(�dD ACTTONs No commi�sion�x had problems '
with the request. T�oen called attent3.on to Condit3.on No. 2 referring "
to dedication �'for open space/park purposes," and suggested that in t.he
absonce of any,intention or funding to make tlzis into a park, tlie word
"park�f should be stricken from t.he Recommendation. Howard agraed,
�tating t.he point was well taken.
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Moen MOVED approval of ZCPD 30-80 at tha Preliminary P1an and ,
' General Flan Review levels for bath Phase I and Phase II, based upon
staff findin�s and recommzndations. The motion was seconded by He].mer
and carried unanimously.
The president announced agenda item 5.3 had been withdrawn. He
then call.ed for t:he Yiearing of Item 5.4, a varianee requost which had
been tabled on November 2,5 in oxder to give time for staff and the �
�pplicant ������i�erns (inc],uding use of flood plain) expressed by
cammis�ioners.
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5.1�. VA�2IANC�, V 14-$0 (STLCO CONSTRUCTION SETBACK VARIANC�) NPO �2 'r:
1� re-hearin� of Var3:aYioe, V ly.-80;`Silco'Construotion�s
reques� for a Variance in the setback r�quirements in an
M-�. "Tndus�rial Park�' Zone to permit eonstruc�ion of a buil.d-
�ng �.acated at 935� SW Tigard Street (Wash. Co. �ax Map 251, ;
2AB, Tax Lot 1�01). �i
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MINUTES
TIGAT3D �L�1.NNIPTG COMMTSSTON
February 3, 1981
Page L�
FioWard read the STAFF REPORT, which consister� of an updating of
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findings for tizis request as prepared for �he November Z5 hea�ing, and '
a chan�e i.n Condition No. 2 of that report. fIe 3.11ustrated at the black-
board the physical factors: location of buildin�s and proposed extension,
parking spaces, 100 year flood plain and the ax�ea in the flood plain
indicated by the Corps of ��ineers study as having no effect on flood
elevations. I� was pointed out that park development is planned, not
on t.his stretch of Fanno Craed, but between Main Street and Hall
Boulevard.
The APPLTCANT'S P�:ESENTATTON wa� made by Bruce Nichol�on of Silco
Construction Company, 1.37g1 SW Martinazzi, Tualatin. He acknowledged
the �completeness of Howard�s description of the site, but added tllat
because of poor drai.nage arrangements at present, there is water stand-
ing after even a moderate ra3.nstorm. He stated the owner desires to
maintain scme outside storage, but pointed out that such. storage was
for practical purposes not visible to the public. Helmer inquired if
the slope from the State Highway fill extended to this property. (It
does not.) Speaker inquired whether the additional space would be used
by �he �ign company, or would be rented to others. Nicholson stated
• that the awnor expected to use the whole building for his own purposes
some time in the future, but until his business developed to that point
he would expect to rent about half of the addition to ot.hers.
Thero �vas no PUBLIC TE.STIr40NY. �
COMMISSION DTSCUSSION AND ACTTON: Bonn inquired about the view of
the outside storage from whatever mi�ht in the future be constructed as
a bike/pedestrian path a.long Fanno Creek. Tt was pointed out the a�pli-
cant does not own the property along the cresk, and that at this time
it is not even lsnovm vthich side of the creek might be used for that
purpose. In any cas� the outside storage lot will be fenced, which was
fe].t to be suffi.cient.
Tepedino commented on flood plai.n encroachment and the commission�s
pa�t attitude toward it� stating he felt that encroac�.ment in this
instance could �be averted in some manner.
Bonn A'iOV�D approval of Variance V 11��-80 based on staff f�.ndings
and rocommenc�ations fo� -the lJovember 25 meeting as suppl.emented for
this meoting, including modi,fication of Recommendation No. 2 as indicated
iii the staff repozt; also t.hat tY�e Recommendation No. 5 be amended to
permit outside storage, but that the storage area be fencod. Helmer �
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seconded the mo�tion, which carried 6 to l� with Tepedino casting the
di�sei�,ting .vote. �
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MINUTES
TZGAI2D PLANNING COMMISSTON
February 3, 1981
Page 5
5•5 CONSIDER�.TTON OF NEIGHBORHOOD PLANNTNG ORGANT'LATION,
NPO }`�5 MEMBERSHIP.
(Commissioners had received in �heir packets filled-out applications
�rom four prospective m�mbers of NPO ,#5•) �lf�er brief discussion,
Tepedino MOVED ap�roval by the pla�ning commission for submission to the
city council of the applications of the followin� for appointment to
NPO �5: Bill Bieker, 1Yalt Durham, John Havery and John Smets. The
motion was seconded by Helmer and carried unanimously.
OTHER BUSINESS•
*'"* T.he requirement for the planning commission to name a president
and vice pre�ident for the calendar year at 3.ts first meeting was brou�ht
up by Howard. There was expression of general satisfaction with the
incumbents. Bonn MOV�ll that Tepedino be reelected president, and
Speaker vice president, of the p].anning commission for �.981. The motion
was seconded by Kol.leas and carried.
*** Tierron exprassed considerable dissatisfaction with the timin� ��
of the .tra�fic lights on Pacific Hi�hway. Howard exp7:ained ODOT is still `�
Working on it--that this is the first system they have installed under
`` the heavy traffic condit9.ons prevailin� in Tigard. He s�ated all com-
plaints should be directed to ODOT.
*** Howard commented briefly on �he inability of the council to
meet with the commission, and asked for suggestionr �o go in a possible
memo from the plannin� commission or department to the council on
imatters w.hic.h need to be considered jointly.
On motion the meetin� was adjourned at 9.15•
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STAFF REPORT
AGEND� 5.1 �
TIGARD PLANNING COMMISSION
February 3, 1981 - 7:30 p.m.
FOWLER JUNIOR HIGH - LECTURE ROOM ;`
10865 SW Walnut Street, Tigard '
NO SUBMISSION OF ADDITIONAL MATERIAL BY APPLICANT SHALL BE MADE AT THE PUBLIC
AEARING UNLESS THE APPLICANT IS REQUESTED TO DO SO. SHOULD THIS OCCUR, '
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UNREQUESTED, THE ITEM WILL BE TABLED UNTIL THE FOLIAWING HEARING.
DOCKET: VARIANCE, V 15-80 and CONDITIONAL USE, CU 14-80 (Attached
Single Family Residence in R-7 Zone) NPO #2
APPLICANT: David Church OWNER: SAME �:
6328 SW Haines Road
Portland, Oregon 97219 �'
APPLICATION DATE: October 15, 1980 ;
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REQUEST: For a re-hearing of Variance, V 15-80 (a Variance of Condition
Number 6 of Minor Land Partition, MLP 20-79 - see attached) .
Also, Conditional Use, CU 14-80 (to construct a single family
attached unit in an R-7 Single Family Residential Zone) .
SITE LOCATION: 12533 SW Grant (Wash. Co. Tax Map 2S1 2BB, Tax Lot 1801)
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SITE DESIGNATION: R-7 "Single Family Residential" +
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PLEASE READ ATTACHED STAFF REPORTS �t
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STAFF NARRATIVE: �`
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On November 25, 1980, the Tigarc3 PZanning Commission denied the applicant's i'�
request for a Variance (V 15-80) to Condition Number 6 of a Minor Lan d Partition '!,
(MLP 20-79) which states "Appiicant agreas to construct only one single family
dwelling on the rear lot" . At the same Hearing, the Planning Commission denied �''
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a Conditional Use (CU 14-80) to allow an attached single family unit on the
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property. The applicant filed an Appeal of the Planning Commissions' decision I
to City Council. While preparing for the Appeal, Staff noted some inconsistencies k�.;
in conditions placed on the property and the Code. Because of this new %"
information and on the advice of legal counsel, Staff asked the City Council +�
at the January 12, 1981 meeting to re mand the matter back to the Planning j
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Conunission for review. Council approved the request. i;
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Inconsistencies in the Staff copy of the Code and Ordinances are as follows: i
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1. Chapter 17.36.020 of the Tigard Muncipal Code reads ". ,,. .each lot sha11
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abut a public street". At a minimum, it was require d that the access
width abut the street, Further, the required aocess width was to be
held in fee ownership with the property the access se rved. An easement ''a
agreement to allow an access tojcantly serve properties or serve one k+
property without being held in ownership was not allowed unless the �'1;
Planning Commission granted approval. ��;
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STAFF REPORT •
AGENDA 5.1/V 15-$0/CU 14-80
TiGARD PLANNING COMMISSION
February 3, 1981
Page 2
2. On November 5, 1979, a new subclivision ordinance was passed (Reference
Ordinance 79-96) which deletes Section 17.36 .020 making the requirement
that each 1ot abut a public street no longer mandatory.
3. Condition Number 6 was placed on Parcel #1 an January 24, .1980 due to
inadequate access.
Lot 2 has the required ten (10') foot access as a ten (10') foot easement
over 12535 SW Grant, Tax Lot 1800. The easement was granted by a previous
owner and recorded in Book 902, Page 614, Washington County Records.
The ten (10') foot easement leaves six and one-half (6�') feet to the
porch on Tax Lot 1800 and approximately eleven and one-half (11�') feet
to the structure on Tax Lot 1800 which exceeds the required sideyard
setback.
The remaining nineteen (19') foot strip (see attached map) could provide
two 9.5 foot easement strips to the proposed single family attached
units. A variance could be granted for six (6") inches for each easement
by the Planning Director.
Single family attached units are allowed as a Condi�ional Use in an R-7
Zone on 10,000 square feet.
STAFF RECOMMENDATIONS:
Staff recommends that the Planning Commission reconsider Condition Number 6
placed on Parcel 1 of Tax Lot 1.801 with Minor Land Partition, MLP 20-79 and
approval of Conditional Use, CU 14-80 for the construction of a single family
attached unit an Parcel 1. If the Planning Commission approves Conditional
Use, CU 19-80, the Planning Staf,f will approve Minor Land Partition, MLP 19-80
and Variance, V 19-80 to allow for two (2) 9.5 foot easement strips, one for
each unit. If Conditional Use CU 14-SO and Variance V 15�-80 are approved,
the following conditions are recommended.
l. A Nonremonstrance Agreement shall be signed for both units on Parcel 1
and the unit on Parcel 2 for the future improvement of Grant Street prior
to the issuance of Building Permits.
2, ,A six (6') foot sight obscuring fence shall be constructed around the
perimeter of Parcels 1 and 2 and down both sides of the twenty-nine
(29') foot easement strip.
3. Twenty-four (24') feet of the twenty-nine (29') foot easement strip shall
be paved to serve all three units for access and egress. The asphalt
may be narrower to accomodate the Ponderosa Pine at the northeast corner
of the driveway, the exact width to be determined by the Planning
Director prior to issuance of Building Permits.
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STAFF REPORT
AGENDA 5.1/V 15-80/CU 14-80
TIGARD PLANNING COMMISSION
February 3, 1981
Page 3
4. Landscaping will be required along both sides of the paved access drive.
The landscape plans shall be approved by the Planning Director prior to
the issuance of Building Permits.
5. A metes and bounds legal description and map shall accompany the easement
agreement for the three parcels. The legal description shall be prepared
by a registered engineer or land surveyor. The easement agreement shall
be approved by the Public Works Director and the City Attorney.
6. No Occupancy Permits shall be issued, until all conditions placed upon
this development by the City of Tigard have been satisfied and inspections
verifying this have been carried out by the appropriate department.
7. No changes wi11 be made to approved plans or specifications unless formal
application is made to the appropriate City department and changes are
t A lications
for chan es will be made in
a roved by that departmen . pp 5
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writin and shall include applicable drawings.
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8. Grading and construction plans for all work in public right�-of-way and
all other public improvements shall be prepared by a registered professional
engineer in accordance with City standards, and sha11 be submitted to the
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Public Works Department for review.
All public improvements will require a Compliance Agreement and must be
(design) approved by the Public Works Department, and must be either
(1) fully and satisfactorily constructed prior to the recording of any
minor land partition, public dedication, or issuance of Building Permi�ts;
or (2) bonded to the City for 100$ of the estimated cost thereof prior �
to the recording of any minor land partition, public dedication, or issuance �
of Building Pexmits. �
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9. All proposed utilities shall be placed underground. Street lighting �
installations shall be approved by the Public Works Department.
10. A City of Tigard approved Nonremonstrance Agreement must be recorded by �
Washington County and returned to the City of Tigard Planni.ng Department �
before issuance of Building Permits or change of property ownership. �
11. All stre�t and parking areas shall be concrete or asphalt. All sidewalks �
shall be concrete. �
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12. No Building Permits shall be issued until the expiration of the twenty �
(20) day appeal period from the date of approval. I
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Pre re d by Elizabeth A. Newton Aldie Howard
Special Assistant To The Planning Director Planning Directox i
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STAFF REPORT ;
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TIGARD PLANNING COMMISSION
February 3, 1981 - 7:30 p.m. �
FOWLER JUNIOR HIGH - LECTURE ROOM ;
10865 SW Walnut Street, Tigard `
NO SUBMISSION OF ADDITIONAL MATERIAL BY APPLICANT SHALL BE MADE AT THE PUBLIC �
HEARING UNLESS THE APPLICANT I5 REQUESTID TO DO SO. SHOULD THIS OCCUR, '
UNREQUESTED, THE ITEM WILL BE TABLED UNTIL THE FOLLOWING HEARING, r'
DOCKET: ZONE CHANGE PLANNED DEVEIAPMENT ZCPD 30-80 (Gentle Woods) NPO #5 �'
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APPLICANT: Gotter-Jaehrling Partnership 064NER: Marvin L. Smith
12995 SW Pacific Highway 3341 NE 57th Avenue #6 �!�
Tigard, Oregon 97223 Vancouver, Washington 98661 �'
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REQUEST: For a Preliminary Plan and General Plan Review for Phases I "
and II on a 7.30 acre si�te. �j
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SITE LOCATION: 15180 SW 79th (Wash. Co. Tax Map 251 12C, Tax Lot 1200 and ;'.
1300)
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PREVIOU5 ACTION: '�'
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On January 6, 1981, the Tigard Planning Commission approved ZCPD 30-80 from '1
Washington County RU-4 to City of Tigard R-7PD "Single �amily Residential i;
Planned Development" Zone. At the same meeting, the Planning Commission
ap�roved Sensitive Lands Permit, M 9-80 to construct a sewer line through
the floodplain.
On April 10, 1980, the Boundary Commission approved the Smith Annexation
involving Tax Lots 1200 and 1300. The City of Tigard Ordinance No. 80-41 i
approving the annexation passed on May 19, 1980. ,,
FINDINGS OF FACT: [
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1. A portion of Phase II (Tax Lot 1400) has not been annexed to the City. �;
The City Council passed a Resolution on January 12, 1981 to send the E;
� annexation proposal to the Boundary Commission. The annexation should
appear before the Boundary Commission in March. ��
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2. The site has been zoned R-7PD in confonrtance with the City of Tigard �
Comprehensive Plan. +,
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3. The site has one existing house on Lot 15 of Phase I. The site slopes �
from southwest to nox�theast. ��
4. �he surrounding land uses consist of a few single family homes on large �I
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lots to the west and north, to the south and east is vacant parcels and �
open space. �
5. Access to the site is provided off SW 79th Avenue which is a forty (40')
foot right-of-way with paving only. The City of Tigard Stree� Plan
designates SW 79th Avenue as a minor collector, requiring a sixty (60' )
foot right-of-way.
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STAFF REPORT I
AGENDA 5.2/ZCPD 30-80 (GENTLEWOOD5) �
TIGARD PLANNING COMMISSION �
February 3, 1981 �
Page 2 �
�6. Sewer will be available to the site with the construction of the new line �
connecting the Fanno Creek Interceptor to the east. Water is available �
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f rom 79th Avenue, i
7. The site plan indicates that 7.3 acres will be divided into twenty-two
(22) lots. The average lot siz� proposed is 7,600 square feet.
8. The applicant proposed to dedicate 64,800 square feet of property which
lies in the floodplain to the City for open space.
9. The Planned Development Designation provides deviation o.f lot sizes,
setback requix�ements, etc. to allow development of a site which contains
sensitive land conditions. The deviation in this case is the mi.nimum
lot size.
10. Density calculations are as follows:
Total site area (Phase I and II) 7.3 acres
less sensitive lands 1.5 acres
5.8 acres
less p,ublic improveznents of 25 a 1.45 acres
PHASES T AND TT BUILDABLE LAND 4.35 acres
4.35 x 43,560 squa�`e �eet/7500 square feet = 25 units total
The applicant is asking for twenty-two (22) units.
11. A11 public rights-of-way are shown as fifty (50') feet dedicated with
full street improvements.
12. A licable olicies from the NPO #5 Plan are as follows:
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Policy 1: The maximum overall density of development will be four
dwelling units or 12 persons per gross acre. This amounts to
a standard of 7500 square feet of land per dwelling unit
allowing for stxeets and other open space.
Policy 2: Residential subdivision will be developed with paved stxeets,
` curbs anc� gutters, str°et lightG, an� walkways, according to
City or County standards all utilities will be placed underground.
Policy 3f Development will coincide with the provision of public streets,
water and sewerage facilities. 7."hese facilities shall be
(a) capable of adequa�.ely serving all intervening properties
as we11 as the proposed development and (b) designed to meet
City or County standards.
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STAFF REPORT '
AGENDA 5.2/ZCPD 30-80 (GENTLEWOODS) I
TIGARD PLANNING COMMISSION ,
February 3, 1981
Page 3
Policy 4: Planned Unit Developments will be encouraged on tracts large
enough to accomodate ten or more dwellings. Planned Unit
Developments will permit a degree of flexibility in design
that will enable a higher quality of development in accordance
with zoning standards.
13. A storm drainage plan was not indicated on the preliminary plat.
CONCLUSIONARY FINDINGS:
1. 5ewer and water are available to the site.
2. If the Tigard Plan is approved and SW 79th Avenue is designatec� an arterial
collector, the applicant wi11 have to dedicate ten (10' ) feet for the
improvement of SW 79th instead of five (5') feet as shown.
3. The density proposed i.s within the maximum allowed in the R-7 Zone.
4. The sensitive lands permit has been approved to allow for the construction `
of a sewer line in the floodplain. The property which lies in the i`
floodplain will be dedicated to the City for open space. ;�
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STAFF RECOMMENDATION: '
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i,�Staff recommends approval of the Preliminary and General �lan fox Phases I
and II of Gentle Woods Subdivision with the following cond3tions: r�
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1. Specific plans sha11 be submitted to the Public Works Directox fox i'
all sewer line construction work in the floodplain. Plans sha11 be t;
approved by the Public Works Director prior to commencement of any work �:
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on the site. �
2. A11 lands below the 135 foot (100 year floodplain) level sha11 be dedic�,te�3 �;�
to the City of Tigaxd for onen space/park purposes. A metes and bounds `i
legal description and map sha11 accompany a dedication of the floodplain r;
area and sha11 be prepared by a registered engineer or land ;�urveyor. ':.'
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3_ ,Applicant sha].l a�plx for permission to operate model houses;in conjuncti,on �
with this development. All signs within this development sha11 be ��
approved by the Planning Department prior to installation.
4. A storm dxainage plan shall be submitted and approved by the Public
Woxks Director priox to the issuance of Building Permits.
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5. No Occupancy Permits shall be issued until all, condi,tians placed upon �
this develo�pment by the City of Tigard have been satisfied and inspections
verifying this have been carried out by the appropriate department.
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STAFF REPORT
AGENDA 5.2/ZCPD 30-80 (GENTLEWOODS)
TIGARD PLANNING COMMISSION
F�bruary 3, 1981
Page 4
6. Full half street improvements sha11 be made to SW 79th Avenue to
collector standards. The amount of dedication made for the improvement
of SW 79th shall be thirty (30') feet from aenterline.
7. No changes will be made to approved plans or specifications unless formal
application is made to the appropriate City department and changes are
approved by that department. Application for changes will be made in
writing and shall include applicable drawings.
8. Grading and construction plans for all work in public rights-of�way 1
and all other public improvements shall be prepared by a registere d
professional engineer in accordance with City standards, and shall be
submitted to the Public Works L�epartment for Review.
All public improvements will require a Compliance Agreement and must
be (design) approved by the Public Works Department, and must be either
(1) fully and satisfactorily constrw�cted prior to the recording of any
public dedication, final plat, or issuance of Building Permits; or (2)
bonded to the City for 100� of the estimated cost thereof prior to the
recording of any public dedication, final plat, or issuance of Building
; Pe rmits.
I 9. All proposed utilities shall be placed underground. Street lighting
" installations shall be approved by the Public Works Department.
10. A metes and bounds legal description and map shall accompany a de dication
of public ric�hts-�of-way, and shall be prepared by a registered engineer
or land surveyorer.
11. All street and parking areas shall be concrete or asphalt. All sidewalks
shall be concrete.
12. No Building Permits shall be issued until the expiration of the twenty
(20) day appeal period from the date of approval.
13.. No minor land partitions shall be made in reference to this project
unless formal application is made to the City of Tigard P1 ning
Department d the minor land partition is approied �n � rded.
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Pre �d y E izaU`bet����� �
Special Assistant to the Planning Director i ctor
EAN/AHvmc
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STAFF REPORT Ii
AGENDA 5.4 '
TIGARD PLANNING COMMISSION
February 3, 1981 - 7:30 p.m.
FOLWER JUNIOR HIGH - LECTURE ROOM
10865 SW Walnut Street, Tigard
NO SUBMISSION OF ADDITIONAL MATERIAL BY APPLICANT 5HALL BE MADE AT THE
PUBLIC HEARING UNLESS THE APPLICANT IS REQUESTED TO DO SO. SHOULD THIS
OCCUR, UNREQUESTED, THE ITEM WILL BE TABLED UNTIL THE FOLLOWING HEARING.
ADDEfNDUM TO STAFF REPORT V 14-80 (Silco Construction/Luminite Si�n Company)
of November 25, 1980, Tigard Planning Commission Public Hearing NPO #2
(See attached) '
This item was tabled by the Planning Commission on November 25, 1980 to
', resolve the floodplain issue. Mr. Frank Currie, Public Works Director
discussed floodplain issues with the Planning Commission on January 6;, 1981.
It is his opinmon that this structure would not signi.ficantly influence
the floodplain in a negative manner based upon a definition of what constitutes
a zero rise floodway, (See definition in attached draft report Flood 2nsurance
Study.)
Condition Number 2 to be changed as follows:
2. The drainageway along the entire east property line shall be cleared of '
a],1 noxi,ous vegetati,on. Culvert pipe be installed from Tigard Street
towar.d Far•uio Creak to Cit�;� requirements. A utility easement be granted
ov�er this culvert. Own�r to use this area to increase depth of parking
spaces to accomodate large trucks used in business. Oregon Department of
' Transportation to approve all work done in this area. Slope drainage
' plan to be incorporated with pipe system.
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Aldie Howard
Planning Director
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, , S'r�.r F REPORT �
'�, ;?�GENDA 5.9 � �. -•-
'�P�� �s�IGARD PLANNING CObL�1ISSION
NOVEMB�R 25, 1980 - 7:30pm
Fpi+�7LER JiTNIOR HIGFi - LECTURE ROOh!
10865 SW Walnut Street, Tigard
No submission of additional material by applicant shall be made at this
P�xblic Hearing unless the applicant is xequested to do so. Should this
occur, unrequested, the item wiZl be tabled until the fnllowing Heari.ng.
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DOCKET: VARIANGE, V 14-80 (Silco Construction Co.) NPO #2
APPLICANT: Si1co Const. Co. OWNER: Axlie and Irene Mawhirter• �
18791 SW Ma�tinazzi 142b5 SW 8�7�h Place
Tuala•tin, Oregon 97062 Tigard, Oregon 97223
REQUEST: For a Variance in the se�tback requi.remen�s in an M-4 zane to
permi.t canstructian of a building.
IACATIObi: 9350 SW 'Pigard Street (Wash. Co. Tax Map 2S1 2AB, Tax Lat 1901) .
STAFF COMMGNTSs '
The p resent 5,000 square foot building was constructed on this s�te years
ago. A lar.ge building was constructed to �he west with twenty (20) feet
of open space between it and the present building on this site. The pmposal
here is to add a 6,000 square foot building. One �f the problems is
the setback requirements in the M-4 zone--side yard to be twen�ty (20) "
feet. In this case the setback serves r�o purpose. If this new building
is constructed, there will be a twenty (20) foot strip between it and. t��*�'i "
building to the west. ahiftinq the proposed to the east to meet the �
setback reguirement would obstruct a drainageway from Ti.gard Stxeet to _
. Fanno Creek.
� One other problem is that the buiTding as proposed would be consfiructed � �
on th� 100-year floodplain. The Public Works Director has xeviswed this
request. Applicant has submitted a Sensitive Lands Permit application.
Canstruction would remove approximately 700 cubic �ards trom the Eloodpl.ain.
Future improvements in stre�..+r, flow at the i�9ain Street Aridqe may change
the floodplain upstream, Note that a portion o£ 'the buil.di.ng immedi.ateiy
to the west is now constructed in the floodplain.
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I. FINDTNGS OF F'ACT:
l. Tigard ,9unicipal Code Section 18.76.020 states that: I
"No variance sha11 be granLed by the �la��nir�g �or�u.ssioi. unl2ss it
can be show that all of the following conditions exist:
(1) Exceptional or extx�aordinary conditions applying to the property
that do not apply generally to other properties in the same zone
or vicinity, which conditions are a result of lot size or shape,
topography, or other cirGUmstances over which the anplicant has no
control;
(2) , The variance is necessary for the preservation of a �roperty
riqht of the applicant substantially the same as possessed by owners
of other pmperty in the same zone or vicinity;
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,STAE'F REPORT � � �
�`� �1�ENDA 5,9 - V 14-Sv �' �
�� 1'IGARD PLANNING COMMISSIOIJ •
NOVENIDER 25, 1980
Page 2
(3) The authorization of the variance shall not be materially detrimental
�o the puzposes of �.his ti'tle, be injurious to property in the zone
or vicinity i.n which the property is located, or be ot,hezwise detrimental
to the objectives of any city development plan or policy; '
(4) The variance requested is the ra3.nimum from the pravisions and
standards of this title which wil]. alleviate the hardship." . �.
Z. A portion of this lot is within �the 100-year floodplain.
3. SW Tiqard Street is in substanda.rd condition. '.
4o A significant drain�geway exists between this property azid the right-
of-way alang Highway 99W to the east. �
�I. CONCLUSIONARY FINDTNGS:
1. In this case the configuration of the lot and ��:sent structure in
x�elationship to development to the west indicates that the setL�ack
xequirements are not ap�ropriate ,far this proposed addi�ion to an
existing builc"i�.ng.
2. Z'he p rimary concern is the building in the floodplain. Section 18.57.040
� F'� does not allow a perntanent bui.lding within the 100-�year floodplain. �'
III. 5TAFF RECOMMENDATIONS: � . ���•'•
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Staf.£ recommends a��roval subject to the tollowing conditions:
1. A full half-street improvement to Collector Street standards be accomplished
oa� SW Tigard Street. /� , �/
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. 2. Z'he drainageway� along the entire east property line be cleared of �
all noxious aegetation�: Cul�rert pipe be installed from Tigard Street
.�,/+rr'�"��slr Fanno Creek to City requirements. A utility easemen� be granted
b�•�Ci� over this Gulvert. Owner �ko use this area to increase
depth o�arkinq spaces to accommodate large txucks used in bu�,ine�s. �.
����"'.f/^j'Y�o�l.�/�"""'7-u ��'j�'�'iI"'^'� -r'�....-r�./�- .�t �-:-.. ��. . .
3. Project shail be subject to Site Design Review. • =
4. Large sign mounted on roof of axisting building shaZl be removed. �
No futur� roof sign shall be.installed.
5. No outside storage of used/abandoned signs shall. be pexmitted orz thi�
parcel in the future.
6. I�suance of Building ?ermit shall be conditioned upon .engineering
and architec.tual certifiaation tha� the imorovements are floodproofed
to or abov� the 100-year flood elevation--153 feet (That is, impermeahle
to passage of water and capable of resisting hydrostatic and hyd'redynami,c
loade and the effects of boyancy) , • �V� ,. ,.,
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-t, �� STAFF REPORT � �-�---
r.� ;1GSNDA 5.9 - V' 14-80
TIGARD PLANNING CON1bIISSION
. NOVEMBER 25,, 1980
Page 3
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7. No Occupancy Pezmits shali be issued until all conditi,ons plac.ed
upon this development by the City of Tigard have been satisfied
and inspections verify.ing this have been carried out by the approrsria,te
department.
8. No changes wil7. be made to approved plans o£ specifications un�les� • �,
formal application is made to the appropriate Cit�r depaztmen.t, and �
� changes are approved by that department. Application for changes '
will be made in writing and shall include a�plicalale dsawings.
9. Grading and construction plans for all wazk in oublic rights-of-way �
and all other public improvem�nts shal7. Y�e �,xepared by a registered
professional engineer in �ccordance with City standards, an8 sha1.I.
be submitted to the Public Works Department for review. '
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AZ1 public improvements will r�quirn a Compliance Agreement and
must be (design) approved by the Public [4orks Depaz�'tment, and must.
be either (1) Eully and satisfactorily constructed pr.ior to the
zecording o� any min�r land partition, public dedication, final plat.
or issuance of Building Permits; or (2) bonded to the Ci.ty for 100�
of the estimated cost thereof prior to the recordi.ng of any minor
• lan d partition, publia dedication, f.in al plat or is�uance of Buildinq . �
, Fermits. .. • „�
I0. All existing and proposed utilities shall be placefl underground. �
Street lighting .installations shall be appr.oved by the Public Works
Department.
' 11. All streets and parking areas shall be conc.rete or asphalt. All � �
sidewalks shall be .concrete. ?
1Z. Nr� Building Permits shall be issued wntil the expi.ration o£ the • ��
�we�ty (2p) day appeal period froa� the da�e o£ appr�val. �
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Ald.ie Howard j
Planning Director . , , 4
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611.00 CONBTRUCTION GOMP+�Mt!
Octoher 31, 198Q
Plann�ng Commis•si:on �
City of Tigard
PO �3ox 2339.7
Tigard, Oregan 47223
. R�: Luminite Sign �ompany
935� S� Tigard �treet
Var�.ance of Setback
Requ�rements
Gentlemen: �
In accordance with tfie "City of Tigard Zoning Ordinance of I970," ._
we hexeBy� reques•t a var�ance from the requirements of thts title;
spe�ifically, Sectian 18.52.o4a "Set�ack Requirements. n Para�;raph
(,2} therein states in part tha� "The side yard setback sYiall be
twenty feet . . . . " We submit that this require�ment creates an
� undue and unnecessary hardship due to �he unus•ual sfiape and size �
of the exist3ng property. We will show that the conditions _
necessary for the City of Tigard to grant a variance do exist.
� The existing lot was created and the building constructed prior
. to tfie adoption of the zoning ordinance. The existing require-
ments �or an M-4 zone states� tfiat the minimum l�t area shall be �� ��
40,000 SF and the minimt�n lot width shall �e 100 feet. The set-
Dack requirements are related to this minimum lot size. The
existing lot is approximately 25,265 SF and has a minimum �ot
width of �!6 feet. Due ta the unusual shape and size of this lot ,
� the conditions• of �he zoning ordinance create extraordinary hard-
' ships on developing this property to the extent typically realiLed
in industrial zones. '
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Due to the narrow and long shape of the 1.ot, the existing building
was construc�ed with a setback of one foot from the n�orthwest '
property line. The only� land available for deve.Iopm�ent would be • II
; southwest of the existing building. Strict interpretation of the '
code for 3ide yard setbacks would create an unaccessible yard on
the northwest s3de, starting 130 feet from �he street, and a 20
� foot access way along tfie southeast side of any addition constructed,
. which orould eliminate the ability f�r direcb truck acaess and
loading necessary for most industr�al usei�s�.
RC BOX 337 • TtJA�.ATIN�OP1800N 970d� � CO3 • d3B-B7$4 / 63�-3�8l4•
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Page 2 �`
Luminite Si�n ` �mpa� � �_ � . �
Variance of Setback Requirements ' ' ' `�
> ., . �.
We are requesting a variance from the side yard setback require-�-
ment along tFy.e nor�Pi.aest property line, s�uch that an addition
may 'Ee. cons�tructed in l�ne �v��h tlie ex�sting Huilding. The
neig�Doring property� fias� �een developed �rith a 20 foo� setback,
so tfiere would He aece5s for firefight�ng equipment. We are also -
requesting a var�ance for the sout�ieast prope.r�y line setback,
allowing a Duilding to b� cons•tructed �rith truck aGCess facing �
the street . This propert�r abuts tfie Pacific Highway Right-of-Way
�along this l�ne wfiich would provide access and separation Prom
other structures• to the southeast . �
We believe that constructing a building of this size and configura-
tion would be an asset to the commun�ty. There is a need for -- -
small user industrial space. The building would� create �obs and
commerce far the community. The building would reduee the current
use of the land for outside storage. The bu3lding would not
adverselyr affect the existing drainage way along tfie southeast
property line. Neighborhood �'lan Two recognizes the need to
develop existing industrial land for many reasons, including
employment opportunities, tax base and the intent of the Comprehensive
Plan. Policy 26 states that industrial developmen� shou�.d canform
to higfi standards for site design. and this is exactly what we
propose. '
We request your favorable considera�ion in allowing a variance for
. the side yard setback requirements on this parcel of land.
1 Sincerely, �
ST•LCO CONSTRUCTION COMPANY
.� ��'�.�� �����
' `"Sruce D. Nicholson '
�
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FLOOD INSURIINCE STUDY .
(DRAFT REPORT)
�
�
,,
, . . �
CITY OF TIGARD
WASHINGTON COUNTY, OREGON
Prepared by
P � Portland District, U.S. Army
Corps of Engineers �
, June 1980
for I
: I
� ;
U.S. F�DERAL EMERG�,NCY rtANAGEMEI�T AGEIZCY
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TABLE �F COIJT�NTS � "
Pa�,e.
1.0 INTRODUCTION . . . . . . . . . . . . ., . . . . . . . . . . . . . . �, ;
1.1 Purpose of Study. . . . . . . . . . . . . . . . . . . . . . . . ,i
. 1.2 Authority and Ackriowledgments . . . . . . . . . . . . . . . . . �,
� 1.3 Coordination. . . �. . . . . . .. . . . . . . . . . . . . . . . . 2
• 2.0 AREA STUDIEA . . . . . . . . . . . . . . . . . . . . . . . . . . . . Z
2.1 Scope of Study. . . . . . . . . . . > . . . . . . . . . . . • 2
2.2 Community Description . . . . . . . . . . . . .. . �. . , �. . . . 3
2.3 Principal Flood Pxoblems. . . . . , . . . . . . . . . . . . . $
2.4 Flaaci Protection Meaaures . . . . . . . . . . . . . . . e . . . '� .
3.0 ENGINEERING �lETHOD5. . . . . . . . . . . . . . . . . . . . . . . ']
� . . . . . . . . . . �
3.1 Hydrolo�ic Analyses . . . . . . . . . . . . . $
. �,��;;�q
3.2 �Iydraulic Anal_yses. . . . . . . . . . . . . . , . . . . . . .
.
4.0 FLOOD PLAIN MANAGEM�NT APPLICATIONS. . . . . . . . . . . . 4 . . . ��
.
4a1. Flood Boundaries. . . . . . . . . . . . . . . . . . . . . . . . �.�
4.2 Floodways . . . . . . . . . . . . . . � . . . . . . , . . . • • . 12
S.0 INSUKANC�; APPLICATI�UNS ., . . . . . . .. . , . . . . . . � • • • • • 18
5.1 Reach Det.erminations. . . . . . . . . „ . . . . . . . . . . . . �$ .
5.2 Flood Hazard Factors (FHF's) . . . . . . . . . . . . . . . . . . �g
5.3 Flood Insurance Zones . . . . . . . . . . . . . . . . . . . . . �q
5.4 Flood Insurance Rate Map Descriptton. . . . . . . . . . . . . . 20
6.0 OTHER STUDIES. . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
�. , � '
.
L � .
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. TA13LE OF CONTEi1TS - (cont'd) �
�
Pa e
j 7.0 LOCATIO.T OF DATA . . . . . . . . . . . . . . . . . . . . . . 22
. � ,
' 8.0 BIBLIOGRAPlIY AidD REFEItENCES. � � � 22
. . . . . . . . . . . . . . . .
� • .
� FIGURES .
� Figure 1 � Vicinity Map. . . . . . . . . . . . . . . . . . . � . . , _ . �
Figure 2 - Expected Future Flood Heigh� Photograph o£ Fanno Creek. . . . 6
Figure 3 - December 1977 Summer Creek flooding at S.W, 116th Avenue. . . 7 ,
Figure 4 - Floodway Schematic . . . . . . . � . . , . . , . . . . . . . �,7
TABLES
k.. �` Table 1� - Summary of Discharges , . . . , . , . , . , , , . . , . . . . 9
.
I' Table 2 - Floodway Data . . . , , , . , , . , � , . . . . . . . . . .
' t3- tG
Table 3 - Flood Insurance Zone Data . . . . . . . . . : . . . . . . . . Z'
i
EXHIBITS
,Flood Profiles
Fanno Creek
Ash Creek
Summer Creek
Flood Boundary and Flood�oay riap Tndex �
Flood Boundary and Floodway :Iap •
PUBLISHED SGPARATELY:�
Flood Insurance Rate riap Index
Flood Insurance RaCe Map
� } �
. •
. 1 �
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� . FLOOU INSURANCL' STUllY
1.0 INTRODUCTION
. 1.1 Pur.pose of,Study
This Flood Insu�ance Study �,nver • ea�es fihe existence and severi_t�._
. �_--
. �f flood hazards in the city o£ Tigard, jJashington County, Oregon,
and aids in the administration of the National Flood Insurance AcC
of 1968 and the F1ood Disastex Protection Act o� 1973. This study
will be used tio convert Tigard to the regular prQgram of flood
insurance by the Federal Insurance Admin3stration (FIA) . Local and
reg ona p anner=,s�wi11P usp�i his st�'a�iy ir; rhA.ir �ffort,s ta prom�ot_e��
sound flood plain management. . �
�I� � In some states or cqmmunities, flood plai_n manaoement G�-i.teria or - �
regulati�ns may exist that are more restrictive or compr.ehensive
than those on w u i these Federally supported gtudies are bas�ed�
�— - t -
These criteria take�pxec�dence over the miniinwv Fedexal criteria •
for purposes of regulating development in the flood plain, as set '
� forth in the Code of Federal Regulations Tie1e 24, Apri7. 1, 1976.
' In such cases, however, it sha11 be understood .that the State (or
ether juriscli.r,.rinr,ai �gency.). shall be able to expla3.n these
requir�n�ei�r._s_. a�rI: ciitet.ia..
1.2 A::�t�o�ity a:�d �eknowledgements �
The source of authority for this Flood Insurance Study is the
National, Flood Tnsurance Act of 1968 and the Flood Disaster Pro- -
tection Act oE 1973.
� .
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•
� R .
� w �� ,� The hydrolo .
&i� anal � . . �
JQS
Y for this study was
��•S. Army CorPs of �n Performed bY the
Federal Insurance gineers, Portlancl D
� , Administra �strict, for the
, consultin tion. Jones Associates, Inc., a
g enSjn,eerin� Firm
' while under con�xact to � pezformed the hydraulic �
' the Cor analyses
� was Frepared for Ps of Engineers.
. the Federal Th�-s study
Inter-��enc Insurance Administra
• Y �€reenent No. H_�_76 tion ur�der ,
Qrder Nuinbers and Ii-Ip_��� and p
i. I7 and 1, respectivel roject
� j� June 1980. Y' The study was com
� pl e ted
� .
' �•3 Coordination '
The initial coordination meetin �
representatives of g Was held September
the Federal �'976 With .
the Cit Insurance Administration
y °f Tioard, and the • �r�IA) ,
�,5. Ar� study contractor P
y Corps �f �n ( ortland District,
studied gineers), to identif
' QXP1ain the Y strearn reaches to be
study conceptS
establish communication and � ident.ify data �
coordination sources, and
� �� procedures,
An intermediate coordinatio
n meeting was held in Tigard on
. > to allow 1oca1
. drawin officials to review
gs showing water Plan and profile
surface profiles, floodway deline'ations
flooded-area outlines.
, and'
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i
'�he final consultation and coordination � �
� In attendance were meeting was lreld on
interested residents of app�Opziate officials and �
the conanunit �
. a rePzesentative pf y' a representative
�he stud� contractor. °f FIA, and
were presented The results of the
to and accepted sGu
d
bY tlie communit � Y
Y. . . �
2.0 AREA STUDIED � � � � `Y
�
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2.2 ScoPe of Study , �'
�;
� � ��
This flood Insurance Stud �
y covers the incorporated area of the �
City of Tigard, Wasfiington County, Oregon, �'he .
� stud �
Y area is sho�,�n
. �':
� 2 . �
,
: �
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�
. � � �� N. � � � ��,
. v�. F � ir � � i } I
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� � on the Vicinity 24ap (Fi�ure 1) . j
�
_ �
' The limits of detailecl and approximate studies in Tigard, . ;
. were detarmined by FIA with community and sCudy contracCor con- , �
sultaC�_an aG the meet3-ng �.n Segtemt�ex..1976.
,.
• A detaile� study was m�de of� floodi.n� from Fanno Creek, Ash
Creek, and Sumraer Creek within the Tigazd corporate limits.
Approximate methods were used to study a small. tributary to
� Fanno Creek, Iocated on the north�oest edge ;of Tigard near
Scholls Ferry Road (Route 210) .
2.2 Community Description
Tigard is locaC.ed in nori:Ii,�esC Gz�gan, in the sou�heast corner
of Wash�.~agton County. It is a.pproa�imatel.y 8 miles southwest of
Portland, Oregon. Tigard was incorporated in 19G1; and its
populat{on has gro�?n fro�. �302 �.n 1970 to an estimated 13,500 �
�: � • ;ra�l
in 1978 (Reference .l) . �;
. . S `�'�I�'f�t� I J
�
Fanno Creek, a tributary to Tualatin River, drains 13 square ;I
� . � ,�
miles upstream of Tigard. It originates in the w�st hills of '�
Portland. The stream fZo�as through Tigard in a generally south- �`
, . i;
� easterl.y direcCior. Ash Creek, a' tributary to Fanno Creek with {'
. . ,,
Y
a 4 square mile dza?.na�;e.. axea.,. flQCas 'in a southwester.ly direc�.ian. fa
SUIIIIII2i Cxec.l�, a1^i w trib.st.azy t� �'anno Creek, fl�ws in an east- �
�
erly direction as. it drains S s�quare miles. A11 three streams `'
� 'il
- are crosse� by nu�aazous bridges and culverr� within the Tigard `
�i
corporate limits. � '
�
, [�
f
Economic activity ir� Tigard. is diversified and growing. Indus- �
G
trial facilities in the commun3ty are vari�d, and are located i
alon� Pacific Highway West (State Highway 99�d) and StaCe Highway �
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� Fcdc:al fn:::rer.ce A�r�in:straticn 4000 0 4000 80Q0 12000 F'EET !:
G CE 1 9� �� � �:�1 y�� �4 :
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217. Commercia'1 development is locatecl priniarily a1on� P�cific
.� ' Hi hwa West and S�jJ. Main Street. Resiclential development i� �
S Y
TiSard is mostly wesC oE I'�anno Creelr. Important transportatzon
� routes in the city axe Pacific High�Jay. West, State Higlaway 217,
� Ha11 Boulevard, and tl�e BurlingCon I�ozthern and 5oukhern Pacific
� ��'Y2� � �c�.� �'�a���15 Ot .5¢J�Yr�.Q. 2�'t'..t5 Q��1�1. t1'u. . .
. railway lines. �d-a�+ � ' ��
s;,.
StYCarn v�enc4�<5 5tud i.S1 are q,..;�nr:�oi.�•�. dc�clo p•,�r.,,T . O��c� areti
� � ._.t..L•._� ... �� .
. .+'?�ri�i�tR`�+ L AC`�'.._. . -�l�ii
' -��s alo�� 5u..�,..er GYeek betwvcr 5.W. i 13 th w,�cA S.f): l21 st
/� ��nd-�-Gr4k�c�.-3-�t—rl�renue . �es��er�►c.e_s�.ax..ra._.
� � I'1V1CI�NC$ w'rtEr�e �Se��er� YY:i:.��. ��i'S QY2 IY\ .'rV'�.i. i {Ci�J:) .y{�A.�� . . .
�ee:t�-et-o--��orl�-E�e.t _.S-kosd�-��o�e�a-�s--a�or►gw�
�t�sa•l��.;� 1`i ,�- N ..- "'r::- ir�c.ikU¢.g Gt�mw�er�io� 4��cQ reS�.AC.�'f'i�
'�'�'lll��'-'G'�!'!`8 e�1•�C f'�..�—•a•i.'�`i'�Rt ' g E'_'9'�"'K]'(75'���Aill^
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.;_ � i,1— . �-� Lr .i.�.-,_t�_.�_l�l_... _1..�.w
rer-�rr�r= ' •
Poc:f�� I�.:�.1�.:)Hy vJest •.�s�Ye�tir•� -b 5 VJ. T�ede��.nv� f�-vev�u.e..
_..� ,,.�....Q�....e}��,..�• e9.;
The cl�mate in Tigard consists of warrn, dry 'sur�ars and mald, •
wet wintexs. Temperatu.res are usually moderate, ranging f.rom
an averase January minimum of 25°F to,an average .7uly maximum af
$1°F (Refexence 2) . The average annual precipitation is nearly
� 45 inr.hes, with '78 percent of �h�e pxecipi�at�on occuxring fsom
October to riay. Snowfall occurs on only a fe�v days each year;
�now on the ground is generally o£ short duration, with depth��;�Y�
, seldom ehceedin� 6 inches (Refer:e�ce 3) .
Soils in and around the city of Tigard are silt loams on nearly
level to stee� slopes. Drainage characteristics for those soils
are poor along the Summer Creek an.d Fanno CrPek flood plains, but
drainaQe�i.m�rnves...nn- ca,opin.g ter.ra3.n. Trees, gra.ss, and shrubs
are the dominant vegetati:on types, The incarporated area .is being
rap�dly urbanized. -
2.3 Yrincipal Flood Problems
.
' Fanno Creek, Ash Greek, and Summer Creek flooding is generally
caused by rainstorms in the winter, the p�riod of greatest storm
�. ,
S
: � __
_ ,
....._�.,...�._.,.ry._._w......_..._...., ___..:._.....�...:.:,,.._.�._.�,:...�......_._.�._.....__.,,...� _�..�........�......_.�_....._.._.W___ ;
� ' _.. .. . _.....__.._._..._�.._._w .
� i
�" ; , , � �
' activity. �loods rise quickly folloi�ing a heavy rainstoxm and
� usually lasC less �han a day on Fanno Creek and half a da on
Y
� Ash and &ummer Creeks. '
Flooc��n� in Tir�wvc� i3 no� Wa11 dO�u���t��'�.".c�•
. � The largest flood on Fanno, Ash, and Summer Creelc� during the -
last 10 years occurred in December 1977. Although stream gage
19"1"i
records are not available, it is estimated that the"f lood recur-
rence inCerval �aas about 10 years for those thr�ee streams.�o-
� �'''��� �'1o�d, �1a�age� ;.^. Tibard were light since the areas
susceptible to flooding were generally known and development was
avoided. •�aac3-fe�-�-; - ��,����„�,,e�
gage�eeord. ��}�—da.va].�nen�--occtrr��-ed�.
� a3.�rg�f�.—.��1•a��gl�nin•: Flooding along Summer Creek is accentuated
by a high �round water table, which causes nuisance flooding to .
numerous residences. Figure 2 shows the heights that would be
expected from 100- �a�nd 500-year floods on ��anno Creek. Figure 3
shows floodinb in Tigard from Summer Creek in December 1977.
�'�-s r 7. Ct:. �• r «-•..x
►"• �"�',t f"'7."!C'�Mf '1 f• .qy:ye+ ,e• .�. y^ -,7 :".?'
;.' ' ,.`��`�,,�; F,y=i�r°-•�r:::;:�:;•,l���l:�s'; 'f •ti . .
� � � �� ;�.•�:� 50o YERR F�LooD;;Y� : . - �'_�:.
' �. � f ��.. ";�i: `Fp,�',.� ; , .;, ::,,,.
�'' �•• ' • 1ir lOQ YEAR Fl.00D .1 � � I�,•.•lf'� � ,i
' �i• .�� ?`�.F. ,`�. „„'rr�`�"�,^�'r,-•��� :N_ F�_� - :-�
i 's+-+.c..v..s.c�...s�`0 ,w � ?� i".•'•,. : •�, �i .S�:L' �•� +%fr� �:
� . ' . . ... .. .. : ���:wt1��,�'�' _ i'` : •., •''.�,�4Yi'�r.• , • .
�..�.o"���, E J. ' , '~� '�'��y��•�� ', " '"� Yw1'��'�'�`'�`�►t« .
•,.� ,� � �t �''�'�;.i�. G,� .,
`P'\T. -�::::::'r;��
�` _.--- .. 1 , _.�" ��-.�-. , �.:,....,.,,..,,,,,..,-:, . ,
- •- - _ ._... _ ;1 •�--• .e �' . .. . -�:,.n.n..,._„ ,...,..�n„�,,,,�„
._.-�_..._._..� �{� � ' • .. -,'i._'•.,;i. r•..,_.'^ M. -�'
q �_....,....,�' �--.�-� �. �.......,...-�.,� �_,---r.-,._. �.a..__...,�
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w• r. 1� � � .
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.�i..� • 4 ��, •i�i . �i ���
+:,... .,,t. •, .` ••, h ,, � � .. 't�`'`,' ?�5,� .
." .�`�� �.{_,• ;'' [ :;�� .y� ' j� �� ' ` '�``.:�`�
'S •�:1"...r�'"'Jrj:���i:�i.e�LLi�i.�L:"�.:iuil�,li�ll'YiG.i►t���'i, �� , �{�!-��_T`'�,:�`L �i►�13 j .
f� � d6G�+i�i'�0.4i.i�.il���W�S�L1 C.rfi�:
Figure 2. Expected future Flood hei�hts of Fanno Creek at �
, S.W. 95th Avenue Bridge.
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_.. .w_r ._�..w ..�..�.,__,u �
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. , w_'
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, � '��.; �,.. . . • .
. �..�r ��J��♦. - •
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,,,.s.i.r:�ai�.-• q. c' '
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� � '�,f' ...+Ea'- °s''° - �±�1�'� .._......e...�.L.: _v. � ' .v
,'�t,i'�.:.�.ALi W%talL'��i a�
.
Figure 3. December 1977 Summer Creek flooding a� S.W. 116th Avenue.
� ��
, 2.4 Flood Protection .Ieasures .
There are no flood control structures within Tigard corporate
t4 D we�e�')
limits. �Dt'on-structural measures of flood pr,otection are being
utilized to aid in pr�vention of future flood damase. These
are in the form of a flood hazard zoning ordinance which follows
FIA's guidelines (Reference 4) for controllind development within
the 100-year flood plain. Tn addi�ion, the city requires building
permits Eor construction and reviacus those permits to assure that
s•ites are reasonably sa£e from flooding.
3.0 ENGINEERING METliODS
For the flooding sources studied in detail in the couanuniry, standard
• hydrologic and hydraulic study methods were used to determine the
f lood hazard data required for this study. Flood events of a magni- •
-- tud.e which are expected to be equalled or exceeded ance on the average ,I
�� �
;
�
: i
' 7 '
.� _ . : �
� ' _ _._--.._N.__�_ . _._.__ . .. _._.._.
.
.. . •
, . •,
� during any 10-, SO-, 100-, or 500-year period (recurrenca interval) ,
- have been selected as having special si�;nificance for Flood plain
mana�ement and for flood it�surance premium rates. These events, com- �
monly termed the 10-, 50-, 100-, and 500-year floods, have a 10, 2, 1,
and 0.2 percent chance, respectively, of being equalled or exceeded
during any year. Althou�li L•Iie recurrence interval represents the long .
term averafie period betcaeen floods of a specific wagnitude, rare
, floods could oecur at short intervals or even wiChin the same year.
The risk of experiencing a rare flood increases cahen peri.ods greater
than one year are considPred. For example, the risic of having a flood
. which equals or exceeds the 100-year flood (1 percent chance of annual �
occurrence) in any 50-year period is about 40 percent (4 in 10) , and
for any 90-year period, the risk increases to about 60 percent (6 in
1.0) . The analyses reported here reflect floodin; potentials based on
conditions existin� 3n the co;�uuunity at the time of- cocnpletion of this
• study. Maps and flood el.evatians will be amPnded by FIA periodically
to reflect furure changes.
: � �
3.1 Hydrol.osi,c Analyses . , . �:.
, �.,.�r:
Hycflrologic analyses were carried out Co establish peak discharge
frequency relationships for floods of the selectec� recuxrence
. intervals fox each flood�ng source, studied in detail, affecting
tir.r �V W1MY�Ll L�.
There are no stzear� gage stations on Fanno Creek, .Ash Creek, or �
Summer Creek. The Sra�,]. Conservation Servi.ceX method for rainfall-
runoff and unit hydxogr.aph determination (Reference 5) was used in
conjunction with Corps of Engineers computer programs (References
' 6 & 7) for hydrograph computing, combining, and routing Co gener-
ate flood hydrographs for selected recurrence intervals on Fanno
, • Creek, Summer Creek, and Ash Creek. � !
� '
$
� , ._v. ___...
.;
, � ;, .
A summary of drainage area-peak clischarge relationships for each
�^
-- stream studied in detail is shown in Table 1.
TABLE 1 - SUr1�ir1RY OF DISCHNtGSS
FLOODING S�URCE DRAIi1AG� AREA PEAK DISClI11RGGS (cfs)
AND LOCATIUN Square Tliles 10-YR 50-YR 100-YR S00-YR
Fanno Creek
at S.W. Durham Road 31 2900 3800 4200 5100
at S.W. Tiedeman
Ave. 24 2750 3500 3$50 4700
at S.W. Dakota
Stree't 17 1900 2450 2700 3250
Ash Creek
at mouth 4.1 750 950 1000 1250
Summer Creek ' .
f �� at mouth 6.2 1050 13�0 1450 1750
at S.W. 135th � �''
Ave. 4.0 800 1000 1100 1350
�� �pproximate 100-year f lood discharg� was developed for a small _
� tributary. to Fanno Creek, located on the northwest ed�e of Tigard
near Scholls Ferry Road (R,oute 210) . The regional procedure
(�eference 8) was used on that Fanno Creek tributary.
3.2 H.ydraulic Analyses
' �
i
Analyses of the hydraulic charact�ristiics of the floocling sources
Scua��a in detail 'in City of Tigard were cazried out to provide
estimates of the elevations of floods of the selected recurrence
intervals alons each of those f lood sources.
' Hydraul.ic analyses were performed using the Corps of Engineers
HEC-2 step-bacicwater computer program (Reference 9) . Gross
�� � �
9
. ,
_
_ _:, _. _ .
�.
, , � , .
�_ .
sections far F�nno Creek, As11 Creek, and Summer Creek were com-
�
posites of dat� from Corps of Engineers fieZd surveys obtained in
1977 and City o£ Tigard topographic maps (Feference 10) . All
bridges, dams, and culverts were field checked to obtain elevation
duta and structural geometry.
• Locations of selected cross-sections used in the hydraulic analy-
. ses are shown on tlie flood profiles. For stream segments for
which a floodway was computed (section 4.2) , selected cross sec-
� tion locations are a�so shown on the Flood Boundary and Floodway
. Map. . .
Hydraulic roughness values (Manning�s "n") for the channel and
averbanks were first estimated f rom field observation. The "n"
values for Famzo Creck were then modified, when necessary, to
match' the hi�h�oater profile af the Decec�ber 1977 flood.• The
final calibrated "n" values for Fanno Creek in the study varied
� from 0.042 to 0.065 for the channel and from 0.075 to 0.110 for �
the overbank. Ash Creek "n" values ranged from 0.052 to 0.062
and 0.065 to 0.180 for the channel and overbanl�s, respectively.
Summer Creek "n" values ranged from 0.045 to 0.030 and 0.075 tc�
0.300 f or the channel and overbank, respectively. �
. , .
Starting water surface elevations for Fanno Creek in Tigard
were obtained from a hydraulic ax�alysis performed by the U.S. �
Army Corps of Engineers for the Washington County Flood
Insurance Study (Reference Il) . Starting etevations for Ash
Creek a Summer� Creek were based on normal depth calculations.
All elevations are measured accoxding to National Geodetic
Vertical Datum (NGVD) of 1929 (adjusted in 1947) , formerly
referred to as Sea Level Datum, 1947 adjustment. Elevation
seference marks used in this study are shown on the Flood
Boundary and Floodway I4ap. ' '
��
' (p �
_.,�..�._,.�..,_.__. .__.... ___..�..._..__....._.___.__._���_�._�T_T._.�.____.�_^.___.� .._.._ _ ...
_ ._...__�__,.__,_ ,.,...�.. , .. . .
.
.. .
. �.:`-.. ....,. --__._� �. . .
. � �
• + � �r , , '
� The hyclraulic analysis for this study i.s based on unabs�.rueted
� flow. The flood elevations shown on the pxofiles are thus con-
sidered valid only if hydraulic structures reinain unobstructed,
and operate properly. '
4.0 FLOOD PLAIN MANAGEDfEidT APPLICATI.ONS
The National Flood Insurance Program ei�cour.ages staCe and local. .
governments C� au�p°� 5ouiic� fiond p1a�.n management �xoGrams. There.fore, .
each Flood Insurance Study includes a £�.00d boundar.y map designed
to assist communities in c2evelopin� �oun.cl f].00d plain management
. measures. .
4.1 �Flood Baundaries
Tn or.der to provide a national staa�dard. withouti x'egional discri- ,
mination, the lOQ-year flood has been adopted by the FIA as the
, � base ilood for purposes of fYood plain management measuzes. The �"�
`���.y
500-year fl�ad is eln�loyed to indi.cate additional areas of flood "
, , ,ry.:-t, �
risk in the community. For each stxeam studied in detail, the��� ;;
��
boundaxies of the 100- and th.e 500-yea.r floods have been deli-
neated using the flood el.evations �determined at each cxoss sec-
�
. tion. Bet�aeen cross secti�ns, �k�e boundaries were interpo2ated
� using top�graptiic maps with scales o� 1 in.ch eguals 400 �eet w?th `_
s
1
� a contour intezval of fo.ur fee4 (Reference ) . In cases where
the 100- and 50U�year. flood houndari.es ar.e c].ose together, only '
the 1Q0-year boundar.y has been shot�n.
The appxoxiinate 100-year flood boundaries for the small CribuCary
to Fanno Creek located in northwest Tigard were obtained from the �
Flood Plai.n Delineation �1a s ublist�,ed b Washin ton Count �
p p y � y {Ref er--
�
, ence 12) . The approximate I00-year fl�od bounc�aries were delineated
on the USGS quadrangle maps. � ��
/' • _
\.._ .
� �
�
, 1
- - _
. �
_ _..___. ... . _ ..._..____...__._..___.�____.._...._. .,�.__ _._,_�..____..�..._....._._.__�_.._._.._.�.____._..._.._w..�.�.._..._.__. . __.
� � :�, .
� ,
� The boundaries of the 1D0-year and 500-year floods are shown on
, the Flood Boundary and Floodway Map. Small areas within the
fl.00d boundaries may Zi.e aUove the flood elevations, and there-
fore may not be subject to flooding. Owiiag to limitations of '
the map and scale and/or lack of detailed topographic data, such
areas are not shown. '
� 4.2 Floodways ,
Encroachments on flood lains, such as structures or earthfill,
reduce the flood-carrying capacity, increase the flood he g s
o s reams, and increase flood hazards in areas beyond the
en roac men i se . agement
nvo ves a ancing t e economic gain from flood plain develop-
ment against the resultino increase in flood hazard. For pur-
poses of the National �lood Insurance Program, the concept of a
floodway is used as a tool to ass�.st local communiCies in this
� �.. --
aspect of flood plain manage�ent. Under this concept, the ar�ea
� o the 100-year flooci is divided into a flood�vay and floodti�ay
..��.�.. �...�,....
frin e. The floodwa is the channel of a �tream 1
us an ad a-
S Y
P Y 3
�
cent f1AOd plain areas that must be kept free of encroachment
i .
in order that the 100-year flood may be carried without sub--
stantial increases in flood heights. Minimuin standards of the
FIA limit such increases in flood hei�hts to 1.� foot, provided
� that hazardous velocities are not produced. The floodway in
this report is presented to local agencies as minimum standards
�hat can be adopted or that can be used as a basis for additional
studies.
�
,
The floodways presented in this study were computed on the basis
of equal canveyance. re�iuction from each side of the flood plain.
• . The results of these computations wer� tabulated £or selected
cross sections for each stream segment fnr which a floodway was
compuCed (Table 2) .
�..,..
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,
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' FLOODING SOURCE FLOOOWAY BASE FLOOD j
} WATER SURFAGE ELEVATIOf�!' �
CROSS 1 WID7H SECTION MEAN WItHOUT iNiTH tNCREASE
jSECTION DISTANCE2 �FT.� ��REA VELOCITY REGUL'ATORY FLOQDWAY
, �
(SO. FT.) (F.P.S.) (FEET lVGVU) F�OODWAY (FEET)
i 2.41 250 1556 2.7 133.8 133.8 134.5 0.7
i �A 2.69 90 903 4.6 135.9 136.9 Z37.5 0.6
� B 2.30 220 1621 2.5 137.7 137.7 138.3 0.6
� C 3,34 400 2412 1.7 140.0 I40.0 140.6 0.6 .
D 3.6$ �: 320 I730 2.4 141.1 141.1 141.7 0.6
� E 3.86 280 � 1379 3.0 141.9 14I.� 142.5 4.6
� F 4. 16 260 19b0 2.1 145.9 145.9 146.4 0.5
G 4.50 240 1517 2.7 146.8 146.8 147.4 0.6
: - � H 4.73 440. 2010 2.0 148.0 148.0 148.6 0.6
� 4i I 4.81 73 5Q1 8.Z I51.0 151.0 151.2 a.2
' J 4.8a 101 843 4.8 3.52.8 152.8 � 152.9 �J. 1
_
' K 4.93 ��5 �487 �.7 �53.6 153.6 i53.7 �.I
� L 5.07 55 513 5.6 153.9 I53.9 154. 1 �.2 -
, M 5.21 28{� �507 1.6 15�s.6 154.6 155.4 0.8
N 5.67 400 2617 1.5 155.3 155.3 155.0 0.7
; 0 5.83 5t1 546 7.i 156.2 i56.2 156.6 0.4
' b.12 150 1Q05 3.2 159,4 159v4 159.4 0.0
;
i 6.23 188 . 1612 2.0 159.7 1.59.7 160.0 �.3
' 6.27 138 1318 , 2.4 159.7 15y.7 160.0 d.3 �
, 6.35 117 744 3.6 160.1 160.1• 160.5 0.4
1. Unlettered cross sections are outside.of Study Area. �
2. Miles above mouth. -
.
. �
�
�. .�� . . '�F . : .
; D D'cRARTMEtiT OF HOUSIHG AND URBAPi DEV�LOF"rREt�T --
,� Fedorsi lrrsur+inco Admiro�stratiar� '���o���� ���aQ1
r- r
m
" CITY OF TIGARD, OREGON � �
N
(t�as}iington County) � • FA�NO CREEK
.
;� PAr,F i OF 2
� -- -- -- - - '
� {� ,1 _ , -
, . � � . .
; .
,
. � � �
FLOODING SOURC� FLOOQWAY BASE FLOOD �
WA7ER SURFACE ELEVATION
� GROSS YVlDTH SEGTION MEAN WITHOUT WITN INCREASE
( I 61STANCE2 AREA VELOCI�Y REGUTATORY FLOODWAY FLOODVdAY {FEET)
SECTION (FT.) (SQ. FT.) (F.P.S.) (FEET NGVD)
i .
, � 6.58 300 2298 1.2 1b0.5 160.5 161.2 0.7
i 6.85 310 1997 I.3 160.8 160.8 161.5 0.7 ,
`j � P 7.09 � 160 1103 2.4 16I.4 � 161.4 162.2 0.8
+ 7.23 44 293 9.1 162.9 162.9 163.5 0.6
I:� 7.44 340 2181 1.2 165.4 � 165.4 165.7 0.3
� �
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''; 1. Unlettered cross sections are outside of Stucly Area.
'; 2. Miles above mouth. -
,�
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�� . --� OEPAATntENTOFHOUSlP1Gb�IDURBANDEVELOPtdENT ��,OODWAY DATA
�� � fedxd taisunnce Admirinuation •
r �
; : m _
, N ' CITY OF TIGARD, OREGON ;
t _ � FANNO CRE�EK
- (Washington, County)
� ' � .
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, .- � � � � . �
. � II
.
¢
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FLOODlNG c,OURCE ' FtOODWAY BASE FIOOD ; �
WATER SURFACE ELEVATION ;
CROSS I 2 WfDTH SECTtON MEAN WITHOtJT yy�T� INCREASE }
SECTfON DtSTANCE ��T} AREA VELOCITY REGU�AZQRY FLQOOWAY F�OODWAY (FEET) �
_ (SQ. FT.) (F.P.S.) CFEET NCVD) �
O.C2 140 566 1.8 160.1 i55.3 156.0 0.7 F
" 0.10 . 47 183 5.6 160.1 155.8 156.4 0.6 �
0.22 �4�i 295 �3.5 160.1 158.4 159.3 0.9 4
A 0.40 � 95 4i7 1.9 I6Q.2 160.2 161.0 0.8 E:
B 0.49 3S 231 � 3.9 160.6 I60.6 t I61.5 0,9 �
0.55 2b 197 4.5 161.8 I61.8 � 162.8 1.0
0.71 240 965 0.
��
9 162.1 162.1 16
3.1 1.0
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1. Unlettered cross sections are outside of Study Area. � �
2. Miles above mouth. - � �
'-� QEPARThiENT QF NOUSIFIG AND UR3AN OEVELOP1ilEt�T ""°
� `� �L��Q1111A� �ATA. � �
Fedara!lrsunnce Fidr�imtrution
m f
^' CITY OF TIGARD, OREGON t
(Washin�ton Coun�y) ASH CREEK �'
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FL,OOOING S�URCE FLOODWAY BASE FLOOD ;
WATER SURFACE ELEYATION ' i
SECTION MEAN WITHOUT ;
CROSS 1 2 WIDTH WITH INCREASE
SECTION DfSTANCE (FT.D AREA VELOCITY REGULATORY FL.00DWAV FIOQDWAY (FEET) �
(SQ. FT.) (F.P.S.) (FEET NGVD) i
a 0.12 120 561 2.6 157.1 154.9 155.5 0.6 '
B 0.3C 89 351 4.1 157.3 157.3 158.1 Oe8
C 0.76 180 b87 Z.1 161.8 161.8 I62.5 0.7 i
D 1.07 120 346 4.1 168.Q 168.0 168.7 0.7 j �i
E 1: 13 125 688 2.1 169.0 169.0 169.5 0.5 �
F 1.30 165 1045 1.3 169.5 169.5 170.1 0.6
G 1.40 65 267 S.0 171.1 . 171. I 171. 1 0.0
H 1.50 55 569 2.2 171.7 171.7 172.Q 0.3 � ��
Z 1.51 60 550 2.3 171.6 171.6 172.I 0.5
J 1.55 60 554 2.3 171.7 171.7 . 172.2 0.5 t
1.74 195 585 2.0 172.5 172e5 173.3 0.8 ',
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4
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' 1. Unlettered cross sections are outside of Study Area. _ , !
2. Miles above mouth. . t
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-� OEPARTNIEfJT OF HOUS111G AND URBAfd DEVfLOPn1EPlT !
WF�dotcl lrtsurnnca A�mir,�strstion F L O O D W A Y D AT� }
m . i
: CITY OF TZGARD, OREGON �
N. I '
(i.'ashin�ton County) �� SU.L"lER CRE�K - � .
• - j
�
� _ '
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. .�....�__..�_._.. __.._ . . ._.....
_ _ _ ,..__._...V...._ _.___.._.., .._... _. .�._.„
� �
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� " , ,�', , '
.
As shown on tlie Flood Boundazy and kloodway tiap, the floodway
� widths were determined at cro�s sectiaxis; t�et��een cross sec- '
t�.ons, the boundaries were interpo7,ated. �n cases where the
boundaries of the floodway and the 100-year i°laod are either .
close to�ether or colinear, only the floodway boundary has �
been shown. ' • . �
The area between the floodway and the boundary of the I00-year
flood is termed the £loodway fringe. The £loodway fringe thus
�ncompasses the portion �of the flaod plain that could be com-
�
pletely obstructed without 3.ncreasin� the water-suxface eleva-
tion of the 104-yeax f].00d more than 1.0 foot at any point.
���
Typical relationships between the Floodway and the f loodtaay
fringe and their significance to flood plain development are �
' shown in figure 4. . .
, �LOOO�'!AY sctic►,�a7ic
� ' .
, (++. __�---•—:�-:a,,.�� ►!M /lOC�O JUIN — � .
� ►1�n•.�v � . . • I • ' . n\�j,
� ��rr:C -- . � /IOMr�r —.... � ,►1P)n.�r 1
. i �
�~ �IFO(
, � � �
� •
I � . � 99PfIU � � �
. �11AMM(��� ' �
' � � ' . .
, • ���'�? [11\l•r•+1 V��/M
� ��;4/11�(=w1-1��1 Il"•::lM�Y �
IY:•' '.�1•ru• � • .
� „�. I'r . (MG�•��(NV(11f�{�
:.Y\�--'__� e cwc ►cri ' �_-___.t
r �1 .'� `��?�.._.�..._ � � yA��_� . — �_' /.. 1.�.
`\ 1� � • 7 � i/4���
' �, ` Y� . . . "��, �i•�•I�.L1.�+.��\'� �". f�
` � ,.:i.. ' .��l:
• �•—` �my� '� •
�.�. c� ri�,�, ',� :"��..• :rvin �`� ~� .
C: O'7� r,� . � l��^v:�! �� �
. ,��...v. ':r:l��: . . Il^:) Ittv.in♦ .
�fJ��� Iw:•':�f.i�4(�1
oe r�ao .�.,,
. l'tiQ •.�� tt h�� rlhp� t11v��iov elrC�t (�c�taC��.�tet ..
lw�� �•0 �� �11� /«•i0 ��.����1SJM ►IS'{� l4CIr.3�AC'IY(MI
Figure 4. Floodway Schematic
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�; � 5.0 INSURANCE APPLICATIO:I -i
,.
In arder to establish actuarial insurance rates, the FIA has developed
� a process to transform the data from the engineering study into flood
insurance' criteria. This process inclu�les the determination of reaches,
Flood Hazard Factors (FHF's), and fload insurance zone designations
� far each significant flood source affecting City of Ti�ard.
5.1 Reach Determinations .
Reaches are deL•ined as lengths of caatercourses having rela-
tively the same flood hazard, based on the average weighted
difference in water sur£ace elevations between the 10- and 100-
year floods. This difference does not have a variation greater
than that indicated in the following table for more than 20
percent of the reach.
� Average Difference Bet�veen ' ' ,
10- and 100-Year Floods Variation
' Less than 2 feet 0.5 -foot
� 2 to 7 f eet 1.0 foot
7.1 to 12 feet 2.0 feet .
.
7
Four reaches meetinb the above criteria were required for the
flooding sources of Tigard. These include two reaches on Fanno
Creek, and one reach each on Ash and Summer Creeks. The loca-
tions of the reaches are shown on the Flood Profiles. ,
;
5.2 Flood Hazard Factors (I'HF's) • I
The Flood Hazard Facto'r is used to correlate flood information
with insurance rate tables. Correlations bet�veen proparty
� damages from floods and their assigned FktF's are used to set
actuarial insurance premium rate tables based on FHF's from 005
�_ to 200. ,
. ,,, ,
__
...._.._...�,�.:.�.,........,.�...��..:..�.o.:._.:.,�.�.�.�.,�......�_..�...:..�.�.,.�_._�,.,� _
....�..:�..a.,�.�..,.-_...:...�..�.....�,�.���.._.._..:..,._.....,.._.�......:a..:..,��:.- _ _:.....�.._.:�:,.�::+........__
. .
, • i
. -;� �, ., • ,
' � � �
The FHF for a reach is .the average weighted ditference between
� the 10- and 100- ear fl d
y oo waeer surface elevaeions expressed -
Co the nearest ane-half fooL•, and stio�an as a three�-digit code.
; For example, if the difference beCween the water surface e1�va- I
tions of the 10- and I00-ye�a�r floods is 0.7 foot, the FHF is 005; II
�f the difference is 1.4 EeeC, rhe k'HF is 015; if the difference ''
is 5..0 feeC, the FHF is 050. When the diffezen�e between the lfJ- I
and 100-year flood waCer surface �elevations is greater than 10.0 �
feet, the accuracy for the FHF is �o the nearest foo�. '
� Se3 Flood Insurance Zones
After dF:ter�nination of reaches and tl►eir corresponding FHF's, .
� the enti�re incorporated area of Tigard was da.vided into zones, �
ea.ci� i;:s��ir.d a cpeci€�c €;.c�3, pct�a�ial or hazard. Each zone was
assigned one of the tollowing flood insurance zone designations:
� Zone A: Special F1ood Hazard Areas inundated by
the lOQ-year flaod, determined by �,,,�,.
.��t
a�proximate methods, no base flood ele-
. vations shown or FHF's determined.
. Zona A1, A2, A3: Special I�'lood Hazard Areas inundated by
the lU0-year flood, dete nnined by
detailed methods; b.ase flood elevations
� shown, and zones assignecl according to
�'HF's. ' �
Zone B: Areas bet�aeen �the Special Flood Hazard �
Areas ancl the limits o£ the 500-year
fXood, including areas of the 500-year
, flood plain that are protected from the
• 100-year flood by dike, levee, or other
water conrrol structure; areas subj�ct
�. '
19 .
.��.. _
. . ._._ _---._�.__.__._... __
. � - �
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��` to certain types of 100-year shallo�r • '
, floodin.g where depths are less than 1.0
foot; or, areas subject to 100-year
floodin� from sources with drainage
� areas of less than one square mile.
Zone B is not subdivided.
Zone C: Areas of minimal flooding. '
�able 3, "Flood Insurance Zone Data," surunariz4s the flood eleva-
� tion differences, F13F's, flood insurance zones, and base flood
' elevations for each flooding source studied in detail in the
community.
S.4 Flood Insurance Rate riap Description
Th� Flood Insurance Rate Map� for City of Tigard is, for '
'�� �' i.nsurance purposes, the principal result of the Flood Insurance
Study, This map (published separately) coutains the official
delineation of flood insurance zones and base flood elevation
' lines. Base flood elevation lines show the locations o.f the
'.
expected �ohple-foot water surface elevations of the base (100-
year) £lood. This map is developed in accordance with the latest
; flood insurance map preparation guidelines published by the FIA
(Reference 13) . . � ,
6.0 OTHER STUDIES
The Corps of Engineers is currently preparing Flood Insurance Studies
for the Cities of Durham and Beaverton (References 14 and 15) , and the
unincorporated areas of WashingCon County (Reference 11) , including the
area adjacent to Tigard. The results of the Tigard, Durham, Beaverton,
an�3 Washington County Flood Insurance� Studies (FIS's) will match
exactly.
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I EtEVATiON DIFFERENCE • •°
BETWEEN BASE FLQOO ANO= f '
� FLOOOING SOURCE PA�IEL� FHF ZONE gASE F�OOD ;
' � )076 2% 0.296 E�EVATION i �
; (10 YR,) (50 YF�.) (SOQ YR.) � f
i . i f
, Fanno Creek - � i
. Reach 1 -I.4 -0.4 p.9 O15 ��3 VARIES � � °
' Reach 2 , =0.9 -0.3 0.7 O10 � �2 VARI.ES ; �
I t
Ash Creek '
� Reach 1 -0.6 -0.2 �.5 005 ��? VARIES � � �
1 � �
� Summer �Creek � � � �
Reach ? —0.7 � —0.2 0:5 005 ElI VARIES
. � �
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1 2
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1. Flood Insurance Rate Map Panel � ' {
2. Wei�hted Average . ; ; �
3. Rounded to the nearest foot-see map. ' . �
, : . �
� ;.�, ------
DEPARTMENT OF HOUSING ANO URBAN DEVEIOPP�fENT ,1 • f
� FederallnsuranceAdministration �f Afli1 1\1[`�]�A��� '7l1�3i' ty��A ' ;
�` �vui� li9Ju rt c�d�rz u r� �
�
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'� CITY OF TIGARD, OREGON °
�' (Washington County) FANNO, ASH, AND SUrL�iER CRE�KS �
�
�
,
.��.�.-�- -----=---- _ - --- -_- =--�- -_—:.E-�- _z_..,.t _ _ _ - - - - � --- - - -
__.._..._.,.,. �,._..._, _. ._...._..w...__ _.._... _—_.___.�---�-- --
I • . P ._ .. ,_.. _..._._._._._..__.�.._�._._.__^______._,_..�.�.__.�...._Y................__._._.._.____.__,_._ .
' . 1
.�• t ' ,v � , '
In 1969 the Corps of �rgineers prepared a FPI report for Washington �.
� County (Refere�nce 16) . The 100-year flood rofile resented
. P p in this
study varies caithin about pLus or minus one foot witl� the FIS 100- .
year profile thraugh City of Tigard. The difference in flood heights
is attributed to improved data obtained for the FIS's. This study
� wi11 superscede all previous Corps of Engineers flood hazard studies.
7.0 LOCATION OF DATA .
�
i Survey, hydrologic, hydraulic, and other pertinent data used in this �
; study can be obtained by conCacting the Federal Insurance and Hazard
�
; Mitigation Divisien, Federal Emergency rianagement Agency, Re�;ional .
Director, 130 228th St., S.W. , Bothell, Wasl�ington 98011.
8.0 BIBLIOGRAPHY AI1D REFEP.ENC�S
.
1. Portland State Universit.y, Population Estimates: Ore�on Counties '
and_Incorporated CiCies, July 1978. �
r �.
�- 2. Pacific Northwest River Basins Commission, Climatolo�ical Handboolc,
Temperature, Valume 1, Part A, 1969.
3. Pacific Northwest River Basins Commission, Climatological Handbook,
Precipitation, Volume 2, 1969.
-
1
!
4. U.S. Department of liousing and Urban Development, Federal Insurance
Administration, Code of Federal Re ulations Title 24 Cha ter 10, �
� � , P
Parts 1910.3A and 3B, Federal Register, Vol. 41, No. 2p7, j
5. U.S. Department of Agriculture, Soil Conservation Service, SCS �
National En�ineering Handbook, Section 4, Hydrolog , January 1971. �
-
6. U.S. Army Corps of Engineers, Hydrologic En�ineering Center, Unit
Graph and Hydrograph Computation, Computer ProQram 23 J2 L223,
Davis, California, Ju1y 1966.
7. U.S. Army Corps of Engineers, Hydrologic Enoineering Center, Hydro_
�raphic Combinin� and Routings, Computer Program 23-J2-L232, Davis,
California, August 1966.
8. U.S. Army Corps of Engineers, Portland District, Procedures for
Determination of Maxinum Annual �'lood Peak and Volum� rrequencies
for Portland District, Report No. 2, February 1969. '
�. � .
22
. _ _ _ _ ,
, .._.`..._. ,�:s.._.".,��:.,....w.._.�,....y........,�.....�..._.._...._...r.....,Y.....v.._..�...._._..�.�::,��:.,,�.�::.�.�....._.�,....:.�.__, _ ...,.w.�....M...._.. . , u. _� ,,.,W,,::-- =�:,;�
<< • ' � °
,a � ' � , . • _
���.�: � .. , I . � .
�. '���n :I� �� . / . , . . .
9. U.S. Army Corps ot Engineers, Iiydrolosical �nsineering Center,' H�C-2
� Water Suxtace 1'rofiles, Generalized Coinputer Pro�ram, Davis.,
. California, Pbvember 19"/b, updated Octot�er 1977,
� 10. Tisard (topographic maps), Aerial rlapping Cotnpany of OreSon, 1974.
11.� Federal �mergency rianagement A�ency, Flood Insuranr.e Studv,
Washinfiton County, Ore�on, lln�uvlisl�ed.
� 12. � Wa�hington County, 0regon,, Department of Public Works, "Flood Plain
� Aelineation riaps," I974. • '
13. . U.S. Department of k�ousing and U'rban Develo�mernt, Federal Insurance
' Admi�istrataon, Guidelines and Specifications for Stud Contractors,
Oeto�ser 1977. ' .
140, Federal Emergency M,3nagement, Asency, Flood Insurance Studv, Durham,
Ore on, Unpublished. �
IS. Federal Emergency 2�anagement Agency, Flood Insurance Stud}=,
Beaverton, Ore�on, Unpublished. . �
16.� U..�. �:r�� �;,r�.s c� �r�g:i�aGe:c�, Fai-tlana Di.strict, "Floodplain
Information, Washingt.on County, Oregon," June 1969. ' ' .
� `
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. � �
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ELEVAZ'ION' REFERNECE MARKS �
� , �
City of Tigar,d Oregon
Reference Elevation in Description of Locakion .
Mark Feet �(NGVD) � �
RM 1 137.23 On S.W. Bonita Road over�
Fanno Creek, a railroad ,
' spike is located centerline
. on east end of bridge. ` • _
RM 2 142.52 On S.W. Hall Blvd. over �
Fanno Creek, a PK nai�
is located centerline
� on north end of bridge.
RM 3 151.65 On S.W, Main StreeC over
� . Fanno Cree`(�a PK nail
. is located centerlig�
on south en3 of bridge.
' � RM 4 150.77 On S.W. Grant Avenue over
' Fanno Cre�k, a PK nail '
is located centerlitie on
" � � south end of bridge. �
,RM 5 156.98 On S.W. North Dakota Street ��'y'
over Fanno Creek, a PK nail
is located on aouth edge
on west end of bridge.
RM 6 163.34. � , On S.W. Scholls Ferry Rpad
. � • over Fanno Creek, a nail ,
and washer is located
centexline of bridge,
' R.'�1 7 lob.23 On S.W. Shady Zane over
Ash Creek, a nail is
� located centerline of
road.
RM 8 163.53 At interseceion of S.W.
Katherine Road and S.W.
116th Avenue, a railroad �
spike is located' centerline.
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,ELEVATION REFERENCE. MARKS ;(continued)
� - '- .`'�
City of Tigard, 0„ regon
Reference , Elevation in Description of Locatinn '
• Mark • �,•, Feet (NGVD)
._--- .,.,;.__ . _
-�-:RM, 9�; .'° :_ Z67.S5. On S<W. 121st Avenue over
. -_ . , Suunner Creek, a railroad
, _ , , „ _ . ,. ' .... . _ spike is located centerline �
' , ,;i. ..• . . , • . . on north end of concrete
box culvert. �
R,M_ 10 �:°. � , ,..a�z 1$0:06 At intersection of S.W.
. . � . _ � • Summer Street and S.W.
. � : :�° � .�. . . � � Summercrest Street, a PK
nail is located centerline.
RM; 1•,l:• � . .� 222..51 At intersection of Scholls
} �- .;, _, .... . Fexry Road and S.W. 130th . .
r ,. , ,.. . _ � . � �. . Avenue, a PK an31 is located ,
centerline. .
. . . . 1: •. . . '. • . , .
� t _ ... . . � �. �
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;
, STAFF REPORT
' .?iGENDA 5.9 � �` .
' Y'IGARD P�,ANNING COMMISSION
NOVEMBER 25, 1980 - 7:30pm
FOWLER JUNIOR HTGFi - LECTUI�E ROOM
1OQ65 SW Walnut Street, Tigard
N� submission of additional material by ap,plicant shall, be made at this
Public Hearing unless the applicant is xequested �� do so. Should this
occur, unre�uested, the item will be tabled until �the �ollowing Hearir�g.
DOCKET: VARIAIQCE, V 14-80 (Silco Construction Co. ) NP� #�2
APPLTCANT: Si.lco Const, Co. UWNER. Az°I.ie and 7i°ene Ma.whzr�er
18791 SW Martinazzi 1�265 ���7 E30th I�'lace
Tualatin, Oregon 97062 TigclY'C�.� Oregon 9'1:1.23
REQUEST: For a Variance in the setback requiremen�� in «rx M•••4 zone ta
permi.t construction crf_ a building:,
LOCATtON: 9350 SW Tigard Street (Wash. Co. 'Sa.x Map 2S1 2AR, Tax I,ot 1901.} ,
STAFF' COMMGNTS:
The p resent 5,000 square �a�t k:uilding was constr_uct�d �n this site years
ago. A larqe building was const�-uct�ct to the west wiL-h twen�q (2G) feet
oE open space betweeii :it �nc! �:he �:resent building �n 'thi.s s:�•t.e. TJ.�e proposal
here is to add a 6,OU0 sq�.ia-�e foot bu.i.Idin�. Ck�e af the problems is
� the setbac}c requiz-�ments i.n i�Y�e A2-4 .�on�--sicle yard to be i�rnrenty (20)
feet. In this case th� se�tk,ac}c serves r�o pur.pose� Tt this zz�w building
is constructed, thpre wa.11 be a twen�ty (�0) �oc�t strip betw�en �.t �nd the
building to the west. S:h:ifting the r�raposed to �:he east i�o inE�et the
setback requix:einent: N*oulr.� ol-�s�.r.uct a clrain�geway from �tiga��d Stre��t to
Fanno Creek.
One o-�het° prob.lem .is tha.t thE btzilding as propUSed wou.l.c� be c�ns�ructed • �
azi the lU0-•yea.r floo�pl�a.in� �'he Publa.c.: Works Di-rectnr Yias .rev:i.ewed this
rPquest„ Applic�-uii: lzas sub�iitted a Sezlsitive Lands �Erinit applica�tion.
Ccanstructi on wc�uld remove a�proximately /00 cubic ajards trom �hc f�.00dplain.
b�uture :improv�m�nts in strearn flow at the ASdin 5treet Briclge may change
the flondplain upst;r.eam, Note that a poxtion of the bui:tdiny immediately
to the wes�t is naw constr_ur.ted in the il�odplain.
:1:� FZNDTNGS OF E'ACT:
:1.. T_igard ,`4unicipal CudeSection 18.7G.02U states that:
"No varianr_e shall be granted by� the planning c�mmission urLless i.t
can be show i:ilat all of the followi.ng coridi.-L-ioris e�si�t: I
(1) Excepi:iona�. or extraordinaz� conditions a�plying to the property ''
th�t do n�t apply generally ��o ather p-r.operties ir! the sazne zone
c�r vicinity�, �vliich conditiuns are a xesult of lot size or shape,
��opography, or othe:r circumstances over which the a;,oplicant has no
ccsn t rr 1;
(2) The variance is necessary for the preaerv�tioz� of a property "I
r.iqht of the appli.cant substantially the same as possessed by owners ' �:J
�if ather properry in the same zone or va.cinity;
�' _ - - -
,STFIFF REPORT �
A�ENDA S.9 - V 14-brL �
� 'LIGARD PLAIVNTDTG COMMTSSION '��
NOVEMBER 25, 1980
Page 2 �I
i
1
(3) The authorization of the variance shall not be materially detrim�ntal �
to the purposes of this title, be injurious to property in the zone i
or vicinity in which the property is located, or be ot,he naise detrimental j
to the objectives of any ci.ty developme.nt plan or policy; ;
i
(4) The variance requested is the rninimum from the provisions and !
standards of this title which will alleviate the hardship." �
i
2. A portion of this lot is within the 100-year fZoodplain.
.
3. SW Tigard Street is in substandard condition. �
4. A significant drainageway exists between this property and the right-
of-way along Highway 99W to the east.
II. CONCLUSIONARY FINDINGS:
1. In this case the configuration of the lot and present structure in
relationship to de�relopment to the west indicates that the setback I
requi�ments are not apprapriate for this proposed addition to an
existing building. ''
2. 'The p rimary concern is the building in the floodplain. Section 18.57.040
does not allow a permanent building within the 100-year floodplain. i
III. STAFF RECOMMGNDAT20NS: �
Staf� recommends approval subject to the following conditions: �
—
1. A full half-street :improvement to Collector Street standards be accomplished �
on SW Tigard Street.
. 2. The drainageway along the entire east nroperty line be cleared of F
all noxious vegetation. Culvert pipe be installed from Tigard Street
to Fanno Creek to City requirements. A utility easement be granted '
to the City over this culvert. Owner to use this area to increase �
depth of parking spaces to accommodate large trucks used in business.
3. Project shall be subject to Site Design Review. �I
fi
4. Large sign mounted on roof of existing building shall be removed.
No future roof sign sha11 be installed. �
r
5. No outside storage of used/abandoned signs shall be permitted on this i'
parcel in the future. �
�
6. Issuance of Building Permit shall be conditioned upon engineering !'
and architec.tual certification that the improvements are floodproofed '
to or abov� the 100-year flood elevation--153 feet (That is, impermeable I
to passage of water and capable of resisting hydrostatic and hyd'rodynamic
loads and the e��fects of boyancy) . � . ;i
�:
, �i
�:
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• � STAFF REPORT � . -
. AGENDA 5.9 - V 14-80
TIGARD PLANNING COMMISSION
, NOVEMI3EFt 25, .1980
Page 3
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7. No Occupancy Pe rmits shaZl be issued until all canditions placed
upon this development by the City of Tigard have been satisfied
and inspections verifying this have been carried out by the ap�ropriate ,'
department.
8. No changes will be made to approved plans of specifications unless •
formal app lication is made to the appropriate Cit�r department, an8
changes are approved by that department. Application for changes
will be made in writing and shall include applicable drawings.
9. Grading an d construction plans for all work in pul�lic rights-of-way
and all othe r public improvements shall be prepared by a reqistered
professional enginePr in accordance with City standards, and shall
be submitted to the Public Works Department for review.
All public improvements will require a Compliance Agreement and
must be (design) approved by the Public Works Department, and must
be either (1) fully and satisfactorily constructed prior to the
recording of any minor land partition, public de dication, final plat
or issuance of Building Permits; or (2) bonded to the City for 100�
of the estimated cost thereof prior to the recording of any minor
land partition, public dedication, final plat or issuance of Building
� Permits. •
�,
10. A11 existing and proposed utilities shall be placed underground. �
Street lighting installations shall be app roved by the Public Works
Department. �
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' 11. All streets and parking areas shall bE concrete or asphalt. A11 ''
sidewalks shall be .concrete.
12. No Building Permits shall be issued until the expiration of the •
twenty (20) day appeal period from the date of approval.
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Aldie Howard
Planning Director s,
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BILCO CONBTRNCTION C011MPANY
October 31, 1980
Planning Commis•sion
City of Tigard
Po Box 23397
Tigard, Oregon 97223
i
. RE : Lum3nite Sign Company !
93�0 SW Tigard Street i
Variance of Setback !
Requirements i
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Gentlemen:
In accordance with tFie "City of Tigard Zoning Or.dinance of I970," ..
we heret�y� rec�ues�t a variance from the requirements of tfi9_s title;
specifically, Section 18. 52.040 "Setback Requirements. " Paragraph
(.2� therein states in part that "The side yard setback shall. be '�
twenty feet . . . . " We submit that this requirement creates an �
undue and unnecessary hardship due to the unusual sfiape and size �
of tfie existing property. We will show that thF conditions �
necessary for the City of Tigard to grant a variance do exist . I
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The existing lot was created and the building constructed prior ���
to the adoption of the zoning ordinance. The existing require- ;;
ments for an M-4 zone states� tfiat the minimum lot area shall be � �� �
40,000 SF and the minimum lot width shall be 100 feet . The set- `''
Hack requirements are related to this minimum lot size. The �';�
existing lot is� approximately 25,265 SF and has a mini.mum lot
, width of 46 feet . Due to the unusual shape and size of this lot , •
the conditions of the zoning ordinance create extraordinary hard- ''
ships on developing this property to the extent typically realized
in industrial zones .
i:
Due �o the narrow and long shape of the lot, the existing building
, was� cons�tructed with a setback of one foot from th.e northw�st
pro�erty line. The only land available for deve.lopment would be
southwest of the existing building. Strict interpretation of tl�e
code for side yard setbacks would create an unaccessible yard on . '•t
the northwest side, starting 130 feet from the street, and a 20
- foot access a�ay along the southeast side of any addition constructed,
��� � ; which would eliminate the ability for direct truck access and
` loading necessary for most industrial users.
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,'' PO OOX 337 • TUALATiN�OAE00N.�70OQ • d03 • 83��87�4 / d39-3�6d� , ,?:
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Luminite Sign l �mpa�,. . �-L ��,' • � .
Variance of Setback Requii�ements ' ; , �
We are requesting a variance from the s�ide yard setbaek require-
rnent along tF�e nor�h�rest property line, such that an addition
may Be cons•tructed j:n l�ne w�th tl2e ex�:sting building. The
neighboring property� flas- Been developed with a 20 foot setback,
so there would Be acces�s .for f�refigfit�ng equipment . We are also
requesting a variance for the s•outfieas� property line se�back,
allowing a Building to be cons•tructed w�th truck acces•s• facing
the street. This property abuts the Pacific Highway Right-of--Way
along this l�ne wF�ich. would provide access and separation from
other structures to the southeast .
We believe that constructing a building of this size and confi$ura-
tion �vould be an asset to the communfity. There is a need for
s�mall user industrial space. The build3ng would create �obs and
commerce for the community. The buil.din� �rould reduce the current
us�e of the land for outside storage. The build3ng would not
adversely� affect the existing drainage way along tfie s�utheast
property line. Neighborhood Plan Two recogn�zes the need to
develop ex�s'ting industrial I.and for many reasons, incZudfing
employment opportunities, �ax base and the interYt of the Comprehensive �
P1an. Polic� 26 states that industrial development should conform
to high standards for site design and this is exactly what we
propose.
We request your favorable consideration in allowing a variance for
. the side yard setback requirements o� this pareel of land.
Sincerely,
SII,CO CONSTRUCTION COMPANY
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7 .��
rixce D. N3cholson
BDN/�an
Attachments
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FLOOD INSU1tANCE STUDY .
(DR.AFT REPORT)
. � '
CITY 0�' TIGARD
WASHINGTON COUNTX, OREGON
Prepared by
� Par
tland District, U.S. Army
�:;�
=��.�`�:;,,�+t �.
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Corps of Engineers �
. June 1980
for
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U.S. FEDERAL EMERGENCY MANAGEMEIIT AGEIZCX
'I
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.� . . . _ _. ....., ._....._. _..__�.,.._...__..._�._..��._._....�..�_,._�.,..........__..,,.�..._.._._....., �.._.
_ .._. .�.. _ _. .. .___._ ._ _.___�..___. _.___W
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� � TABLE OF COi1T�NT5
Pa e.
1.0 INTRODUCTIO:V . . . . . . . . . . . . . . . . . . . . . . . . . . . • 1
1.1 Purpose of Study. . . . . . . . . . . . . : a • o • . • • • • • .i
1.2 Authority and Acknowledgments . . . . . . . . . . . . . . . . . �
1.3 CoordinatiAn. . . . . . . . . . . . . . . . . . . . . . . . . . 2
• 2.0 AREA STUDIED . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2,
2.1 Scope of Study. . . . . . . . . . . . . . . o . . . . • • . • 2
2.2 CommuniCy Description . . . . . . . . . . . . . . . . • • • • • 3
2.3 Principal Flood Problems. . . . . . . . . . . . . . . . . . . . 5
2.4 Flood Protection Measures . . . . . . . . . . . . . . . . . . . ?
,
3.0 ENGINEERING ��ETHODS. . . . . . . . . . . . . . . . . . . . . . . . . 7
' �- . . . . . . . . . . . . . . . . . '
3.1 Hydrologic Analyses . . . • • $
3.2 Hydraulic Analyses. . . . . . . . . . . . . . , . . . . . . . q
4.0 FLOOD PLAIN MAVAGEr�NT APPLICATIONS. . . . . . . . . . . . . . . . • II
4.1 Flood Boundaries. . . . . . . . . . . . . . . . . . . . . . . . ��
4.2 Floodcaays . . . . . . . . . . . . . . . . . . . . . . . . . . • (Z
5.0 INSUR.ANCE APPLICATIONS . . . . . . . . . . . . . . . . . . . . . . �$
5.1 Reach Determinations. . . . . . . . . . . . . . . . . . . . . . �$ .
5.2 Flood Hazard Factors (FHF's) . . . . . . . . . . . . . . . . . �g
5.3 Flood Insurance Zones . . . . . . . . . . • • • • • • • • • • • Iq
5.4 Flood Insurance Rate Map Description. . . . . . . . . . . . . . x,0
6.0 OTHER STUDIES. . . . . . . . . . . . . . . . . . . . . . . . . . . • 20
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TA13LE OF CO�TEi1TS - (cont'd) �
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7.0 LOCATION OF DATA . . . . o . . . . . s . . . . . . . e . . . . . . �2
' 8�0 BIBLIOGRAPiIY A�vD REFEFt�NCES. . . . . . e . . . . . . . . . . . . . . 22
FIGUR�S
. '.,
Figure 1 � Vicinity Map. . . . . e > . . . . . . . . . . . . . . . . . . ¢
Figure 2 - Expected Future Flood Height Photograph of Fanno Creek. . . 6 ��
�
Figure 3 - December 1977 Sununer Creek flooding at S.W. 116th Avenue. . . 7 . �
� . 5
Figure 4 - Floodway Schematic . . . . . . . . . . a . . . . . o . . . . �'� i
� � �
� TABLES !
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� Table 1� - Summary of Discharges . . . . . . . . . . . o . . . . . . . 9 `''"
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Table 2 - Flood�oay Data . . . e . . . . . . . . . . . . . . •.����_ ((,
. . . .
Table 3 - Fl:ood Insura�nce Zone Data . . . . . o . . e . . . . . . . . 2 �
. EXElIBITS
,Flood Profiles
I�anno Creek
Ash Creek
Summer Creek .
Flood Baundary and Flood�say Aiap Index •
Flood Boundary and Flood�vay Map '
PUBLISHED SEPARATELY:�
Flood Insurance Rate Tiap Index
Flood Insurance Rate Map . ,
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� . FLOOU INSURANCL STUllY
1.0 INTRODUCTION
. 1.1 Purpose of Study
This Flood Insurance Study invesriea�es the existence and sever�
. of fload hazards in the city of Tigard, Washington County, Qregon,
and aids in the admini,stration of the N3tiona7. Flood 7nsurance AcC
of 1968 and the Flood Disaster Protection Act of 1973. This skudy
.
I will be used to convert Tigard to the regular program of f].00d
i u
ns rance by the Federal Insurance Administration (FIA . Local and
) .�...�.
regiona p anners wi11 use this study in their efforCs to promote
sound flood plain management. .
.
� Yn some states or communities, flood plain managemenC crii:eria or - ,a;,
� °�.—o-�-------�-- -
regula�ions may exist that are more restrictive or comprehensive
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than those on whicli these Federally supported �tudies are based.
�..��. ..��, - —
These criteria take precedence over the miniinw�i Federal criteria �
f�or purposes of regulating development in the flood plain, as set-
£orth in the Code of Federal Regulations Title 24, April 1, 1976.
xn such cases, however, i.t shall be understood that the State (or
other jurisdictional a;ency) shall be able to explain these
requirements and criteria.
1.2 Authority and Acknowledgements
The source of authority for this Flood Insurance Study is the
National. Flood Insurance Act of 1,968 and the F1ood Disast�r Pro- .
tection Act of 1973.
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4 k � ;; 4 The hydrolo .
. fiic analyses for ttiis '
• ��•S• Army Cor s study was performed b
P of Engineers,� Portland p• Y the
� Federal Tnsurance istrict, for tl�e
Administrati.on.
consultin Jones Associates
g engineerin� firm ' In�•� a
while under contract r� � Per�ormed the hydraulic �
Che Gor S o� analyses
was r �' Engineers. This study
p epared for the Federal T
Inter-�g�nc nsuxance Administration u
Y Agreement No, H-7�7C, and H�- nder
� Order Numbexs 17 and 10-77� and Pro'
. 1, respectivel Ject
in June 1980. y' Th� study was completed
1.3 Coordination �
�he initial coordinat;ion meetin �
repx�esentatives of g was held vSeptember 1976 wi�h .
the Federal Insurance Administration (�•I
the City of Tigard . A)
� and the study contractor p �
U.Se Army Cozps of En � ortland Districr,
gineers), to identif •
studier�, exp1a�n the stud y streain reaches to be
est�blish co' y concepts, identif �
m�nunicatian and Y data sour�es� and
coordination procedures.
� � ��
An intermediate coordi.nation meeting was hel ' ..
, to alloco d in Tigard on < � .:�:•.�
�ocal officials � � '
drawingw St�oW�i� to review plan and
g water surface profiles Profile
floodeci-area outlines. ' f�-oodway deline'ations
, and
7'he final consultation and coordination meet
• In attendance ��er� � �ng was t�eld on
int�rested rP�� �'�xOprzate officials and
���nt-s' af the cotmnunit
� representative Y� a representative of FI�,
of the study contractor, � and
wexg pr�s�nted to and acce�te� b . �he results of the
Y ttie coxnmuna.ty. study E
2.0 AItEA STUDIED �
. 3
. � . 1
2.1 Sco e ' l
P of Study ` �
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xhis f].00d Insurance Study covers tEae
.. City of T3 ard incorporated area of the '
g , Washington CountY, Oregon. The study area
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on the Vicinity Map (�i�ure 1) . • '
The limits of detailecl and approxin�ate studies in Tigard, .
. were determined by FIA with communiCy and study contractor con-
sultation at the meeting in September 1976.
• A detailed study was made of flooding from Fanno Creek, Ash
Creek, and Summer Creek within the Ti�ard corporate limits.
Approximate methods were used to study a small tributary to
Fanno Creek, located on Che northwest edge of Tigard near .
Scholls Ferry Road (Route 210) .
2.2 Community D escription
Tigard is located in northwest Oregon, in the southeast corner
of Washington County. It is approximately 8 miles southwe�t of
Porkland, Oregon. Tigard was incorporated in 19G1, and �.ts
t � population has grown from 4302 in 1970 to an estimated 13,500
in 1978 (Reference l) .
Fanno Creek, a tributary to Tualatin River, drains 13 square
miles upstream of Tigard. It originates in the west hills of �
Portland. The stream flows through Tigard in a generally south-
easterly direction. Ash Creek, a' tributary to Fanno Creek with
a 4 square mile drainage area, flo�as in a southwesterly direction.
Sumnier Creek, also a tributary to Fanno Creek, flows in an east-
erly direction as. it drains 5 square miles. All three streams
are crossed by numerous bridges and culverts within the Tigard
�orporaCe limits.
Economic activity in Tigard. is diversxfied and growing. Indus-
trial facilities in the community are varied, and are I.ocated
along Pacific Highway West (State Highway 99tJ) and State Highway �
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� Fcd.��in::rtnce P.�ctiin:s;raticn 4000 0 4000 800Q .12Q00 FEE't'
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.1, 4
Y 'y ` /
217. Commercial development is located prin►arily along Pacific
� Hi hwa jdest and �
g y S. d. Main Street. Residential developnient in �
Tigard is mostly west of ranno Creek. Imporeant Cransportation
routes in ttle city are Pacific High�ray West, State Higl�way 2J.7,
� Hall Boulevard, ��nd tlie IIurlington i�ortliern and Southern PacifiG
, �
The t I�o `�,,,��s ot .5¢J�v'a.Q. a�eas 41����, t�u..
railway lines. �-ar�+��ei: flCBH�' ".. ,,^••rarni --- � ,.i ,..-�. �,,,.,
St'veam YEAG4�C5 5�'uc.� i C� 0.rG �r.;�l��Oi �} d�2JC�0�.��m �'t' . �nC�arQc�
. �t�£14c�. .�_ -� -8i�8'-.r-�x'ea-a�••�6.�tg--btttlti�te�-b�r..1, i,
i 5 Alo�� 5 u..,.,.er G.�e¢K be1'w<cn 5.W. l 13 t4� a,�::� 5.��1. l21 st
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'S�9�'�.'�-�O�!+ �t3t�^!3Hl�93�--F�l36�"r}i£�.k.`'� . @""$3G2B�'9'-$-�Aiig-•A--- ^
A 11J'1'�1���'' 7 �oJt��- �rJt�f 0.Yt.w IY1c�4lL{¢.S CAW�1✓�e^1-^...ia-Q 0.�1� YC Si.�C.�'�1n-�C
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• , 8ev�lo��„w�� alon�^ a i- �•n�E'� reach of Fan„o Cr�:ek tr��.,
'-�v�-�-r.r��� . —
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--�..r.�...._.5.,-' - -L.J_-�..,� a,„,.,� a ;tegesr�.
�3"-- -- __ �
The climate in Tigard consists of warm, dry summers and mi1d, .
• wet winters. Temperatures are usually moderate, ranging from
an average January r�inimum of 25°F to.an average July maximum of �
81°F (Reference 2) . The average annual precipitation is nearly
45 inches, with 78 percent of the precipitation occurring from
October to May. Snowfall occurs on only a feca days each year;
snow on the ground is �enerally of short duration, with depths
. seldom exceeding 6 inches (Rei'erence 3) . '
Soils in and around the city of Tigard are silt l�ams on ne�rly
level to steep slopes. Drainage characteristics for those soils
are poor along the Summer Creek and Fanno Creek flood plain�, but
drainage improves on sloping terrain. Trees, �rass, and shrubs
are the dominant vegetation types. The incarporated area is being
rapidly urbanized.
2.3 Pri.ncipal Flood Problems
' Fanno Creek, Ash Creek, and Su�ner Creek flooding is generally
caused by rainstorms in the winter, the period of greatest storm
�� �
. I
5 �• I
� . ...._. . . _._.�._.._-. .._ . .,..... ...._.. ... ..,....,. __�._..T ._._--__.._._.._ ____---___.____..�..�_.�_�..�_�..__._...._._.._,__�.�._.__�. _ ._....�_
� , . _ �
� �,'.�_ ... __._._�_LL.,,..__......_._ ._ . .....,..W._.,.,.,..�._..._.._�_,...�._.___�.w....__�_.�,M�.... w.._. ,.._._�..._.._...ti..__.�___..._._.._.._._._. ._....�_..�.._
r . ' .
' • � ,
activity. Floods rise quickly follo�aing a heavy rai��storm and
� usually last less than a day on Fanno Creek and half a da on
Y
� Ash and Summer Creeks. '
Flooc4;�a, ir, 'j'";�,�v� is not we.11 dvcu�ti.c�.'t'e.�l. �
. � The largest flood on Fanno, Ash, and Sumcner Creek� during the
last 10 years occurred in December 1977. Althoush stream gage
records are not available, it is estimated that theYflood recur- �
Yence interval was about 10 years for those three stre��ms.� �
Flood clamages in Ti;ard were light since Che areas �
. susceptible to flooding wer� generally kno�,m and development was '�
avoided. �at�i. ot.,:wel:�:�}oc.cu¢eu�c3::-s�ee�-et-peem . I
$a8e�z�ecot�ci.
" ��.-a�t�en�-oe�,.-crr�ed, �
. a-lon�iQar3�-gl•ei�t: Flooding along Summer Creek is accentuaCeci
by a high ground water table, which causes nuisance flooding to ,
numerous residences. Figure 2 shows the heights that would be
expected from 100- and S00-year floods on Fanno Creek. Figure 3
shows flooding in Tigard from Summer Creek in December 1977.
rr-- j'� '•"�'�a. � c � ,
, r` e�..f'� '"'3 . �. ,� pt."�,." ;'r�+i.•.4. :.n .:!L'P."�";;x ,
�. ; . • i:�`�,i`S; F.:,nL',r?"ac;;;'�;-:.'1���.�r.;.;f' . .
�„ � �� ;-��t��+r 500 YERR F�LooD'��� . � „�:.
• t. � ' r•��.. �r: F'''"�, �; ., �!r:'�,.,�
� ' ' . 'I`r 100 YEAR F'l.OoD � �' :�•�+�.�
, ; �i'��t�;v
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'4':�.•�• �.-.....J�ri,a��i:.:eG�ia...�.t,:!l�.�','sl�t��G'��rl:1��:1il� ''�r�i, ���'?� � �
ucG�::4tiL'i7"��:�rl '��vt, C•.a�l�: '
�igure 2. Expected Euture flood heights of �anno Creek at �
S.W. 95th Avenu� Bridge. �
�
4'
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- �
. �
6 � �,
�
�,
,,
....w.,... .._.
.. . _ _.__.._.. .._
. ._ ........._.�...�._._...._.._.��.�..�....._..w._.._�....__.__._..�...w_�.,_.._....._k....,...�..._�..._..�..._�...��._..__..�.,.,�w_�_�__..._...
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'� + '
+ � , � �
i
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�` •� .�',- ;�"�"�--� t ' ••°
. 't��'�''��'�' + _ ���,- .
'VI -• �.�..�. i.
.._. r;��:, , _ . �',
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't • ' -
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. /a 'l!' • �,7 , .
t � ��1 ., • �1�.;�' � . . . .. }
I� Yk ...........�.. .,�Gti�.. `.r '�}y..^��:J.iiWIJL'�aii� �
' Fi.gure 3. Dacember 1977 Suminer Creek f•looding at S.W. 116th Avenue,
�i 2.4 Flood Protection Measures
� �
:�,.-�
� . .\,•i�.
There are no flood control structures within Tigard corporate
Fi a we�e✓�
i
limits. �Dt'on-structural measures of flood protection are being
utilized to aid in prevention of future flood da;nage. These
` , are in the form of a flood hazard zoning ordinance which follows
FIA's guiueiines (Reference 4) for controlling development within
the 1�Q-;,A�� �i��� Yi�;y�;, I,-� addition, the city requires buildi.ng
permits foir construction and reviews those permits to assure that
sites are reasonably safe from floodine. .
3.0 ENGINEERING MET110llS
For the flooding sources studied in d�:�ail in the conununiCy, standard
� hydrologic and hydraulic study methods were used to determine the �
flood hazard data required for tliis study. Flood events of a magni_ �
tude which are expected to be equalled or exceeded once on the average
C •
�
� . � � . � :
_ .. _ _ _ _ _
� ... ...�t.aw.u�..+Yt..�a...�• . .......... ..�.,...�...�.,.�_........ .•��r........ r,.n.. .....�r....�..�.� .u...,.c........�..��.,...�..���..���...r.....r....�.�a1�..u.��r�r.�.n��.���.....����.�..�nw.r......�� - . �ar.�...m .
� � • ♦
L
f . �r ' ,
r,
{ durins any 10-, 50-, 100-, or 500-year period (recurrence intervalj �
\ ;.
have been selected as having special sibnificance for flood plain '"
management and for £lood insurance premiun► rates. These events, com- � � ;;
monly termed the lU-, 50-, 100-, and 500-yea.r floods, have a 10, 2, 1,
and 0.2 percent cl�ance, respectively, of being equalled or exceeded �
during any year. Altliou�li tlie recurrence interval represents the long ,
Cerm a�verage period between £loods of a specific magnitude, rare
. flaods could occur at shorC intervals or even within the same year. ,
The risk of experiencing a rare f].00d increases when periods greater �
than one year are considered. For example, the risk of having a flood '
. which equals or exceeds the 100-year flood (1 percen t chance of annual �
.occurrence) in any 50-year period is about 40 percent (4 in 10) , and
for any 90-year period, the risk increases to about 60 percent (6 in
10) . The analyses reported here reflect Flooding potentials based on
conditions existing in the community at the time of completion of this
study. rlaps and flood elevations will be amended by FIA periodically
to reflect future changes.
,, � '
3.1 Hydrologic Analyses
Hydrologic analyses were carried out to establisti peak discharge
frequency relationships for floods of the selected recuxrence
intervals for each flooding so�urce, studied in detail, affecting
the community.
There are no s�rear► gage stations on Fanno Creek,. Ash Creek, or
Summer Creek. The Soil Conservation ServiceX method for rainfall-
runoff and unit hydrograph determination (Reference S) was used in
conjunction with Corps of Engineers computer programs (References
6 & 7) for hydrograph computing, combining, and routing [o gener- '
ate flood hydro�raphs for selected recurrence intervals on Fanno
� Creek, Summer Creek, and Ash Creek. �
�-
. $ • !
,_ _ �
._.,�.'�,�,..,� _ _ _. _ . _
>�.w_ . _:_._ _.....:._..�,.. .� ..e�__., ..._,...._..v.�.V.,..:.,...�u....__...�._,.�..........':.::_�.�.._...�.:•;:�.L...,�.:.:._.�...._...._..�. .
� , _.__. .�.._
., ,;
� �.� �
�
,
� A summary of drainage area-neak discharse relationshfps for e�ch
` stream studied in detail is shown in Tal�1e 1.
�'ABLE 1 - SU1!i�fARY OF DLSCi{ARG�S
. FLOODING SOURCE DRAIIIAG� AREA PEAt: DISCIiAI2��S (cfs) -
AND LOCATION Square Tliles lO�YR SO-YK 100-YR 500-YR
� Fanno Creek
at S.W. D�rham Road 3I 290Q 3800 4200 5100
at S.W. Tiedeman �
Ave. 24 2750 3500 3850 4700
at S.W. Dakota
Stree�t 17 1900 2450 2T00 325A
Ash Creek
at mouth 4,i 750 950 1000 1250
Summer Creek ' .
at mouth 6.2 1050 1300 1450 1750
'� �, at S.W. 135th � � �`
Ave. 4.0 � 800 1000 1100 �„�,350
,� ,`,;;^�y
�^ �pproximate 100-year f lood dischazge was developed for a small
txibutary to Fanno Creek, located on the norZhwest edge oi Tigard
; near Scholls Ferry Road (Route 21U) . Tt-ie regional procedure
(Reference 8) was used on that Fanno Creelc tributary.
3.2 Hydr?,,1�.� �:;�1}�s�s ,
Analyses of the hydrauli.c charactaristics of the floociing sources
studied in detail in City of Tigard were carrieci out to provide
estimates of the elevations of floods of the selected recurrencp
intervals along each of th:ose flood sources.
' Hydraulic analyses were performed using the Gorps of Engineers
HEC-2 step-bacicwater computer program (Refezence 9) . Cross
�. �
9
� .
__ _ . _
, ,
.
., , '
� � , , .
� sections £ar Fanna �reek, Ash Creek, and Summer Creek were com-
�
posites oE data from Corps of Engineers fteld surveys obtained in
1977 and City of Tigard topographic maps (C.eference 10) . A1].
bridges, dams, and culverts were field checked to obtain elevation
dnta and strucCural geometry. �I
� . '
I
• Locations of selected cross-sections used in the hydraulic analy- I
; ses are shown on the flood profiles. For stream segments for , I
which a flood::ay was computed (section 4.2) , selected cross sec- '
• tion locations are a�so shown on the Flood Boundary and Floodway ,i
rYap. I
Hydraulic roughness values (Manning�s "n") for the channel and II
overbanks were first estimated from field observation. The "n"
values for Fanuo Creek were then modified, when necessary, to i
match' the hi�hwater profile of th� Decexiber 1977 flood.• The I
final calibrated "n" values for Fax�no Creek in the study varied I
,, � from 0.042 to 0.065 for the channel and from 0.075 to 0.110 for � .Yz
the overbank. t'.sF �reek "n" values ranged from 0.052 to 0.062
, �,.;.., .
an� O.OG5 to 0.180 for the channel and overbanl�s, r.espectivelj%:1!
Summer Creek "n" values ranged from 0.045 to 0.030 and 0.075 to
0.300 for the channel and overbank, respectively. �
� ' .j
' Starting water surface elevations for Fanno Creelc in Tigard �1
were obCained from a hydrauli,c analysis periormed by the U.S. II
A�Cmj* C:nrnc �f Frg;n��zs fer the Washinston Count� Flood
Tnsurance Study (Reference 11) . Starting elevations for Ash
Cfeek a Suruuer Ereek were based on normal depth calculations. �
All elevations are measured according to National Geodetic
Vertical Datum (NGVD) of 1929 (adjusted in 1947) , formerly
referred to as Sea Level Datum, 1947 ad�ustment. Elevation
reference marks used in this study are shown on the F1ood
Boundary and Floodway I•iap. ' •
/.•-
\�
1O
9 . �
� �. � . ••f � r . . � .
� � The hydraulic analysis for this study is based on unobstructed
flow. The f lood elevations shown on the profiles are thus con-
sidered valid only if hydraulic structures remain unobstructed,
and operate properly. '
4.0 FLOOD PLAIN. MANAGErfEi1T APPLICATI:OIdS
. The National Flood Insurance Program encourages state and local
governments to adopt souncl flood plain management programs. Therefore, .
each Flood Insurance Study includes a flood boundary map designed
to assisC communities in cleveloping sound flood plain management j
I
measures, i
�
4.1 �Flood Boundaries �
1
. �
i
r
In order to provide a national standard without regional discri- . �
m�nation, the 100-year flood has been adopted by the FIA as the `
r � base flood for purposes of flood plain management measures. The
500-year flood is employed to indicate additional areas of flood
risk in the communitiy. For each stream studiecl in detail, the
boundaries of the 100- and the 500-year floods have beere deli-
neated using the flood elevations determined at each cross sec- �.
� tion. Between cross sections, the boundaries were interpolated f,
using topographic maps with scales of 1 inch equals 400 feet with ,
1 �Ij
a contaur interval of four feet (Reference �) . In cases where !?
�i
the 100- and 500-year flood boundaries are close together, oniy
. �
the 100-year boundary has been sha�vn. ;;
�
. };
�;
The approximate 100-year flood boundaries fox the small tributary i
to Fanno Creek located in nnrthwest Tigard were obtained from the
� ��'
Flood Plain Delineation Maps publis�ied by Washington County (Refer-
. ence 12) . The approximate '100-year flood boundaries were delineated �
on the USCS quadran�le maps. �
� €:
\ ' _
�.
�
. �''
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� �
.. . ..> .:__._..... .........._' ',._�..�._.,.
,�_.�._...�...�.�...._,-.__.� __.�.....r..w . . r.�.._.._.�.�.�..�� , .�...
..:,w....__......��. �
. ;_'. - .. ... _.�._.__..� _...........,.__.......��._.�._._...�.�._.._.__.�,...._.......... ..._..M,�.._M..._..�,,.�...�._. �..�.,._._...�._._._...._....w... .. ..�...
. _ '
.� , .
� � . . � , ,
� The boundaries of Che 100-year and 500-year floods are �hown on
the Flood T3aundary and Floodway Map. Small areas within the
flood boundaries may lie above the flood elevations, and tt�ere- �
fore may not be subject to flooding. Owing to limitations af �
the map and scale and/or lack of detailed topographic data, such
areas are not shown.
� 4.2 ri��uwas-, , . �
Encroachments on flood lains, such as sCructures or earthfill, �
reduce the flood-carrying capacity, increase the flaod he � s '
,
s reams, and increase flood hazards in areas beyond the
men se . gement . �
nvo ves a ancing t e economic gain £rom flood plain develop-
ment against the resulting increase in flood hazard. For pur- � %
poses of the National rlooc� Insurance Program, the concept of a ;
• floodway is used as a tool to ass�st local communities in this
. �. _.�.._.
aspect of flood plain management. Under this concept, the area �
o the 100- ear flood is divided into a flood�aa and floodwa k I
Y � Y Y�- .';�
�r
fringe. The floodway is the channel of a stream plus any adja-
ce_nt flood plain areas that must be kept free of encroachment I
in order that the 100-year flood may be carried withaut sub-
• stantial increases in flood he�.ghts. Minimuin standards of the �
FIA limit such increases in flood hei�hts to 1.0 foot, provided �
� that hazard��� ;:alocitie� are not produced. The floodway in
�
this reg�rt is presented to local agencies as minimum standards
that can be adopted or that can be used as a basis for additional
studies. �
. �
The floodways presented in this study were computed on the bas3.s �
of equal conveyance re�iuction from each side of the flood plain.. � �
• . The xesults of these computations �vere tabulated for selected �
cross sections for each stream segment for which a floodway was ;
' computed (Table 2).
� �
� �
;
' ' • r
1?.- ` (':
� ` � � - _ . �
,
; FLOOOING SOURCE �LOOQWAY BASE FLOOD +
WATfR SURFACE ELEVATIpN �
� SECTION MEAN WITHOUT
� SECT ON 1 DISTANCE2 WIDTH AREA VELOClTY REGULATORY FLOODWAY WITH INGRE/�SE
ti (FT.) (Sa. FT.) (F.P.S.) (FEET NGVD) FLOODWAY (FEET)
i
i
' 2.41 250 1556 2.7 � 133.8 133.8 134.5 0.7
t 'A 2.69 90 903 4.6 136.9 136.9 137.5 0.6
' B 2.80 220 Z621 2.5 137.7 237.7 138.3 0.6
C 3..34 400 2412 1.7 140.0 140.0 140.6 0.6
� D 3.68 320 1730 2.4 141.1 141. 1 I41.7 0.6
? E 3.86 280 1379 3.0 141.9 141.9 142.5 0.6
F 4.16 260 1960 2.1 145.9 145.9 146.4 0.5
G 4.50 240 1517 2.7 i46.8 146.8 147.4 0.6
� w H 4.73 440 2010 2.0 148.0 148.0 148.6 0.6
I 4.81 73 501 8.1 151.0 151.0 151.2 0.2
J 4.86 101 . 843 4.8 152.8 152.8 ' 152.9 0. 1
K 4.93 195 1487 I 2.7 153.6 153.6 153.7 0.1
L 5.07 55 6I3 6.6 153.9 153.9 154. 1 �.2
� M 5.21 280 2507 1.6 154.6 154.6 155.4 0.8
' N S.b7 400 2617 1.5 155.3 155.3 156.0 0.7
i
; 0 5.83 60 546 7.1 156.2 156.2 156.6 0.4
� 6.22 150 1005 3.2 159.4 159.4 159.4 0.0
� 6.23 188 . 1612 2.0 159.7 I59.7 160.0 0.3
� b.27 � 138 1318 , 2.4 159.7 159..7 160.0 0.3
;
6.35 117 744 3.6 160.1 1b0.1• 160.5 0.4
,
; .
j 1. Unlettered cross sections are outside.of Studv Area. '
� 2. rliles above mouth. � .
;
,
�
�
� D DfPAfiTMEN7 OF HOJS!?�G AP�D URBAP�DEVELOF"r�fi�T
' � Fe�or:l iasunaca Ad mi�tration F L O O D Vi/A Y D A�"A
� �
1 m
CZTY OF TIGARD, OREGON
N {;,lastiington County) • FANNO CREEK
1
}� �� . . . . .. .
1
j P�1(:E 1 OF 2
f ' �
�I � � .
� . •
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�
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s -
i
� FLOODING SOURCE , FLOODWAY BASE FLOOD •
� WATER SURFAGE ELEVATIOH _ i
� SECTiON MEAN WITHOUT �
� WITH INGREASE
SECT ON 1 DISTANCE2 ���T� AREA VELOG7Y REGULATORY FLOODWAY FLOODWAY (FEET)
(SQ. FT.) <F.P.S.) (FEET NGVD)
I
6.58 300 2298 1.2 160.5 160.5 16I.2 0.7
6.85 310 1997 1.3 160.8 160.8 161.5 0.7
P 7.09 160 1103 2.4 161.4 161.4 162.2 0�.8
7.23 44 293 9.1 162.9 I62.9 163.5 U.6
7.44 340 2181 1.2 165.4 165.4 165.7 0.3
^ •
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3
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3
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1. Unlettered cross sections are outside of Study Area.
� � 2, Miles above mouth. -
�, . �:
� DEPARTn1Et�T OFHDUSlPJG AND URBAN DEVELOPt�1EtiT ''� �LOODiNAY DATA
�j Fedxd lnauronce Admi�tr�tion .
,� �
�� m�
r , �„ CITY OF TIGARD, OREGON
(Washington, County) � FANNO .CRE�EK
� , '
� _ � •Der.F � �F �
� l� � � : '
t
. , .
F�OODtNG SOURCE FLOODWAY BASE FLOOD `
WATER SUAFACE ELEVATION I
SECTlOt� MEAN WITHOUT
CROSS 1 DISTANCE 2. WIDTH Ar�EA VELOCITY REGULATORY FLOODWAY W�TH tNCREASE
SECTION (FT.) (SQ. FT.) (F.P.S.) (FEET NGYD) FLOODWAY (FEET)
0.02 140 56b 1.8 160.1 155.3 156.0 0.7
' 0. 10 47 183 5.6 16Q.1 155.8 156.4 0.6
0.22 46 295 3.5 160.1 158.4 159.3 0.9
A 0.40 95 477 1.9 160.2 160.2 161.0 0.8 :
B Q.49 35 231 � 3.9 I60.6 I60.6 151.5 0.9
0.55 26 197 4.b 161.8 161.8 162.$ 1.0
0.71 240 965 0.9 162.1 162,1 153. 1 1.0 F
i
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1. Unlettered cross sections are outside of Study Area. ;
2. Miles above mouth. � ;
�
i
�
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i
D DEPART�dENT OF HQUSlP1G AND UR3AN DEYELOF�r9Et�T ,^I ^ `
W Fsdarot lrsunnce A�nitistration �L Q 0 Q Y Y A Y �K�/�.
m ;
^' CITY OF TIGARD, OREGON �
(Washin�ton County) ASH CREEK � �
E
i
. �
��, � ,-�, �_ . . �
,
. ;
? �
,
. • �
. �
f
FLOODING SOURCE �FLOOD'�IVAY BASE FtAOD ' �
WATER SUAFACE ELEVATION I
SECTIaN MEAlJ WITHOUT '
CROSS 1 2 WIDTH WlTH tNCREASE �
SECTfON d�STANCE �FT�� AREA ' YELOCITY REGULAT�JRY FLOODWAY FLOODWAY (FEETD `'a,
(SQ. FT.) (F.P_S.) (FEEI' NGVD). E
� �
A 0.12 � 120 561 2.6 157.I 154.9 155.5 0.6 �
B 0.30 � 89 351 4.1 157.3 157.3 158.1 0.8 . �
C Q.76 L80 687 2.1 I61.8 16I.8 ` 162.5 0.7 (
D 1.07 L20 346 4.1 168.0 168.0 168.7 0.7 !
E 1:I3 '� .125 688 2.I 169.0 I69.0 169.5 0.5 i
F 1.30 L65 1045 1.3 169.5 169.5 170.1 Q.6 �
G 1.40 65 267 5.0 I71.1 171.i 171. 1 0.0 � �
H 1.50 55 569 2.2 171.7 I71.; 172.a 0.3 ;
� I 1.51 60 550 2.3 1?I.6 17I.6 172.1 0.5 �}
J 1.55 60 554 2.3 171.7 17I.7 . 172.2 0.5 E
1.74 195 585 2.0 172.5 I72.5 173.3 0.8 �
. !
. • �
�
b
�
' 1. Unlettered cross sections are outside of Study Area. . , �
2. Miles above mouth. -
.
�
��� , �
'� DEPAflTMENT OF HQUSfYG AHO URBAfd OEVELOPi1ENT :�� ;/�, E
� Fsdoret Insurnnss Admirzstration F L O O D Y V A� D A�A, E
r . �
m _ �
N
CITY OF TIGARD, OREGON �
(idashin�ton County) S'�7�L*1ER CREEK
�
_ ... __ _ . _ _ _ _ .. .. .:_ .:.::. ....--�...
. .
�,
' � � � �
,
As shown on tlie Flood Boundary and �loodt�ay Tiap, the floodway
�+; widths were determined at cross sections; betcaeen cross sec- '
tions, the boundaries were inGerpolated. In cases where the
boundaries of the floodway and the 100-year tlood are either '
close �o�ether or colinear, only the floodway boundary has �
been shown. ' '
The area between the floodway and the boundary of the 100-year
flood is termed the floodway fringe. The floodway fringe thus
encompasses the portion of the flood plain that could be com-
pleCely obstructed without increasing the water-surface eleva-
tion of the 100-year flood more than 1.0 foqt at any point.
.�.�....��
Typical relationships between the floodway and the flood�vay
fringe and their sign3ficance to flood plain development are
sho��n in tigure 4.
. , FL0oo1�r�1Y SCr1C1,lr�7iC
�,_ •
. �- ---., ao rtui rtoc�o ►�siw � �
' � .
(` r�,..,..�r . .� .
i r,iH.0 r� /IOMw�'f � tld?n��r 1
I��bOC 1
� � 1
� t
i 1 � ft�(1Y � �
IC11{yNfl~r 1
, � I�'�.'.� �I(Il'i'al r�i/y• .
� tCr�n.((� .�f„♦ rl"�:�rAY I
`�1 Cw�.: ..�..rv� �_ —'� [MC�.,-i���uC�r� �^
�i\�� ! � � A MC /h'T I•' �'���-,./
�. i ' � —`___ u a r , /i-_.`.
. '"` �� '�----_ .- �.�_ ��_�" _ -=+� I ti;.,�1
� . '_-t�f� i
. i..,.. I _' _..__ ' , ^�,� �
. �..a �. �lr:� ,� . .. :rv�P ,`, t -�.._ •
�i V':7 � ' •l�l� !�! 71
�ll!..�i . •:l'\; � . /��:J ' .
fll�•�tn�
�t/�•f (^:••:�C.�u���
Oh /IOCJ ►��iy
�. l'yC l.i It T�b( /lf`OJ fllva110Y p/It•( fMC�C.�C����f��
l�( C`D �1 in( 1lC•,0 �ll��llU�y ��11�[1 LhCh3AC'�v(M�
Figure 4. Floodway Schematic
� I
. �
' � �
�
1'1 . �
_. ,.. ..__....,. ....._ . ,._ _....w . .:_ . .... ..�.. ...
,
, ;
. ....... _...�.,. . ... .. �
,_��:�.w,._.y.;.�.....__.�_� _. .......�,.�.._,_..._.�._..:......__....�_._�.. ,_._.,...........� . :..__ -.
. .
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,
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5.0 INSURANCE APPLICATION a
In order to establish actuarial insurance rates, the FIA has developed
� a process to Cransform the data from the enoineering study into flood
insurance criteria. This process inclucles the determinatian of reaches,
Flood Hazard Factors (FHF's) , and flood insurance zone designations
� for each signi£icant flood source affecCing City of Tigard.
� 5.1 Reach D eterminations .
Reaches are defined as lengChs of watercourses having rela-
tively the same flood hazard, based on the average weighted
difference in water surface elevaCions between the 10- and 100-
year floods. This difference does not have a variatian greater
than that indicated in the following table for more than 20
p�r�;.�c1t of Clle Y�a+::€i.
,�:
' � Averagc Difference Bet�aeen � �
� . �.�
10- and 100-Year Floods Variation �'r�
� Less than 2 feet 0.5 -foot
2 to 7 feet 1..0 foot
7.1 to 12 feet 2,0 feet .
Four reaches meetinb the above criteria were required for the
flQodins sources of T3.gard. These include two reaches on Fanno
Creek, and one reach each on Ash and Summer Creeks. The loca- ��
i
tions of the reaches are shown on the Flood Profiles.
�
5.2 Flood Hazard Factors (I'HF's) ' . �,'
The Flood Hazard Facto'r is used to correlate flood information
with insurance rate tabl.es. Correlations bet�veen property
- damages from floods and their assigned Fk1F's are used to set
actuarial insurance premium rate tables based on FHF's from 005
�. ta 200. .
. '
.
� >
. ..�,....�.... . . . W _ .__,...._.,Ta__.....___._.�..._._�,..__...�__....�.....,._u_.,___._.._.�..._�.� ,. .
. .
_ .v. . ..._.. _ .._..___. . __ _ ...._�___... .,.._..�_�_w____.. _...
I . .
,
. ,, .
Y, �
.�, ,� ,
,
The FIiF for a react� is ,the average wei�;hted dit�erence bctween
�,. the 10- and 100- ear flood water surface elevation
Y s expressed
to the nearest one-half foot, and shocvn as a three-d.isit code.
. For example, if the diL•terence between the water surface eleva°
tions of the 10- and 100-year floods is 0.7 foot, the FHF is 005;
if the clifference is 1.4 feeC, ttie FtiF is 015; if the differen.ce
is 5..0 feet, the FHF is 050. When tlxe differance between rhe I.0-
and 100-year flood water surface elevations is greater than 10.0
feet, the accuracy for the FHF is to tlie nearest foot. '
5.3 Flood Insurance Zones
After deterinination of reaches and their corresponding F�IF's, .
the entire incorporated area of Tigard was divided into zones, '
each having a specific flood potenti�l or hazard. Each zone was
t
assigned one of the following flood insurance zone designations: j;
. ,
�
Zone A: Special F'lood Hazard Are,as inundated by ��!�'
� the 00-
. 1 year flood, determined by
approximate methods, no base flood ele-
.
vations shown or FHF's determined.
. ;
. Zone A1, A2, A3: Special I`lood Hazard Areas inundated by� �!
the 100-year flood, dete nnined by 4'
S;
detailed me�hods; base flood elevations �'
. ;,
shown, and zones assigned according Co ��
. FHF's. ' �;I
� r::
4,
. �.;
Zone B: Areas between the Special Flood Hazard ��
Areas and the limits of the S00-year ��
f ood i ��
� , ncludin� areas of the 500-year �
� . r,�
. flooci lain ttiat are �
p protected from the k''
��
• 100-year floocl by dike, levee, or other ��"
water control structure; areas subject �t�
�r
� �..._� ' . . . : F;q
x
�fi'
�:w
a
,� � � ��
. . � � . . .... ;'A
�q ' :
�� -
• e ......,.._......r......."-_�.�..r.............`_,._.._..._..._..__._._.._........�_..........................._�.�..._............�..�._.�_. ...�.__.e...._,.... .......- ..
�
• � �
�` • .
� '�� .� � � . ..
i
` to certain types ot 100-year shallow �
� flooding t�here de t.hs are less
P than 1.0
foot; or, areas subject to 100-year '
flooding from sources with drainage ;
' � areas of less than one square mile. _ '
Zone B is not subdivided. '
I
Zone C: Areas of minimal f lood ing�. � �
Table 3, "Flood Insurance Zone Data," summarizes the flood eleva-
� tion differences, FHF's, flood insur�nce zones, and base flood ' .
' elevations for each flooding source studied 'in detail in the
community. "
5.4 Flood Insurance Rate Piap Description
The Flood Insurance Rate Map for City of Tigard is, for �
� . insurance purposes, the principal result of the F].00d Insurance
� K' � Study. This map (publi.shed separately) cou[ains the officia
1
delineation of flood insurance zones and base flood elevation�'�t,
' lines. Base flood elevation lines show the locarions of the
` expected �ahole-foot water surface elevations oF the base (100-
�,
year) £lood. This map is developed in accordance with the latest
, flood insurance -map preparation guidelines pt�blished by the FIA
(Reference I3} . ' '
6.0 OTI3ER STUDIES �
The Corps of Engineers is currently preparing Flood Insurance Studies �
for the Cities of Durham and Beaverton (References 14 and 15) , and the
unincorporated areas of Washinoton County (Reference il) , inc�uding the
area adjacenC to Tigard. The results of the Ti�ard, Durhan, Beaverton,
and Washington Coun�y Flood Insurance Studies (FIS's) will match
exactly.
�w .
� _ 20
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,
} ELEVATION OIFFERENCE 2 • i
I FLOOOFNG SOURCE PANEL� BE�WEEN BASE FLO00 AND: FHF ZONE BASE FLOOD `
` � 1A% 2%a 0.2% ELEVATION i
, !10 YRJ 150 YR.) (500 YR.)
1 . �' Fanno Creek � � ,
�; . : Reach 1 -1.4 -0.4 0.9 OIS A3 VARIES � � �
� Reach 2 " . -0.9 -0.3 0.7 O10 A2 VARIES ;
lAsh Creek f
� Reach 1 -0.6 -0.2 0.5 005 A1 VARIr^,S � �
r � �
� Summer Creek _ � � ;
! �
Reach Z -0.7 0.2 0:5 005 A1 VARIES �
�
. �
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' � :
1. Flood Insurance Rate Map Panel �
2. Weighted Average . ; ; � ;
3. Rounded to the nearest foot-see map. . ' , E ,
� _ . . . �
�
� '
� ------ . �
z
� DEPARTMEN70F H�USING AND URBAPJ DEVElOYi�fEMT � f
� Fedetailnw�enceAdministration Fi.00D 1�dS(lR��dCE Z��E DATA �
� .
� ► ,
r.._ . F
^' CZTY OF TIGARD9 OREGON = '
; ;
�"' ' (Washington County) FANNO, ASH, ANB SUri�`fER C�tEEKS ' f :
i ;
. �'
...�w..._�..�._ .�......_....,..�.�.,w.._..u..�_.�._...,...__:.._......_._.___�,...�.._�.. �..;..��..�,_._�—.._.�......�.._.._.��.
_._.... _.,.__.._ _...,_�..�_.,y....w.....,�.�.�.._�_,._._..___..,_....,.�w..�_.w._
; � , `
l ' �
. �
'y
� r'' ..�► � .
In 1969 Che Corps of Engineers prepared a FPI report for tdasl�ington
: � County (Reference 16) . The 100- ear flood r f �
. Y p o i l� p r e s e i�t e d i n t h i s
, study vartes �aithin about plus or minus one foot with the FIS 100- .
year profile throu�h City Qf Tigard. The difference in flood heights
is attributcd to improved data ob�ained for the FIS's. This study
' will superscede all previous Corps of Engineers flood hazard studies.
. 7.0 LOCATION OF DATA
Survey, hydrologic, hydraulic, and other pertinent data used in this
studg can be obtained by contactin� tlae Federai Insurance and liazard
Mit3.ga�ian Divisiar,, Fedcrul Emergeticy IYanagement Agency, Re�ional .
Director, 130 ?_28th St., S.W. , Bothell, Washington 98011.
j
8,0 BIBLIOGRAPHY AIZD RY,FERENC�S �
--°---------,.----- _.. =.-.-w,,._.__ .._
1. Portland State Universit.y, Population Estimates: Ore£on Countie5
� and Incozporated Cities, July 1978.
(, � - .
2. Pacific Northwest River Basins Commission, ClimatoloQical Han����� rok,
Temperature, Volume 1, Part A, 1969.
� 3. Pacific Northwest River Basins Commission, Climatological Handbook,
Precipitation, Volun�e 2, 1969.
4. U.S. Department af liousin� and Urban Development, Federal Insurance
� Administrationy Code of Federal Regulations, Title 24, Chapter 10,
Parts ISl^v.3A and 3B, Federal Re,ga.ster, Vol. 41, No. 207.
5. U.3. DepartmeriG of Agriculture, Soil Conservation Service, SCS
N'ational_EnetnPerinn Handbflok, 5ection 4s Hydrology, January 1971.
6. U.S. .Army Cn,ps of Fngineers, Hydrolo�ic Engineering Center, Unit I
Graph_ az�d Hydrogra�h Computation, Computer Pro�ram 23 J2 L223, '
Davis, California, July 1966. , '
7. U.S. Army Corps of Engineers, Hydrologic Enoineering C�nter, H dro-
graphic Combining and Routin�s, Computer Pro�ram 23-J2-L232, Davis,
Cali£ornia, Au�ust 1966.
8. U.S. Army Corps of Engineers, Portland District, Procedures for
Determination of Maximum Annual Flood Peak and Volume Fre uencies
for Portland DistricC, Report No. 2, February 1969. '
�. '
. 22
. : ,�
"-._. , _
._._��:.u.w... _.... _ . _. _.., ___...._____._.,._�... ...____._.__.,�__._�_...._w_�.... ._,...... ��._,. ._...__....�_.k,_..,._ ,,._ .
� ., _....___. . . __,._.. .. _. _..._ ._.._.,
� • � �
E
� , � •
• r
,-� ,,,�.• :+ � .
� . 9e U.S. Army Corps ot Engineers, liydiological �nsineering Center, H�C-2
Water 5urface 1'rofiles, Generalized Com�uter Pro�ram, Davis,
Ca].itornia, I�bvember 1976, upeiated Octot�er 1977.
� lU. T�gard (topographic maps), Aerial rta�pins Cornpany of Oregon, 1974.
�,
; 11. Federal �mersency Dtanagemenr. A�eizcy, F1ood Insurance Study,
� Washington CounEv, Or��on, UnPublislaed.
; ,
F
� 12. Washington County, Oregon, Department of Public Works, "Flood Plain
� Delineation riaps," 1974. '
� .
� 13. U.S. Department of Housing and IIrban Develo�ment, Federal Insurance
�
Admfnistration, Guidelines and Specifications for Study Contractors,
` October 1977.
� 14. Federal Emergency Management, Agency, Flood Ynsurane.e Study, Durham,
� Ore o�ny Un�ublished.
� � 15. Federal Emergency 2danagement Agency, Flood Insurance Stud1�,
Beaverton, Oregon, Unpublished. • �
16.. U.S. Army Corps of Engineers, Portland District, "Floodplain
Information, Washin�ton County, Oregon," June 1969. ' .
�
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ELEVATION' REFERNECE MARKS
� City of Tigard, Ore�on �
Reference Elevation in Descri.ption of Location
Mark Feet �(NGVD) •
.
RM 1 137.23 On S.W. Bonita Road c,ver
Fanno Creek, a railroad
� spike is located centerline
- . on east end of bridge. .
RM 2 142.52 On S.W, Hall Blvd, over
. Fanno Creek, a PK nail
is located centerline
on north end of bridge.
RM 3 15I.65 On S.W. Main Street over
� Fanno Cree`(�a PK nail
is located centerlidB �
on south end of bridge.
� � Rrs 4 �iso.77 On S.W. G�ant Avenue over
. � . Fanno Creek, a PK nail '
is located centerline on „�
' � south end of bridge.
,RM S 156.98 On S.W. North Dakota Street
over Fanno Creek, a PK nail
is located on south edge
on west end of bridge.
RM 6 163.34 , On S.W. Scholls lEerry Road
over Fanno Creek, a nail .
� , and washer is located
� centerline of bridge,
� 7 166.23 On S.W. Shady Lane over
" A3h Creek, a nail is
� located centerline of
road.
RM 8 163.53 At intersection of S.W.
Katherine Road and S.W.
116th Avenue, a railroad � .
spike is located' centerline.
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ELEVATION REFERENCE MARKS ,(continued) k.
Y ' j'I
City of Tigard, Oregnn �ai
. . , �i
Reference , Elevation in Description of Location �
- Mark ` - Feet (NGVD)
. RM 9 • , , 167.5� On S.W. 121st Avenue uver i
� . •�: ' . ;�. , Summer Creek, a railroad �'
, , , spike is located centerline �
� ' . �. .; ; , on north end of conc:rete
box Gulvert.
RM 10 , ,, 180.Qfi At intersection of S.W.
, ; ,_ � . . � Summer Street and S.W.
. . , . . . , Summercrest SCreet, a PK
nail is located centerline.
, • �'
.. . ,,. ..
RM 11.. .•� 222�,5T At intersection of Scholls
. _ , . - _ . Ferry Road and S.W. 13�th . ;
. . , ,_, , . , - , Avenue, a PK anil is located '�
centerline. , . �;i
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