HomeMy WebLinkAboutRIVERSIDE COMMUNITY SOLAR GARDEN - PDP - PDP140013 - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORT1437 Larimer St.
Denver, CO 80202
720•473•3131
sean.ohearn@enertiacg.com
July 21, 2014
Ms. Michelle Zimmerman, Land Manager
Clean Energy Collective
3005 Center Green Drive, #205
Boulder, CO 80301
RE: Drainage Letter
Riverside Community Solar Garden
NE of East Mulberry St/Riverside Ave Intersection
Dear Ms. Zimmerman:
This drainage letter is intended to provide the Fort Collins Utilities Department with information
related to the proposed Clean Energy Collective (CEC) solar garden located northeast of the
East Mulberry St/Riverside Ave Intersection in north central Fort Collins.
Project Specific Information
Project Name and Address
CEC Riverside Community Solar Garden, 500 Riverside Drive, Fort Collins
Developer/Owner
Clean Energy Collective, 3005 Center Green Drive, #205, Boulder, CO 80301
Civil Engineer
Enertia Consulting Group, LLC, 1437 Larimer Street, Denver, CO 80202
Project Description
The Project covers approximately 3.52 acres of the 7.34 acre City of Fort Collins property and
includes: a two phase solar garden (Phase I – 333kW and Phase II 192 kW) with a total of
approximately 1,700 solar panels mounted on steel I-beams; concrete pad mounted transformer
and inverter; an access drive; and perimeter fence with gate. The area west of the proposed
solar garden along Riverside Ave will be reserved for a pedestrian trail, to be completed by
others. Land clearing, grubbing or grading will not be required to install the solar garden
components (with the exception of the concrete pads). Clearing, grubbing and grading will be
required to install the access driveway. The attached erosion and sediment control plan with
details illustrates the Project components and proposed storm water best management
practices.
Existing Ground Surface Conditions
The 7.34 acre site is currently vacant and is the former location of a pickle plant (pickles were
processed at the site from the 1930’s to 1991). The ground surface is relatively flat and
generally slopes from northwest to southeast at an average grade of 1 percent. Surface
vegetation generally consists of native grasses. Site soils are well draining, granular “B” soils
(loamy sand) with low runoff potential when thoroughly wet.
Ms. Michelle Zimmerman
Page 2
Land Disturbance Activities
The site improvements include installation of: (i) solar energy conversion system components;
and (ii) an all-weather surface access drive.
Solar Energy Conversion System - Installation of the 3.48 acre solar energy conversion
system will be completed in two phases. Phase 1 includes 1,059 solar arrays placed on
+/- 235 steel I-beams (driven into the ground), an inverter and transformer placed on
concrete foundations and a gated perimeter fence. Phase 2 includes 618 solar arrays
placed on +/- 140 steel I-beams (driven into the ground).
Access Driveway – An all-weather, gravel surface access drive will extend from the main
entrance to the City of Fort Collins wastewater treatment plant to the Site. The access
drive components (4” Class 5 or 6 gravel placed over 8” aggregate base course) will be
placed over the existing ground surface and will be capable of handling a load of 85,000
lbs.
Land Disturbance Quantities
A total of approximately 3,967 square feet (0.09 acres) of the Site is anticipated to be disturbed
installing the access drive (3,605 sf.), foundations for the solar array system (+/- 12 sf. of
disturbance from 375 I-beams driven into the ground), transformer pad (100 sf.) and inverter
pad (250 sf.).
Impervious Surface
The Project will change approximately 362 square feet (I-beam, transformer pad and inverter
pad footprint) of surface area from pervious to impervious. The access road will be an all-
weather gravel surface.
Existing Drainage Patterns
The Site is located in the Cache La Poudre drainage basin and is within close proximity to the
Poudre River (major tributary to the South Platte River). Since the solar garden will not require
clearing, grubbing or grading (with the exception of inverter pad and transformer pad
preparation), existing drainage patterns will not change.
Proposed Storm Water BMP’s
As shown on the attached erosion and sediment control plan with details, storm water BMP’s
specified for the project include sediment control logs (SCL), a vehicle tracking pad (VTC) and if
required, a concrete washout area (CWA). The SCL’s shall be installed in accordance with E&S
plan details and maintained during construction of the solar garden. Once the solar garden
installation has been completed, the SCL’s will be removed and properly disposed. The vehicle
tracking control will be installed adjacent to and abutting the City of Fort Collins wastewater
treatment plant entrance drive. It’s anticipated that the crushed stone VTC will be incorporated
into the all-weather surface access drive.
Ms. Michelle Zimmerman
Page 3
Summary
1. Land disturbance resulting from solar garden component installation and access drive is
minimal with a total disturbed area of approximately 3,967 sf (0.09 acres).
2. Clearing and grubbing as well as soil cutting, filling or stockpiling will not be required to
construct the solar garden, except for concrete pad installation (350 sf.).
3. Installation of the solar garden is not expected to impact existing drainage patterns or flow
rates on the site or toward the Poudre River. Runoff water quality will not be impacted by the
solar garden components.
4. Installation of water quality or detention facilities would require clearing, grubbing, grading
and reseeding of a portion of the site.
5. Installation of water quality and detention facilities would likely increase the potential for
erosion, sediment transport and concentrated flow.
6. Due to the minimal land disturbance and implementation of the erosion and sediment control
BMP’s illustrated on the erosion and sediment control plan, additional storm water controls are
not warranted.
7. Solar garden component installation and access drive construction will follow Fort Collins
MS4 guidelines and meet applicable requirements.
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We trust that the information provided is acceptable and complete. Please let me know if you
have any questions or require additional information.
Sincerely,
ENERTIA CONSULTING GROUP, LLC
Sean O’Hearn, PE, PG
Managing Partner
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