20140908 report of findings bishop tube

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Ingram Engineering Services, Inc.16 Hagerty Blvd. Suite 400

West Chester PA 19382

Office 484-947-5549 Fax 610-431-7015

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CLIENT: Inland DesignPROJECT: 10 Malin Road

REQUIREMENT: PROFESSIONAL ENGINEERING SERVICES: Geotech/SWLOCATION: 10 Malin Road, West Whiteland Township

DATE: September 8, 2014

ATTENTION: Chuck Dobson, P.E. via Email

Bo Erixxon, Project Manager via Email

PURPOSE

The purpose of this report is to present the Findings, Conclusions and Recommendations relative

to the physical investigation performed at the above captioned project location.

INVESTIGATION

Jason Culp, P.E. and Nick Banta were present on site Friday September 5th, 2014 to conduct a

subsurface investigation at the above mentioned project location. The investigation included

eight (8) double ring infiltrometer tests to be conducted within proposed infiltration areas. The

exact design of the stormwater facilities was not currently known as site data was required toprovide preliminary design. The findings and conclusions generated are to provide the initial

broad range characteristics for design. A final more detailed investigation of the site may be

required as the design proceeds further. In additional to information for the Stormwater relatedfacilities IES was also requested to record pertinent construction costs aspects of the site such as

shallow groundwater, soil suitability, rock depth etc. Testing was conducted according to thePennsylvania Stormwater Best Management Guidelines’ Appendix C: Site Evaluation and Soil

Testing Procedures. All double ring tests were presoaked for a minimum of one hour or two 30

minute intervals prior to recording measured infiltration readings.

FINDINGS

The Findings below use abbreviated nomenclature germane to soil morphology and other BMPterminology.


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Test Pit Logs:

TP no. 1 Tested at 65”

0-8” Topsoil Root mat

8”-30” Lt. Brn. To Red Sandy SILT

30”-132” Decomposed Schist 80-90% Coarse Fragments, veryfriable coarse Fragments (Channers)

can be broken with significant hand

pressure to rock hammer strikes

Near vertical strikedipping towards

the upslope side

Limiting Zone Encountered-Rock @ 11’, lack of sufficient soil ‘medium’ will require filtering



10”-30” Reddish Gravels andChannerrs

w/ Sandy SILT

30”-165” Reddish Channers (schist)fragments with soil filled

bedding/fracture planes

Soil fill is reddish Silty SAND;coarse Fragments (Channers) can be

broken with significant hand

pressure to rock hammer strikes

Near vertical strikedipping towards

the upslope side

No GW or Limiting Zone Encountered, lack of sufficient soil ‘medium’ will require filtering



7”-55” Reddish Brn Channery Mica SILT

55”-168”Tan/White Mica v.f. SAND & SILT Channery Friable coarse fragmentsNo GW or Limiting Zone Encountered

TP no. 4 Tested @ 74” BGS


12”-36” Lt. Brn Channery Sandy SILT

36”-72” Reddish Brn Channery Mica SILT Friable coarse fragments

72”-15’ Tan/White Mica v.f. SAND & SILT Channery Friable coarse fragments

No GW or Limiting Zone Encountered


0-8” Topsoil Root mat8”-89” Lt Brn Gravels/Channers & f.

Sandy Mica SILT

89”-111” Reddish Brn Channery Mica SILT Friable coarse fragments

111”-168”

Tan/White Mica v.f. SAND & SILT



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0-3” Asphalt

3”-8”

Subbase 3A modified

8”-15” Tan Sandy SILT Previous fill

15”-96” Reddish Brn-Grey-Var v.f. Sandy Mica SILT Saprilite, very Friable CF’s

96”-172” Grey Mica SILT, Saprolite Friable CF’s



0-3” Asphalt

3”-8” Subbase 3A modified

8”-30” Brn f. Sandy Mica SILT l/s

Gravels

Previous fill

30”-168” Grey Mica SILT S Saprolite of parent formation

96”-172” Grey Mica SILT, Saprolite Friable CF’s



0-3” Asphalt

3”-8” Subbase 3A modified

8”-65” Gravelly v.f. Sandy Mica SILT Friable CF’s, Fill

65”-194”Grey/Tan/Var. v.f. Sandy SILT v. micaceous very steeply

to near vertical bedding

Very friable CF’s,

decomposed schist


Infiltration Testing

TP No. 1 4” 4” 4” 4” 4” 4” final stabilized reading with 10 minute intervals24.0 inches/hour Final Stabilized Reading @ 65 inches BGS

TP No. 2 3 ½” 3 ½” 3 ½” 3 ½” 3 ½” 3 ½” 3 ½” final stabilized reading with 10 minuteintervals

21.0 inches/hour Final Stabilized Reading @ 58 inches BGS

TP No. 3 ⅝” ¼” ¼” ¼” ¼” final stabilized reading with 30 minute intervals


TP No. 4 ½” ½” ½” 3/8” 3/8” 3/8” final stabilized reading with 30 minute intervals0.75inches/hour Final Stabilized Reading @ 74 inches BGS

TP No. 5 1” 1” ⅝” ½” ½” ½” ½” final stabilized reading with 30 minute intervals


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TP No. 6 1” 1” 1” 1” 1” final stabilized reading with 30 minute intervals

2.0

inches/hour Final Stabilized Reading @ 78 inches BGS

TP No. 7 ¼” ¼” ¼” ¼” ¼” final stabilized reading with 30 minute intervals

0.5inches/hour Final Stabilized Reading @ 78 inches BGS

TP No. 8 2” 1¼” 1¼” 1¼” 1¼” 1¼” final stabilized reading with 30 minute intervals

2.5inches/hour Final Stabilized Reading @ 84 inches BGS

CONCLUSIONS

1.

The Design Engineer is recommended to use the above information for sizing the

Proposed Stormwater Management Facilities with a slight rate reduction for

subsurface infiltration facilities to ensure the longevity of the systems given the

presence of fine grain soils and cohesive soil content.

2. The saprolite to residium strata that all tests were conducted within is highly variable

both vertically and laterally. The majority of test areas with well draining tests wasdue to the near vertical bedding planes of the decomposed parent material (schist).

The rapidly draining areas of test pits 1 and 2 is composed of decomposed parent

rock, in this case Micaceous Schist to Gneiss. The material is highly decomposedhowever is in a platy, vertical orientation which promotes infiltration through the

macropores of the soil/rock medium. In this area a filter layer of concrete sand will

be necessary to ensure the proper filtering of pollutants to ensure water quality

requirements are met.

3. We strongly recommends that a qualified Soil Engineer or representative thereof be

present during infiltration facility installation to ensure the stone facility-sand-soilinterface is placed at an appropriate depth to maximize recharge. Facility bottom

elevation often varies as overlying soils are not uniform thus requiring over

excavation in localized areas of the facility to maximize infiltration potential.

4.

The geotextile fabric is recommended to not be utilized at the bottom of any

infiltration facility as the liner is serving too often as a hydraulically restrictive

material and creating a ‘bath tub’ effect, ergo – only utilize the geotextile on thesides and top of the trench.

5. Test Pit no. 1 is the only area which exhibited somewhat shallow rock refusal. Allother test pits were excavated down to the maximum reach of the excavator. Most of

the material is fractured and decomposed and therefore rippable, especially in a

larger excavation.


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6. The soils encountered are fine grained soils that are very moisture sensitive. Areasthat achieve compaction will be susceptible to breakdown with repeated construction

traffic on top of those areas. Additionally, the coarse fragments throughout the site

are easily fractured and broken down and therefore will have similar negative effectwith repeated traffic.

7. The site topography and open rapidly draining strata encountered at the upslopeportion of the site may result in areas downslope receiving intermittent seepage in

localized areas. This should be considered for design of retaining walls and for

mitigation in any construction activities.

8.

Refer to the attached laboratory data for additional information regarding the

findings above.

9.

Test Pit locations were provided in the field by Inland Design. Please refer to theattached image of then plan provided to IES for test pit locations.

10.

Please contact IES should questions/concerns relative to subsurface geology arise

during planning or construction phases of this project as actual field conditions are

expected to vary and this report does not speak to all possible issues that might arise.

Very Truly Yours,

Jason Culp, P.E.Project Manager

Ingram Engineering Services, Inc.

484.947.5549 office

610.431.7015 fax [email protected]

Chadd W. Ingram, P.E.(DE, MD, NJ, PA), S.E.O.

Principal & CEO

Ingram Engineering Services, Inc.484.947.5549 office

610.431.7015 fax

[email protected]


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20140908 report of findings bishop tube

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