HomeMy WebLinkAbout1045 Main St Cotuit Septic_system_flow__capacity_letter_10-31-2023_Mon_Nov_13_2023_14-22-21
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October 31, 2023
By Electronic Mail (e-mail) Only
Mr. William Caulder
CJ Riley Builders, Inc.
749 Main Street Unit D
Osterville, MA 02655
RE: 1045 Main Street, Cotuit – Existing septic system wastewater flow capacity analysis
Dear Mr. Caulder:
As you requested, please accept this letter as our analysis of the existing septic system wastewater
flow capacity for the residence at 1045 Main Street, Cotuit, MA. Based on the voluntary Title 5
inspection and our understanding of the existing septic system, the system’s wastewater leaching
capacity is estimated at 471 gallons per day (gpd).
OVERVIEW
The property is identified by the Town of Barnstable Assessors as Map 034 Parcel 017 and it is noted
to be a four-bedroom dwelling built in 1916 on a property that contains 1.75 acres of land area. The
town of Barnstable Health Department could not provide us with record information from their files
for this property. The lack of public records for a development from the early 1900s is not unusual.
Information from the voluntary Title 5 inspection performed by Cape Septic Inspections (inspection
letter enclosed) indicates that the system is a “main cesspool and an overflow cesspool.” This report
also describes the dimensions of the components as 5’x5’ each. This system is typical of pre-Title 5
septic system installations in Massachusetts. Crushed stone typically is installed all around the
cesspools. Our office did not perform a separate site inspection to confirm this information.
The site is located within a geologic soil formation know as an outwash plain consisting of Carver
coarse sand texture soils (USDA soil information enclosed). These types of soils are known for high
rates of water infiltration which in itself translates to high percolation rates.
Given the lack of records for the existing septic system the analysis presented here is based on
several assumptions as noted below and used in the analysis to determine the existing septic system
capacity.
ASSUMPTIONS
Given the description of the existing septic system from the voluntary Title 5 inspection, given that
the facility and septic system pre dates Title 5 regulations, and given a site geology of outwash plain,
the following assumptions are used in the septic system wastewater capacity analysis:
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• Two structures that are five feet in diameter and five feet in height. Based on the Title 5
report holding capacity these dimensions are presumed to be interior dimensions.
• The exterior dimension is analyzed as a 6’ in exterior diameter.
• The first cesspool is analyzed as a settling component.
• The overflow cesspool is analyzed for the leaching capacity.
• A minimum of two-foot (2’) of crushed stone all around the structure is analyzed.
• The loading rates and system analysis is based on the 1978 sanitary code.
• The system is presumed to be installed in sand texture soils.
• The sand soil is assigned a percolation rate of less than 2 minutes per inch.
FACILITY WASTEWATER DESIGN CAPACITY ANALYSIS
There first cesspool is simply analyzed as the settling component for the septic system. Based on the voluntary
Title 5 inspection report, the holding volume capacity of the first cesspool is calculated as 734 gallons.
The overflow cesspool is analyzed as the leaching component for this septic system. The loading rate for the
bottom area of the leaching system is 1 gallon per day per square feet per (gpd/sf) and the loading rate for the
sidewall area is 2.5 gpd/sf according to the 1978 sanitary code loading rates.
Overflow leaching pit description: 6-foot diameter pit + 2-foot stone and 5 feet height for leaching side wall
Leaching pit bottom area = 5’ x 5’ x 3.17 = 78.5 square feet
Bottom area capacity = 78.5 sf x 1 gpd/sf = 78.5 gpd
Leaching pit sidewall area = 10’ x 3.17 x 5’ = 157 square feet
Side area capacity = 157 sf x 2.5 gpd/sf = 392.5 gpd
Calculated Wastewater Leaching Capacity Estimation = 78.5 gpd + 392.5 gpd = 471 gpd
Based on this analysis, and the assumptions noted above, the overflow leaching cesspool’s capacity is 471 gpd.
Please contact me for any questions.
Sincerely,
Raúl Lizardi-Rivera, P.E.
Director of Engineering
cc. Bill Caulder – by email only to bcaulder@6mdev.com
enclosures
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TOWN OF BARNSTABLE GIS MAP
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USDA SOIL MAP – BARNSTABLE COUNTY, 1045 MAIN ST, COTUIT, MA
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COPY OF CAPE SEPTIC INSPECTION VOLUNTARY TITLE 5 INSPECTION REPORT
BLANK PAGE FOR TESTING