HomeMy WebLinkAbout1984-04-17 Memo, Subdivision Soil Testing ReviewTO: Jeanne A. Mabusth, Zoning Administrator
FROM: Michael P. Gaffron, Septic Systems Inspector
DATE: April 17, 1984
SUBJECT: #804 - Painters Creek (Ski -Tonka) Bayside Road - Subdivision -
Soil Testing Review
The additional testing required on Lot 9 has been completed and a report
has been submitted for City review. The lots which required additional
work have been reevaluated and this information i3 now on file. I met
with the site evaluator in early March and I am comfortable with his
interpretations of the soil borings, which I had earlier questioned. I
would like to make the following comments:
Lot 1 (Sites 9A 6 9B)
- Slope at tested sites averages 16-188
- Topographic location acceptable
- Site drainage looks qood
- HOUSE SITING CAPABILITY - I RECOMMEND WE ALLOW LESS THAN A 100' HOUSE
SETBACK TO BAYSIDE ROAD, IN ORDER TO MINIMIZE POSSIBLE HOUSE ENCROACHMENT
ON DRAINFIELD AREAS
- Reported perc rates averagely MPI in top foot of soil, both sites
- Depth to seasonal saturation zone 4-5'
- Soil survey indicates Kilkenny Loam
- BECAUSE OF THE STEEP SLOPES, I WOULD RECOMMEND THE TRENCHES BE NO
WIDER THAN 2'
- Based on depths to seasonal saturation indicated, the primary site should
have a maximum trench depth of 1', and the alternate site trenches no
deeper than 2'
- As for the site evaluator':, notes, a curtain drain might have some benefit
here, although its effect might be minimal due to the fine soil textures
present
Lot 2 ( Sites 10A 6 10B)
- Slope at tested sites averages 128
- "opographic location - OK, but this is a slightly concive slope which
will tend to hold water, s additional site drainage wcrk may be beneficial
during construction
- House siting capability - I recommend that specific house site "envelopes"
be established to protect drainfield sites
4804 - Patiners Creek
April 17, 1984
Page 4
ILot 10 - (Sites 17A, 17B, 10A (4/11/84) and 10B (4/11/84))
- This lot was retested since the original sites were located in a low
drainage area - --�
- The new sites are located on slopes of out 109
- Perc rates averaged 11 MPI primary s e, 13 MPI alternate site
Seasonal saturation zones at 44-50" a rima;y_site would allow shallow
trenches if a curtain drain is used to lower the seasonal water table.
The alternate site should support a standard trench system. The propose
house location near the southeast lot corner may not be feasible and a
lift pump might ultimately be required for this site
SUMMARY
All ten proposed lots have sites which appear suitable for septic systems.
On Lots 1-7, the drainfield site locations place some limitations on usable
house sites. I recommend that house site "envelopes" be incorporated into
the plat to help preserve the tested drainfield sites. Curtain drains
may be of some benefit to certain sites and allow the use of shallow trench
drainfields rather than mound systems.
Based on the information submitted, I recommend approval of this PRD. The
developers should be notified it is their responsibility to keep all traffic,
qrading, fill, etc. away from the tested sites.