4B - 3005 Arapahoe Ave - Floodplain Variance - LUR2011-00022
MEMORANDUM
TO: Planning Board
FROM: Katie Knapp, Civil Engineer, Floodplain and Wetlands Permitting
DATE: April 21, 2011
SUBJECT: Call Up Item: 3005 Arapahoe Ave. (Conoco Gas Station)
Floodplain Variance (LUR2011-00022)
This decision may be called up before Planning Board on or before
May S, 2011
A Floodplain Variance was approved by Planning and Development staff on April 21,
2011. The variance is to allow the installation of larger, replacement underground fuel
tanks at the existing fuel station located at 3005 Arapahoe. The floodplain regulations
(Section 9-3-3(a)(8), B.R.C.) do not allow the storage of a hazardous substance at or
below the flood protection elevation within the 100-year floodplain, except for the
storage of gasoline in existing and replacement underground tanks in existing gasoline
service stations. A variance to the floodplain regulations is required because the
proposed underground storage tanks are larger and in a different configuration than the
existing tanks at the existing fuel station.
The project includes the redevelopment of the existing Conoco gas station site located at
the northeast corner of 30th St. and Arapahoe Ave. The existing fuel station contains four
underground storage tanks with a total storage capacity of 22,500 gallons. The individual
tank sizes of the existing tanks are 8,000, 8,000, 6,000 and 500 gallons. Petroleum fuel
leaks and contaminated soils from the existing tanks have been reported. The proposed
redevelopment includes removing the existing underground fuel tanks and contaminated
soils and installing two new underground storage tanks with a total capacity of 38,000
gallons. The individual tank sizes will be 20,000 and 18,000 gallons. The new
underground storage tanks will be double walled, designed to prevent infiltration and
anchored with straps connected to concrete. The redevelopment will also include raising
the grade of the site approximately 1-foot so that it will be above the 100-year floodwater
elevation and eligible to be removed from the floodplain through the FEMA Letter of
Map Revision based on Fill (LOMR-F) process after construction.
Staff finds that the proposed project meets the intent of Section 9-1-1, "Legislative
Intent," Boulder Revised Code 1981 (B.R.C.), and provisions of Section 9-3-7,
"Variances," B.R.C. A copy of the floodplain variance and the application materials is
attached.
This floodplain variance was approved by Planning and Development Services staff on
April 21, 2011, and the decision may be called up before Planning Board on or before
29 Agenda Item 4B Page 1 of 7
May 5, 2011. There is one Planning Board meeting within the required 14-day call-up
period on May 5, 2011. Questions regarding this floodplain variance should be directed
to Katie Knapp in Planning and Development Services at 303-441-3273 or
knapp~c,bouldercolorado. gov.
Attachments:
A. Floodplain Variance
B. Application Materials
30 Agenda Item 413 Page 2 of 7
Attachment A
, Ar",
CITY OF BOULDER
FLOODPLAIN VARIANCE
Approved: April 21, 2011 Flood Variance No: LUR2011-00022
Location/Address: 3005 Arapahoe Ave. - Conoco Gas Station
Property Owner: Sunrise Center Partnership
Applicant: Dan Hubbell, King Soopers (303) 416-0866
Floodplain Designation: Boulder Creek, 100-year Floodplain
PROJECT/ACTIVITY DESCRIPTION: This variance is to allow the installation of underground fuel
tanks at the existing fuel station located at 3005 Arapahoe. The floodplain regulations (Section
9-3-3(a)(8), B.R.C.) do not allow the storage of a hazardous substance at or below the flood
protection elevation within the 100-year floodplain, except for the storage of gasoline in existing
and replacement underground tanks in existing gasoline service stations. A variance is required
for the proposed underground storage tanks because the proposed tanks are larger and in a
different configuration than the existing tanks at the existing fuel station.
The project includes the redevelopment of the existing Conoco gas station site located at the
northeast corner of 30th St. and Arapahoe Ave. The existing fuel station contains four
underground storage tanks with a total storage capacity of 22,500 gallons. The individual tank
sizes of the existing tanks are 8,000, 8,000, 6,000 and 500 gallons. Petroleum fuel leaks and
contaminated soils from the existing tanks have been reported. The proposed redevelopment
includes removing the existing underground fuel tanks and contaminated soils and installing two
new underground storage tanks with a total capacity of 38,000 gallons. The individual tank sizes
will be 20,000 and 18,000 gallons. The new underground storage tanks will be double walled,
designed to prevent infiltration and anchored with straps connected to concrete. The
redevelopment will also include raising the grade of the site so that it will be above the 100-year
floodwater elevation and eligible to be removed from the floodplain through the FEMA Letter of
Map Revision based on Fill (LOMR-F) process after construction.
BASIS OF APPROVAL: The applicant is requesting a variance to the requirements of Chapter 9-
3-3, "Regulations Governing the Floodplain," Boulder Revised Code 1981 (B.R.C.), which
3005 Arapahoe Ave. LUR2011-00022
31 Agenda Item 413 Page 3 of 7
states that no person shall store a hazardous substance at or below the flood protection elevation
for the area of the floodplain in which it is located, except for the storage of gasoline in existing
and replacement underground tanks in existing gasoline service stations and service garages,
which tanks are designed to prevent infiltration and discharge into floodwaters and which are
adequately anchored and shielded against rupture. A variance from floodplain requirements may
be approved subject to meeting the provisions set forth under Section 9-3-7, "Variances," B.R.C.
The city has recently completed a new floodplain analysis of Boulder Creek which indicates that
the subject property will only experience shallow flooding at the proposed location of the
underground storage tanks. The applicant is proposing to add approximately 1 foot of fill to the
site to raise the grade above the 100-year flood water elevation. This will reduce the flood
hazard risk for the subject property and will remove the project from the floodplain. No increase
in the risk to life safety is anticipated.
Staff finds that the proposed project/activity meets the intent of Section 9-1-1, "Legislative
Intent," Boulder Revised Code 1981 (B.R.C.), and provisions of Section 9-3-7, "Variances,"
B.R.C.
CONDITIONS:
1. As-built drawings shall be submitted to the City of Boulder upon completion of the
project to verify that the site has been filled above the 100-year flood water elevation.
2. Unless called-up or appealed, the floodplain variance will be effective on May 5, 2011.
3005 Arapahoe Ave. LUR2011-00022
32 Agenda Item 413 Page 4 of 7
Attachment B
G a owa
March 21, 2011
City of Boulder
Developmental Services
1739 Broadway, 3rd Floor
Boulder, Colorado 80306-0791
Attention: Katie Knapp - Flood Control Engineer
Jessica Vaughn - Planner I
Re: 3005 Arapahoe Road/ADR2010-00077 Variance request for King Soopers Fuel
Station #61 Underground Fuel Storage Tanks replacement.
Dear Katie/Jessica;
The following is our application for a variance from the following code:
9-3-3 (a) (7), B.R.C
City of Boulder Staff Report received via e-mail February 16, 2010 via e-mail:
Flood, Katie Knapp, 303-441-3273
In accordance with 9-3-3 (a) (7), B.R.C., no person shall store a hazardous
substance at or below the flood protection elevation for the area of the floodplain in
which it is located, except for the storage of gasoline in existing and replacement
underground tanks in existing gasoline service stations and service garages, which
tanks are designed to prevent infiltration and discharge into floodwaters and which
are adequately anchored and shielded against rupture.
Because this redevelopment replaces the existing 2 underground fuel storage tanks
(UST'S) with 2 larger UST'S and 1 tank would be approximately 10 feet south of the
currant UST field, City of Boulder staff is requiring a flood plain variance application.
Project location and existing conditions:
The site is an existing Conoco Gas Station located at 3005 Arapahoe Road (NE corner)
constructed in 1968. The gas station/convenience store has an internal carwash with 4
fuel product dispensers under a metal canopy at the southern portion of the site. The
existing underground fuel storage tank (UST) field is in the Boulder Creek Floodplain
(1983) and the proposed revised Boulder Creek Floodplain (2010) (See attached plan
sheet 1 of 2).
Petroleum fuel leaks into the sub-surface around the UST's have been reported by the
previous owner to the State of Colorado Oil and Gas Division the contaminated soils and
water are being monitored by the previous owner and reported to the State of Colorado.
This project will remove all contaminated soils and water to the standards set by the
State of Colorado Oil and Gas Division.
Galic;%~jy & Company, Inc. • 303.770.8884. 5300 DTC Parkway, Suite 100, Greenwood village, CCAgenda Itemw4v6'Wage 5 Xf7'com
City of Boulder
3005 Arapahoe Road
King Soopers Fuel #61
March 21, 2011
The existing UST storage capacity is:
1 - Unleaded Regular (RUL) 8,000 gallons
2 - Unleaded Mid-Grade (MUL) 6,000 gallons
3 - Unleaded Premium (PUL) 8,000 gallons
6 - Used Oil (Waste 411) 500 gallons
Total current underground fuel/oil storage is 22,500 gallons.
Project Description:
King Soopers will remove the existing gas station, underground fuel storage tanks
(UST), fuel piping, contaminated soil and water, concrete and asphalt pavement and
construct a new fueling station with 5 fuel product dispensers under a 92' x 43' canopy
with a kiosk, petroleum fuel sales require new doubled wall underground fuel storage
tanks (1 - 20,000 gallon unleaded, 1-18,000 gallon double compartment,
premium/diesel) total underground fuel storage capacity of 35,000 gallons is proposed.
The increase in underground fuel storage tank volume will reduce the frequency of fuel
truck deliveries.
Floodplain Modification:
Redevelopment of the site requires raising the site approximately 0.5' improving sheet
flaw drainage this will not remove the existing or proposed UST's field from the 100year
water surface elevation of the 1983 Boulder Creek Flood Plain.
Redevelopment of the site will raise the UST's field above the 100year water surface
elevation of the (2010) Boulder Creek flood plain study. See attached plan sheet 2 of 2.
The site is outside of the conveyance zone of the 2010 revised Boulder Creek floodplain
study as shown on the attached Boulder Creek Floodplain Study Flood Hazard Work
Map sheet 7.
The UST's are designed to prevent infiltration and are anchored with straps connected to
concrete dead man and are shielded against rupture by an 5" reinforced concrete slab
over the tanks.
King Soopers has reviewed alternate placements of the UST's at the northern end of the
site. Placement of the UST's north of the proposed northern location results in a fuel
tanker truck blocking the ingress and egress at the 30th street access drive, vehicles
accessing the site will have restricted visibility and may result in backups on 30th Avenue
affecting public safety at the 30th & Arapahoe intersection.
A Letter of Map Amendment by Fill (LOMA-F) will be submitted when the City of Boulder
accepts the 2010 revised Boulder Creek floodplain study.
Gallo%~jy & Company, Inc. 9 303.770.8884.5300 DTC Parkway, Suite 100, Greenwood Village, CC}~i~nda Item ~l`3*q
q~e"'~gf T'cam
City of Boulder
3005 Arapahoe Road
King Soopers Fuel #61
March 21, 2011
2 site plans are attached showing the following:
1) Existing site topography (1 of 2) with
a) Effective Boulder Creek 100 year floodplain (1983)
b) Proposed Boulder Creek 100 year flood plain (2010)
2) Proposed site redevelopment grading (2of 2)
a) Effective Boulder Creek. 100 year floodplain (1983)
b) Proposed Boulder Creek 100 year flood plain (2010)
c) Revised Boulder Creek 100 year floodplain (2010) with the proposed grading
raising the underground fuel tank location above the proposed 100 year
floodplain (2010) Base Flood Elevations (BFE).
All of the floodplain boundaries were plotted from cross section data and floodplain
profiles obtained from the City of Boulder website.
All of the proposed underground fuel storage tanks are designed to prevent ground
water and flood water infiltration are adequately anchored and shielded against rupture.
In addition the tanks, fueling piping and fuel dispensers are monitored continuously with
leak/pressure detection sensors.
Proposed Floodplain Variance;
A meeting with city staff was held on February 28, 2011 to review the options for the
floodplain variance to meet the intent of the City of Boulder Zoning code.
If a variance is issued it will only be for the duration the current Boulder Creek 100 year
floodplain (1983) is in effect, if the new.Boulder Creek 100 year floodplain (2010) is
adopted a Letter of Map Amendment by Fill (LOMA-F) removing the UST field from
floodplain would be required. This is acceptable to the applicant.
Sincerely,
Galloway
Matthew Duhaime P.E., P.L.S.
Project Manager
mattduhaime@gallowayUS.com
cc: King Soopers (Mike Scheckel)
Variance Request UST 2011-03-21.doc
Gallov% & Company, Inc. • 303.770.8884.5300 DTC Parkway, Suite 100, Greenwood Village, C0ABe01n1da1 •Itemww)& FaageilowPXR.com