HomeMy WebLinkAboutSDP 16-13; OAK VETERANS HOUSING; REPORT OF PRELIMINARY RECOMMENDATIONS AFFIRMED OAK AVENUE; 2016-04-20April 20, 2016
Affirmed Housing Group CWE 2160236.01
13520 Evening Creek Drive N, Suite 160
San Diego, California 92128 L1'J_, 1,L. W,
Attention: Sydney Cordova MAR 16 2020
LAND DEVELOPMENT
Subject: Report of Preliminary Recommendations ENGINEERING
Affirmed Oak Avenue, 965-967 Oak Avenue, Carlsbad, California
Ladies and Gentlemen:
In accordance with your request, we have prepared this report to present preliminary findings of a
geotechnical investigation currently being performed by our firm for the subject project.
PRELIMINARY SITE INFORMATION AND PROJECT DESCRIPTION
The subject site is located 965-967 Oak Avenue, Carlsbad, California. The rectangular-shaped lot
presently supports two residential structures and a detached garage. Topographically, the site is near flat-
lying. The property is bounded on the northwest by Oak Avenue and is otherwise bounded by single-
family residential developments.
We understand that it is proposed to demolish the existing improvements and construct a three'-story •
apartment building. The lower level of the structure will consist primarily of parking. The building will
be of wood-frame construction, will be supported by shallow foundations, and will incorporate a
conventional concrete slab-on-grade floor system. Grading is expected to consist of cuts and fills up to
about 2 feet in depth.
IN
CWE 2160236.01 April 20, 2016 Page No. 2
To assist in the preparation of this report, we were provided with miscellaneous plans prepared by Dahlin
Group, dated January 19, 2016, and an undated topographic map of unknown origin. A copy of the
topographic map was used as a base map for our Site Plan and Geologic Map, and is included herein as Plate
No. 1.
SUBSURFACE CONDITIONS
GEOLOGIC SETTING AND SOIL DESCRIPTION: The subject site is located within the Coastal
Plains Physiographic Province of San Diego County. Based on the results of our subsurface explorations,
and analysis of readily available, pertinent geologic literature, it was determined that the site is generally
underlain by topsoil, old paralic deposits, and Santiago Formation deposits (see Plate Nos. 2 through 4).
These materials are described below:
TOPSOIL: The site is underlain by a relatively thin layer of topsoil extending to a depth of about
2 feet below existing grade. These materials generally consisted of brown, dry to damp, loose, silty
sand (SM. The topsoil was judged to have a very low expansion potential (El <20).
OLD PARALIC DEPOSITS (Qop): Quaternary-age old paralic (terrace) deposits were
encountered underlying the topsoil. The old paralic deposits extended to a depth of about 13 feet
to 15 feet below existing grade. The old paralic deposits generally consisted of orangish-brown,
damp to moist, medium dense to dense, poorly graded sand with silt (SP-SM), with some
interbedded layers of silty sand (SM), and sand (SP). The upper approximately 2 feet was loose to
medium dense and moderately to highly weathered. The old paralic deposits were judged to have a
very low Expansion Index (El <20).
SANTIAGO FORMATION (Ta): Tertiary-age sedimentary deposits of the Santiago Formation
were encountered underlying the old paralic deposits at a depth of about 13 feet below existing
grade in borings B-i and B-2. The formational soils generally consisted of light gray, very moist
and moist, silty poorly graded sand with silt (SP-SM). Approximately the upper ½ feet to 3 feet of
the formational soils were medium dense. Below said depth the formational soils are very dense.
The Santiago Formation was judged to have a very low Expansion Index (El <20).
CWE 2160236.01 April 20, 2016 Page No. 3
GROUNDWATER: Perched groundwater was encountered in all the borings at the contact between the
old paralic deposits and the Santiago Formation. In general, groundwater was encountered at a depth of
about 13 feet to 14 feet below existing grade.
POTENTIAL STORM WATER INFILTRATION HAZARDS
SETTLEMENT AND VOLUME CHANGE: Settlement and volume change can occur when water is
introduced below grade. Settlement refers to a condition when soils decrease in volume (i.e. hydro collapse,
calcareous soils, consolidation or liquefaction). Heave refers to expansion of soils or an increase in volume
(i.e. expansive soils or frost heave). Based upon the subgrade soil conditions observed in our borings and the
anticipated grading for the proposed improvements, the site is underlain by sandy soil that would be prone
to hydro collapse when saturated. Therefore, the risk of settlement due to infiltration of stormwater would
be considered to be high.
SLOPE STABILITY: Infiltration of water has the potential to increase the risk of failure to nearby slopes.
The site is relatively level, and no descending slopes are located within a reasonable proximity of the site.
Therefore, the risk of slope failure due to infiltration of stormwater would be considered low.
UTILITY CONSIDERATIONS: Utilities are either public or private infrastructure components that
include underground pipelines, vaults, and wires/conduit, and above ground wiring and associated
structures. Infiltration of water can pose a risk to subsurface utilities, or geotechnical hazards can occur
within the utility trenches when water is introduced. The planned use of the site will be an apartment
structure. Underground utilities are anticipated as part of the construction. The risk of introducing water
into a utility trench would be considered moderate to high depending on the proximity of the stormwater
BUT to utilities.
GROUNDWATER MOUNDING: Groundwater mounding occurs when infiltrated water creates a rise
in the groundwater table beneath the facility. Groundwater mounding can affect nearby subterranean
structures and utilities. Based on the soil conditions and perched groundwater encountered below the site,
the risk of groundwater mounding below the basin is expected to be low to moderate.
CWE 2160236.01 April 20, 2016 Page No. 4
RETAINING WALL AND FOUNDATIONS: Infiltration of water can result in potential increases in
lateral pressures and potential reduction in soil strength. Retaining walls and foundations can be negatively
impacted by these changes in soil conditions. We understand that retaining walls will not be constructed as
part of the proposed project. The footprint of the proposed structure is expected to take up a large portion
of the property. The risk of a potential reduction in soil strength below foundations is expected to be high.
SOIL AND GROUNDWATER CONTAMINATION: Infiltration should be avoided in areas where
infiltration could contribute to the movement or dispersion of soil or groundwater contamination or
adversely affect ongoing clean-up efforts, either on site or down-gradient of the project. We have no
knowledge of any soil or groundwater contamination on or adjacent the subject site.
WELLHEAD PROTECTION: Wellheads, natural and man-made, are water resources that may
potentially be adversely impacted by storm water infiltration through the introduction of contaminants or
alterations in water supply and levels. Infiltration BMPs must be located a minimum of 100 feet
horizontally from any water supply well. We have no knowledge of any water supply wells within 100 feet
of the site.
PRELIMINARY CONCLUSIONS
In general, it is our professional opinion and judgment that the subject property is suitable for the
construction of the proposed apartment structure provided the recommendations presented herein are
implemented. The main geotechnical condition encountered affecting the proposed project consists of
potentially compressible topsoils and old paralic deposits. These conditions are discussed hereinafter.
The site is underlain by relatively thin layer of potentially compressible topsoil extending to a depth of
about 2 feet from existing grade. In addition, the upper approximately 2 feet of old paralic deposits are
moderately to highly weathered. These deposits are considered unsuitable, in their present condition, for
the support of settlement sensitive improvements. Therefore, it is recommended that potentially
compressible topsoil and old paralic deposits be removed and replaced as compacted fill.
It is our opinion that storm water systems incorporating infiltration are not appropriate for the site due to
the potential for hydro-consolidation of the site soils. A completed and signed "Worksheet C.4-1:
CWE 2160236.01 April 20, 2016 Page No. 5
Categorization of Infiltration Feasibility Condition" for the subject project is included in Appendix A of
this report.
The following foundation recommendations should be considered preliminary, and may require
revisions after the results of laboratory tests currently being performed are analyzed.
PRELIMINARY RECOMMENDATIONS
FOUNDATIONS
GENERAL: Based on our findings and engineering judgment, the proposed structure and associated
improvements may be supported by conventional shallow continuous and isolated spread footings. The
following recommendations are considered the minimum based on the anticipated soil conditions after
site preparation as recommended in our forthcoming geotechnical report is performed, and are not
intended to be lieu of structural considerations. All foundations should be designed by a qualified
professional.
DIMENSIONS: Spread footings supporting the proposed structure should be embedded at least 18 inches
below lowest adjacent finish pad grade. Continuous and isolated footings should have a minimum width
of 12 inches and 24 inches, respectively. Continuous and isolated footings supporting exterior light
improvements should have a minimum embedment of 12 inches, and have a minimum width of 12 inches
and 18 inches, respectively.
BEARING CAPACITY: Spread footings supporting the proposed structure and exterior improvements
may be designed for an allowable soil bearing pressure of 2,000 pounds per square foot (psf). This value
may be increased by 600 pounds per square foot for each additional foot of embedment and 300 pounds
per square foot for each additional foot of width up to a maximum of 4,000 pounds per square foot.
Property line footings may be design for an allowable soil bearing pressure of 1,000 psf. These values may
be increased by one-third for combinations of temporary loads such as those due to wind or seismic loads.
FOOTING REINFORCING: Reinforcement requirements for foundations should be provided by a
structural designer. However, based on the expected soil conditions, we recommend that the minimum
CWE 2160236.01 April 20, 2016 Page No. 6
reinforcing for continuous footings consist of at least 2 No. 5 bars positioned near the bottom of the
footing and 2 No. 5 bars positioned near the top of the footing.
LATERAL LOAD RESISTANCE: Lateral loads against foundations may be resisted by friction between
the bottom of the footing and the supporting soil, and by the passive pressure against the footing. The
coefficient of friction between concrete and soil may be considered to be 0.30. The passive resistance may
be considered to be equal to an equivalent fluid weight of 300 pounds per cubic foot. These values are
based on the assumption that the footings are poured tight against undisturbed soil. If a combination of the
passive pressure and friction is used, the friction value should be reduced by one-third.
FOUNDATION EXCAVATION OBSERVATION: All footing excavations should be observed by
Christian Wheeler Engineering prior to placing of forms and reinforcing steel to determine whether the
foundation recommendations presented herein are followed and that the foundation soils are as anticipated
in the preparation of this report. All footing excavations should be excavated neat, level, and square. All
loose or unsuitable material should be removed prior to the placement of concrete.
SETTLEMENT CHARACTERISTICS: The anticipated total and differential settlement is expected to
be less than about 1 inch and 1 inch over 40 feet, respectively, provided the recommendations presented
in this report are followed. It should be recognized that minor cracks normally occur in concrete slabs
and foundations due to concrete shrinkage during curing or redistribution of stresses, therefore some
cracks should be anticipated. Such cracks are not necessarily an indication of excessive vertical
movements.
EXPANSIVE CHARACTERISTICS: The prevailing foundation soils are assumed to have a very low
expansive potential (El <20). The recommendations within this report reflect these conditions.
FOUNDATION PLAN REVIEW: The final foundation plan and accompanying details and notes should
be submitted to this office for review. The intent of our review will be to verify that the plans used for
construction reflect the minimum dimensioning and reinforcing criteria presented in this section and that
no additional criteria are required due to changes in the foundation type or layout. It is not our intent to
review structural plans, notes, details, or calculations to verify that the design engineer has correctly
applied the geotechnical design values. It is the responsibility of the design engineer to properly
CWE 2160236.01 April 20, 2016 Page No. 7
design/specify the foundations and other structural elements based on the requirements of the structure
and considering the information presented in this report.
SEISMIC DESIGN FACTORS
The seismic design factors applicable to the subject site are provided below. The seismic design factors
were determined in accordance with the 2013 California Building Code. The site coefficients and
adjusted maximum considered earthquake spectral response acceleration parameters are presented in the
following Table I.
TABLE I: SEISMIC DESIGN FACTORS
Site Coordinates: Latitude
Longitude
33.1610
-117.0410
Site Class D
Site Coefficient Fa 1.043
Site Coefficient F 1.562
Spectral Response Acceleration at Short Periods S,_ 1.143 g
Spectral Response Acceleration at 1 Second Period Si 0.438 g
SMS=FaSs 1.192g
SM1FvS1 0.685 g
SDS= 2/3*Siis 0795 g
SDI=2/3*SMI 0.456 g
Probable ground shaking levels at the site could range from slight to moderate, depending on such
factors as the magnitude of the seismic event and the distance to the epicenter. It is likely that the site
will experience the effects of at least one moderate to large earthquake during the life of the proposed
improvements.
ON-GRADE SLABS
GENERAL: It is our understanding that the floor system of the proposed structure will consist of a
concrete slab-on-grade. The following recommendations are considered the minimum slab requirements
based on the soil conditions and are not intended in lieu of structural considerations. These
recommendations assume that the site preparation recommendations contained in this report are
implemented.
ME 2160236.01 April 20, 2016 Page No. 8
INTERIOR FLOOR SLABS: The minimum slab thickness should be 4 inches (actual) and the slab
should be reinforced with at least No. 3 bars spaced at 18 inches on center each way. Slab reinforcement
should be supported on chairs such that the reinforcing bars are positioned at mid-height in the floor
slab. The slab reinforcement should extend down into the perimeter footings at least 6 inches.
UNDER-SLAB VAPOR RETARDERS: Steps should be taken to minimize the transmission of
moisture vapor from the subsoil through the interior slabs where it can potentially damage the interior
floor coverings. Local industry standards typically include the placement of a vapor retarder, such as
plastic, in a layer of coarse sand placed directly beneath the concrete slab. Two inches of sand are
typically used above and below the plastic. The vapor retarder should be at least 15-mil Stegowrap® or
similar material with sealed seams and should extend at least 12 inches down the sides of the interior and
perimeter footings. The sand should have a sand equivalent of at least 30, and contain less than 10%
passing the Number 100 sieve and less than 5% passing the Number 200 sieve. The membrane should be
placed in accordance with the recommendation and consideration of ACI 302, "Guide for Concrete
Floor and Slab Construction" and ASTM E1643, "Standards Practice for Installation of Water Vapor
Retarder Used in Contact with Earth or Granular Fill Under Concrete Slabs." It is the flooring
contractor's responsibility to place floor coverings in accordance with the flooring manufacturer
specifications.
EXTERIOR CONCRETE FLATWORK: Exterior concrete slabs on grade should have a minimum
thickness of 4 inches and be reinforced with at least No. 3 bars placed at 18 inches on center each way
(ocew). Driveway slabs should have a minimum thickness of 5 inches and be reinforced with at least No.
4 bars placed at 12 inches ocew. Driveway slabs should be provided with a thickened edge a least 12
inches deep and 6 inches wide. All slabs should be provided with weakened plane joints in accordance
with the American Concrete Institute (AC1) guidelines. Special attention should be paid to the method
of concrete curing to reduce the potential for excessive shrinkage cracking. It should be recognized that
minor cracks occur normally in concrete slabs due to shrinkage. Some shrinkage cracks should be
expected and are not necessarily an indication of excessive movement or structural distress.
CWE 2160236.01 April 20,2016 Page No. 9
CLOSURE
If you have any questions after reviewing this letter, please do not hesitate to contact this office. This
opportunity to be of professional service is sincerely appreciated.-
Respectfully submitted,
CHRIS WHEELER ENGINEERING
1-~-f7 Daniel B. Adler, RCE #36037
DBA:dbatsw
end: Plate Nos. 1.4
Appendix A
cc: Sydney@affirmedhousing.com
S.
* ENGINEERINGGEOLOGIST ) *
9 )
OP CA*°
Troy S Wilson, CEG #2551
L07G 71OF TEST BORING B-1 Sample Laboratory Test Legend
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SA Sieve Analysis El Expansion Index Existing Elevation: 70.0 feet Drive Type: 1401bil30 inches HA Hdsoinawr a1 Resistance Value
SE Sand Equivalent Chi Soluble Chlori~m Proposed Elevation: N/A Depth to Water 14.0 feet P1 Plasticity Index Res pH&Rcsisuvny ci' Collapse Potential SD Sample Density
I 0 g SUMMARY OF SUBSURFACE CONDONS
(based on Unified Soil Classification System)
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Boring terminated at 20 feet. Seepage encountered at 14 feet.
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Symbol Legend
Groundwater Level During Drilling
OAK AVENUE AFFIRMED HOUSING
965-967 OAK AVENUE Re
Groundwater Level After Drilling CARLSBAD, CALIFORNIA
Apparent Seepage
No Sample ltecovery CHRISTIAN WHEELER DATE: APRIL 2016 JOB NO.: 2160236.01
** Non-Representative Blow Count ENGINEERING
BY: SRD PLATE NO.: 2 (rocks present)
IL LOG OF TEST BORING B-2 Sample Type and Laboratory Test Legend
SPT Standard DR Drive Ring ST Shelby Tube
MD Max Density DS Direct Shear
SO4 Soluble Sulfates Co" Consolidation
SA Sieve Analytis El Expansion Index HA Hydrometer
SE Sand Equivalent Chl Soluble Chlori~do
P1 Plassicnylndex Run pH&Rcsistivity
Cis Collapse Potential SD Sample Density
Date Logged: 4/13/16 Equipment Mobil 8-61
Logged By: DJF Auger Type 6 inch Hollow Stem
Existing Elevation: 70.0 feet Drive Type: 140lbil30 inches
Proposed Elevation: N/A Depth to Water. 13.0 feet
SUMMARY OF SUBSURFACE CONDITIONS
(based on Unified Soil Classification System)
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•• .•- -- 25- .-45--•—•—— __. --. - -
Symbol Legend
Groundwater Level During Drilling
Groundwater Level After Drilling
AppazeneSeepage
NoSampleRecoveay
** Non-Representative Blow Count
OAK AVENUE AFFIRMED HOUSING
965-967 OAK AVENUE
CARLSBAD, CALIFORNIA
CHRJSTIAN WHEELER,
ENCINEEkINC
DATE: APRIL 2016 JOB NO.: 2160236.01
BY: SRD PLATE NO.: 3
LOG OF TEST BORING B-3 Sample Type and Laboratory Test Legend
Cal M0&fiicd
P
Uf=:
T
=tr CK Chunk
SP'r Standard DR Drive Ring ST Shelby Tube
Date Logged: 4/13/16 Equipment: Mobil 1-61 MD Max Density DS Direct Shear
Logged By: DJF Auger Type 6 inch Hollow Stem SO4 Soluble Sulfates Con Consolidation
SA Sieve Analysis E L"nsion Index Existing Elevation: 69.0 feet Drive Type: 1401bs/30 inches HA Hydrometer R-Val Resistance Value
Proposed Elevation: N/A Depth to Water 14.0 feet
SE Sand Equivalent Chl Soluble Chlorides
P1 plasticity Index Res pH&Resistivity
CP Collapse Potenthi SD Sample Density
0
8
ç SUMMARY OF SUBSURFACE CONDITIONS J. 14
(based on on Unified Soil Classification System)
0 69
1 SI4 Topsoil (Distuibed: Brown' dazp, li!osejver fine- to nedism-raind, SkLT'I
-r .-s rti-rt--t1 trIt"++ t-1 fF +
- I s- si
Old Páralic
.--fine--
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ED raihedj~puo
_2U_ damp, loOse to mediuni dene, —
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I I perousj34feet. I I silthighly-watheed-ad.---•--
36 Cal M6ist)medium lensk 5 64 II
31 Cal
-
II 1Ir!III IIIIIIIIIIIIIIII 11111 ii I I I
34 Cal
_- —10--59----------•----------•--•--..-••-.--.---
liIITIIII11:::T
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Heavyseepage/perchedwateratl4feet.
nse,finetocoarse-grainedPOORLYGRADED.SAND._f_444.
to ijhtErown very moist,
]
meum
—
30 Cal
—
-
Wet. -- I I -
Boring terminated at' 15 feet. Seepage encountered at 14 feet. -
---20- -4------------ -------•-- - - -.------ -- .-- --
- --------- -
- --- --- -- -- -- --
Symbol Legend OAK AVENUE AFFIRMED HOUSING
Groundwater Level During Drilling 965-967 OAK AVENUE
Groundwater Level After Drilling CARLSBAD, CALIFORNIA
ME
*
Apparent Seepage
NoSaznpleRecovery CHRiSTIAN \VHEELER. DATE: APRIL 2016 JOB NO.: 2160236.01
ENGINEERING
BY : SRD PLATE NO.: 4 ** Non-Representative Blow COunt
Appendix A
Worksheet C.4-1: Categorization of Infiltration Feasibility
Condition
Appendix C: Geotechnical and Groundwater Investigation
Worksheet C.4-1: Categorization of Infiltration Feasibility Condition
r
Part 1 - Full Infiltration Feasibility Screening Criteria
Would infiltration of the full design volume be feasible from a physical perspective without any
undesirable consequences that cannot be reasonably mitigated?
Criteria Screening Question Yes No
Is the estimated reliable infiltration rate below proposed facility locations
1 greater than 0.5 inches per hour? The response to this Screening Question
shall be based on a comprehensive evaluation of the factors presented in
ADDendix C.2 and ADDendix D.
Provide basis:
The infiltration rate of the on-site soils has not been measured.
Can infiltration greater than 0.5 inches per hour be allowed without
increasing risk of geotechnical hazards (slope stability, groundwater
2 mounding, utilities, or other factors) that cannot be mitigated to an x acceptable level? The response to this Screening Question shall be based
on a comnrehengiye evaluation of the factors nrecentecl in Annenclix C2 I
Provide basis:
C.2.2 Settlement and Volume Change: The on- and off-site fills and paralic deposits are subject to
consolidation and/or hydro-collapse as a result of increased moisture content.
C.2.4 Utility Considerations: The existing and proposed on-and off-site utility trenches are
considered susceptible to saturation and lateral migration of infiltrated storm water.
C.2.6 Retaining Walls and Foundations: The proposed project will include heavily-loaded
foundations. Any proposed infiltration facility would necessarily infiltrate storm water adjacent to
planned foundations.
C.2.7 Other Factors: Adjacent subgrade soils in right-of-ways are subject to degradation as a result of infiltration.
Storm Water Standards
Part 1: BUT Design
Manual C-12
..i'•Sin P4!a
APãpOiTIøP & STORM WTLP.
Appendix C: Geotechnical and Groundwater Investigation
Worksheet C.4-1 Page 2 of
Criteria Screening Question Yes
1
No
Can infiltration greater than 0.5 inches per hour be allowed without
increasing risk of groundwater contamination (shallow water table, storm
3 water pollutants or other factors) that cannot be mitigated to an acceptable
level? The response to this Screening Question shall be based on a
I cnmnreheniye evalli2tinn of the f2ctnrc nrecented in Annendix C-3-
Provide basis:
The risk of groundwater contamination has not been evaluated at this time.
Can infiltration greater than 0.5 inches per hour be allowed without
causing potential water balance issues such as change of seasonality of
4 ephemeral streams or increased discharge of contaminated groundwater to
surface waters? The response to this Screening Question shall be based on
2 roninrehencive ey21n2ti0n of the factnr!c nrecen1P11 in Annenciix C
Provide basis:
The risk of causing potential water balance issues such as change of seasonality of ephemeral streams
or increased discharge of contaminated groundwater to surface waters has not been evaluated at this
time.
If all answers to rows 1 - 4 are "Yes" a full infiltration design is potentially feasible.
The feasibility screening category is Full Infiltration
Part 1
Result* If any answer from row 1-4 is "No", infiltration may be possible to some
extent but would not generally be feasible or desirable to achieve a "full
-
infiltration" design. Proceed to Part 2
1 o be completed using gathered site information and best professional judgment considering the definition of
MEP in
the MS4 Permit. Additional testing and/or studies may be required by City Engineer to substantiate findings.
Storm Water Standards
Part 1: BMP Design
Manual C-12
Appendix C: Geotechnical and Groundwater Investigation
Part 2 - Partial Infiltration vs. No Infiltration Feasibility Screening Criteria
Would infiltration of water in any appreciable amount be physically feasible without any
negative consequences that cannot be reasonably mitigated?
Criteria Screening Question Yes No
Do soil and geologic conditions allow for infiltration in any appreciable
rate or volume? The response to this Screening Question shall be based on
a comprehensive evaluation of the factors presented in Appendix C.2 and
Appendix D.
Provide basis:
C.2.2 Settlement and Volume Change: The on- and off-site fills and paralic deposits are subject to consolidation and/or hydro-collapse as a result of increased moisture content.
C.2.4 Utility Considerations: The existing and proposed on- and off-site utility trenches are
considered susceptible to saturation and lateral migration of infiltrated storm water.
C.2.6 Retaining Walls and Foundations: The proposed project will include heavily-loaded
foundations. Any proposed infiltration facility would necessarily infiltrate storm water adjacent to
planned foundations.
C.2.7 Other Factors: Adjacent subgrade soils in right-of-ways are subject to degradation as a result of
infiltration.
Can Infiltration in any appreciable quantity be allowed without
increasing risk of geotechmcal hazards (slope stability, groundwater
6 mounding, utilities, or other factors) that cannot be mitigated to an x acceptable level? The response to this Screening Question shall be based
on a comprehensive evaluation of the factors presented in Appendix C.2.
Provide basis:
C.2.2 Settlement and Volume Change: The on- and off-site fills and paralic deposits are subject to consolidation and/or hydro-collapse as a result of increased moisture content.
C.2.4 Utility Considerations: The existing and proposed on-and off-site utility trenches are
considered susceptible to saturation and lateral migration of infiltrated storm water.
C.2.6 Retaining Walls and Foundations: The proposed project will include heavily-loaded
foundations. Any proposed infiltration facility would necessarily infiltrate storm water adjacent to
planned foundations.
C.2.7 Other Factors: Adjacent subgrade soils in right-of-ways are subject to degradation as a result of
infiltration.
Storm Water Standards
Part 1: BMP Design
Manual C-14
Criter.
7
Provic
The ri
8
Provic
The ri
or mci
time.
Part 2
Result
*To be
MEP in
the MS4
Storm Water Standards
Part 1: BUT Design
Manual C-14