HomeMy WebLinkAboutOWTS Design 01.03.2020Huddleston-Berry
Engineering & Testing, LLC
United Companies
PO Box 3609
Grand Junction, Colorado 81502
Attention: Mr. Robert Lewis
Subject: OWTS Design
New Batch Plant
Rifle, Colorado
2789 Riverside Parkway
Grand Junction, Colorado 81501
Phone: 970-255-8005
Info@huddlestonberry.com
January 3, 2020
Project#00256-0079
Reference: Foundation Recommendations, New Batch Plant, Rifle, Colorado by Huddleston-
Berry Engineering & Testing, LLC for United Companies, October 28, 2019.
Dear Mr. Lewis,
At your request, Huddleston-Berry Engineering & Testing, LLC completed design of an Onsite
Wastewater Treatment System (OWTS) for a new concrete batch plant in Rifle, Colorado. The
site location is shown on Figure 1 — Site Location Map. A site plan is included as Figure 2.
Subsurface Investigation
As discussed in the referenced report, the soils at the site consisted of sandy gravel and cobble
(pit -run) materials. Groundwater was observed in the excavation at a depth of approximately
eight feet at the time of the investigation.
Onsite Wastewater Treatment System
Seepage Bed Design
The design of the absorption system follows the requirements of the Garfield County On -Site
Wastewater Treatment System (OWTS) Regulations, Adopted June 2018. Due to site constraints,
a conventional OWTS with a soil treatment area is not possible. As a result, a vault system is
proposed. Based upon information provided to HBET, no more than twelve employees will be
working at the facility during a single shift. No showers will be provided at the facility. The
daily flow of the OWTS is calculated below.
Average Industrial Daily Flow = (12 employees/shift)(1 shift)(20 GPD/person)
= 240 GPD
HBET understands that a commercially available 1,500 gallon tank is proposed. A 1,500 gallon
tank will provide for approximately six days of storage capacity. In accordance with the
regulations, a visual and/or audible signal must be provided indicating when the tank has been
filled to 75% of its capacity.
Rifle Batch Plant
#00256-0079
01/03/20
Huddleston-Berry
Engineering& Testing, LLC
In addition, HBET understands that the tank is proposed to be placed in an automobile parking
area. The concrete tank is not traffic rated. In order to accommodate vehicular loading, HBET
recommends that a 6-inch thick reinforced concrete slab be placed above the tank.
System Installation
The installation of the septic tank and effluent lines should be completed in accordance with the
Garfield County On -Site Wastewater Treatment System (OWTS) Regulations. In addition, the
following construction procedures are recommended:
• The septic tank should be placed level over native soils that have been scarified to a
depth of 8 to 12 inches, moisture conditioned, and recompacted to a minimum of 95%
of the standard Proctor maximum dry density, within ±2% of optimum moisture
content. However, up to 3-inches of washed rock or pipe bedding passing the 1-inch
sieve may be used as a leveling course under the septic tank.
• The bottoms of trenches and backfill around the septic tank which will support sewer
or effluent lines should be compacted to at least 90 percent of the standard Proctor
maximum dry density, within ±2% of optimum moisture content. Pipe bedding
should have a maximum particle size of 1-inch.
Inspection Schedule
Huddleston-Berry Engineering & Testing LLC should be retained to monitor the construction of
the OWTS. The following schedule of observation and/or testing should be followed:
■ Observe placement of the septic tank and all connecting sewer and effluent lines prior
to backfill. Verify proper fall between inverts.
In conformance with Garfield County regulations, HBET will be required to provide Garfield
County with documentation certifying that the OWTS was placed in conformance to the plan and
Garfield County regulations.
General Notes
The OWTS design was based upon the results of the subsurface investigation, information
provided to HBET, and on our local experience. The design is valid only for the proposed
construction
We are pleased to be of service to your project. Please contact us if you have any questions or
comments regarding the contents of this report.
Respectfully Submitted:
Huddleston-Berry Engineering and Testing, LLC
Michael A. Berry, P.E.
Vice President of Engineering
C:\HBET\Project Files\2019\00256-0079 Rifle Plant\200 - Geo\00256-0079 LR010320.doc
2
FIGURES
Go gle Earth mikl ems
1
1
A
SCALE: 1" = 100'
(ON 11 X 17)
cP
FLY ASH
SILO
BATCH
\ OFFICE
SCALE
OFFICE t
a E \age
Wfault
RIAC
PLANT
^141'_--1—
r
r—
r—
Project No.: 00256-0079
Date: 01/03/20
By: MAB
"NM
mot
,A16.
Huddleston-Berry
Engineering & Testing, LLC
2789 Riverside Parkway
Grand Junction, CO 81501
UNITED RIFLE PLANT
PARCELS 217711300450
AND 217711300451
FIGURE 2 - SITE PLAN