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February 13, 2012
Mr. Frank Trieu
c/o Mel Maertz
M2 Architects
Re: 7109 Lake Ballinger Way — Tax Parcel 00488800800700
Lake Ballinger Flood Hazard Assessment
Dear Mr. Trieu:
9957 171 AVENUE S
l ENTON, WA 98059
I've completed a flood hazard assessment for your property located at 7109 Lake
Ballinger Way in Edmonds. This assessment meets the requirements of Edmonds City
Code 23.70.020 for special studies and reports.
The subject property is on the south shore of Lake Ballinger and is in an area mapped by
FEMA as a Zone A flood hazard area (Attachment A). Zone A areas have a one percent
annual chance of flooding. Because Zone A flood areas do not have a FEMA -approved
flood study, no depths or base flood elevations are shown within these zones on the
FEMA map.
I understand that the existing single-family structure on the subject property will be
replaced with a new one. The finished floor elevation of the existing structure on the site
is at elevation 288.29 feet NAVD 88 (J.C. McDonnell, December 2011).
City of Edmonds Operational Policy
The City of Edmonds Building Department has adopted an operational policy to adopt a
base flood elevation of Lake Ballinger. The City has adopted a base flood elevation
(BFE) of 286.14 feet NAVD 88 for the lake (Figure 1). This elevation is based on the
highest observed water level in the lake, which occurred during a storm in January 1997.
Other Past Flood Studies
Hydrologic studies for Lake Ballinger have been conducted as part of past basin and
flood studies for the City of Edmonds and the City of Lake Forest Park (Aqua Terra,
June 1999; Clear Creek Solutions, June 2008; Clear Creek Solutions, January 2009;
Otak, December 2009). None of the studies have resulted in a base flood elevation for the
lake that has been approved by FEMA. Based on HSP -F hydrologic modeling, the
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Mr. Frank Trieu
Page 2
February 13, 2012
elevations of the lake have been predicted to be 284.14 feet NAVD 881 for the 10 -year,
284.90 feet NAVD 88 for the 50 -year, and 285.19 feet NAVD 88 for the 100 -year flood
elevation (Clear Creek Solutions, June 2008). I could not find any reference to the
estimated return period of the January 1997 storm that resulted in an observed peak
flood elevation that is higher than the 100 -year flood elevation predicted by Clear Creek
Solutions.
Recommendations
The applicant must follow local building code requirements in construction of the new
structure. I recommend the following flood control related measures, provided they are
not in conflict with any of the City's building requirements:
The finished floor elevation of the proposed structure on the project site must be a
minimum of 1 foot above the City's adopted BFE of 286.14 feet NAVD 88.
Given the lack of an approved FEMA flood study, I recommend constructing the
finished floor for the new structure 2 or 3 feet above the City's adopted BFE.
Selecting a higher finished floor elevation would help protect against uncertainty
in the adopted BFE. In addition, a conservative selection of the finished floor
elevation would help protect the structure against the potential effects of wind
generated waves. For instance, the wind fetch across the lake is a distance of
approximately 2,800 feet. Assuming a 60 mph wind velocity across the lake, a
wave height of 1.9 feet could develop as a result of the wind (Washington State
Department of Ecology, 1993).
If any portion of the structure is to be located below the BFE, the structure must
be designed and constructed to resist flotation, collapse, and lateral movement
when subjected to base flooding conditions. All materials installed below the base
flood elevation must be flood resistant materials, such as concrete and corrosion
resistant metals
Vents are required in any enclosed space below the BFE not designed to resist
hydrostatic forces to relieve hydrostatic pressure on the structure. A minimum of
one (1) square inch of vent area is required for each square foot of enclosed space.
Vents must be installed on a minimum of two sides of the structure, with the
bottom of the vent within one (1) foot of the exterior adjacent grade and the top of
the vent no higher than the BFE. Vents may be equipped with screens or louvers
which allow for the automatic entry and exit of floodwaters.
1 The original report cites these elevations using a vertical datum of NGVD29. The following conversion
was used: NAVD 88 = NGVD 29 + 3.60
Mr. Frank Trieu
Page 3
February 13, 2012
All machinery, and equipment should be elevated above the BFE or be designed,
constructed and installed to prevent floodwaters from entering or accumulating
within its components.
® The Flood Elevation Certificate provided in Attachment B must be updated with
changes in the site plan. If required by any agency or lending institution, a final
version of the Elevation Certificate must be prepared once the building is
constructed and data entered onto the form have been field -verified.
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Mr. Frank Trieu
Page 4
February 13, 2012
References
City of Edmonds, June 2011. Building Department Operation Policy 062011 — Flood
Plain Elevation of Lake Ballinger.
Clear Creek Solutions Inc., 2008. Lake Ballinger Lake Level and Outlet Study. Prepared
for the City of Edmonds.
Hammond, Collier & Wade Livingstone Associates and Aqua Terra Consultants, 1999,
McAleer and Lyon Creeks Drainage Basin Study. Prepared for the City of Lake
Forest Park.
J.C. McDonnell, December 14, 2011. Trieu. Site Plan and Base Map. Mill Creek, Wash.
Otak, 2009. Flood Reduction Planning Study Lyon CreeklMcA leer Creek Drainage
Basins. Prepared for the City of Lake Forest Park.
Washington State Department of Ecology, 1993. Dam Safety Guidelines- Part IV Dam
Design and Construction. Water Resources Program — Dam Safety Office.
Olympia, Wash.
10 -YR AND 50 -IR: CLEAR CREEK
SOLUTIONS LAHE LEVEL STUDY (JUNE
2008)
TIM CITY OF EDMONDS OPERATION
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FIGURE 1. SITE TOPOGRAPHY
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Attachment B. Draft Elevation Certificate
U.S. DEPARTMENT OF HOMELAND SECURITY ELEVATION CERTIFICATE OMB No. 1660-0008
Federal Emergency Management Agency I Expires March 31, 2012
National Flood Insurance Program Important: Read the instructions on pages 1-9.
SECTION A - PROPERTY INFORMATION Foi"Insurance Company Use:
Al. Building Owner's Name Frank Trieu Policy Numbi r
A2. Building Street Address (including Apt., Unit, Suite, and/or Bldg. No.) or P.O. Route and Box No. Company NAIL Number
7109 Lake Ballinger Way
City Edmonds State WA ZIP Code 98026
A3. Property Description (Lot and Block Numbers, Tax Parcel Number, Legal Description, etc.)
Tax Parcel Number 00488800800700
A4. Building Use (e.g., Residential, Non -Residential, Addition, Accessory, etc.) Residential
A5. Latitude/Longitude: Lat. 47 46'42.42" Long. 122 19'43.77" Horizontal Datum: ❑ NAD 1927 ❑ NAD 1983
A6. Attach at least 2 photographs of the building if the Certificate is being used to obtain flood insurance.
A7. Building Diagram Number 1B
A8. For a building with a crawlspace or enclosure(s): A9. For a building with an attached garage:
a) Square footage of crawlspace or enclosure(s) sq ft a) Square footage of attached garage sq ft
b) No. of permanent flood openings in the crawlspace or b) No. of permanent flood openings in the attached garage
enclosure(s) within 1.0 foot above adjacent grade within 1.0 foot above adjacent grade
c) Total net area of flood openings in A8.b sq in c) Total net area of flood openings in A9.b sq in
d) Engineered flood openings? ❑ Yes ❑ No d) Engineered flood openings? ❑ Yes ❑ No
SECTION B - FLOOD INSURANCE RATE MAP (FIRM) INFORMATION
B1. NFIP Community Name & Community Number
B2. County Name TB3.
State
City of Edmonds 530163
1 Snohomish I
WA
B4. Map/Panel Number
B5. Suffix
B6. FIRM Index
67. FIRM Panel
B8. Flood
B9 Base Flood Elevation(s) (Zone
Map 53061C Panel 1315
E
Date
Effective/Revised Date
Zone(s)
AO, use base flood depth)
11/8/99
11/8199
A
286.14
B10. Indicate the source of the Base Flood Elevation (BFE) data or base flood depth entered in Item B9.
❑ FIS Profile ❑ FIRM ® Community Determined ❑ Other (Describe)
B11. Indicate elevation datum used for BFE in Item B9: ❑ NGVD 1929 ® NAVD 1988 ❑ Other (Describe)
B12. Is the building located in a Coastal Barrier Resources System (CBRS) area or Otherwise Protected Area (OPA)? ❑ Yes ® No
Designation Date ❑ CBRS ❑ OPA
SECTION C - BUILDING ELEVATION INFORMATION (SURVEY REQUIRED)
Cl. Building elevations are based on: ® Construction Drawings* ❑ Building Under Construction* ❑ Finished Construction
*A new Elevation Certificate will be required when construction of the building is complete.
C2. Elevations - Zones Al -A30, AE, AH, A (with BFE), VE, V1 -V30, V (with BFE), AR, AR/A, AR/AE, AR/A1-A30, AR/AH, AR/AO. Complete Items C2.a-h
below according to the building diagram specified in Item A7. Use the same datum as the BFE.
Benchmark Utilized Field tie to tidal watersVertical Datum NAVD 88
Conversion/Comments N/A
Check the measurement used.
a) Top of bottom floor (including basement, crawlspace, or enclosure floor) 287.0 ® feet ❑ meters (Puerto Rico only)
b) Top of the next higher floor 297.0 ® feet ❑ meters (Puerto Rico only)
c) Bottom of the lowest horizontal structural member (V Zones only) ❑ feet ❑ meters (Puerto Rico only)
d) Attached garage (top of slab) ❑ feet ❑ meters (Puerto Rico only)
e) Lowest elevation of machinery or equipment servicing the building 287.0 ® feet ❑ meters (Puerto Rico only)
(Describe type of equipment and location in Comments)
0 Lowest adjacent (finished) grade next to building (LAG) 287.0 ® feet ❑ meters (Puerto Rico only)
g) Highest adjacent (finished) grade next to building (HAG) 296. ® feet ❑ meters (Puerto Rico only)
h) Lowest adjacent grade at lowest elevation of deck or stairs, including 287.0 ® feet ❑ meters (Puerto Rico only)
structural support
SECTION D - SURVEYOR, ENGINEER, OR ARCHITECT CERTIFICATION
This certification is to be signed and sealed by a land surveyor, engineer, or architect authorized by law to certify elevation
information. / certify that the information on this Certificate represents my best efforts to interpret the data available.)
understand that any false statement may be punishable by fine or imprisonment under 18 U.S. Code, Section 1001.
Check here if comments are provided on back of form. Were latitude and longitude in Section A provided by a
licensed land surveyor? ❑ Yes ® No
Certifier's Name
License Number 28576
Title Water Resource Engineer Company Name Ed McCarthy, PE, PS
Address 9957 171 Ave SE City Renton State WA ZIP Code 98059
Signature Date 2-10-12 Telephone 425-271-5734
FEMA Form 81-31, Mar 09 See reverse side for continuation. Replaces all previous editions
IMPORTANT: In these spaces, copy the corresponding information from Section A.
Building Street Address (including Apt., Unit, Suite, and/or Bldg. No.) or P.O. Route and Box No.
7109 Lake Ballinger Way y
City EdmondsState WA ZIP Code 98026
SECTION D - SURVEYOR, ENGINEER, OR ARCHITECT CERTIFICATION (CONTINUED)
Copy both sides of this Elevation Certificate for (1) community official, (2) insurance agent/company, and (3) building owner.
Comments
Signature Date 2-10-12
❑ Check here if attachments
SECTION E - BUILDING ELEVATION INFORMATION (SURVEY NOT REQUIRED) FOR ZONE AO AND ZONE A (WITHOUT BFE)
For Zones AO and A (without BFE), complete Items E1 -E5. If the Certificate is intended to support a LOMA or LOMR-F request, complete Sections A, B,
and C. For Items E1 -E4, use natural grade, if available. Check the measurement used. In Puerto Rico only, enter meters.
E1. Provide elevation information for the following and check the appropriate boxes to show whether the elevation is above or below the highest adjacent
grade (HAG) and the lowest adjacent grade (LAG).
a) Top of bottom floor (including basement, crawlspace, or enclosure) is ❑ feet ❑ meters ❑ above or ❑ below the HAG.
b) Top of bottom floor (including basement, crawlspace, or enclosure) is ❑ feet ❑ meters ❑ above or ❑ below the LAG.
E2. For Building Diagrams 6-9 with permanent flood openings provided in Section A Items 8 and/or 9 (see pages 8-9 of Instructions), the next higher floor
(elevation C2.b in the diagrams) of the building is ❑ feet ❑ meters ❑ above or ❑ below the HAG.
E3. Attached garage (top of slab) is ❑ feet ❑ meters ❑ above or ❑ below the HAG.
E4. Top of platform of machinery and/or equipment servicing the building is Elfeet ❑ meters ❑above or E] below the HAG.
E5. Zone AO only: If no flood depth number is available, is the top of the bottom floor elevated in accordance with the community's floodplain management
ordinance? ❑ Yes ❑ No ❑ Unknown. The local official must certify this information in Section G.
SECTION F - PROPERTY OWNER (OR OWNER'S REPRESENTATIVE) CERTIFICATION
The property owner or owner's authorized representative who completes Sections A, B, and E for Zone A (without a FEMA -issued or community -issued BFE)
or Zone AO must sign here. The statements in Sections A, B, and E are correct to the best of my knowledge.
Property Owner's or Owner's Authorized Representative's Name
Address City State ZIP Code
Signature Date Telephone
Comments
❑ Check here if attachments
SECTION G - COMMUNITY INFORMATION (OPTIONAL)
The local official who is authorized by law or ordinance to administer the community's floodplain management ordinance can complete Sections A, B, C (or E),
and G of this Elevation Certificate. Complete the applicable item(s) and sign below. Check the measurement used in Items G8 and G9.
G1. ❑ The information in Section C was taken from other documentation that has been signed and sealed by a licensed surveyor, engineer, or architect who
is authorized by law to certify elevation information. (Indicate the source and date of the elevation data in the Comments area below.)
G2. ❑ A community official completed Section E for a building located in Zone A (without a FEMA -issued or community -issued BFE) or Zone AO.
G3. ❑ The following information (Items G4 -G9) is provided for community floodplain management purposes.
G4. Permit Number G5. Date Permit Issued G6. Date Certificate Of Compliance/Occupancy Issued
G7. This permit has been issued for: ❑ New Construction ❑ Substantial Improvement
G8. Elevation of as -built lowest floor (including basement) of the building: ❑ feet ❑ meters (PR) Datum
G9. BFE or (in Zone AO) depth of flooding at the building site: ❑ feet ❑ meters (PR) Datum
G10. Community's design flood elevation ❑ feet ❑ meters (PR) Datum
Local Official's Name Title
Community Name Telephone
Signature Date
Comments
❑ Check here if attachments
FEMA Form 81-31, Mar 09 Replaces all previous editions
Building r
See Instructions for Item A6.
Building Photographs
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