8.d)1) City Engineer Study of Expansion of the Anderson-Erickson Portion of the 201 Wastewater Treatment System f
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Meeting Date: 2/21/2012
Agenda item: �/ 1� e
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City Council Agenda Report
City of Scandia
14727 209�' St.North
Scandia, MN 55073 (651) 433-2274
Action Requested: Receive a status report on the City Engineer's study of the possible
expansion of the Anderson-Erickson portion of the 201 Wastewater
Treatment System.
Deadline/Timeline: The Council authorized the study at its December 20, 2011 meeting.
The full report will be completed within the next week or two.
Background: • The study was initiated in response to an application from James
and Sandra Continenza for a variance to allow construction of a
new home on Big Marine Lake. The new home and a home next
door owned by the Continenza family would both need new sewer
service. They would prefer to connect both dwellings to the City's
201 Sewer System. The deadline for review of the variance has
been waived to allow time to determine if an expansion of the
sewer system is feasible.
• The attached memo reports on the initial findings of the study.
The final report will contain a more complete discussion of the
observations, opinions and conclusions about the system, and a
more detailed discussion of potential upgrade options.
Recommendation: The Council should receive the status report. A discussion of the full
report should be scheduled after it is complete, potentially at the
March 13, 2012 CiTy Council Work Session meeting.
Attachments/ • Stantec Memo dated February 16, 2012
Materials provided:
Contact(s): Ryan Goodman, PE (651) 967-4616
Prepared by: Anne Hurlburt, Administrator
(Anderson Erickson study status report)
Page 1 of 1
02/17/12
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Memo
5��� To: Ryan Goodman From: Ciint Jordahl
Stantec, St. Paul MN Stantec, St. Cloud, MN
File: 193802153 Date: February 16,2012
Reference: Anderson/Erickson Wastewater System—City of Scandia
Ryan,
This memo has been prepared to update you on the status of our study of the above-
referenced system.To date we have reviewed the available background data,
completed soil borings within the residual treatment area, and met with Pete Ganzel of
Washington County to review the components and operating history of the system. The
following is intended to provide you with some discussion points for you�meeting with
the City. A full report is being prepared for distribution the week of February 20�'.
Drainfield
The existing drainfield was designed to accept 6700 gallons per day but is not being
operated in accordance with the original design. It was intended that two thirds of the
system be used at one time allowing one third of the system to rest. Currently, one third
of the system is used for a year then allowed to rest for two years before it is used
again.With an average daily flow 5600 gallons it would appear the system is being
overloaded since only one cell is being used and each cell was intended to receive only
3350 gallons per day. Neverthelsss,the system appears to be hydraulically functioning
(i.e. not backing up to the surface).
The residual drainfield area would atlow for some limited expansion of the system.
Given the soil conditions on the property, an elevated bed or mound would be required.
Additional capacity in the range of about 2000 to 2500 gallons per day appears to be
achievable within#he remaining area.
The existing drainfield could be loaded at a higher rate if the septic tank effluent were to
be pretreated. This would require the installation of an aerobic treatment unit and at
Isast two additional tanks at the drainfield site. Effluent would also need to be
' distributed by pressure pipe to the trenches, so some modification of the drainfield
would be required. Pretreatment could increase the design capacity of the system to a
daily flow greater than 10,000 gallons, which would move the system from a Couniy-
permitted system to a S#ate-permitted system.
It would also be possible to expand the capacity of the system through the acquisition of
adjacent land and the installation of additional soil dispersal area.
One Team.Infinite Solutions.
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February 16,2012
Ryan Goodman
Page 2 of 2
Reference: Anderson/Erickson Wastewater System—City oi Scandia
Coliection System
!t appears that there are currently about 30 homes and cabins connected to the system.
In 2001, pipe was installed past at least 20 more existing and potential building sites. It
is our understanding #he some of the land along the service area could be subdivided
potentially increasing the ultimate number of connections to 45 or more.The force main
installed in 2001 appears adequate to handle this increased flow, but the repair or
replacement of the electrica�control panel at the community lift station is recommended.
Recommendations for Additional Connections
Unless there is a commitment on the part of the City to repair, upgrade or replace the
current system; we can not recommend the connection of additional homes or cabins to
the system at this time. The full design capacity of 6700 gallons per day could be
realized by restoring the planned drainfield dosing functionality and this might allow the
connection of one or two more homes. However, summertime peak flows already
exceed 7500 gallons which is greater than the design capacity of the system. Therefore
some serious consideration should be given to a longer term solution that would meet
not only the immediate need, but would also aflow additional connections along the
service area where the City has already installed collection pipe. Furthermore, there are
at least 9 seasonal properties connected to the system that could become year-round
properties at any time thus increasing the flow to the system. If the use change does not
require any construction the City would have no ability to control these increased flows.
Our full report will contain a more complete discussion of the observations, opinions,
and conclusions about the system, and a more detailed discussion of potential upgrade
options for the City.
Stantec Consulting Services
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Clinton . Jord hl, PG
Senior G ' t
clinton.jordahl�stantec.com