3__Soil_Report.pdf
PDF 1 MB Posted
- Attached to
- Septic Replacement Project at Monte Vista NWR Federal contract opportunity
- Solicitation number
- 140FGA24Q0023
About this file
This document is a Site and Soil Evaluation Memo for a septic system replacement project at the Monte Vista National Wildlife Refuge in Colorado. The memo provides details on the soil investigation, groundwater considerations, and other site factors that inform the septic system design.
The key details include:
- The soil profile at the site is sandy clay loam with pockets of gravel and sand. Depth to groundwater is 4.5-5 feet.
- The required drainfield area is 1,228 square feet, with a total length of 500 feet divided into 5 legs.
- The drinking water well is located approximately 100 feet from the drainfield and 50 feet from the septic tank, meeting required setback distances.
- The site is located in a minimal flood hazard zone.
- The memo is authored by a licensed Professional Engineer with over 11 years of experience designing on-site treatment systems.
The related federal contract opportunity is for the Septic Replacement Project at Monte Vista NWR, solicitation number 140FGA24Q0023, issued by the Department of the Interior Fish and Wildlife Service.
View the file
Other files for this federal contract opportunity
| File | Type | Posted |
|---|---|---|
| Sol_140FGA24Q0023_Amd_0001.pdf | ||
| Updated_Drawing_Packet_0001.pdf | ||
| 6___Data_Entry_Form.pdf | ||
| 4__Wage_Rates.pdf | ||
| 5__Price_Schedule.pdf | ||
| Sol_140FGA24Q0023.pdf | ||
| 2__Drawings.pdf | ||
| 1__Statement_of_Work.pdf |
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Text version
United States Department of the Interior
FISH AND WILDLIFE SERVICE
Mountain-Prairie Region
IN REPLY REFER TO:
BA/EN BID INVI
Mail Stop 60190
Project 24-001G
Memorandum
To: Suzanne Beauchaine, Project Leader, Monte Vista NWR
From: Michael Wandersee, PE, Engineering Department
Through: Douglas Smith, PE, Engineering Department
Subject: Site and Soil Evaluation Memo – Replace Septic System (24-001G) at the Monte
Vista NWR, Rio Grande County, Monte Vista, CO
This memo addresses the site and soil evaluation based on the State of Colorado requirements.
SOIL INVESTIGATION
A site investigation was conducted on 10/12/2023. The site location is at 6627 CO-15, Monte
Vista, CO. The legal location is T37N R7E S1 NE1/4SE1/4. Please be aware that the regulation agency is Rio Grande Building Department. Photo 1 shows the test pit locations and surrounding structures as it relates to the new septic system. No wells are located on the immediate proximity within the required offsets. Please be aware that the treatment system will be located east of the existing system.
MAILING ADDRESS: STREET LOCATION:
Post Office Box 25486 134 Union Blvd.
Denver Federal Center Lakewood, Colorado 80228-1807 Denver, Colorado 80225-0486
Photo 1: Test Pit and Site Location
A ribbon test was conducted at at north and south test pits. Photo 2 and Photo 3 show the test pits.
Photo 2: North Pit
Photo 3: South Pit
The soil profiles were the same for north and south pit. It was discovered that the water and water mark in the pictures is from groundwater at 5.5 feet depth from the surface in south pit.
The soil profile was:
• 0-72 inches sandy clay loam with pockets of gravel and sand
This result was compared to the NRCS Site Soil Survey website. Photo 4 shows the map from this website.
Photo 4: NRCS Soil Survey
The NRCS designates Sc as San Arcacio loam.
The soil profile was:
• 0-8 inches loam
• 8-25 inches sandy clay loam
• 25-60 inches very gravelly sand
The profiles are very similar. The design will use the test pits because the drainage rate is less than the NRCS website. Please be aware that the existing footprint soil will be completely removed and be replaced with fine sand that creates a large storage capability.
PROJECT SITE
Photo 5 shows that the topographic map from Google Earth. The site is flat and overland flow is a minimal risk.
Photo 5: Topo of Site with Yellow Pin
A well is located on site. The drinking potable water well is located approximately 100 feet from the drainfield system and 50 feet from the septic tank. The offset requirements of the site is as follows:
1. Septic tank
a) 50 feet well
b) 10 feet potable water supply
c) 10 feet from irrigation lateral
d) 50 feet from lake, water course, irrigation ditch, stream, and wetland
e) 10 feet from dry gulch, cut ban, and fill area
2. Sewer Lines
a) 50 feet spring well
b) 5 feet potable water supply
c) 10 feet from irrigation lateral
d) 50 feet from lake, water course, irrigation ditch, stream, and wetland
e) 10 feet from dry gulch, cut ban, and fill area
f) If these offsets are not possible to meet with the system expectations, the alternative method may be used as described in the drawings.
3. Drainfield
a) 100 feet spring well
b) 25 feet potable water supply
c) 20 feet from basement
d) 10 feet from non-basement structures
e) 25 feet from irrigation lateral
f) 50 feet from lake, water course, irrigation ditch, stream, and wetland
g) 25 feet from dry gulch, cut ban, and fill area
All components will meet this offset requirements, as shown in the drawings. The drawings provide required offsets. The drinking water potable water well is approximately north of the existing drainfield that can be seen in Photo 1 and 4.
DRAINFIELD AREA
The calculated area is based on desired TL1 treatment and the flows of the attached buildings.
SEPTIC DESIGN FROM CHAMBERS
Soil Type (3)
Sandy Clay Loam
TL1 0.35 gal/d/ft^2
Wastewater Flow
Shop 14.2 gal/day 3 employees, one bathroom, and one sink; peak 10 people per day
RV 1 300 gal/day 2 bedrooms
RV 2 300 gal/day 2 bedrooms
Total Flow 614.2 gal/day
Surface Area 1754.857 ft^2
Table 10-3 Factor 0.7 Adjusted Surface Area 1228.4 ft^2
Chamber Width 3 ft
Total Length Required 409.46 ft Rounded Length 500 ft
The drainfield system requires an impact of 500 feet long. Each leg of drainfield will run 100 feet, totaling 5 legs. The legs will have a centerline distance of separation of 7 feet; therefore, the total width of the area will be 27 feet.
GROUNDWATER CONSIDERATIONS
As mentioned earlier, moist soil was discovered during the test pit excavation of a depth of 72 inches. Photo 6 shows a map from USGS title Conceptual Understanding and Groundwater
Quality of Selected Basin-Fill Aquifers in the Southwestern United States dated 2010. The link can be found here.
The location of the facility is located in the dark blue. The dark blue indicates that the depth to groundwater is likely six feet or less. This verifies that the test pits water came from a groundwater source. The depth to groundwater in the north pit is 5 feet and the south pit is 4.5 feet.
LAND USE CHANGES
The land around the site is owned by USFWS and does not expect land use change during the life capacity of the system, 50 years. The land west of the site is agricultural with a center pivot;
therefore, it is anticipated that the land use will not change within 50 years.
FLOODPLAIN
The floodplain was researched using the FEMA.gov website. Photo 7 shows the area is in minimal flood hazard zone.
https://pubs.usgs.gov/pp/1781/
MY QUALIFICATIONS
Based on requirements from the State of Colorado, my qualifications for my analysis of the soil conditions and treatment required are below.
Michael Wandersee
Licensed Professional Engineer in South Dakota
BS Biosystem Engineering
MS Environmental Engineering
303-236-4479
Michael_wandersee@fws.gov
United States Fish and Wildlife Service
Experience: Conducting and designing on-site treatment systems for over 11 years.
ADDITIONAL INFORMATION
Please be aware that the specifications and drawings are meant to be supplemental information beyond this memo.
If you have any questions, please contact Michael Wandersee at 303-236-4479.
mailto:Michael_wandersee@fws.gov
Photo 6: Depth to Groundwater
Photo 7: Floodplain Map
File details come from the government source that posted it. Updated .