Attachment A-4_Mitigated Negative Declaration ND23-013 (GPA22-0005 Pico Place) — San Marcos City Council, October 24, 2023 (part 3 of 3)

b) Excavation of three (3) borings utilizing a hollow stem auger drill rig to a maximum depth of 40 feet below ground surface. One of the borings was drilled to a depth of 5 feet below ground surface for the purpose of percolation testing; c) Sampling and logging of subsurface materials encountered in the borings; d) Field percolation testing to determine the infiltrations rate; e) Laboratory testing of samples representative of those obtained in the field, in order to evaluate relevant engineering properties;
f) Engineering and geologic analyses of the field and laboratory data; g) Preparation of a report presenting our findings, conclusions and recommendations.

3. FIELD EXPLORATION AND LABORATORY TESTING
The field exploration program is given in Appendix B, which includes the Logs of Borings.

The results of the laboratory testing are included in Appendix C.

4. SITE DESCRIPTION

4.1 Location

a) The project site is located along the southwest side of Pico Avenue, approximately 280 feet northwest of San Marcos Boulevard, in the city of San Marcos, California.
b) The approximate site location is shown on the Location Map, Figure 1.

4.2 Existing Surface Conditions
a) The subject property is currently vacant and void of any building structures. b) The ground surface throughout the project site is relatively level. The natural topography of the site area descends to the south at an approximate gradient of one percent.
c) Surface drainage consists of sheet flow runoff of incident rainfall water derived primarily within the property boundaries and adjacent properties.

LOCATION MAP
244 Pico Avenue
San Marcos, California
Date: August 2022
Project No.: 9421-04
Figure No:

GLOBAL GEO-ENGINEERING, INC.

GEOLOGIC AND SOILS ENGINEERING IRVINE, CALIFORNIA
1 2000 0 2000 4000

SCALE FEET
BASE MAP: USGS 7.5-Minute Topographic Map,
San Marcos Quadrangle, 1999 N
O
R
T
H
SITE
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4.3 Geology

4.3.1 Regional Geologic Setting
The subject property is located within the Peninsular Ranges Geomorphic Province of California. The Peninsular Ranges consist of a series of mountain ranges separated by longitudinal valleys. The ranges trend northwest-southeast and are sub parallel to faults branching from the San Andreas Fault. The Peninsular Ranges extend from the southern side of the Santa Monica and San Gabriel Mountains into Baja California, Mexico (CDMG, 1997).

4.3.2 Local Geologic Setting
In general, the project site area is underlain by Recent- to Older-aged alluvial deposits which overlie granitic bedrock.

4.4 Subsurface Conditions
a) The subsurface conditions, as encountered in our explorations, are described in the following sections.
b) More detailed descriptions of the subsurface conditions are presented in our Logs of Borings, which are enclosed as Figures B-2 through B-4 in Appendix B. The locations of the borings are shown on our Boring Location Plan, Figure B-5.

4.4.1 Alluvium
a) Alluvial deposits were encountered in all of our borings excavated on-site.
b) The alluvium was found to generally consist of interlayers of Silty SAND, SAND and Sandy to Clayey SILT.
c) The Silty SAND and SAND sediments were generally found to be fine to coarse grained, slightly moist to very moist and medium dense.
d) The Sandy to Clayey SILT deposits were observed to be slightly moist to moist and stiff.

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4.4.2 Bedrock
a) Bedrock, classified as Tonalite, was encountered at a depth of 37 feet below ground surface in Boring B-1.
b) The bedrock encountered in our boring was noted to be fine textured and hard.

4.4.3 Groundwater
a) Groundwater was encountered in our deeper boring (Boring B-1) at a depth of 24 feet below ground surface. The static water level was measured at a depth of 23.5 feet below ground surface approximately 30 minutes after termination of drilling.
b) No nearby groundwater wells were found to be listed during our review of the California Department of Water Resources internet website.

5. SEISMICITY

5.1 General
a) The property is located in the general proximity of several active and potentially active faults, which are typical for sites in the Southern California region. Earthquakes occurring on active faults within a 70-mile radius are capable of generating ground shaking of engineering significance to the proposed construction.
b) In Southern California, most of the seismic damage to manmade structures results from ground shaking and, to a lesser degree, from liquefaction and ground rupture caused by earthquakes along active fault zones. In general, the greater the magnitude of the earthquake, greater is the potential damage.

5.2 Ground Surface Rupture
a) The closest known active fault is the Elsinore Fault, located at a distance of about 16.3 miles northeast of the project site. Other nearby active or potentially active faults include the Rose Canyon Fault and the San Jacinto Fault located at distances of about 20.8 miles and 40.8 miles, respectively, from the subject property.
b) Due to the distance of the closest active fault to the site, ground rupture is not considered a significant hazard at the site.

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5.3 Ground Shaking
a) We utilized the California Office of Statewide Health Planning and Development (OSHPD) Seismic Design Maps internet program to calculate the peak ground acceleration (PGA) at the project site location.

Using the ASCE 7-16 standard and Site Class D, the PGA at the subject property resulted to be 0.47g.
b) Figure 2 shows the geographical relationships among the site locations, nearby faults and the epicenters of significant occurrences. The project site is not located within any State of California delineated Earthquake Fault Zone; however, during historic times, a number of major earthquakes have occurred along the active faults in Southern California. From the seismic history of the region and proximity, the Elsinore Fault and Rose Canyon Fault have the greatest potential for causing earthquake damage related to ground shaking at this site.

5.4 Liquefaction
The subject site is underlain by dense soil layers overlying a Tonalite bedrock.

The potential for the liquefaction is considered to be low.

6. CONCLUSIONS AND RECOMMENDATIONS

6.1 General
a) It is our opinion that the site will be suitable for the proposed development, from a geotechnical aspect, assuming that our recommendations are implemented.
b) We are of the opinion that the proposed structures can be supported on shallow spread footings founded in the existing competent soils. c) We consider that the anticipated grading will not adversely affect, nor be adversely affected by adjoining property, with due precautions being taken.
d) The final grading plans and foundation plans/design loads should be reviewed by the Geotechnical Engineer.
e) The design recommendations in the report should be reviewed during the construction phase.
244 Pico Avenue
San Marcos, California
Date: August 2022
Project No: 9421-04
Figure No:
2 GLOBAL GEO-ENGINEERING, INC.

GEOLOGIC AND SOILS ENGINEERING

IRVINE, CALIFORNIA

MAJOR EARTHQUAKES AND RECENTLY ACTIVE FAULTS IN THE

SOUTHERN CALIFORNIA REGION

EXPLANATION

EARTHQUAKE LOCATIONS
Approximate epicentral area of earthquakes that
occurred 1769-1933. magnitudes not recorded by
instruments prior to 1906 were estimated from
damage reports assigned on Intensity VII (Modified
Mercali scale) or greater; this is roughly equivalent
to Richter M 6.0. 31 moderate**earthquakes, 7 major
and one great earthquake (1857) were reported in the
164-year period 1769-1933.

Earthquake epicenters since 1933, plotted from
instruments. 33 moderate** and five major
earthquakes were in the 66-year period 1933 to 1999.

ACTIVE FAULTS
Total length of fault zone that breaks
Halocene deposits or that has had
seismic activity.

Fault segment with surface rupture
during an historic earthquake, or with
aseismic fault creep.

Halocene volcanic activity
(Amboy, Pisgah, Cerro Prieto and Salton
Buttes
1899
M7+
1952
M7.7
**Code recommendations by the Structural Engineers Association of California define a great earthquake as one that has a Richter Magnitude of 7 ¾ or greater; a major earthquake 7 to 7 ¾; a moderate earthquake 6 to 7.

Compiled by Richard J. Proctor mainly from published and unpublished data of the California Division of Mines and Geology; California Department of Water Resources Bulletin 116-2 (1964); selections from bulletins of the Geological and Seismological Societies of America; from C.F. Richter, Elementary Seismology (1958); and the National Atlas, p. 66, and from Working Group on California Earthquake Probabilities- SSA Bulletin V 85.

SITE
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6.2 Grading

6.2.1 Processing of On-Site Soils
a) To provide uniform support conditions, the subgrade soils should be overexcavated to a depth of one foot below the foundation bottom and three feet below the slab-on-grade, subject to review during construction. The overexcavation should laterally extend for a distance of 5 feet.
b) There should be at least one foot of reworked soils or compacted fill below the pavements.
c) Wherever structural fills are to be placed, the upper 6 to 8 inches of the subgrade should, after stripping or overexcavation, first be scarified, reworked and wetted down thoroughly.
d) Any loosening of reworked or native material, consequent to the passage of construction traffic, weathering, etc., should be made good prior to further construction.
e) The depths of overexcavation should be reviewed by the Geotechnical Engineer during the actual construction. Any surface or subsurface obstructions, or questionable material encountered during grading should be brought immediately to the attention of the Geotechnical Engineer for proper exposure, removal or processing as directed. No underground obstructions or facilities should remain in any structural areas. Depressions and/or cavities created as a result of the removal of obstructions should be backfilled properly with suitable material, and compacted.

6.2.2 Material Selection
After the site has been stripped of any debris, vegetation and organic soils, excavated on-site soils are considered satisfactory for reuse in the construction of on-site fills, with the following provisions:
a) Significant water will be required to be added to the existing soils; b) The organic content does not exceed 3 percent by volume; c) Large size rocks greater than 8 inches in diameter should not be incorporated in compacted fill;
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d) Rocks greater than 4 inches in diameter should not be incorporated in compacted fill to within one foot of the underside of the footings and slabs.

6.2.3 Compaction Requirements
a) Reworking/compaction shall include moisture-conditioning as needed to bring the soils to slightly above the optimum moisture content. All reworked soils and structural fills should be densified to achieve at least 90 percent relative compaction with reference to laboratory compaction standard. The optimum moisture content and maximum dry density should be determined in the laboratory in accordance with ASTM Test Designation D1557.
b) Fill should be compacted in lifts not exceeding 8 inches (loose).

6.2.4 Excavating Conditions
a) Excavation of on-site materials may be accomplished with standard earthmoving or trenching equipment. No hard rock was encountered which will require blasting.
b) Ground water was encountered at a depth of 24 feet below ground surface in our deeper boring. Dewatering is not anticipated in excavations shallower than 24 feet below ground surface.

6.2.5 Shrinkage
For preliminary earthwork calculation, an average shrinkage factor of approximately 5 percent is recommended for the soils (this does not include handling losses).

6.2.6 Expansion Potential
a) Based upon our visual observations, the expansion potential for the on-site soils is considered to be medium. The recommendations provided in the following sections will reduce the effects of the expansive subgrade soils.
b) Any imported material, or doubtful material exposed during grading, should be evaluated for its expansive properties. c) In any event, the subgrade soils should be tested for their expansion potential or during the final stages of grading.

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6.2.7 Sulphate Content
a) The sulphate contents of representative samples of the soil are less than 0.1%. The sulphate exposure is considered to be negligible.

Type II Portland cement is recommended for the construction. a) The fill materials should be tested for their sulphate content during the final stage of rough grading.

6.2.8 Utility Trenching
a) The walls of temporary construction trenches in fill should stand nearly vertical, with only minor sloughing, provided the total depth does not exceed 3 feet (approximately). Shoring of excavation walls or flattening of slopes may be required, if greater depths are necessary.
b) Trenches should be located so as not to impair the bearing capacity or to cause settlement under foundations. As a guide, trenches should be clear of a 45-degree plane, extending outward and downward from the edge of foundations. Shoring should comply with Cal-OSHA regulations.
c) Existing soils may be utilized for trenching backfill, provided they are free of organic materials.
d) All work associated with trench shoring must conform to the state and federal safety codes.

6.2.9 Surface Drainage Provisions
Positive surface gradients should be provided adjacent to the buildings to direct surface water run-off away from structural foundations and to suitable discharge facilities.

6.2.10 Grading Control
All grading and earthwork should be performed under the observation of a Geotechnical Engineer in order to achieve proper subgrade preparation, selection of satisfactory materials, placement and compaction of all structural fill. Sufficient notification prior to stripping and earthwork construction is essential to make certain that the work will be adequately observed and tested.

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6.3 Slab-on-Grade
a) Concrete floor slabs may be founded on the reworked existing soils or compacted fill.
b) The slab should be underlain by four inches of granular material. A plastic vapor barrier is recommended to be placed at the mid-height of the base layer.
c) It is recommended that #4 bars on 12-inch center, both ways, or equivalent be provided as minimum reinforcement in slabs-on-grade. Joints should be provided and slabs supporting no vehicular traffic should be at least 5 inches thick.
d) The FFL should be at least 6 inches above highest adjacent grade. e) The subgrade soils should be kept moist prior to the concrete pour.

6.4 Spread Foundations
The proposed structures can be founded on shallow spread footings. The criteria presented as follows should be adopted:

6.4.1 Dimensions/Embedment Depths
Number of Stories
(floors supported)
Minimum Width
(ft.)
Minimum Footing
Thickness
(in.)
Minimum Embedment
Below Lowest Finished Surface
(ft.)
3 1.5 6 Perimeter 2.5
Interior 2.5
Square Column
Footings
To 50 kip
2 - 2.5

6.4.2 Allowable Bearing Capacity
Embedment Depth
(ft.)
Allowable Bearing Capacity
(lb/ft2)

1.0 2,000
(Notes:
• The allowable bearing capacity may be increased by 800 lb/ft2 for each additional foot increase in the depth or by 200 lb/ft2 he width to a maximum value of 4,000 lb/ft2
;
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• These values may be increased by one-third in the case of shortduration loads, such as induced by wind or seismic forces; • At least 2x#4 bars should be provided in wall footings, one on top and one at the bottom;
• In the event that footings are founded in structural fills consisting of imported materials, the allowable bearing capacities will depend on the type of these materials, and should be re-evaluated;
• Bearing capacities should be re-evaluated when loads have been obtained and footings sized during the preliminary design; • Planter areas should not be sited adjacent to walls;
• Footing excavations should be observed by the Geotechnical Engineer; • Footing excavations should be kept moist prior to the concrete pour; • It should be insured that the embedment depths do not become reduced or adversely affected by erosion, softening, planting, digging, etc.)

6.4.3 Settlements
Total and differential settlements under spread footings are expected to be within tolerable limits and are not expected to exceed 1 and ¾ inches in a horizontal distance of 40 feet, respectively.

6.5 Lateral Pressures
a) The following lateral pressures are recommended for the design of retaining structures.

Pressure (lb/ft2/ft depth)
Lateral Force Soil Profile Unrestrained Wall Rigidly Supported Wall Active Pressure Level 36 -
At-Rest Pressure Level - 65
Passive Resistance
(ignore upper 1.5 ft.) Level 300 -
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b) Friction coefficient: 0.35 (includes a Factor of Safety of 1.5). While combining friction with passive resistance, reduce passive by 1/3. c) These values apply to the existing soil, and to compacted backfill generated from in-situ material. Imported material should be evaluated separately. It is recommended that where feasible, imported granular backfill be utilized, for a width equal to approximately one-quarter the wall height, and not less than 1.5 feet.
d) Backfill should be placed under engineering control. e) Subdrains comprised of 4-inch perforated SDR-35 or equivalent PVC pipe covered in a minimum of one cubic foot per linear foot of filter rock and wrapped in Mirafi 140N filter fabric should be provided behind retaining walls.

6.6 Seismic Coefficients and Liquefaction Potential
a) For seismic analysis of the proposed project in accordance with the seismic provisions of ASCE 7-16, we recommend the following:

ITEM VALUE
Site Latitude (Decimal-degrees) 33.14197
Site Longitude (Decimal-degrees) -117.16598
Site Class D
Risk Category II
Mapped Spectral Response Acceleration-Short Period (0.2 Sec) - SS 0.897 Mapped Spectral Response Acceleration-1 Second Period – S1 0.33 Short Period Site Coefficient-Fa 1.141
Long Period Site Coefficient Fv 1.90
Adjusted Spectral Response Acceleration @ 0.2 Sec. Period (Sms) 1.024 Adjusted Spectral Response Acceleration @ 1Sec.Period (Sm1) 0.627 Design Spectral Response Acceleration @ 0.2 Sec. Period (SDs) 0.682 Design Spectral Response Acceleration @ 1-Sec. Period (SD1) 0.418 b) Ground water was encountered at a depth of 24 feet below ground surface, however, the subject site is underlain by dense soil layers. The potential for liquefaction is considered to be low.

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6.7 Pavement Design

6.7.1 Asphalt Pavement Section
a) Based on Traffic Indices (T.I) and on the anticipated “R” – Value of 42 of the subgrade, the following tentative structural pavement sections are recommended.
b) The subgrade soils should be tested for R-Value at the conclusion of rough grading and the pavement sections should be finalized then.

6.7.2 Subgrade Preparation
Subgrade soils within the upper 12 inches of finished grade shall be moisture-conditioned where necessary, shall be compacted to at least 90 percent relative compaction per ASTM D1557, and shall be free of any loose or soft areas.

6.7.3 Base Preparation
Unless otherwise specified, the base shall consist of Class II ¾-inch aggregate base or approved Crushed Miscellaneous Base. The base shall be compacted to a minimum of 95 percent relative compaction in accordance with the procedures described in ASTM Test Method D1557.

6.7.4 Concrete Pavement

If proposed, the concrete pavement should be at least 5 inches thick, reinforced with #4 bars on 12 inches center bothways, underlain by 4 inches thick base as recommended above. Thicker concrete section will be required for traffic greater than T.I. of 6.0.

6.8 Corrosion Potential
a) Soil Corrosion potential for metal and concrete was estimated by performing water-soluble sulfate, chloride, pH, and electrical resistivity tests during this investigation.

Location T.I. Asphaltic Concrete
(inches)
Aggregate Base
(inches)
Parking and Driveways Up to 5.0 3 4
Driveway
(light truck traffic) 6.0 3 6
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b) Electrical resistivity is a measure of soil resistance to the flow of corrosion currents. Corrosion currents are generally high in low resistivity soils.

The electrical resistivity of a soil decreases primarily with an increase in its chemical and moisture contents.
c) A commonly accepted correlation between electrical resistivity and corrosivity for buried ferrous metals is presented below:

Electrical Resistivity, Ohm-cm Corrosion Potential
Less than 1,000 Severe
1,000-2,000 Corrosive
2,000-10,000 Moderate
Greater than 10,000 Mild
d) Results of electrical resistivity test indicate a value of 3,339 ohm-cm for the near-surface soils. Based on this data, it is our opinion that, in general, on-site near-surface soils are considered moderately corrosive in nature.

This potential should be considered in design of underground metal pipes.

6.9 Percolation Study
a) The soils in the upper 5 feet were Clayey Silty SAND underlain by Silty SAND/Sandy SILT. We recommend the basin to be at least 6 feet deep. b) As more granular soils are anticipated at that depth, we estimate the following infiltration rate. During the grading operation, a percolation test should be conducted to verify the infiltration rate.

Boring No. Percolation Rate (inch/hour)
P-1 3.0
c) These rates are calculated using a factor of safety of 1.0. Appropriate factor of safety should be utilized while designing the basin.

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7. LIMITATIONS
a) Soils and bedrock over an area show variations in geological structure, type, strength and other properties from what can be observed, sampled and tested from specimens extracted from necessarily limited exploratory borings. Therefore, there are natural limitations inherent in making geologic and soil engineering studies and analyses.

Our findings, interpretations, analyses and recommendations are based on observation, laboratory data and our professional experience; and the projections we make are professional judgments conforming to the usual standards of the profession. No other warranty is herein expressed or implied. b) In the event that during construction, conditions are exposed which are significantly different from those described in this report, they should be brought to the attention of the Geotechnical Engineer.

The opportunity to be of service is sincerely appreciated. If you have any questions or if we can be of further assistance, please call.

Very truly yours,
GLOBAL GEO-ENGINEERING, INC.

Mohan B. Upasani Kevin B. Young
Principal Geotechnical Engineer Principal Engineering Geologist RGE 2301 CEG 2253
(Exp. March 31, 2023) (Exp. October 31, 2023)
MBU/KBY: fdg
Enclosures:

Location Map
Seismicity Map
References
Field Exploration
Unified Soils Classification System
Logs of Borings
- Figure 1
- Figure 2
- Appendix A
- Appendix B
Figure B-1
Figures B-2 through B-3
Boring Location Plan Figure B-4
Laboratory Testing - Appendix C
Project 9421-04

APPENDIX A
References

1. California Geological Survey, Earthquake Fault Zones of Required Investigation, (Internet).

2. California Division of Mines and Geology, 1996, Geologic Maps of the Northwestern Part of San Diego County, California, CDMG Open File Report 96-02.

3. California Office of Statewide Health Planning and Development, Seismic Design Maps Web Tool, ASCE 7-16 Standard (Internet).

4. United States Geological Survey, 1948, San Marcos Quadrangle, 7.5-Minute Topographic Series.

5. United States Geological Survey, 1968, San Marcos Quadrangle, 7.5-Minute Topographic Series.

6. United States Geological Survey, 1968 photorevised 1983, San Marcos Quadrangle, 7.5- Minute Topographic Series.

Project 9421-04

APPENDIX B
Field Exploration
a) The site was explored on May 17, 2022, utilizing a B-61 Mobile hollow stem drill rig to excavate three borings to a maximum depth of 40 feet below the existing ground surface.

One of the borings were subsequently backfilled. Three-inch diameter perforated pipe with gravel rock encasement was installed in Boring P-1 for the purpose of percolation testing b) The soils encountered in the excavations were logged and sampled by our Engineering Geologist. The soils were classified in accordance with the Unified Soil Classification System described in Figure B-1. The Logs of Borings are presented in Figures B-2 through B-4. The approximate locations of the borings are shown on the Boring Location Plan, Plate

1. The logs, as presented, are based on the field logs, modified as required from the results of the laboratory tests. Driven ring and bulk samples were obtained from the excavations for laboratory inspection and testing. The depths at which the samples were obtained are indicated on the logs.
c) The number of blows of the driving weight during sampling was recorded, together with the depth of penetration, the driving weight and the height of fall. The blows required per foot of penetration for given samples was then calculated and shown on the logs. d) Groundwater was encountered at a depth of 24 feet below ground surface in Boring B-1. e) Caving occurred in all of the borings to the depths noted on the logs.

UNIFIED SOILS CLASSIFICATION (ASTM D-2487)

PRIMARY DIVISION GROUP SYMBOL SECONDARY DIVISIONS

COARSE GRAINED SOILS
More than half of materials is
larger than #200 sieve size

GRAVELS
More than half
of coarse
fraction is larger
than #4 sieve
Clean
Gravels
(<5% fines)
GW Well graded gravels, gravel-sand mixture, little or no fines GP Poorly graded gravels or gravel-sand mixtures, little or no fines Gravel with
Fines
GM Silty gravels, gravel-sand-silt mixture. Non-plastic fines.

GC Clayey gravels, gravel-sand-clay mixtures. Plastic fines SANDS
More than half
of coarse
fraction is
smaller than
#4 sieve
Clean Sands
(<5% fines)
SW Well-graded gravels, gravel-sand mixtures, little or no fines.

SP Poorly graded sands or gravelly sands, little or no fines.

Sands with
Fines
SM Silty sands, sand-silt mixtures. Non-Plastic fines.

SC Clayey sands, sand-clay mixtures. Plastic fines.

FINE GRAINED SOILS
More than half of material is
smaller than #200 sieve size

SILTS AND
CLAYS

LIQUID LIMIT

IS LESS THAN
50 ML Inorganic silts and very fine sands, rock flour, silty or clayey fine sands or clayey silts, with slight plasticity
CL Inorganic clays of low to medium plasticity, gravelly clays, sandy clays, silty clays, lean clays.

OL Organic silts and organic silty clays of low plasticity.

SILTS AND
CLAYS

LIQUID LIMIT

IS GREATER
THAN 50
MH Inorganic silts, micaceous or diatomaceous fine sandy or silty soils, elastic silts.

CH Inorganic clays of high plasticity, fat clays
OH Organic clays of medium to high plasticity, organic silts.

Highly Organic Soils PT Peat and other highly organic soils.

CLASSIFICATION BASED ON FIELD TESTS

CLASSIFICATION CRITERIA BASED ON LAB TESTS

PENETRATION RESISTANCE (PR)
Sands and Gravels
Relative Density Blows/foot
Very loose 0-4
Loose 4-10
Medium Dense 10-30
Dense 30-50
Very Dense Over 50
Clays and Silts
Consistency Blows/foot* Strength**
Very Soft 0-2 0-½
Soft 2-4 ¼-½
Firm 4-8 ½-1
Stiff 8-15 1-2
Very Stiff 15-30 2-4
Hard Over 30 Over 4
*Numbers of blows of 140 lb hammer
falling 30 inches to drive a 2-inch O.D.
(1 3/8 in. I.D.) Split Barrel sampler
(ASTM-1568 Standard Penetration Test)
**Unconfined Compressive strength in
tons/sq. ft. Read from pocket
penetrometer
Liquid Limit
Plasticity chart for laboratory
Classification of Fine-grained soils
0 10 20 30 40 50 60 70 80 90 100
60 50
40 30
20 10
0 Plasticity Index
Comparing soils at equal liquid limit
Toughness and dry strength increase with
increasing plasticity index
Fines (Silty or Clay) Fine Sand Medium Sand Coarse Sand Fine Gravel Coarse Gravel Cobbles Boulders Sieve Sizes 200 40 10 4 ¾” 3” 10”
GW and SW – Cu= D60/D10 greater than 4 for GW and 6 for SW; Cc = (D30) 2/D10x D60 between 1 and 3
GP and SP – Clean gravel or sand not meeting requirement for GW and SW GM and SM – Atterberg limit below “A” line or P.I. less than 4 GC and SC – Atterberg limit above “A” line P.I. greater than 7

CLASSIFICATION OF EARTH MATERIAL IS BASED ON FIELD INSPECTION

AND SHOULD NOT BE CONSTRUED TO IMPLY LABORATORY ANALYSIS UNLESS SO STATED.

C
L
CL
CL-ML
OH
Or
MH
OL
or
ML ML
CH
GLOBAL GEO-ENGINEERING, INC.

GEOLOGIC AND SOILS ENGINEERING, IRVINE, CALIFORNIA
244 Pico Avenue
San Marcos, California
Date: August 2022
Project No.: 9421-04
Figure No.:

B-1
Global Geo-Engineering, Inc.

Irvine, California
Geologists and Geotechnical Engineers
Project 9421-04
San Marcos, California
244 Pico Avenue
Figure B-2.1
LOG OF BORING B-1
Date : May 17, 2022
Logged By : KBY
Diameter of Boring : 6''
Drilling Company : Cal Pac Drilling
Drilling Rig : Mobile B-61
Drilling Method : Hollow Stem
Sampling Method : California Modified
Hammer Weight (lbs) : 140
Hammer Drop (in) : 30
Depth in Feet
0 5
10 15
20 25
Sample
Field Moisture% Dry Weight

7.6 6.8

12.9 15.0

19.3 15.0
Dry Densitylb./cubic ft.
116.7
112.6
116.2
115.5
109.6
115.4
Blow Count
55 29
100
39 38
23 Relative Compaction
Water Level
USCS
SM
SM/ML
ML
SP

GRAPHIC

DESCRIPTION
Sample Type
Ring
Bulk
Standard Penetration Testing
Water Levels
Groundwater Encountered
Seepage Encountered
Clayey Silty SAND: fine to medium grained, light reddish brown, slightly moist, medium dense
Silty SAND: fine grained, yellow brown, slightly moist, medium dense with SILT interbeds
Clayey SILT: light reddish to reddish brown, slightly moist to moist, stiff
@19' moist
SAND: medium to coarse grained, reddish brown, very moist to wet, medium dense, water encountered
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Project 9421-04
San Marcos, California
244 Pico Avenue
Figure B-2.2
LOG OF BORING B-1
Date : May 17, 2022
Logged By : KBY
Diameter of Boring : 6''
Drilling Company : Cal Pac Drilling
Drilling Rig : Mobile B-61
Drilling Method : Hollow Stem
Sampling Method : California Modified
Hammer Weight (lbs) : 140
Hammer Drop (in) : 30
Depth in Feet
25 30
35 40
45 50
Sample
Field Moisture% Dry Weight

19.5 17.2

9.1 Dry Densitylb./cubic ft.
106.0
104.9
129.3
Blow Count
18 12
100
Relative Compaction
Water Level
USCS
SP
SP/ML
GR

GRAPHIC

DESCRIPTION
Sample Type
Ring
Bulk
Standard Penetration Testing
Water Levels
Groundwater Encountered
Seepage Encountered
@29' fine to medium grained with SILT interbeds
@34' medium grained, olive brown

ALLUVIUM
TONALITE: fine textured, hard

BASEMENT ROCK
Bottom of Boring at 40 feet:

Notes:

1. Caving to 23 feet after augers were removed

2. Water encountered at 24', Static water level measured at 23.5'

3. Boring backfilled
Global Geo-Engineering, Inc.

Irvine, California
Geologists and Geotechnical Engineers
Project 9421-04
San Marcos, California
244 Pico Avenue
Figure B-3
LOG OF BORING B-2
Date : May 17, 2022
Logged By : KBY
Diameter of Boring : 6''
Drilling Company : Cal Pac Drilling
Drilling Rig : Mobile B-61
Drilling Method : Hollow Stem
Sampling Method : California Modified
Hammer Weight (lbs) : 140
Hammer Drop (in) : 30
Depth in Feet
0 5
10 15
20 25
Sample
Field Moisture% Dry Weight

13.5 11.0

11.2 14.0

12.0 Dry Densitylb./cubic ft.
113.8
107.2
112.5
114.2
113.4
Blow Count
20 45
35 48
20 Relative Compaction
Water Level
USCS
CL/ML
ML
ML/SM
ML
SM

GRAPHIC

DESCRIPTION
Sample Type
Ring
Bulk
Standard Penetration Testing
Water Levels
Groundwater Encountered
Seepage Encountered
Sandy Silty CLAY: reddish brown, slightly moist, medium stiff with Clayey SILT interbeds
Sandy SILT: yellow to light reddish brown, slightly moist, stiff @9' with Silty SAND interbeds
Clayey SILT: olive gray to light reddish brown, slightly moist, stiff Clayey Silty SAND: fine to medium grained, light reddish brown, moist, medium dense ALLUVIUM
Bottom of Boring at 20 feet:

Notes:

1. Caving to 15.5 feet after augers were removed

2. No groundwater or seepage encountered

3. Boring backfilled
244 Pico Avenue
San Marcos, California
Date: January 2023
Project No.: 9421-04
Figure No:

GLOBAL GEO-ENGINEERING, INC.

GEOLOGIC AND SOILS ENGINEERING IRVINE, CALIFORNIA B-5

BORING LOCATION PLAN
N
B-2
20’
B-1

39.5 ’
Not to Scale
P-1
5’
Approximate Location of Percolation
Boring, Showing Total Depth
KEY
P-1
5’
Approximate Location of Boring,
Showing Total Depth
B-2
20’
Project 9421-04

APPENDIX C
Laboratory Testing Program
The laboratory-testing program was directed towards providing quantitative data relating to the relevant engineering properties of the soils. Samples considered representative of site conditions were tested as described below.
a) Moisture and Density
Moisture-density information usually provides a gross indication of soil consistency.

Local variations at the time of the investigation can be delineated, and a correlation obtained between soils found on this site and nearby sites. The dry unit weights and field moisture contents were determined for selected samples. The results are shown on the Logs of Borings.
b) Compaction
A representative soil sample was tested in the laboratory to determine the maximum dry density and optimum moisture content, using the ASTM D1557 compaction test method.

This test procedure requires 25 blows of a 10-pound hammer falling a height of 18 inches on each of five layers, in a 1/30 cubic foot cylinder. The results of the test are presented below.

Boring No. Sample Depth
(ft.) Soil Description
Optimum
Moisture
Content
(%)
Maximum
Dry Density
(lb/ft3
)
B-1 1-3 Clayey Silty SAND 9.9 127.3
Appendix C
Project 9421-04

Page 18 ends

c) Direct Shear
Direct shear tests were made on remolded samples, using a direct shear machine at a constant rate of strain. Variable normal or confining loads are applied vertically and the soil shear strengths are obtained at these loads. The angle of internal friction and the cohesion are then evaluated. The samples were tested at saturated moisture contents. The results are shown below in terms of the Coulomb shear strength parameters.

Boring No. Sample Depth
(ft)
Soil
Description
Coulomb
Cohesion
(lb/ft2
)
Angle of
Internal
Friction
(°)
Peak/Residual
B-1 1-3 Clayey Silty SAND 250
250
29 29
Peak
Ultimate
d) Sulfate Content
A representative soil sample was analyzed for its sulphate content. The results are given below:

Boring No. Sample Depth
(ft.) Soil Description Sulphate Content
(%)
B-1 1-3 Clayey Silty SAND 0.0026
e) Chloride Content
A representative soil sample was analyzed for chloride content in accordance with California Test Method CA422. The result is given below:

Boring No. Sample Depth
(ft)
Soil
Description
Chloride Content
(%)
B-1 1-3 Clayey Silty SAND 0.0023
Appendix C
Project 9421-04

Page 19 ends

f) Resistivity and pH
A representative soil sample was analyzed in accordance with California Test Methods CA532 and CA643 to determine the minimum resistivity and pH. The result is provided below:

Boring No. Sample Depth
(ft)
Soil
Description pH
Minimum
Resistivity
(Ohm-cm)
B-1

1-3 Clayey Silty SAND 8.1 3,339

g) Expansion Potential
Surface soils were collected in the field and tested in the laboratory in accordance with the ASTM Test Designation D4829. The degree of expansion potential is determined from soil volume changes occurring during saturation of the specimen. The results of the tests are presented below:

Boring No. Sample Depth
(ft)
Soil
Description
Expansion
Index
Expansion
Potential
B-2 2 Sandy Silty CLAY 70 Medium

Category # Description i ii iii iv v vi vii viii ix x Units 1 Drainage Basin ID or Name DMA-1 unitless2 85th Percentile 24-hr Storm Depth 0.67 inches3 Impervious Surfaces Not Directed to Dispersion Area (C=0.90) 21,975 sq-ft 4 Semi-Pervious Surfaces Not Serving as Dispersion Area (C=0.30) sq-ft5 Engineered Pervious Surfaces Not Serving as Dispersion Area (C=0.10) 7,407 sq-ft6 Natural Type A Soil Not Serving as Dispersion Area (C=0.10) sq-ft 7 Natural Type B Soil Not Serving as Dispersion Area (C=0.14) sq-ft 8 Natural Type C Soil Not Serving as Dispersion Area (C=0.23) sq-ft9 Natural Type D Soil Not Serving as Dispersion Area (C=0.30) sq-ft 10 Does Tributary Incorporate Dispersion, Tree Wells, and/or Rain Barrels? No No No No No No No No No No yes/no11 Impervious Surfaces Directed to Dispersion Area per SD-B (Ci=0.90) sq-ft 12 Semi-Pervious Surfaces Serving as Dispersion Area per SD-B (Ci=0.30) sq-ft13 Engineered Pervious Surfaces Serving as Dispersion Area per SD-B (Ci=0.10) sq-ft14 Natural Type A Soil Serving as Dispersion Area per SD-B (Ci=0.10) sq-ft15 Natural Type B Soil Serving as Dispersion Area per SD-B (Ci=0.14) sq-ft16 Natural Type C Soil Serving as Dispersion Area per SD-B (Ci=0.23) sq-ft17 Natural Type D Soil Serving as Dispersion Area per SD-B (Ci=0.30) sq-ft18 Number of Tree Wells Proposed per SD-A #19 Average Mature Tree Canopy Diameter ft20 Number of Rain Barrels Proposed per SD-E #21 Average Rain Barrel Size gal22 Total Tributary Area 29,382 000000000 sq-ft 23 Initial Runoff Factor for Standard Drainage Areas 0.70 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 unitless24 Initial Runoff Factor for Dispersed & Dispersion Areas 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 unitless25 Initial Weighted Runoff Factor 0.70 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 unitless26 Initial Design Capture Volume 1,148 000000000 cubic-feet 27 Total Impervious Area Dispersed to Pervious Surface 0000000000 sq-ft28 Total Pervious Dispersion Area 0000000000 sq-ft29 Ratio of Dispersed Impervious Area to Pervious Dispersion Area n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a ratio30 Adjustment Factor for Dispersed & Dispersion Areas 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 ratio31 Runoff Factor After Dispersion Techniques 0.70 n/a n/a n/a n/a n/a n/a n/a n/a n/a unitless32 Design Capture Volume After Dispersion Techniques 1,148 000000000 cubic-feet 33 Total Tree Well Volume Reduction 0000000000 cubic-feet34 Total Rain Barrel Volume Reduction 0000000000 cubic-feet35 Final Adjusted Runoff Factor 0.70 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 unitless36 Final Effective Tributary Area 20,567 000000000 sq-ft 37 Initial Design Capture Volume Retained by Site Design Elements 0000000000 cubic-feet38 Final Design Capture Volume Tributary to BMP 1,148 000000000 cubic-feet FalseFalse
Automated Worksheet B.1: Calculation of Design Capture Volume (V2.0) Dispersion
Area, Tree Well
& Rain Barrel
Inputs
(Optional)
Standard
Drainage Basin
Inputs
Results
Tree & Barrel
Adjustments
Initial Runoff
Factor
Calculation
Dispersion
Area
Adjustments
No Warning Messages
Appendix B: Storm Water Pollutant Control Hydrologic Calculations and Sizing Methods B-20 February 2016
B.4.1 Simple Method
Stepwise Instructions:

1. Compute DCV using Worksheet B.4-1

2. Estimate design infiltration rate using Worksheet D.5-1

3. Design BMP(s) to ensure that the DCV is fully retained (i.e., no surface discharge during the design event) and the stored effective depth draws down in no longer than 36 hours.

Worksheet B.4-1: Simple Sizing Method for Infiltration BMPs Simple Sizing Method for Infiltration BMPs Worksheet B.4-1 1 DCV (Worksheet B-2.1) DCV= cubic-feet
2 Estimated design infiltration rate (Worksheet D.5-1) Kdesign= in/hr 3 Available BMP surface area ABMP= sq-ft
4 Average effective depth in the BMP footprint (DCV/ABMP) Davg= feet 5 Drawdown time, T (Davg *12/Kdesign) T= hours
6 Provide alternative calculation of drawdown time, if needed.

Notes:
x Drawdown time must be less than 36 hours. This criterion was set to achieve average annual capture of 80% to account for back to back storms (See rationale in Section B.4.3). In order to use a different drawdown time, BMPs should be sized using the percent capture method (Section B.4.2).
x The average effective depth calculation should account for any aggregate/media in the BMP.

For example, 4 feet of stone at a porosity of 0.4 would equate to 1.6 feet of effective depth. x This method may overestimate drawdown time for BMPs that drain through both the bottom and walls of the system. BMP specific calculations of drawdown time may be provided that account for BMP-specific geometry.

Stage‐Storage‐Discharge Summary Table
Depth (ft) Area (ft2) Volume (ft3) Ac‐Ft Q‐out (cfs)
0 400 0 0 0
1 400 400 0.009183 0
2 400 800 0.018365 0
3 400 1200 0.027548 0 DCV Contained

3.2 400 1280 0.029385 0.015
4 400 1600 0.036731 0.015
5 400 2000 0.045914 0.015
6 400 2400 0.055096 0.015
7 400 2800 0.064279 0.015

7.25 400 2900 0.066575 1.5015
8 400 3200 0.073462 1.5015
9 400 3600 0.082645 1.5015
City of San Marcos PDP SWQMP Template Date: March 15, 2016 PDP SWQMP Preparation Date: May 12, 2017

THIS PAGE INTENTIONALLY LEFT BLANK FOR DOUBLE SIDED PRINTING City of San Marcos PDP SWQMP Template Date: March 15, 2016 PDP SWQMP Preparation Date: May 12, 2017
ATTACHMENT 2

BACKUP FOR PDP HYDROMODIFICATION CONTROL MEASURES
This is the cover sheet for Attachment 2.
☐Mark this box if this attachment is empty because the project is exempt from PDP hydromodification management requirements.

Indicate which Items are Included behind this cover sheet:

Attachment
Sequence
Contents Checklist
Attachment 2a Hydromodification Management Exhibit
(Required)
☒ Included
See Hydromodification Management
Exhibit Checklist on the back of this
Attachment cover sheet.

Attachment 2b Management of Critical Coarse Sediment
Yield Areas (WMAA Exhibit is required,
additional analyses are optional)
See Section 6.2 of the BMP Design
Manual.
☒ Exhibit showing project drainage
boundaries marked on WMAA Critical
Coarse Sediment Yield Area Map
(Required)
Optional analyses for Critical Coarse
Sediment Yield Area Determination
☐ 6.2.1 Verification of Geomorphic
Landscape Units Onsite
☐ 6.2.2 Downstream Systems
Sensitivity to Coarse Sediment
☐ 6.2.3 Optional Additional Analysis of
Potential Critical Coarse Sediment Yield
Areas Onsite
Attachment 2c Geomorphic Assessment of Receiving
Channels (Optional)
See Section 6.3.4 of the BMP Design
Manual.
☒ Not performed
☐ Included
☐ Submitted as separate stand‐alone
document
Attachment 2d Flow Control Facility Design, including
Structural BMP Drawdown Calculations
and Overflow Design Summary
(Required)
See Chapter 6 and Appendix G of the
BMP Design Manual
☒ Included
☐ Submitted as separate stand‐alone
document
Attachment 2e Vector Control Plan (Required when
structural BMPs will not drain in 96
hours)
☐ Included
☒ Not required because BMPs will drain
in less than 96 hours
City of San Marcos PDP SWQMP Template Date: March 15, 2016 PDP SWQMP Preparation Date: May 12, 2017
Use this checklist to ensure the required information has been included on the Hydromodification Management Exhibit:

The Hydromodification Management Exhibit must identify:
☒ Underlying hydrologic soil group
☒ Approximate depth to groundwater
☒ Existing natural hydrologic features (watercourses, seeps, springs, wetlands) ☒ Critical coarse sediment yield areas to be protected
☒ Existing topography
☒ Existing and proposed site drainage network and connections to drainage offsite ☒ Proposed grading
☒ Proposed impervious features
☒ Proposed design features and surface treatments used to minimize imperviousness ☒ Point(s) of Compliance (POC) for Hydromodification Management ☒ Existing and proposed drainage boundary and drainage area to each POC (when necessary, create separate exhibits for pre‐development and post‐project conditions) ☒ Structural BMPs for hydromodification management (identify location, type of BMP, and size/detail)

1 DMA/BMP PLAN - PROPOSED

PICO PLACE
236-244 SAN MARCOS PICO AVENUE
SAN MARCOS, CA 92069
WMAA Exhibit
Legend
Pico Ave
Yes
1000 ft
N
➤
TECHNICAL MEMORANDUM:

SWMM Modeling for
Hydromodification Compliance of:

Pico Place
Prepared For:

DMS Consultants, Inc.

Prepared by:

Luis Parra, PhD, CPSWQ, ToR, D.WRE.

R.C.E. 66377
November 3, 2022
REC Consultants
2442 Second Avenue
San Diego, CA 92101
Telephone: (619) 232-9200

TECHNICAL MEMORANDUM
TO: DMS Consultants, Inc.

FROM: Luis Parra, PhD, PE, CPSWQ, ToR, D.WRE, CFM.

David Edwards, MS, PE, CFM.

DATE: November 3, 2022, Revised February 27, 2023
RE: Summary of SWMM Modeling for Hydromodification Compliance for Pico Place, San Marcos, CA.

INTRODUCTION
This memorandum summarizes the approach used to model the proposed residential development project site in the City of San Marcos using the Environmental Protection Agency (EPA) Storm Water Management Model 5.0 (SWMM). SWMM models were prepared for the pre and post‐developed conditions at the site in order to determine if the proposed LID facilities have sufficient volume to meet Order R9‐2013‐001 requirements of the California Regional Water Quality Control Board San Diego Region (SDRWQCB), as explained in the Final Hydromodification Management Plan (HMP), dated March 2011, prepared for the County of San Diego by Brown and Caldwell.

SWMM MODEL DEVELOPMENT
The Pico Place project comprises of a multi0family development inclusive of a private drive accessway and vegetated landscaped areas. Two (2) SWMM models were prepared for this study: the first for the pre‐development and the second for the post‐developed conditions. The project site drains to one (1) overall Point of Compliance (POC‐1), located at the existing storm drain system to the eastern boundary of the project site within the adjacent Pico Avenue.

Per Section G.1.2 in Appendix G of the 2016 City of San Marcos’ BMP Design Manual, the EPA SWMM model was used to perform the continuous hydrologic simulation. For both SWMM models, flow duration curves were prepared to determine if the proposed HMP facility is sufficient to meet the current HMP requirements.

The inputs required to develop SWMM models include rainfall, watershed characteristics, and BMP configurations. The Poway gauge from the Project Clean Water website was used for this study, since it is the most representative of the project site precipitation due to elevation and proximity to the project site. Please see gauge location and project location map on Attachment 5.

The Escondido gage is not recommended for continuous simulation because (a) 22% of the intensities higher than 0.4 in/hr have data problems, and (b) the highest intensities measured in this station do not belong to the location of the gage (were copied from Wolford, at an elevation 850 ft higher than Escondido). Similarly, Wohlford data was not used mainly because the difference in elevation. At this point, we decided that the closest gage, with no significant data problems at similar elevation than the project elevation, was the most appropriate, therefore we used Poway precipitation.

Pico Place
November 3, 2022

2 Per the California Irrigation Management Information System “Reference Evaporation Zones” (CIMIS ETo Zone Map), the project site is located within the Zone 6 Evapotranspiration Area. Thus evapotranspiration values for the site were modeled using Zone 9 average monthly values from Table G.1‐1 from the City of San Marcos’ 2016 BMP Design Manual. The site was modeled with type C hydrologic soil per the site‐specific geotechnical report undertaken for the project site (please refer to Attachment 8 of this memo).

Soils have been assumed to be compacted in the existing condition to represent the current developed condition of the site. In the post developed conditions, the soils have been modeled as fully compacted.

Other SWMM inputs for the subareas are discussed in the appendices to this document, where the selection of the parameters is explained in detail.

HMP MODELING

PRE DEVELOPED CONDITIONS
The current property consists on a developed residential site that drains via overland flow to a receiving storm drain system (POC‐1) located within Pico Avenue to the east of the project site. Flows split to the east and west of the site however both outlets are then drained to the same receiving system within Pico Avenue. Table 1 below illustrates the pre‐developed area to be developed and impervious percentage accordingly.

TABLE 1 – SUMMARY OF PRE‐DEVELOPED CONDITIONS
POC DMA Tributary Area, A
(Ac)
Impervious Percentage,
Ip(1)
POC‐1 DMA‐1C 0.675 0%
TOTAL ‐‐ 0.675 0%
Notes: (1) – Per the 2013 RWQCB permit, existing condition impervious surfaces are not to be accounted for in existing conditions analysis.

DEVELOPED CONDITIONS
Runoff from the developed project site is drained to one (1) onsite receiving LID Infiltration BMP. Once flows are routed via the proposed LID BMPs, developed onsite flows are then conveyed to the aforementioned POC. Table 2 below summarizes the DMAs for the developed site.

TABLE 2 – SUMMARY OF DEVELOPED CONDITIONS
POC DMA Tributary Area, A
(Ac) Impervious Percentage, Ip
POC‐1 DMA‐1C 0.675 74.79%
TOTAL ‐‐ 0.675 ‐‐
Developed flows from the project site are conveyed to one (1) onsite detention facility prior to discharging to the existing storm drain system. The vault system is approximately 9‐feet deep with a width of 8‐feet and length of 50‐feet. Due to the limited grade on the project site and utility constraints, the vault is to be located several feet below the existing storm drain invert in Pico Avenue such that the Pico Place
November 3, 2022

3 vault can only be drained via the use of pumps. Due to HMP criteria, two (2) separate pumps will be employed on the project site, a low flow pump outlet will be located at 3.0 feet from the bottom of the basin invert while the peak Q100 flow pump will be located at 7.25 feet from the basin invert. In an extreme event, flows will outlet via the surface private drive to Pico Avenue without risk of flooding the residential structures and also providing single vehicular lane access.

Due to the high rate of measured infiltration onsite experienced during the geotechnical investigation, the base of the vault will be unlined such that flows can infiltrate into the underlying base. The filtration basin has been modeled directly as basins within SWMM can have infiltration associated with the base footprint accordingly.

Water Quality BMP Sizing &Drawdown Calculations
It is assumed all storm water quality requirements for the project will be met by the LID BMPs detailed in the SWQMP and other BMPs included within the site design. However, detailed water quality requirements are not discussed within this technical memo. For further information in regards to storm water quality requirements for the project (including sizing and drawdown) please refer to the site‐ specific Storm Water Quality Management Plan (SWQMP).

BMP MODELING FOR HMP PURPOSES
Modeling of HMP BMPs
One (1) LID BMP basin is proposed for hydromodification conformance for the project site. Tables 4 and 5 illustrates the dimensions required for HMP compliance according to the SWMM model that was undertaken for the project. It should be noted that pumps are the only possible outlet structure such that an elevation and flow will be identified for the system.

TABLE 4 – SUMMARY OF BIOFILTRATION / PARTIAL INFILTRATION BMP

BMP DIMENSIONS
Tributary
Area (ft2) Vault Width (ft) Vault Length (ft) Vault Depth (ft) Total VaultVolume (ft3) Vault 30,596 8 50 9 3,600
TABLE 5 – SUMMARY OF OUTLET PUMP DETAILS
BMP
Low Flow Pump Peak Flow Pump
Flow Rate (cfs) Elevation(1) (ft) Flow Rate (cfs) Elevation(1) (ft) Vault 0.0185 3.0 1.5 7.25
Notes: (1): Basin ground surface elevation assumed to be 0.00 ft elevation..

Pico Place
November 3, 2022

4 FLOW DURATION CURVE COMPARISON
The Flow Duration Curve (FDC) for the site was compared at the POCs by exporting the hourly runoff time series results from SWMM to a spreadsheet.

Q2 and Q10 were determined with a partial duration statistical analysis of the runoff time series in an Excel spreadsheet using the Cunnane plotting position method (which is the preferred plotting methodology in the HMP Permit). As the SWMM Model includes a statistical analysis based on the Weibull Plotting Position Method, the Weibull Method was also used within the spreadsheet to ensure that the results were similar to those obtained by the SWMM Model.

The range between 10% of Q2 and Q10 was divided into 100 equal time intervals; the number of hours that each flow rate was exceeded was counted from the hourly series. Additionally, the intermediate peaks with a return period “i” were obtained (Qi with i=3 to 9). For the purpose of the plot, the values were presented as percentage of time exceeded for each flow rate. FDC comparison at the POC is illustrated in Figure 1 in both normal and logarithmic scale.

As can be seen in Figure 1, the FDC for the proposed condition with the HMP BMPs is within 110% of the curve for the existing condition in both peak flows and durations. The additional runoff volume generated from developing the site will be released to the existing point of discharge at a flow rate below the 10% Q2 lower threshold for the POC. Additionally, the project will also not increase peak flow rates between the Q2 and the Q10, as shown in the peak flow table in Attachment 1.

Discussion of the Manning’s coefficient (Pervious Areas) for Pre and Post‐Development Conditions Typically, the Manning’s coefficient is selected as n = 0.10 for pervious areas and n = 0.012 for impervious areas. However, due to the impact that n has in the continuous simulation a more accurate value of the Manning’s coefficient has been chosen for pervious areas. Taken into consideration the study prepared by TRWE (Reference [6]) a value of n = 0.05 has been selected (see Table 1 of Reference [6] included in Attachment 7). An average n value between average grass plus pasture (0.04) and dense grass (0.06) has been selected per the reference cited, for light rain (<0.8 in/hr) as more than 99% of the rainfall has been measured with this intensity.

SUMMARY
This study has demonstrated that the proposed HMP BMP provided for the Pico Place site is sufficient to meet the current HMP criteria if the cross‐section areas and volumes recommended within this technical memorandum, and the respective orifice and outlet structure are incorporated as specified within the proposed project site.

Pico Place
November 3, 2022

5 KEY ASSUMPTIONS

1. Type C Soil is representative of the existing condition site. This is based on the site‐specific geotechnical investigation undertaken for the project site.

ATTACHMENTS

1. Q2 to Q10 Comparison Tables

2. FDC Plots (log and natural “x” scale) and Flow Duration Table.

3. List of the “n” largest Peaks: Pre‐Development and Post‐Development Conditions

4. Elevations vs. Discharge Curves to be used in SWMM

5. Pre & Post Development Maps, Project plan and section sketches

6. SWMM Input Data in Input Format (Existing and Proposed Models)

7. SWMM Screens and Explanation of Significant Variables

8. Geotechnical Documentation

9. Summary files from the SWMM Model

REFERENCES
[1] – “Review and Analysis of San Diego County Hydromodification Management Plan (HMP):

Assumptions, Criteria, Methods, & Modeling Tools – Prepared for the Cities of San Marcos, Oceanside & Vista”, May 2012, TRW Engineering.
[2] – “Final Hydromodification Management Plan (HMP) prepared for the County of San Diego”, March 2011, Brown and Caldwell.
[3] ‐ Order R9‐2013‐001, California Regional Water Quality Control Board San Diego Region (SDRWQCB).
[4] – “Handbook of Hydrology”, David R. Maidment, Editor in Chief. 1992, McGraw Hill. [5] – “City of San Marcos BMP Design Manual”, February 2016. [6] – “Improving Accuracy in Continuous Hydrologic Modeling: Guidance for Selecting Pervious Overland Flow Manning’s n Values in the San Diego Region”, TRWE, 2016.

Pico Place
November 3, 2022

6 Figure 1a and 1b. Flow Duration Curve Comparison (logarithmic and normal “x” scale) Pico Place
November 3, 2022

7 ATTACHMENT 1.

Q2 to Q10 Comparison Table – POC 1
Return Period Existing Condition (cfs) Mitigated Condition (cfs) Reduction, Exist ‐ Mitigated (cfs)
2‐year 0.193 0.019 0.174
3‐year 0.227 0.019 0.208
4‐year 0.242 0.019 0.223
5‐year 0.258 0.019 0.239
6‐year 0.276 0.019 0.257
7‐year 0.277 0.019 0.258
8‐year 0.285 0.019 0.266
9‐year 0.302 0.022 0.281
10‐year 0.317 0.037 0.280
ATTACHMENT 2

FLOW DURATION CURVE ANALYSIS
1) Flow duration curve shall not exceed the existing conditions by more than 10%, neither in peak flow nor duration.

The figures on the following pages illustrate that the flow duration curve in post‐development conditions after the proposed BMP is below the existing flow duration curve. The flow duration curve table following the curve shows that if the interval 0.10Q2 – Q10 is divided in 100 sub‐ intervals, then a) the post development divided by pre‐development durations are never larger than 110% (the permit allows up to 110%); and b) there are no more than 10 intervals in the range 101%‐110% which would imply an excess over 10% of the length of the curve (the permit allows less than 10% of excesses measured as 101‐110%).

Consequently, the design passes the hydromodification test.

It is important to note that the flow duration curve can be expressed in the “x” axis as percentage of time, hours per year, total number of hours, or any other similar time variable. As those variables only differ by a multiplying constant, their plot in logarithmic scale is going to look exactly the same, and compliance can be observed regardless of the variable selected.

However, in order to satisfy the City of San Marcos HMP example, % of time exceeded is the variable of choice in the flow duration curve. The selection of a logarithmic scale in lieu of the normal scale is preferred, as differences between the pre‐development and post‐development curves can be seen more clearly in the entire range of analysis. Both graphics are presented just to prove the difference.

In terms of the “y” axis, the peak flow value is the variable of choice. As an additional analysis performed by REC, not only the range of analysis is clearly depicted (10% of Q2 to Q10) but also all intermediate flows are shown (Q2, Q3, Q4, Q5, Q6, Q7, Q8 and Q9) in order to demonstrate compliance at any range Qx – Qx+1. It must be pointed out that one of the limitations of both the SWMM and SDHM models is that the intermediate analysis is not performed (to obtain Qi from i = 2 to 10). REC performed the analysis using the Cunnane Plotting position Method (the preferred method in the HMP permit) from the “n” largest independent peak flows obtained from the continuous time series.

The largest “n” peak flows are attached in this appendix, as well as the values of Qi with a return period “i”, from i=2 to 10. The Qi values are also added into the flow‐duration plot.

0.00 0.020.040.060.080.100.120.140.160.180.200.220.240.260.280.300.32

0.001 0.01 0.1
Q (cfs)
Percentage of time exceeded (%)
POC‐1 Pico Place ‐ Flow Duration Curve
ExistingProposedQx
0 0.020.040.060.08

0.1 0.120.140.160.18

0.2 0.220.240.260.28

0.3 0.32
0 0.02 0.04 0.06
Q (cfs)
Percentage of time exceeded (%)
POC‐1 Pico Place ‐ Flow Duration Curve
ExistingProposedQx
Flow Duration Curve Data for Pico Place POC 1 ‐ San Marcos, CA Q2 = 0.193 cfs Fraction 10 %
Q10 = 0.32 cfs
Step = 0.0030 cfs
Count = 394487 hours

45.00 years
Pass or
Q (cfs) Hours > Q% time Hours>Q % time Post/Pre Fail?
1 0.019 280 7.10E‐02 6 1.52E‐03 2% Pass
2 0.022 268 6.79E‐02 6 1.52E‐03 2% Pass
3 0.025 256 6.49E‐02 5 1.27E‐03 2% Pass
4 0.028 244 6.19E‐02 5 1.27E‐03 2% Pass
5 0.031 240 6.08E‐02 5 1.27E‐03 2% Pass
6 0.034 234 5.93E‐02 5 1.27E‐03 2% Pass
7 0.037 222 5.63E‐02 5 1.27E‐03 2% Pass
8 0.040 213 5.40E‐02 5 1.27E‐03 2% Pass
9 0.043 198 5.02E‐02 5 1.27E‐03 3% Pass
10 0.046 184 4.66E‐02 5 1.27E‐03 3% Pass
11 0.049 174 4.41E‐02 5 1.27E‐03 3% Pass
12 0.052 164 4.16E‐02 5 1.27E‐03 3% Pass
13 0.055 154 3.90E‐02 5 1.27E‐03 3% Pass
14 0.058 147 3.73E‐02 5 1.27E‐03 3% Pass
15 0.061 139 3.52E‐02 5 1.27E‐03 4% Pass
16 0.064 131 3.32E‐02 5 1.27E‐03 4% Pass
17 0.067 125 3.17E‐02 5 1.27E‐03 4% Pass
18 0.070 120 3.04E‐02 5 1.27E‐03 4% Pass
19 0.073 112 2.84E‐02 5 1.27E‐03 4% Pass
20 0.076 108 2.74E‐02 5 1.27E‐03 5% Pass
21 0.079 105 2.66E‐02 5 1.27E‐03 5% Pass
22 0.082 98 2.48E‐02 5 1.27E‐03 5% Pass
23 0.085 93 2.36E‐02 5 1.27E‐03 5% Pass
24 0.089 89 2.26E‐02 5 1.27E‐03 6% Pass
25 0.092 85 2.15E‐02 5 1.27E‐03 6% Pass
26 0.095 81 2.05E‐02 5 1.27E‐03 6% Pass
27 0.098 79 2.00E‐02 5 1.27E‐03 6% Pass
28 0.101 77 1.95E‐02 5 1.27E‐03 6% Pass
29 0.104 75 1.90E‐02 5 1.27E‐03 7% Pass
30 0.107 72 1.83E‐02 5 1.27E‐03 7% Pass
31 0.110 68 1.72E‐02 5 1.27E‐03 7% Pass
32 0.113 65 1.65E‐02 5 1.27E‐03 8% Pass
33 0.116 65 1.65E‐02 5 1.27E‐03 8% Pass
34 0.119 63 1.60E‐02 5 1.27E‐03 8% Pass
35 0.122 61 1.55E‐02 5 1.27E‐03 8% Pass
36 0.125 59 1.50E‐02 5 1.27E‐03 8% Pass
Detention Optimized
Interval
Existing Condition
Pass or
Q (cfs) Hours > Q% time Hours>Q % time Post/Pre Fail?
Detention Optimized
Interval
Existing Condition
37 0.128 57 1.44E‐02 5 1.27E‐03 9% Pass
38 0.131 57 1.44E‐02 5 1.27E‐03 9% Pass
39 0.134 51 1.29E‐02 5 1.27E‐03 10% Pass
40 0.137 49 1.24E‐02 5 1.27E‐03 10% Pass
41 0.140 48 1.22E‐02 5 1.27E‐03 10% Pass
42 0.143 45 1.14E‐02 5 1.27E‐03 11% Pass
43 0.146 43 1.09E‐02 5 1.27E‐03 12% Pass
44 0.149 42 1.06E‐02 5 1.27E‐03 12% Pass
45 0.152 41 1.04E‐02 5 1.27E‐03 12% Pass
46 0.155 41 1.04E‐02 5 1.27E‐03 12% Pass
47 0.158 41 1.04E‐02 5 1.27E‐03 12% Pass
48 0.161 41 1.04E‐02 5 1.27E‐03 12% Pass
49 0.164 40 1.01E‐02 5 1.27E‐03 13% Pass
50 0.167 39 9.89E‐03 5 1.27E‐03 13% Pass
51 0.170 35 8.87E‐03 5 1.27E‐03 14% Pass
52 0.173 30 7.60E‐03 5 1.27E‐03 17% Pass
53 0.176 29 7.35E‐03 5 1.27E‐03 17% Pass
54 0.179 28 7.10E‐03 5 1.27E‐03 18% Pass
55 0.182 27 6.84E‐03 5 1.27E‐03 19% Pass
56 0.185 27 6.84E‐03 5 1.27E‐03 19% Pass
57 0.188 27 6.84E‐03 5 1.27E‐03 19% Pass
58 0.191 25 6.34E‐03 5 1.27E‐03 20% Pass
59 0.194 22 5.58E‐03 5 1.27E‐03 23% Pass
60 0.197 22 5.58E‐03 5 1.27E‐03 23% Pass
61 0.200 22 5.58E‐03 5 1.27E‐03 23% Pass
62 0.203 20 5.07E‐03 5 1.27E‐03 25% Pass
63 0.206 18 4.56E‐03 5 1.27E‐03 28% Pass
64 0.209 18 4.56E‐03 5 1.27E‐03 28% Pass
65 0.212 17 4.31E‐03 5 1.27E‐03 29% Pass
66 0.215 17 4.31E‐03 5 1.27E‐03 29% Pass
67 0.218 16 4.06E‐03 5 1.27E‐03 31% Pass
68 0.221 16 4.06E‐03 5 1.27E‐03 31% Pass
69 0.224 16 4.06E‐03 5 1.27E‐03 31% Pass
70 0.227 15 3.80E‐03 4 1.01E‐03 27% Pass
71 0.230 14 3.55E‐03 4 1.01E‐03 29% Pass
72 0.233 12 3.04E‐03 4 1.01E‐03 33% Pass
73 0.236 12 3.04E‐03 4 1.01E‐03 33% Pass
74 0.239 12 3.04E‐03 4 1.01E‐03 33% Pass
75 0.242 11 2.79E‐03 4 1.01E‐03 36% Pass
76 0.245 11 2.79E‐03 4 1.01E‐03 36% Pass
77 0.248 11 2.79E‐03 4 1.01E‐03 36% Pass
78 0.251 9 2.28E‐03 4 1.01E‐03 44% Pass
79 0.254 9 2.28E‐03 4 1.01E‐03 44% Pass
80 0.257 9 2.28E‐03 4 1.01E‐03 44% Pass
81 0.260 9 2.28E‐03 4 1.01E‐03 44% Pass
Pass or
Q (cfs) Hours > Q% time Hours>Q % time Post/Pre Fail?
Detention Optimized
Interval
Existing Condition
82 0.263 9 2.28E‐03 4 1.01E‐03 44% Pass
83 0.266 8 2.03E‐03 4 1.01E‐03 50% Pass
84 0.269 8 2.03E‐03 4 1.01E‐03 50% Pass
85 0.272 8 2.03E‐03 4 1.01E‐03 50% Pass
86 0.275 8 2.03E‐03 4 1.01E‐03 50% Pass
87 0.278 6 1.52E‐03 4 1.01E‐03 67% Pass
88 0.281 6 1.52E‐03 4 1.01E‐03 67% Pass
89 0.284 6 1.52E‐03 4 1.01E‐03 67% Pass
90 0.287 5 1.27E‐03 4 1.01E‐03 80% Pass
91 0.290 5 1.27E‐03 4 1.01E‐03 80% Pass
92 0.293 5 1.27E‐03 4 1.01E‐03 80% Pass
93 0.296 5 1.27E‐03 4 1.01E‐03 80% Pass
94 0.299 5 1.27E‐03 4 1.01E‐03 80% Pass
95 0.302 5 1.27E‐03 4 1.01E‐03 80% Pass
96 0.305 5 1.27E‐03 4 1.01E‐03 80% Pass
97 0.308 5 1.27E‐03 4 1.01E‐03 80% Pass
98 0.311 5 1.27E‐03 4 1.01E‐03 80% Pass
99 0.314 5 1.27E‐03 4 1.01E‐03 80% Pass
100 0.317 4 1.01E‐03 4 1.01E‐03 100% Pass
Peak Flows calculated with Cunnane Plotting Position
Return Period
(years) Pre‐dev. Q (cfs) Post‐Dev. Q
(cfs)
Reduction
(cfs)
10 0.317 0.037 0.280
9 0.302 0.022 0.281
8 0.285 0.019 0.266
7 0.277 0.019 0.258
6 0.276 0.019 0.257
5 0.258 0.019 0.239
4 0.242 0.019 0.223
3 0.227 0.019 0.208
2 0.193 0.019 0.174
ATTACHMENT 3
List of the “n” Largest Peaks: Pre & Post‐Developed Conditions Basic Probabilistic Equation:

R = 1/P R: Return period (years).

P: Probability of a flow to be equaled or exceeded any given year (dimensionless).

Cunnane Equation: Weibull Equation:

Pൌ ୧ି଴.ସ
୬ା଴.ଶ Pൌ ୧୬ାଵ
i: Position of the peak whose probability is desired (sorted from large to small) n: number of years analyzed.

Explanation of Variables for the Tables in this Attachment Peak: Refers to the peak flow at the date given, taken from the continuous simulation hourly results of the n year analyzed.

Posit: If all peaks are sorted from large to small, the position of the peak in a sorting analysis is included under the variable Posit.

Date: Date of the occurrence of the peak at the outlet from the continuous simulation Note: all peaks are not annual maxima; instead they are defined as event maxima, with a threshold to separate peaks of at least 12 hours. In other words, any peak P in a time series is defined as a value where dP/dt = 0, and the peak is the largest value in 25 hours (12 hours before, the hour of occurrence and 12 hours after the occurrence, so it is in essence a daily peak).

List of Peak events and Determination of P2 and P10 (Pre‐Development) Pico Place POC 1 ‐ San Marcos
T
(Year)
Cunnane
(cfs)
Weibull
(cfs)
10 0.38 0.39 Date Posit Weibull Cunnane
9 0.36 0.38 0.155 12/6/1966 45 1.02 1.01
8 0.34 0.35 0.157 2/15/1992 44 1.05 1.04
7 0.34 0.34 0.157 2/8/1993 43 1.07 1.06
6 0.34 0.34 0.158 4/14/2003 42 1.10 1.09
5 0.31 0.31 0.163 4/1/1982 41 1.12 1.11
4 0.29 0.29 0.163 1/9/1998 40 1.15 1.14
3 0.27 0.27 0.174 12/5/1966 39 1.18 1.17
2 0.23 0.23 0.179 11/29/1982 38 1.21 1.20

0.182 2/21/2005 37 1.24 1.23

0.191 2/21/2000 36 1.28 1.27
Note: 0.198 3/8/1974 35 1.31 1.31
Cunnane is the preferred 0.198 1/18/1993 34 1.35 1.35
method by the HMP permit. 0.199 2/17/1998 33 1.39 1.39

0.2 1/4/1995 32 1.44 1.43

0.201 2/6/1976 31 1.48 1.48

0.201 9/10/1976 30 1.53 1.53

0.201 2/16/1980 29 1.59 1.58

0.204 4/21/1988 28 1.64 1.64

0.205 11/16/1972 27 1.70 1.70

0.209 11/23/1965 26 1.77 1.77

0.224 2/27/2001 25 1.84 1.84

0.224 2/12/2003 24 1.92 1.92

0.225 3/17/1963 23 2.00 2.00

0.24 1/29/1980 22 2.09 2.09

0.24 4/18/1995 21 2.19 2.19

0.246 1/6/1979 20 2.30 2.31

0.253 3/1/1983 19 2.42 2.43

0.257 1/9/2005 18 2.56 2.57

0.26 2/8/1983 17 2.71 2.72

0.266 11/30/1982 16 2.88 2.90

0.273 1/7/1974 15 3.07 3.10

0.282 2/28/1970 14 3.29 3.32

0.284 11/12/1976 13 3.54 3.59

0.294 12/18/1978 12 3.83 3.90

0.294 12/29/1978 11 4.18 4.26

0.302 2/14/1998 10 4.60 4.71

0.315 11/5/1987 9 5.11 5.26

0.339 2/3/1998 8 5.75 5.95

0.339 2/8/1998 7 6.57 6.85

0.341 12/29/2004 6 7.67 8.07

0.382 3/17/1982 5 9.20 9.83

0.392 1/10/1978 4 11.50 12.56

0.413 1/25/1995 3 15.33 17.38

0.423 3/24/1983 2 23.00 28.25

0.472 2/21/1980 1 46.00 75.33
Peaks (cfs)
Period of Return
(Years)
List of Peak events and Determination of P2 and P10 (Post‐Development) Pico Place POC 1 ‐ San Marcos
T
(Year)
Cunnane
(cfs)
Weibull
(cfs)
10 0.04 0.09 Date Posit Weibull Cunnane
9 0.02 0.02 0.019 2/9/1963 45 1.02 1.01
8 0.02 0.02 0.019 2/9/1963 44 1.05 1.04
7 0.02 0.02 0.019 2/9/1963 43 1.07 1.06
6 0.02 0.02 0.019 2/9/1963 42 1.10 1.09
5 0.02 0.02 0.019 2/10/1963 41 1.12 1.11
4 0.02 0.02 0.019 2/10/1963 40 1.15 1.14
3 0.02 0.02 0.019 2/10/1963 39 1.18 1.17
2 0.02 0.02 0.019 2/10/1963 38 1.21 1.20

0.019 2/10/1963 37 1.24 1.23

0.019 2/10/1963 36 1.28 1.27
Note: 0.019 2/10/1963 35 1.31 1.31
Cunnane is the preferred 0.019 2/10/1963 34 1.35 1.35
method by the HMP permit. 0.019 2/11/1963 33 1.39 1.39

0.019 2/11/1963 32 1.44 1.43

0.019 2/11/1963 31 1.48 1.48

0.019 2/11/1963 30 1.53 1.53

0.019 2/11/1963 29 1.59 1.58

0.019 2/11/1963 28 1.64 1.64

0.019 2/11/1963 27 1.70 1.70

0.019 3/17/1963 26 1.77 1.77

0.019 3/17/1963 25 1.84 1.84

0.019 3/17/1963 24 1.92 1.92

0.019 3/17/1963 23 2.00 2.00

0.019 11/21/1963 22 2.09 2.09

0.019 11/21/1963 21 2.19 2.19

0.019 11/16/1965 20 2.30 2.31

0.019 11/16/1965 19 2.42 2.43

0.019 11/16/1965 18 2.56 2.57

0.019 11/16/1965 17 2.71 2.72

0.019 11/17/1965 16 2.88 2.90

0.019 11/17/1965 15 3.07 3.10

0.019 11/22/1965 14 3.29 3.32

0.019 11/22/1965 13 3.54 3.59

0.019 11/22/1965 12 3.83 3.90

0.019 11/22/1965 11 4.18 4.26

0.019 11/22/1965 10 4.60 4.71

0.019 11/22/1965 9 5.11 5.26

0.019 11/23/1965 8 5.75 5.95

0.019 11/23/1965 7 6.57 6.85

0.019 11/23/1965 6 7.67 8.07

0.024 1/29/1980 5 9.20 9.83

0.226 1/29/1980 4 11.50 12.56

0.89 2/21/1980 3 15.33 17.38

1.34 12/5/1966 2 23.00 28.25

1.5 1/4/1995 1 46.00 75.33
Peaks (cfs)
Period of Return
(Years)
ATTACHMENT 4

AREA VS ELEVATION
The storage provided by the detention vault is entered into the Storage Module within SWMM – please refer to Attachment 7 for further information. It should be noted that all facilities are walled; as such the stage‐area relationship is a constant. A stage‐storage calculation is provided on the following page for verification.

DISCHARGE VS ELEVATION
Due to elevation constraints on the project site, the outlets from the vault are pumps – as such a constant flow out from the vault is experienced when the volume within the basin exceeds the invert elevation of the pump outlet invert.

DISCHARGE EQUATIONS
1) Weir:
ܳௐ ൌ ܥௐ ൉ܮ൉ܪଷ/ଶ (1)
2) Slot:

As an orifice: ܳ௦ ൌܤ௦ ൉݄௦ ൉ܿ௚ ൉ ට2݃ ቀܪെ ௛ೞ
ଶ ቁ   (2.a)
As a weir: ܳ௦ ൌܥௐ ൉ܤ௦ ൉ܪଷ/ଶ   (2.b)
For H > hs slot works as weir until orifice equation provides a smaller discharge.   The elevation such that equation (2.a) = equation (2.b) is the elevation at which the behavior changes from weir to orifice. 3) Vertical Orifices
As an orifice:   ܳ௢ ൌ 0.25 ൉ ܦߨଶ ൉ܿ௚ ൉ ට2݃ ቀܪെ ஽
ଶ
ቁ   (3.a)
As a weir:  Critical depth and geometric family of circular sector must be solved to determined Q as a function of H:
ܳை
ଶ
݃ ൌ ܣ௥௖
ଷ
ܶ௖௥
൅ ௥௖ݕ ൌ ܪ ;
௥௖ܣ
2൉ܶ௖௥
; ܶ௖௥ ൌ2ඥݕ௥௖ሺܦെݕ௥௖ሻ ; ܣ ௥௖ൌ
ܦଶ
8 ሾߙ ௥௖െ ݏ݅݊ሺߙ௥௖ሻሿ ;
ݕ ௥௖ൌ
஽
ଶ ሾ1 െ ݏ݅݊ሺ0.5 ൉ ߙ௥௖ሻሿ         (3.b.1, 3.b.2, 3.b.3, 3.b.4 and 3.b.5) There is a value of H (approximately H = 110% D) from which orifices no longer work as weirs as critical depth is not possible at the entrance of the orifice. This value of H is obtained equaling the discharge using critical equations and equations (3.b).

A mathematical model is prepared with the previous equations depending on the type o discharge.

The following are the variables used above:

QW, Qs, QO = Discharge of weir, slot or orifice (cfs)
CW, cg : Coefficients of discharge of weir (typically 3.1) and orifice (0.61 to 0.62) L, Bs, D, hs : Length of weir, width of slot, diameter of orifice and height of slot, respectively; (ft) H: Level of water in the pond over the invert of slot, weir or orifice (ft) Acr, Tcr, ycr, αcr: Critical variables for circular sector: area (sq‐ft), top width (ft), critical depth (ft), and angle to the center, respectively.

Stage‐Storage‐Discharge Summary Table
Depth (ft) Area (ft2) Volume (ft3) Ac‐Ft Q‐out (cfs)
0 400 0 0 0
1 400 400 0.009183 0
2 400 800 0.018365 0
3 400 1200 0.027548 0 DCV Contained

3.2 400 1280 0.029385 0.015
4 400 1600 0.036731 0.015
5 400 2000 0.045914 0.015
6 400 2400 0.055096 0.015
7 400 2800 0.064279 0.015

7.25 400 2900 0.066575 1.5015
8 400 3200 0.073462 1.5015
9 400 3600 0.082645 1.5015
ATTACHMENT 5
Pre & Post‐Developed Maps, Project Plan and Detention
Section Sketches

1 DMA/BMP PLAN - PROPOSED

PICO PLACE
236-244 SAN MARCOS PICO AVENUE
SAN MARCOS, CA 92069

ATTACHMENT 6
SWMM Input Data in Input Format (Existing & Proposed Models)

PRE_DEV
[TITLE]
[OPTIONS]
FLOW_UNITS CFS
INFILTRATION GREEN_AMPT
FLOW_ROUTING KINWAVE
START_DATE 10/05/1962
START_TIME 00:00:00
REPORT_START_DATE 10/05/1962
REPORT_START_TIME 00:00:00
END_DATE 10/05/2007
END_TIME 23:00:00
SWEEP_START 01/01
SWEEP_END 12/31
DRY_DAYS 0
REPORT_STEP 01:00:00
WET_STEP 00:15:00
DRY_STEP 04:00:00
ROUTING_STEP 0:01:00
ALLOW_PONDING NO
INERTIAL_DAMPING PARTIAL
VARIABLE_STEP 0.75
LENGTHENING_STEP 0
MIN_SURFAREA 0
NORMAL_FLOW_LIMITED BOTH
SKIP_STEADY_STATE NO
FORCE_MAIN_EQUATION H-W
LINK_OFFSETS DEPTH
MIN_SLOPE 0
[EVAPORATION]
;;Type Parameters
;;---------- ----------
MONTHLY 0.07 0.1 0.13 0.17 0.19 0.22 0.24 0.22 0.19 0.13 0.09 0.06 DRY_ONLY NO
[RAINGAGES]
;; Rain Time Snow Data
;;Name Type Intrvl Catch Source
;;-------------- --------- ------ ------ ----------
Poway INTENSITY 1:00 1.0 TIMESERIES Poway
[SUBCATCHMENTS]
;; Total Pcnt. Pcnt. Curb Snow
;;Name Raingage Outlet Area Imperv Width Slope Length Pack ;;-------------- ---------------- ---------------- -------- -------- -------- -------- -------- -------- DMA-1-C Poway POC-1 0.675 0 114 1 0
[SUBAREAS]
;;Subcatchment N-Imperv N-Perv S-Imperv S-Perv PctZero RouteTo PctRouted ;;-------------- ---------- ---------- ---------- ---------- ---------- ---------- ---------- DMA-1-C 0.012 0.05 0.05 0.1 25 OUTLET
[INFILTRATION]
;;Subcatchment Suction HydCon IMDmax
;;-------------- ---------- ---------- ----------
DMA-1-C 6 0.075 0.32
[OUTFALLS]
;; Invert Outfall Stage/Table Tide
;;Name Elev. Type Time Series Gate
;;-------------- ---------- ---------- ---------------- ---- POC-1 0 FREE NO
[TIMESERIES]
;;Name Date Time Value
;;-------------- ---------- ---------- ----------
Poway FILE "PowayRain.prn"
[REPORT]

INPUT NO
PRE_DEV

CONTROLS NO

SUBCATCHMENTS ALL

NODES ALL

LINKS ALL
[TAGS]
[MAP]
DIMENSIONS -2332.031 5700.000 3253.906 12300.000
Units None
[COORDINATES]
;;Node X-Coord Y-Coord
;;-------------- ------------------ ------------------
POC-1 -1889.283 9043.612
[VERTICES]
;;Link X-Coord Y-Coord
;;-------------- ------------------ ------------------
[Polygons]
;;Subcatchment X-Coord Y-Coord
;;-------------- ------------------ ------------------
DMA-1-C -2819.679 11253.304
[SYMBOLS]
;;Gage X-Coord Y-Coord
;;-------------- ------------------ ------------------
Poway 3324.814 11388.987
POST_DEV
[TITLE]
[OPTIONS]
FLOW_UNITS CFS
INFILTRATION GREEN_AMPT
FLOW_ROUTING KINWAVE
START_DATE 10/05/1962
START_TIME 00:00:00
REPORT_START_DATE 10/05/1962
REPORT_START_TIME 00:00:00
END_DATE 10/05/2007
END_TIME 23:00:00
SWEEP_START 01/01
SWEEP_END 12/31
DRY_DAYS 0
REPORT_STEP 01:00:00
WET_STEP 00:15:00
DRY_STEP 04:00:00
ROUTING_STEP 0:01:00
ALLOW_PONDING NO
INERTIAL_DAMPING PARTIAL
VARIABLE_STEP 0.75
LENGTHENING_STEP 0
MIN_SURFAREA 0
NORMAL_FLOW_LIMITED BOTH
SKIP_STEADY_STATE NO
FORCE_MAIN_EQUATION H-W
LINK_OFFSETS DEPTH
MIN_SLOPE 0
[EVAPORATION]
;;Type Parameters
;;---------- ----------
MONTHLY 0.07 0.1 0.13 0.17 0.19 0.22 0.24 0.22 0.19 0.13 0.09 0.06 DRY_ONLY NO
[RAINGAGES]
;; Rain Time Snow Data
;;Name Type Intrvl Catch Source
;;-------------- --------- ------ ------ ----------
Poway INTENSITY 1:00 1.0 TIMESERIES Poway
[SUBCATCHMENTS]
;; Total Pcnt. Pcnt. Curb Snow
;;Name Raingage Outlet Area Imperv Width Slope Length Pack ;;-------------- ---------------- ---------------- -------- -------- -------- -------- -------- -------- DMA-1-C Poway 1 0.675 74.79 114 1 0
[SUBAREAS]
;;Subcatchment N-Imperv N-Perv S-Imperv S-Perv PctZero RouteTo PctRouted ;;-------------- ---------- ---------- ---------- ---------- ---------- ---------- ---------- DMA-1-C 0.012 0.05 0.05 0.1 25 OUTLET
[INFILTRATION]
;;Subcatchment Suction HydCon IMDmax
;;-------------- ---------- ---------- ----------
DMA-1-C 6 0.075 0.32
[OUTFALLS]
;; Invert Outfall Stage/Table Tide
;;Name Elev. Type Time Series Gate
;;-------------- ---------- ---------- ---------------- ---- POC-1 0 FREE NO
[STORAGE]
;; Invert Max. Init. Storage Curve Ponded Evap.
;;Name Elev. Depth Depth Curve Params Area Frac. Infiltration Parameters
;;-------------- -------- -------- -------- ---------- -------- -------- -------- -------- -------- ----------------- ------
1 0 9 0 TABULAR Vault 400 0 6 1.37

0.32 POST_DEV
[OUTLETS]
;; Inlet Outlet Outflow Outlet Qcoeff/ Flap
;;Name Node Node Height Type QTable Qexpon Gate
;;-------------- ---------------- ---------------- ---------- --------------- ---------------- ---------- ---- 1 1 POC-1 0 TABULAR/DEPTH Out NO
[CURVES]
;;Name Type X-Value Y-Value
;;-------------- ---------- ---------- ----------
Out Rating 0 0
Out 0.49 0
Out 0.5 0
Out 1 0
Out 2 0
Out 2.99 0.0001
Out 3.0 0.0185
Out 3.2 0.0185
Out 4 0.0185
Out 5 0.0185
Out 6 0.0185
Out 7 0.0185
Out 7.24 0.0185
Out 7.25 1.50
Out 8 1.51
Out 9 1.52
Vault Storage 0 400
Vault 9 400
[TIMESERIES]
;;Name Date Time Value
;;-------------- ---------- ---------- ----------
Poway FILE "PowayRain.prn"
[REPORT]

INPUT NO

CONTROLS NO

SUBCATCHMENTS ALL

NODES ALL

EPA SWMM FIGURES AND EXPLANATIONS
Per the attached, the reader can see the screens associated with the EPA‐SWMM Model in both pre‐development and post‐development conditions. Each portion, i.e., sub‐catchments, outfalls, storage units, weir as a discharge, and outfalls (point of compliance), are also shown.

Variables for modeling are associated with typical recommended values by the EPA‐SWMM model, typical values found in technical literature (such as Maidment’s Handbook of Hydrology). Recommended values for the SWMM model have been attained from Appendix G of the 2016 City of San Marcos BMP Design Manual.

Soil characteristics of the existing soils were determined from the NRCS Web Soil Survey and site specific geotechnical report (located in Attachment 8 of this report).

A Technical document prepared by Tory R Walker Engineering for the Cities of San Marcos, Oceanside and Vista (Reference [1]) can also be consulted for additional information regarding typical values for SWMM parameters.

Manning’s roughness coefficients have been based upon the findings of the “Improving Accuracy in Continuous Hydrologic Modeling: Guidance for Selecting Pervious Overland Flow Manning’s n Values in the San Diego Region” date 2016 by TRW Engineering (Reference [6]).

PRE‐DEVELOPED CONDITION

POST‐DEVELOPED CONDITION

Detention Basin

EXPLANATION OF SELECTED VARIABLES
Sub Catchment Areas:

Please refer to the attached diagrams that indicate the DMA and detention BMPs (BMP) sub areas modeled within the project site at both the pre and post developed conditions draining to the POC.

Parameters for the pre‐ and post‐developed models include soil type C as determined from the NRCS websoil survey review (attached at the end of this appendix). Suction head, conductivity and initial deficit corresponds to average values expected for these soils types, according to Appendix G of the 2016 City of San Marcos BMP Design Manual.

For surface runoff infiltration values, REC selected infiltration values per Appendix G of the 2016 City of San Marcos BMP Design Manual corresponding to hydrologic soil type.

Selection of a Kinematic Approach: As the continuous model is based on hourly rainfall, and the time of concentration for the pre‐development and post‐development conditions is significantly smaller than 60 minutes, precise routing of the flows through the impervious surfaces, the underdrain pipe system, and the discharge pipe was considered unnecessary. The truncation error of the precipitation into hourly steps is much more significant than the precise routing in a system where the time of concentration is much smaller than 1 hour.

Overland Flow Manning’s Coefficient per TRWE (Reference [6]) 3 Further discussion is provided on page 6 under “Discussion of Differences Between Manning’s n Values” 3 appeal of a de facto value, we anticipate that jurisdictions will not be inclined to approve land surfaces other than short prairie grass. Therefore, in order to provide SWMM users with a wider range of land surfaces suitable for local application and to provide Copermittees with confidence in the design parameters, we recommend using the values published by Yen and Chow in Table 3-5 of the EPA SWMM Reference Manual Volume I – Hydrology.

SWMM-Endorsed Values Will Improve Model Quality
In January 2016, the EPA released the SWMM Reference Manual Volume I – Hydrology (SWMM Hydrology Reference Manual). The SWMM Hydrology Reference Manual complements the SWMM 5 User’s Manual and SWMM 5 Applications Manual by providing an in-depth description of the program’s hydrologic components (EPA 2016). Table 3-5 of the SWMM Hydrology Reference Manual expounds upon SWMM 5 User’s Manual Table A.6 by providing Manning’s n values for additional overland flow surfaces3
. The values are provided in Table 1:

Table 1: Manning’s n Values for Overland Flow (EPA, 2016; Yen 2001; Yen and Chow, 1983).

Overland Surface Light Rain
(< 0.8 in/hr)
Moderate Rain
(0.8-1.2 in/hr)
Heavy Rain
(> 1.2 in/hr)
Smooth asphalt pavement 0.010 0.012 0.015
Smooth impervious surface 0.011 0.013 0.015
Tar and sand pavement 0.012 0.014 0.016
Concrete pavement 0.014 0.017 0.020
Rough impervious surface 0.015 0.019 0.023
Smooth bare packed soil 0.017 0.021 0.025
Moderate bare packed soil 0.025 0.030 0.035
Rough bare packed soil 0.032 0.038 0.045
Gravel soil 0.025 0.032 0.045
Mowed poor grass 0.030 0.038 0.045
Average grass, closely clipped sod 0.040 0.050 0.060
Pasture 0.040 0.055 0.070
Timberland 0.060 0.090 0.120
Dense grass 0.060 0.090 0.120
Shrubs and bushes 0.080 0.120 0.180
Land Use
Business 0.014 0.022 0.035
Semibusiness 0.022 0.035 0.050
Industrial 0.020 0.035 0.050
Dense residential 0.025 0.040 0.060
Suburban residential 0.030 0.055 0.080
Parks and lawns 0.040 0.075 0.120
For purposes of local hydromodification management BMP design, these Manning’s n values are an improvement upon the values presented by Engman (1986) in SWMM 5 User’s Manual Table A.6. Values from SWMM 5 User’s Manual Table A.6, while completely suitable for the intended application to certain agricultural land covers, comes with the disclaimer that the provided Manning’s n values are valid for shallow-depth overland flow that match the conditions in the experimental plots (Engman, ATTACHMENT 8
Geotechnical Documentation

3 Corporate Park, Suite 270, Irvine, California 92606
Office (949) 221-0900 Fax (949) 221-0091
Email: [email protected]
August 31, 2022
Project 9421-04
DMS Consultants, Inc.
12377 Lewis Street, Suite 203
Garden Grove, California 92840
Attention: Mr. Surender Dewan, P. E.

President
Subject: Geotechnical Investigation
Proposed Multi-Family Residential Development
236 and 244 Pico Avenue
San Marcos, California
References: See Appendix A
Dear Mr. Dewan:

1. INTRODUCTION
a) In accordance with your request, we have conducted a geotechnical investigation for the proposed residential development located in San Marcos, California. b) We understand that the proposed development will consist of the construction of four 3-story, multi-family residential structures, each unit approximately 1,170- squarefoot, with related parking/driveway areas on a 0.67-acre parcel of land. In addition, an infiltration system is planned to be installed for potential stormwater runoff.
c) Grading and structural plans are not available at present. We are assuming that the existing grades will remain unchanged. We anticipate the loads from the proposed structures will not exceed 3 kip/ft for the continuous footings and 50 kips for the column footings.

2. SCOPE
The scope of services we provided were as follows:
a) Preliminary planning and evaluations, and review of geotechnical reports related to the project site and nearby surrounding area (See References – Appendix A); GLOBAL GEO-ENGINEERING, INC.

DMS Consultants, Inc.

August 31, 2022
Project 9421-04

Page 2 ends

3. FIELD EXPLORATION AND LABORATORY TESTING
The field exploration program is given in Appendix B, which includes the Logs of Borings.

The results of the laboratory testing are included in Appendix C.

4. SITE DESCRIPTION

4.1 Location

LOCATION MAP
244 Pico Avenue
San Marcos, California
Date: August 2022
Project No.: 9421-04
Figure No:

GLOBAL GEO-ENGINEERING, INC.

GEOLOGIC AND SOILS ENGINEERING IRVINE, CALIFORNIA
1 2000 0 2000 4000

SCALE FEET
BASE MAP: USGS 7.5-Minute Topographic Map,
San Marcos Quadrangle, 1999 N
O
R
T
H
SITE
DMS Consultants, Inc.

August 31, 2022
Project 9421-04

Page 3 ends

4.3 Geology

4.3.2 Local Geologic Setting
In general, the project site area is underlain by Recent- to Older-aged alluvial deposits which overlie granitic bedrock.

DMS Consultants, Inc.

August 31, 2022
Project 9421-04

Page 4 ends

5. SEISMICITY

DMS Consultants, Inc.

August 31, 2022
Project 9421-04

Page 5 ends

5.4 Liquefaction
The subject site is underlain by dense soil layers overlying a Tonalite bedrock.

The potential for the liquefaction is considered to be low.

6. CONCLUSIONS AND RECOMMENDATIONS

GEOLOGIC AND SOILS ENGINEERING

IRVINE, CALIFORNIA

MAJOR EARTHQUAKES AND RECENTLY ACTIVE FAULTS IN THE

SOUTHERN CALIFORNIA REGION

EXPLANATION

Earthquake epicenters since 1933, plotted from
instruments. 33 moderate** and five major
earthquakes were in the 66-year period 1933 to 1999.

ACTIVE FAULTS
Total length of fault zone that breaks
Halocene deposits or that has had
seismic activity.

Fault segment with surface rupture
during an historic earthquake, or with
aseismic fault creep.

SITE
DMS Consultants, Inc.

August 31, 2022
Project 9421-04

Page 6 ends

6.2 Grading

August 31, 2022
Project 9421-04

Page 7 ends

d) Rocks greater than 4 inches in diameter should not be incorporated in compacted fill to within one foot of the underside of the footings and slabs.

6.2.5 Shrinkage
For preliminary earthwork calculation, an average shrinkage factor of approximately 5 percent is recommended for the soils (this does not include handling losses).

DMS Consultants, Inc.

August 31, 2022
Project 9421-04

Page 8 ends

6.2.7 Sulphate Content
a) The sulphate contents of representative samples of the soil are less than 0.1%. The sulphate exposure is considered to be negligible.

Type II Portland cement is recommended for the construction. a) The fill materials should be tested for their sulphate content during the final stage of rough grading.

DMS Consultants, Inc.

August 31, 2022
Project 9421-04

Page 9 ends

6.4 Spread Foundations
The proposed structures can be founded on shallow spread footings. The criteria presented as follows should be adopted:

6.4.2 Allowable Bearing Capacity
Embedment Depth
(ft.)
Allowable Bearing Capacity
(lb/ft2)

August 31, 2022
Project 9421-04

Page 10 ends

6.5 Lateral Pressures
a) The following lateral pressures are recommended for the design of retaining structures.

August 31, 2022
Project 9421-04

Page 11 ends

6.6 Seismic Coefficients and Liquefaction Potential
a) For seismic analysis of the proposed project in accordance with the seismic provisions of ASCE 7-16, we recommend the following:

DMS Consultants, Inc.

August 31, 2022
Project 9421-04

Page 12 ends

6.7 Pavement Design

6.7.4 Concrete Pavement

6.8 Corrosion Potential
a) Soil Corrosion potential for metal and concrete was estimated by performing water-soluble sulfate, chloride, pH, and electrical resistivity tests during this investigation.

Location T.I. Asphaltic Concrete
(inches)
Aggregate Base
(inches)
Parking and Driveways Up to 5.0 3 4
Driveway
(light truck traffic) 6.0 3 6
DMS Consultants, Inc.

August 31, 2022
Project 9421-04

Page 13 ends

b) Electrical resistivity is a measure of soil resistance to the flow of corrosion currents. Corrosion currents are generally high in low resistivity soils.

This potential should be considered in design of underground metal pipes.

Boring No. Percolation Rate (inch/hour)
P-1 3.0
c) These rates are calculated using a factor of safety of 1.0. Appropriate factor of safety should be utilized while designing the basin.

DMS Consultants, Inc.

August 31, 2022
Project 9421-04

Page 14 ends

The opportunity to be of service is sincerely appreciated. If you have any questions or if we can be of further assistance, please call.

Very truly yours,
GLOBAL GEO-ENGINEERING, INC.

Mohan B. Upasani Kevin B. Young
Principal Geotechnical Engineer Principal Engineering Geologist RGE 2301 CEG 2253
(Exp. March 31, 2023) (Exp. October 31, 2023)
MBU/KBY: fdg
Enclosures:

APPENDIX A
References

1. California Geological Survey, Earthquake Fault Zones of Required Investigation, (Internet).

2. California Division of Mines and Geology, 1996, Geologic Maps of the Northwestern Part of San Diego County, California, CDMG Open File Report 96-02.

3. California Office of Statewide Health Planning and Development, Seismic Design Maps Web Tool, ASCE 7-16 Standard (Internet).

4. United States Geological Survey, 1948, San Marcos Quadrangle, 7.5-Minute Topographic Series.

5. United States Geological Survey, 1968, San Marcos Quadrangle, 7.5-Minute Topographic Series.

6. United States Geological Survey, 1968 photorevised 1983, San Marcos Quadrangle, 7.5- Minute Topographic Series.

Project 9421-04

UNIFIED SOILS CLASSIFICATION (ASTM D-2487)

PRIMARY DIVISION GROUP SYMBOL SECONDARY DIVISIONS

COARSE GRAINED SOILS
More than half of materials is
larger than #200 sieve size

SP Poorly graded sands or gravelly sands, little or no fines.

Sands with
Fines
SM Silty sands, sand-silt mixtures. Non-Plastic fines.

SC Clayey sands, sand-clay mixtures. Plastic fines.

FINE GRAINED SOILS
More than half of material is
smaller than #200 sieve size

SILTS AND
CLAYS

LIQUID LIMIT

OL Organic silts and organic silty clays of low plasticity.

SILTS AND
CLAYS

LIQUID LIMIT

IS GREATER
THAN 50
MH Inorganic silts, micaceous or diatomaceous fine sandy or silty soils, elastic silts.

CH Inorganic clays of high plasticity, fat clays
OH Organic clays of medium to high plasticity, organic silts.

Highly Organic Soils PT Peat and other highly organic soils.

CLASSIFICATION BASED ON FIELD TESTS

CLASSIFICATION CRITERIA BASED ON LAB TESTS

CLASSIFICATION OF EARTH MATERIAL IS BASED ON FIELD INSPECTION

AND SHOULD NOT BE CONSTRUED TO IMPLY LABORATORY ANALYSIS UNLESS SO STATED.

C
L
CL
CL-ML
OH
Or
MH
OL
or
ML ML
CH
GLOBAL GEO-ENGINEERING, INC.

GEOLOGIC AND SOILS ENGINEERING, IRVINE, CALIFORNIA
244 Pico Avenue
San Marcos, California
Date: August 2022
Project No.: 9421-04
Figure No.:

B-1
Global Geo-Engineering, Inc.

7.6 6.8

12.9 15.0

19.3 15.0
Dry Densitylb./cubic ft.
116.7
112.6
116.2
115.5
109.6
115.4
Blow Count
55 29
100
39 38
23 Relative Compaction
Water Level
USCS
SM
SM/ML
ML
SP

GRAPHIC

19.5 17.2

9.1 Dry Densitylb./cubic ft.
106.0
104.9
129.3
Blow Count
18 12
100
Relative Compaction
Water Level
USCS
SP
SP/ML
GR

GRAPHIC

ALLUVIUM
TONALITE: fine textured, hard

BASEMENT ROCK
Bottom of Boring at 40 feet:

Notes:

1. Caving to 23 feet after augers were removed

2. Water encountered at 24', Static water level measured at 23.5'

3. Boring backfilled
Global Geo-Engineering, Inc.

13.5 11.0

11.2 14.0

12.0 Dry Densitylb./cubic ft.
113.8
107.2
112.5
114.2
113.4
Blow Count
20 45
35 48
20 Relative Compaction
Water Level
USCS
CL/ML
ML
ML/SM
ML
SM

GRAPHIC

Notes:

1. Caving to 15.5 feet after augers were removed

2. No groundwater or seepage encountered

3. Boring backfilled
244 Pico Avenue
San Marcos, California
Date: January 2023
Project No.: 9421-04
Figure No:

GLOBAL GEO-ENGINEERING, INC.

GEOLOGIC AND SOILS ENGINEERING IRVINE, CALIFORNIA B-5

BORING LOCATION PLAN
N
B-2
20’
B-1

39.5 ’
Not to Scale
P-1
5’
Approximate Location of Percolation
Boring, Showing Total Depth
KEY
P-1
5’
Approximate Location of Boring,
Showing Total Depth
B-2
20’
Project 9421-04

This test procedure requires 25 blows of a 10-pound hammer falling a height of 18 inches on each of five layers, in a 1/30 cubic foot cylinder. The results of the test are presented below.

Boring No. Sample Depth
(ft.) Soil Description
Optimum
Moisture
Content
(%)
Maximum
Dry Density
(lb/ft3
)
B-1 1-3 Clayey Silty SAND 9.9 127.3
Appendix C
Project 9421-04

Page 18 ends

Boring No. Sample Depth
(ft)
Soil
Description
Chloride Content
(%)
B-1 1-3 Clayey Silty SAND 0.0023
Appendix C
Project 9421-04

Page 19 ends

f) Resistivity and pH
A representative soil sample was analyzed in accordance with California Test Methods CA532 and CA643 to determine the minimum resistivity and pH. The result is provided below:

Boring No. Sample Depth
(ft)
Soil
Description pH
Minimum
Resistivity
(Ohm-cm)
B-1

1-3 Clayey Silty SAND 8.1 3,339

Boring No. Sample Depth
(ft)
Soil
Description
Expansion
Index
Expansion
Potential
B-2 2 Sandy Silty CLAY 70 Medium
ATTACHMENT 9
Summary Files from the SWMM Model
PRE_DEV
EPA STORM WATER MANAGEMENT MODEL - VERSION 5.0 (Build 5.0.022) --------------------------------------------------------------

********************************************************* NOTE: The summary statistics displayed in this report are based on results found at every computational time step, not just on results from each reporting time step.
*********************************************************

****************
Analysis Options
****************
Flow Units ............... CFS
Process Models:

Rainfall/Runoff ........ YES
Snowmelt ............... NO
Groundwater ............ NO
Flow Routing ........... NO
Water Quality .......... NO
Infiltration Method ...... GREEN_AMPT
Starting Date ............ OCT-05-1962 00:00:00
Ending Date .............. OCT-05-2007 23:00:00
Antecedent Dry Days ...... 0.0
Report Time Step ......... 01:00:00
Wet Time Step ............ 00:15:00
Dry Time Step ............ 04:00:00

************************** Volume Depth
Runoff Quantity Continuity acre-feet inches
************************** --------- -------
Total Precipitation ...... 30.777 547.150
Evaporation Loss ......... 0.477 8.477
Infiltration Loss ........ 28.588 508.225
Surface Runoff ........... 1.944 34.554
Final Surface Storage .... 0.000 0.000
Continuity Error (%) ..... -0.750

************************** Volume Volume
Flow Routing Continuity acre-feet 10^6 gal
************************** --------- ---------
Dry Weather Inflow ....... 0.000 0.000
Wet Weather Inflow ....... 1.944 0.633
Groundwater Inflow ....... 0.000 0.000
RDII Inflow .............. 0.000 0.000
External Inflow .......... 0.000 0.000
External Outflow ......... 1.944 0.633
Internal Outflow ......... 0.000 0.000
Storage Losses ........... 0.000 0.000
Initial Stored Volume .... 0.000 0.000
Final Stored Volume ...... 0.000 0.000
Continuity Error (%) ..... 0.000

***************************
Subcatchment Runoff Summary
***************************

-------------------------------------------------------------------------------------------------------- Total Total Total Total Total Total Peak Runoff
Precip Runon Evap Infil Runoff Runoff Runoff Coeff
Subcatchment in in in in in 10^6 gal CFS
-------------------------------------------------------------------------------------------------------- DMA-1-C 547.15 0.00 8.48 508.22 34.55 0.63 0.47 0.063

Analysis begun on: Sat Nov 05 10:52:00 2022
Analysis ended on: Sat Nov 05 10:52:24 2022
Total elapsed time: 00:00:24
POST_DEV
EPA STORM WATER MANAGEMENT MODEL - VERSION 5.0 (Build 5.0.022) --------------------------------------------------------------

****************
Analysis Options
****************
Flow Units ............... CFS
Process Models:

Rainfall/Runoff ........ YES
Snowmelt ............... NO
Groundwater ............ NO
Flow Routing ........... YES
Ponding Allowed ........ NO
Water Quality .......... NO
Infiltration Method ...... GREEN_AMPT
Flow Routing Method ...... KINWAVE
Starting Date ............ OCT-05-1962 00:00:00
Ending Date .............. OCT-05-2007 23:00:00
Antecedent Dry Days ...... 0.0
Report Time Step ......... 01:00:00
Wet Time Step ............ 00:15:00
Dry Time Step ............ 04:00:00
Routing Time Step ........ 60.00 sec

************************** Volume Depth
Runoff Quantity Continuity acre-feet inches
************************** --------- -------
Total Precipitation ...... 30.777 547.150
Evaporation Loss ......... 4.429 78.736
Infiltration Loss ........ 7.152 127.142
Surface Runoff ........... 19.497 346.620
Final Surface Storage .... 0.000 0.000
Continuity Error (%) ..... -0.977

************************** Volume Volume
Flow Routing Continuity acre-feet 10^6 gal
************************** --------- ---------
Dry Weather Inflow ....... 0.000 0.000
Wet Weather Inflow ....... 19.497 6.354
Groundwater Inflow ....... 0.000 0.000
RDII Inflow .............. 0.000 0.000
External Inflow .......... 0.000 0.000
External Outflow ......... 2.259 0.736
Internal Outflow ......... 0.000 0.000
Storage Losses ........... 17.348 5.653
Initial Stored Volume .... 0.000 0.000
Final Stored Volume ...... 0.000 0.000
Continuity Error (%) ..... -0.561

********************************
Highest Flow Instability Indexes
********************************
All links are stable.

*************************
Routing Time Step Summary
*************************
Minimum Time Step : 60.00 sec
Average Time Step : 60.00 sec
POST_DEV
Maximum Time Step : 60.00 sec
Percent in Steady State : 0.00
Average Iterations per Step : 1.00

***************************
Subcatchment Runoff Summary
***************************

******************
Node Depth Summary
******************

--------------------------------------------------------------------- Average Maximum Maximum Time of Max
Depth Depth HGL Occurrence
Node Type Feet Feet Feet days hr:min
--------------------------------------------------------------------- POC-1 OUTFALL 0.00 0.00 0.00 0 00:00
1 STORAGE 0.05 7.28 7.28 6325 04:38

*******************
Node Inflow Summary
*******************

------------------------------------------------------------------------------------- Maximum Maximum Lateral Total
Lateral Total Time of Max Inflow Inflow
Inflow Inflow Occurrence Volume Volume
Node Type CFS CFS days hr:min 10^6 gal 10^6 gal
------------------------------------------------------------------------------------- POC-1 OUTFALL 0.00 1.50 6325 04:38 0.000 0.736
1 STORAGE 0.53 0.53 6348 00:00 6.353 6.353

**********************
Node Surcharge Summary
**********************

Surcharging occurs when water rises above the top of the highest conduit. --------------------------------------------------------------------- Max. Height Min. Depth
Hours Above Crown Below Rim
Node Type Surcharged Feet Feet
--------------------------------------------------------------------- 1 STORAGE 394487.02 7.278 1.722

*********************
Node Flooding Summary
*********************

No nodes were flooded.

**********************
Storage Volume Summary
**********************

-------------------------------------------------------------------------------------------- Average Avg E&I Maximum Max Time of Max Maximum
Volume Pcnt Pcnt Volume Pcnt Occurrence Outflow
POST_DEV
Storage Unit 1000 ft3 Full Loss 1000 ft3 Full days hr:min CFS -------------------------------------------------------------------------------------------- 1 0.018 1 89 2.925 81 6325 04:38 1.50

***********************
Outfall Loading Summary
***********************

----------------------------------------------------------- Flow Avg. Max. Total
Freq. Flow Flow Volume
Outfall Node Pcnt. CFS CFS 10^6 gal
----------------------------------------------------------- POC-1 0.33 0.02 1.50 0.736
----------------------------------------------------------- System 0.33 0.02 1.50 0.736

********************
Link Flow Summary
********************

----------------------------------------------------------------------------- Maximum Time of Max Maximum Max/ Max/
|Flow| Occurrence |Veloc| Full Full
Link Type CFS days hr:min ft/sec Flow Depth
----------------------------------------------------------------------------- 1 DUMMY 1.50 6325 04:38

*************************
Conduit Surcharge Summary
*************************

No conduits were surcharged.

Analysis begun on: Mon Feb 27 14:51:05 2023
Analysis ended on: Mon Feb 27 14:51:37 2023
Total elapsed time: 00:00:32
City of San Marcos PDP SWQMP Template Date: March 15, 2016 PDP SWQMP Preparation Date: May 12, 2017
ATTACHMENT 3
Structural BMP Maintenance Information
This is the cover sheet for Attachment 3.

Indicate which Items are Included behind this cover sheet:

Attachment
Sequence
Contents Checklist
Attachment 3a Structural BMP Maintenance Thresholds
and Actions (Required)
☒ Included
See Structural BMP Maintenance
Information Checklist on the back of this
Attachment cover sheet.

Attachment 3b Draft Maintenance Agreement (when
applicable)
☐ Included
☒ Not Applicable

City of San Marcos PDP SWQMP Template Date: March 15, 2016 PDP SWQMP Preparation Date: May 12, 2017
Use this checklist to ensure the required information has been included in the Structural BMP Maintenance Information Attachment:
☒ Preliminary Design / Planning / CEQA level submittal:

Attachment 3a must identify:
☒ Typical maintenance indicators and actions for proposed structural BMP(s) based on Section 7.7 of the BMP Design Manual
Attachment 3b is not required for preliminary design / planning / CEQA level submittal.

Final Design level submittal:

Attachment 3a must identify:

Specific maintenance indicators and actions for proposed structural BMP(s). This shall be based on Section 7.7 of the BMP Design Manual and enhanced to reflect actual proposed components of the structural BMP(s)
How to access the structural BMP(s) to inspect and perform maintenance Features that are provided to facilitate inspection (e.g., observation ports, cleanouts, silt posts, or other features that allow the inspector to view necessary components of the structural BMP and compare to maintenance thresholds)
Manufacturer and part number for proprietary parts of structural BMP(s) when applicable
Maintenance thresholds specific to the structural BMP(s), with a location‐specific frame of reference (e.g., level of accumulated materials that triggers removal of the materials, to be identified based on viewing marks on silt posts or measured with a survey rod with respect to a fixed benchmark within the BMP)
Recommended equipment to perform maintenance
When applicable, necessary special training or certification requirements for inspection and maintenance personnel such as confined space entry or hazardous waste management
Attachment 3b: For private entity operation and maintenance, Attachment 3b shall include a draft maintenance agreement in the local jurisdiction's standard format (PDP applicant to contact the [City Engineer] to obtain the current maintenance agreement forms).

INF-1 Infiltration Basin
www.sandiegocounty.gov/stormwater E-63 Effective September 15, 2020 downstream storm drain system or discharge point.

3. If an infiltration basin cannot fully provide the flow rate and duration control required by this manual, an upstream or downstream structure with appropriate storage volume such as an underground vault can be used to provide additional control.

4. After the infiltration basin has been designed to meet flow control requirements, calculations must be completed to verify if storm water pollutant control requirements to treat the DCV have been met.

Maintenance Overview
Normal Expected Maintenance. Infiltration basins require routine maintenance to: remove accumulated materials such as sediment, trash or debris from the forebay and the basin; maintain vegetation health if the BMP includes vegetation; and maintain integrity of side slopes, inlets, energy dissipators, and outlets. A summary table of standard inspection and maintenance indicators is provided within this Fact Sheet.

Non-Standard Maintenance or BMP Failure. If any of the following scenarios are observed, the BMP is not performing as intended to protect downstream waterways from pollution and/or erosion.

Corrective maintenance, increased inspection and maintenance, BMP replacement, or a different BMP type will be required.
x The BMP is not drained between storm events. Surface ponding longer than approximately 24 hours following a storm event may be detrimental to vegetation health, and surface or subsurface ponding longer than approximately 96 hours following a storm event poses a risk of vector (mosquito) breeding. Poor drainage can result from clogging of the underlying native soils, or clogging of covers applied at the basin surface such as topsoil, mulch, or rock layer.

The specific cause of the drainage issue must be determined and corrected. For surface-level basins (i.e., not underground infiltration galleries), surface cover materials can be removed and replaced, and/or native soils can be scarified or tilled to help reestablish infiltration. If it is determined that the underlying native soils have been compacted or do not have the infiltration capacity expected, or if the infiltration surface area is not accessible (e.g., an underground infiltration gallery) the County reviewer shall be contacted prior to any additional repairs or reconstruction.
x Sediment, trash, or debris accumulation has filled the forebay or other pretreatment device within one month, or if no forebay or other pretreatment device is present, has filled greater than 25% of the surface ponding volume within one maintenance cycle. This means the load from the tributary drainage area is too high, reducing BMP function or clogging the BMP.

This would require adding a forebay or other pretreatment measures within the tributary area draining to the BMP to intercept the materials if no pretreatment component is present, or increased maintenance frequency for an existing forebay or other pretreatment device.

Pretreatment components, especially for sediment, will extend the life of the infiltration basin. x Erosion due to concentrated storm water runoff flow that is not readily corrected by adding INF-1 Infiltration Basin
www.sandiegocounty.gov/stormwater E-64 Effective September 15, 2020 erosion control blankets, adding stone at flow entry points, or minor re-grading to restore proper drainage according to the original plan. If the issue is not corrected by restoring the BMP to the original plan and grade, the County reviewer shall be contacted prior to any additional repairs or reconstruction.

Other Special Considerations. If the infiltration basin is vegetated: Vegetated structural BMPs that are constructed in the vicinity of, or connected to, an existing jurisdictional water or wetland could inadvertently result in creation of expanded waters or wetlands. As such, vegetated structural BMPs have the potential to come under the jurisdiction of the United States Army Corps of Engineers, SDRWQCB, California Department of Fish and Wildlife, or the United States Fish and Wildlife Service. This could result in the need for specific resource agency permits and costly mitigation to perform maintenance of the structural BMP. Along with proper placement of a structural BMP, routine maintenance is key to preventing this scenario
.

INF-1 Infiltration Basin
www.sandiegocounty.gov/stormwater E-65 Effective September 15, 2020 Summary of Standard Inspection and Maintenance The property owner is responsible to ensure inspection, operation and maintenance of permanent BMPs on their property unless responsibility has been formally transferred to an agency, community facilities district, homeowners association, property owners association, or other special district. Maintenance frequencies listed in this table are average/typical frequencies. Actual maintenance needs are site-specific, and maintenance may be required more frequently. Maintenance must be performed whenever needed, based on maintenance indicators presented in this table. The BMP owner is responsible for conducting regular inspections to see when maintenance is needed based on the maintenance indicators.

During the first year of operation of a structural BMP, inspection is recommended at least once prior to August 31 and then monthly from September through May. Inspection during a storm event is also recommended. After the initial period of frequent inspections, the minimum inspection and maintenance frequency can be determined based on the results of the first year inspections.

Threshold/Indicator Maintenance Action Inspection and Maintenance Frequency Accumulation of sediment, litter, or debris in forebay and/or basin Remove and properly dispose of accumulated materials, (without damage to vegetation when applicable). x Inspect monthly. If the forebay is 25% full*
or more in one month, increase inspection frequency to monthly plus after every 0.1-inch or larger storm event. xRemove any accumulated materials found
within the infiltration area at each
inspection.
xWhen the BMP includes a forebay,
materials must be removed from the forebay when the forebay is 25% full*, or if accumulation within the forebay blocks flow to the infiltration area.

Obstructed inlet or outlet structure Clear blockage. x Inspect monthly and after every 0.5-inch or larger storm event.
xRemove any accumulated materials found
at each inspection.

INF-1 Infiltration Basin
www.sandiegocounty.gov/stormwater E-66 Effective September 15, 2020 Threshold/Indicator Maintenance Action Inspection and Maintenance Frequency Poor vegetation establishment (when the BMP includes vegetated surface by design) Re-seed, re-plant, or re-establish vegetation per original plans. x Inspect monthly. x Maintain when needed.

Dead or diseased vegetation (when the BMP includes vegetated surface by design) Remove dead or diseased vegetation, re-seed, re-plant, or re-establish vegetation per original plans. x Inspect monthly. x Maintain when needed.

Overgrown vegetation (when the BMP includes vegetated surface by design) Mow or trim as appropriate. x Inspect monthly.
x Maintain when needed.

Erosion due to concentrated irrigation flow Repair/re-seed/re-plant eroded areas and adjust the irrigation system.
x Inspect monthly. x Maintain when needed.

Erosion due to concentrated storm water runoff flow
Repair/re-seed/re-plant eroded areas, and make appropriate corrective measures such as adding erosion control blankets, adding stone at flow entry points, or minor regrading to restore proper drainage according to the original plan. If the issue is not corrected by restoring the BMP to the original plan and grade, the County reviewer
shall be contacted prior to any additional
repairs or reconstruction.
x Inspect after every 0.5-inch or larger storm
event. If erosion due to storm water flow has been observed, increase inspection frequency to after every 0.1-inch or larger storm event. x Maintain when needed. If the issue is not
corrected by restoring the BMP to the
original plan and grade, the County reviewer shall be contacted prior to any additional repairs or reconstruction.

INF-1 Infiltration Basin
www.sandiegocounty.gov/stormwater E-67 Effective September 15, 2020 Threshold/Indicator Maintenance Action Inspection and Maintenance Frequency Standing water in infiltration basin without subsurface infiltration gallery for longer than 24-96 hours following a storm event Make appropriate corrective measures such as adjusting irrigation system, removing obstructions of debris or invasive vegetation, or removing/replacing clogged or compacted surface treatments and/or scarifying or tilling native soils. Always remove deposited sediments before scarification, and use a hand-guided rotary tiller. If it is determined that the underlying native soils have been
compacted or do not have the infiltration capacity expected, the County reviewer shall be contacted prior to any additional repairs or reconstruction. x Inspect monthly and after every 0.5-inch or
larger storm event. If standing water is observed, increase inspection frequency to after every 0.1-inch or larger storm event. x Maintain when needed.

Standing water in subsurface infiltration gallery for longer than 24-96 hours following a storm event This condition requires investigation of why infiltration is not occurring. If feasible, corrective action shall be taken to restore infiltration (e.g., flush fine sediment or remove and replace clogged soils). BMP may require retrofit if infiltration cannot be restored. The County reviewer shall be contacted prior to any repairs or reconstruction. x Inspect monthly and after every 0.5-inch or
larger storm event. If standing water is observed, increase inspection frequency to after every 0.1-inch or larger storm event. x Maintain when needed.

INF-1 Infiltration Basin
www.sandiegocounty.gov/stormwater E-68 Effective September 15, 2020 Threshold/Indicator Maintenance Action Inspection and Maintenance Frequency Presence of mosquitos/larvae For images of egg rafts, larva, pupa, and adult mosquitos, see http://www.mosquito.org/biology If mosquitos/larvae are observed: first, immediately remove any standing water by dispersing to nearby landscaping; second, make corrective measures as applicable to restore BMP drainage to prevent standing water. For subsurface infiltration galleries, ensure access covers are tight fitting, with gaps or holes no greater than 1/16 inch, and/or install barriers such as inserts or screens that prevent mosquito access to the subsurface storage. If mosquitos persist following corrective measures to remove standing water, or if the BMP design does not meet the 96-hour drawdown criteria because the underlying native soils have been compacted or do not have the infiltration capacity expected, the
County reviewer shall be contacted to
determine a solution. A different BMP type, or a Vector Management Plan prepared with concurrence from the County of San Diego Department of Environmental Health, may be required.
x Inspect monthly and after every 0.5-inch or
larger storm event. If mosquitos are observed, increase inspection frequency to after every 0.1-inch or larger storm event. x Maintain when needed
Damage to structural components such as weirs, inlet or outlet structures Repair or replace as applicable. x Inspect annually.
x Maintain when needed.
“25% full” is defined as ¼ of the depth from the design bottom elevation to the crest of the outflow structure (e.g., if the height to the outflow opening is 12 inches from the bottom elevation, then the materials must be removed when there is 3 inches of accumulation – this should be marked on the outflow structure).

City of San Marcos PDP SWQMP Template Date: March 15, 2016 PDP SWQMP Preparation Date: May 12, 2017
ATTACHMENT 4
Copy of Plan Sheets Showing Permanent Storm Water BMPs
This is the cover sheet for Attachment 4.

Use this checklist to ensure the required information has been included on the plans:

The plans must identify:
☒ Structural BMP(s) with ID numbers matching Form I‐6 Summary of PDP Structural BMPs ☒ The grading and drainage design shown on the plans must be consistent with the delineation of DMAs shown on the DMA exhibit
☒ Details and specifications for construction of structural BMP(s) ☒ Signage indicating the location and boundary of structural BMP(s) as required by the [City Engineer] ☒ How to access the structural BMP(s) to inspect and perform maintenance ☒ Features that are provided to facilitate inspection (e.g., observation ports, cleanouts, silt posts, or other features that allow the inspector to view necessary components of the structural BMP and compare to maintenance thresholds)
☒ Manufacturer and part number for proprietary parts of structural BMP(s) when applicable ☒ Maintenance thresholds specific to the structural BMP(s), with a location‐specific frame of reference (e.g., level of accumulated materials that triggers removal of the materials, to be identified based on viewing marks on silt posts or measured with a survey rod with respect to a fixed benchmark within the BMP)
☒ Recommended equipment to perform maintenance
☒ When applicable, necessary special training or certification requirements for inspection and maintenance personnel such as confined space entry or hazardous waste management ☒ Include landscaping plan sheets showing vegetation requirements for vegetated structural BMP(s) ☒ All BMPs must be fully dimensioned on the plans
☒ When proprietary BMPs are used, site‐specific cross section with outflow, inflow, and model number shall be provided. Photocopies of general brochures are not acceptable.

Appendix H. Drainage Study
This page intentionally left blank.

TM DRAINAGE STUDY
For

PICO PLACE
Prepared for:

DMS Consultants, Inc.

Prepared by:

Dr. Luis Parra
REC Consultants, Inc
27349 Jefferson Ave, Suite 112
Temecula, CA 92590
Telephone: 951-693-2400

Report Prepared:

November 3, 2022
Revised April 14, 2023
Pico Place
TM Drainage Study
1 TABLE OF CONTENTS

SECTION
Chapter 1 - Executive Summary I

1.1 Introduction

1.2 Summary of Existing Conditions

1.3 Summary of Proposed Condition

1.4 Summary of Results

1.5 Conclusions

1.6 References

1.7 Declaration of Responsible Charge
Chapter 2 - Methodology II

2.1 County of San Diego Drainage Design Criteria

2.2 Hydrograph Development Summary
(from San Diego County Hydrology Manual)
Chapter 3 – HEC-HMS Modified-Puls Routing Analysis III

3.1 Rational Method Hydrographs

3.2 Stage-Storage & Stage-Discharge Relationships

3.3 HEC-HMS Modified-Puls Routing Results
Chapter 4 – Storm Drain Hydraulic Analysis IV
Chapter 5 – Existing Condition 100-Year Hydrologic Analysis V Chapter 6 – Developed Condition 100-Year Hydrologic Analysis VI Chapter 7 – Hydrology Exhibits VII
Pico Place
TM Drainage Study
CHAPTER 1 - EXECUTIVE SUMMARY

1.1 – Introduction
The Pico Place residential project site is located adjacent to Pico Avenue in the City of San Marcos, California.

Runoff from the proposed site will drain to a single point of discharge from the project site, the existing storm drain system located with the adjacent Pico Avenue to the eastern boundary of the site.

This study analyzes existing and developed condition 100-year peak flowrates from the development to the existing point of discharge.

The project site lies outside any FEMA 100-year floodplain zones. Therefore, no Letters of Map Revision will be required.

Treatment of storm water runoff from the site has been addressed in a separate report - the “Storm Water Quality Management Plan for Pico Place”, dated April 2023 by REC.

Per County of San Diego drainage criteria, the Modified Rational Method should be used to determine peak design flowrates when the contributing drainage area is less than 1.0 square mile. Since the total watershed area discharging from the site is less than 1.0 square mile, AES computer software was used to model the pre & post developed condition runoff response per the Modified Rational Method.

Methodology used for the computation of design rainfall events, hydrographs, runoff coefficients, and rainfall intensity values are consistent with criteria set forth in the “County of San Diego Drainage Design Manual”. A more detailed explanation of methodology used for this analysis is listed in Chapter 2 of this report.

Hydraulic Modified-Puls detention basin routing of the aforementioned modified rational method hydrology was performed using the Army Corps of Engineers HEC-HMS software. Hydrographs were generated using the RatHydro program developed by Rick Engineering Company.

1.2 – Summary of Existing Conditions
In existing conditions, the Pico Place project site is a developed residential lot featuring a single residential structure including several paved surface areas with an adjoining undeveloped lot to the north that is sparsely vegetated. An exhibit is provided on the following page to illustrate the existing impervious condition of the site accordingly.

Pico Place
TM Drainage Study
Runoff from the existing site flows overland to two (2) points of discharge; POC-1, an existing RCP storm drain located at the eastern boundary of the project site within Pico Avenue and POC-2, the westerly boundary of the site.

Per County of San Diego rainfall isopluvial maps, the design 100-year rainfall depth for the project site is 3.4 inches. The project site comprises of hydrologic soil class C soils such that runoff coefficients of 0.75 and 0.34 were used for the tributaries to POC-1 and POC-2 respectively (see weighted runoff calculations in Chapter 4). Table 1 summarizes the existing condition design 100-year peak flow from the project site.

Table 1 – SUMMARY OF EXISTING CONDITIONS FLOWS
Drainage Area
Drainage
Area
(Ac)
Runoff
Coefficient
(C)
100-Year
Peak Flow
(cfs)
Pico Drive Tributary
(POC-1) 0.234 0.75 1.57
Western Boundary Tributary
(POC-2) 0.51* 0.34** 0.91
Total 0.744 -- 2.48
* = inclusive of 0.068 Ac of offsite area to the west of the project site. ** = onsite area coefficient only.

Pico Place
TM Drainage Study

1.3 – Summary of Developed Conditions
The Pico Place project proposes the construction of multi- family residences, inclusive of a servicing drive and associated landscaping. Runoff from the project is drained to one (1) receiving multiple purpose water quality/HMP/Q100 detention vault. Detained flows are drained from the BMP facility and discharged to the existing storm drain system within the adjacent Pico Avenue.

Per County of San Diego rainfall isopluvial maps, the design 100-year rainfall depth for the project site is 3.4 inches. The project site comprises of hydrologic soil class C soils such that a runoff coefficient of 0.75 was used for the proposed residential (see weighted runoff calculations in Chapter 4). Table 2 summarizes the developed condition design 100-year peak flow from the project site.

Table 2 – SUMMARY OF DEVELOPED CONDITIONS FLOWS UNMITTIGATED Drainage Area
Drainage
Area
(Ac)
Runoff
Coefficient
(C)
100-Year
Peak Flow
(cfs)
Pico Place Project Site 0.674 0.75 3.9
POC-1 Total 0.674 0.75 3.9
Prior to discharging from the project site, first flush runoff will be treated via an onsite filtration BMP in accordance with standards set forth by the Regional Water Quality Control Board and the City of San Marcos’ BMP Design Manual (see “Storm Water Quality Management Plan for Pico Place”).

Peak developed flows from the project site are conveyed to one (1) onsite detention facility prior to discharging to the existing storm drain system. The vault system is approximately 9-feet deep with a width of 9-feet and length of 54-feet. Due to the limited grade on the project site and utility constraints, the vault is to be located several feet below the existing storm drain invert in Pico Avenue such that the vault can only be drained via the use of pumps. Due to HMP criteria, two (2) separate pumps will be employed on the project site, a low flow pump outlet will be located at 3.0 feet from the bottom of the basin invert while the peak Q100 flow pump will be located at 7.25 feet from the basin invert. In an extreme event, flows will outlet via the surface private drive to Pico Avenue without risk of flooding the residential structures and also providing single vehicular lane access.

The developed condition peak flows calculated using modified rational method was then routed through the detention facility on the project site in HEC-HMS. The HMS Modified-Puls results are summarized in Table 3.

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TM Drainage Study
TABLE 3 – SUMMARY OF DETENTION BASIN ROUTING
Detention
Basin
100-Year
Peak Inflow
(cfs)
100-Year
Peak Outflow
(cfs)
Time of
Concentration (tc)
Peak Water
Surface Elevation
(ft)
Vault 3.9 1.5 10.3 8.96
Input hydrographs for the HMS analysis were generated using the RatHydro program developed by Rick Engineering Company and are provided Chapter 3 of this report.

Rational method hydrographs, stage-storage, stage-discharge relationships and HECHMS model output is provided in Chapter 3 of this report.

There is an existing Day Care site located adjacent to the western boundary of the project site. This small 0.068 Ac tributary of 0.5 cfs offsite run-on will be intercepted by a proposed storm drain system that will convey these flows through the project site such that they do not comingle with onsite flows. As these flows are generated by a neighboring site, this run-on is not required to be treated or detained within the proposed project site.

A proposed 12-inch RCP will be constructed within the adjacent Pico Avenue conveying the project and offsite flows in a northerly direction, ultimately converging with an existing 15-inch RCP storm drain. A hydraulic analysis has been undertaken with Chapter 4 of this report demonstrating that the existing 15-inch storm drain has capacity to safely convey these flows. A conservative outlet tailwater condition assumed the top of pipe of the 15-inch downstream for this analysis.

1.4 – Summary of Results
Table 4 summarizes developed and existing condition drainage areas and resultant 100-year peak flow rates at the receiving discharge location from the Pico Place Development site. Per County of San Diego rainfall isopluvial maps, the design 100- year rainfall depth for the site area is 3.4 inches.

Table 4 – SUMMARY OF ONSITE PEAK FLOWS MITIGATED
Discharge
Location
Area (ac) 100 Year Peak Flow (cfs)
Existing Developed Difference Existing Developed Difference Pico Ave
(POC-1) 0.234 0.674 +0.44* 1.57 1.50 -0.07
Western
Boundary
(POC-2)

0.44 0.0 -0.44 0.67 0.00 -0.67
* = note, rounding discrepancy for 0.005 Ac difference.

Pico Place
TM Drainage Study
As illustrated in Table 4, the proposed Pico Place project site will result in a net decrease of peak flows discharged from the project site by approximately 0.07 cfs at POC-1 while fully removing flows tributary to the western boundary location (POC-2), thus the project has no net impact to the receiving watershed. All developed runoff will receive water quality treatment in accordance with the site specific SWQMP.

Total runoff tributary to the Pico Avenue 15-inch storm drain increases from 1.57 cfs to

1.8 cfs due to the interception of runoff from the adjacent property site that previously discharged to the western point of discharge. The hydraulic analysis prepared in Chapter 4 of this report demonstrates that this 0.23 cfs increase does not negatively impact this existing storm drains capacity to convey peak flow.

Final design details will be provided at the final engineering phase of the development.

1.5 – Conclusions
This report has been prepared in accordance with the County of San Diego Hydrology Manual. This report has evaluated and addressed the potential impacts and proposed mitigation measures. A summary of the facts and findings associated with this project and the measures addressed by this report is as follows:
● The project will not alter drainage patterns on the site or increase runoff after development.
● The ultimate discharge points will not be changed.
● Graded areas and slopes will be hydroseeded to reduce or eliminate sediment discharge.
● Identify and discuss, with appropriate backup/research information, the following question item by item for CEQA purposes. Would the project:

A. Substantially alter the existing drainage patterns of the site or area, including through the alteration if the course of a stream or river, in a manner which would result in substantial erosion or siltation on – or off-site?
The project does not substantially alter the existing drainage pattern of the area and does not alter the course of a stream or river.

The storm drain system for the entire project is designed to route and convey all resulting runoff from developed conditions to existing point of discharge.

B. Substantially alter the existing drainage patterns of the site or area, including through the alteration of the course of a stream or river, or substantially increase the rate or amount of surface runoff in a manner which would result in flooding on- or off-site? Pico Place
TM Drainage Study
The project will not substantially alter the existing drainage pattern of the area as it will not alter the course of a stream or river, and also will not substantially increase the rate or amount of surface runoff in a manner which would result in on- or off-site flooding.

C. Create or contribute runoff water which would exceed the capacity of existing or planned storm water drainage systems?
No. The project drains directly to the existing storm drain system and does not increase flows to existing storm water drainage systems.

D. Place housing within a 100-year flood hazard area as mapped on a federal Flood Hazard Boundary or Flood insurance Rate Map or other flood hazard delineation map, including County Floodplain Maps? For example; research the foregoing and provide same (to indicate applicability or not) in the study?
The project does not place any structure within a 100-year flood hazard area.

E. Place within a 100-year flood hazard area structures which would impede or redirect flood flows?
There are no structures proposed within a 100-year flood hazard area.

F. Expose people or structures to a significant risk of loss, injury or death involving flooding, including flooding as a result of the failure of a levee or dam on-sit or off-site? NA

1.6 – References
“County of San Diego Hydrology Manual”, June 2003
“San Diego County Hydraulic Design Manual”, September 2014 “Stormwater Quality Management Plan for Pico Place Development”, April 2023, REC Consultants.

Pico Place
TM Drainage Study

1.7 – Declaration of Responsible Charge

THIS PRELIMINARY DRAINAGE STUDY HAS BEEN PREPARED UNDER THE DIRECTION OF THE FOLLOWING REGISTERED CIVIL ENGINEER. THE REGISTERED ENGINEER ATTESTS TO

THE TECHNICAL INFORMATION CONTAINED HEREIN AND THE ENGINEERING DATA UPON WHICH RECOMMENDATIONS, CONCLUSIONS, AND DECISIONS ARE BASED.

Luis A. Parra‐Rosales R.C.E. 66377
Pico Place
TM Drainage Study
CHAPTER 2 - METHODOLOGY

2.1 – County of San Diego Design Criteria
Pico Place
TM Drainage Study 2.2 – Design Rainfall Determination 2.2.1 – 100-Year, 6-Hour Rainfall Isopluvial Map

SITE LOCATION

3.4”
Pico Place
TM Drainage Study 2.2.2 – 100-Year, 24-Hour Rainfall Isopluvial Map

SITE LOCATION

6.6”
Pico Place
TM Drainage Study 2.3 – Runoff Coefficient Determination Pico Place
TM Drainage Study
Pico Place
TM Drainage Study
Pico Place
TM Drainage Study

2.4 – Urban Watershed Overland Time of Flow Nomograph
Pico Place
TM Drainage Study
Pico Place
TM Drainage Study 2.5 – County of San Diego Intensity- Duration Curve

3.4 6.6 52
Pico Place
TM Drainage Study

2.6 – Model Development Summary (from County of San Diego Hydrology Manual)
Pico Place
TM Drainage Study
Pico Place
TM Drainage Study

Pico Place
TM Drainage Study

Pico Place
TM Drainage Study
Pico Place
TM Drainage Study
CHAPTER 3 - HEC-HMS Modified-Puls Routing Analysis
Stage‐Storage‐Discharge Summary Table
Depth (ft) Area (ft2) Volume (ft3) Ac‐Ft Q‐out (cfs)
0 400 0 0 0
1 400 400 0.009183 0
2 400 800 0.018365 0
3 400 1200 0.027548 0 DCV Contained

3.2 400 1280 0.029385 0.015
4 400 1600 0.036731 0.015
5 400 2000 0.045914 0.015
6 400 2400 0.055096 0.015
7 400 2800 0.064279 0.015

7.25 400 2900 0.066575 1.5015
8 400 3200 0.073462 1.5015
9 400 3600 0.082645 1.5015

RATIONAL METHOD HYDROGRAPH PROGRAM
COPYRIGHT 1992, 2001 RICK ENGINEERING COMPANY
RUN DATE 10/21/2022
HYDROGRAPH FILE NAME Text1
TIME OF CONCENTRATION 6 MIN.
6 HOUR RAINFALL 3.4 INCHES
BASIN AREA 0.67 ACRES
RUNOFF COEFFICIENT 0.75
PEAK DISCHARGE 3.9 CFS
TIME (MIN) = 0 DISCHARGE (CFS) = 0
TIME (MIN) = 6 DISCHARGE (CFS) = 0.1
TIME (MIN) = 12 DISCHARGE (CFS) = 0.1
TIME (MIN) = 18 DISCHARGE (CFS) = 0.1
TIME (MIN) = 24 DISCHARGE (CFS) = 0.1
TIME (MIN) = 30 DISCHARGE (CFS) = 0.1
TIME (MIN) = 36 DISCHARGE (CFS) = 0.1
TIME (MIN) = 42 DISCHARGE (CFS) = 0.1
TIME (MIN) = 48 DISCHARGE (CFS) = 0.1
TIME (MIN) = 54 DISCHARGE (CFS) = 0.1
TIME (MIN) = 60 DISCHARGE (CFS) = 0.1
TIME (MIN) = 66 DISCHARGE (CFS) = 0.1
TIME (MIN) = 72 DISCHARGE (CFS) = 0.1
TIME (MIN) = 78 DISCHARGE (CFS) = 0.1
TIME (MIN) = 84 DISCHARGE (CFS) = 0.1
TIME (MIN) = 90 DISCHARGE (CFS) = 0.1
TIME (MIN) = 96 DISCHARGE (CFS) = 0.1
TIME (MIN) = 102 DISCHARGE (CFS) = 0.1
TIME (MIN) = 108 DISCHARGE (CFS) = 0.1
TIME (MIN) = 114 DISCHARGE (CFS) = 0.2
TIME (MIN) = 120 DISCHARGE (CFS) = 0.2
TIME (MIN) = 126 DISCHARGE (CFS) = 0.2
TIME (MIN) = 132 DISCHARGE (CFS) = 0.2
TIME (MIN) = 138 DISCHARGE (CFS) = 0.2
TIME (MIN) = 144 DISCHARGE (CFS) = 0.2
TIME (MIN) = 150 DISCHARGE (CFS) = 0.2
TIME (MIN) = 156 DISCHARGE (CFS) = 0.2
TIME (MIN) = 162 DISCHARGE (CFS) = 0.2
TIME (MIN) = 168 DISCHARGE (CFS) = 0.2
TIME (MIN) = 174 DISCHARGE (CFS) = 0.2
TIME (MIN) = 180 DISCHARGE (CFS) = 0.2
TIME (MIN) = 186 DISCHARGE (CFS) = 0.3
TIME (MIN) = 192 DISCHARGE (CFS) = 0.3
TIME (MIN) = 198 DISCHARGE (CFS) = 0.3
TIME (MIN) = 204 DISCHARGE (CFS) = 0.3
TIME (MIN) = 210 DISCHARGE (CFS) = 0.4
TIME (MIN) = 216 DISCHARGE (CFS) = 0.4
TIME (MIN) = 222 DISCHARGE (CFS) = 0.5
TIME (MIN) = 228 DISCHARGE (CFS) = 0.5
TIME (MIN) = 234 DISCHARGE (CFS) = 0.8
TIME (MIN) = 240 DISCHARGE (CFS) = 1.2
TIME (MIN) = 246 DISCHARGE (CFS) = 3.9
TIME (MIN) = 252 DISCHARGE (CFS) = 0.6
TIME (MIN) = 258 DISCHARGE (CFS) = 0.4
TIME (MIN) = 264 DISCHARGE (CFS) = 0.3
TIME (MIN) = 270 DISCHARGE (CFS) = 0.3
TIME (MIN) = 276 DISCHARGE (CFS) = 0.2
TIME (MIN) = 282 DISCHARGE (CFS) = 0.2
TIME (MIN) = 288 DISCHARGE (CFS) = 0.2
TIME (MIN) = 294 DISCHARGE (CFS) = 0.2
TIME (MIN) = 300 DISCHARGE (CFS) = 0.2
TIME (MIN) = 306 DISCHARGE (CFS) = 0.2
TIME (MIN) = 312 DISCHARGE (CFS) = 0.1
TIME (MIN) = 318 DISCHARGE (CFS) = 0.1
TIME (MIN) = 324 DISCHARGE (CFS) = 0.1
TIME (MIN) = 330 DISCHARGE (CFS) = 0.1
TIME (MIN) = 336 DISCHARGE (CFS) = 0.1
TIME (MIN) = 342 DISCHARGE (CFS) = 0.1
TIME (MIN) = 348 DISCHARGE (CFS) = 0.1
TIME (MIN) = 354 DISCHARGE (CFS) = 0.1
TIME (MIN) = 360 DISCHARGE (CFS) = 0.1
TIME (MIN) = 366 DISCHARGE (CFS) = 0
Project: Pico Simulation Run: Q100
Reservoir: Reservoir-1
Start of Run: 01Jan2000, 00:00 Basin Model: Basin 1
End of Run: 01Jan2000, 07:00 Meteorologic Model: Met 1
Compute Time: 22Feb2023, 09:18:17 Control Specifications: Control 1 Volume Units:IN
Computed Results
Peak Inflow: 3.90 (CFS) Date/Time of Peak Inflow: 01Jan2000, 04:06 Peak Discharge: 1.50 (CFS) Date/Time of Peak Discharge:01Jan2000, 04:10 Inflow Volume: n/a Peak Storage: 0.08 (ACRE-FT)
Discharge Volume:n/a Peak Elevation: 8.964 (FT)

Project: Pico Simulation Run: Q100
Reservoir: Reservoir-1
Start of Run: 01Jan2000, 00:00 Basin Model: Basin 1
End of Run: 01Jan2000, 07:00 Meteorologic Model: Met 1
Compute Time: 22Feb2023, 09:18:17 Control Specifications:Control 1 Date Time Inflow
(CFS)
Storage
(ACRE-FT)
Elevation
(FT)
Outflow
(CFS)
01Jan2000 00:00 0.00 0.01 1.000 0.00
01Jan2000 00:01 0.02 0.01 1.001 0.00
01Jan2000 00:02 0.03 0.01 1.005 0.00
01Jan2000 00:03 0.05 0.01 1.011 0.00
01Jan2000 00:04 0.07 0.01 1.020 0.00
01Jan2000 00:05 0.08 0.01 1.031 0.00
01Jan2000 00:06 0.10 0.01 1.045 0.00
01Jan2000 00:07 0.10 0.01 1.060 0.00
01Jan2000 00:08 0.10 0.01 1.075 0.00
01Jan2000 00:09 0.10 0.01 1.090 0.00
01Jan2000 00:10 0.10 0.01 1.105 0.00
01Jan2000 00:11 0.10 0.01 1.120 0.00
01Jan2000 00:12 0.10 0.01 1.135 0.00
01Jan2000 00:13 0.10 0.01 1.150 0.00
01Jan2000 00:14 0.10 0.01 1.165 0.00
01Jan2000 00:15 0.10 0.01 1.180 0.00
01Jan2000 00:16 0.10 0.01 1.195 0.00
01Jan2000 00:17 0.10 0.01 1.210 0.00
01Jan2000 00:18 0.10 0.01 1.225 0.00
01Jan2000 00:19 0.10 0.01 1.240 0.00
01Jan2000 00:20 0.10 0.01 1.255 0.00
01Jan2000 00:21 0.10 0.01 1.270 0.00
01Jan2000 00:22 0.10 0.01 1.285 0.00
01Jan2000 00:23 0.10 0.01 1.300 0.00
01Jan2000 00:24 0.10 0.01 1.315 0.00
01Jan2000 00:25 0.10 0.01 1.330 0.00

Page 1 ends

Date Time Inflow
(CFS)
Storage
(ACRE-FT)
Elevation
(FT)
Outflow
(CFS)
01Jan2000 00:26 0.10 0.01 1.345 0.00
01Jan2000 00:27 0.10 0.01 1.360 0.00
01Jan2000 00:28 0.10 0.01 1.375 0.00
01Jan2000 00:29 0.10 0.01 1.390 0.00
01Jan2000 00:30 0.10 0.01 1.405 0.00
01Jan2000 00:31 0.10 0.01 1.420 0.00
01Jan2000 00:32 0.10 0.01 1.435 0.00
01Jan2000 00:33 0.10 0.01 1.450 0.00
01Jan2000 00:34 0.10 0.01 1.465 0.00
01Jan2000 00:35 0.10 0.01 1.480 0.00
01Jan2000 00:36 0.10 0.01 1.495 0.00
01Jan2000 00:37 0.10 0.01 1.510 0.00
01Jan2000 00:38 0.10 0.01 1.525 0.00
01Jan2000 00:39 0.10 0.01 1.540 0.00
01Jan2000 00:40 0.10 0.01 1.555 0.00
01Jan2000 00:41 0.10 0.01 1.570 0.00
01Jan2000 00:42 0.10 0.01 1.585 0.00
01Jan2000 00:43 0.10 0.01 1.600 0.00
01Jan2000 00:44 0.10 0.01 1.615 0.00
01Jan2000 00:45 0.10 0.01 1.630 0.00
01Jan2000 00:46 0.10 0.02 1.645 0.00
01Jan2000 00:47 0.10 0.02 1.660 0.00
01Jan2000 00:48 0.10 0.02 1.675 0.00
01Jan2000 00:49 0.10 0.02 1.690 0.00
01Jan2000 00:50 0.10 0.02 1.705 0.00
01Jan2000 00:51 0.10 0.02 1.720 0.00
01Jan2000 00:52 0.10 0.02 1.735 0.00
01Jan2000 00:53 0.10 0.02 1.750 0.00
01Jan2000 00:54 0.10 0.02 1.765 0.00
01Jan2000 00:55 0.10 0.02 1.780 0.00
01Jan2000 00:56 0.10 0.02 1.795 0.00

Page 2 ends

Date Time Inflow
(CFS)
Storage
(ACRE-FT)
Elevation
(FT)
Outflow
(CFS)
01Jan2000 00:57 0.10 0.02 1.810 0.00
01Jan2000 00:58 0.10 0.02 1.825 0.00
01Jan2000 00:59 0.10 0.02 1.840 0.00
01Jan2000 01:00 0.10 0.02 1.855 0.00
01Jan2000 01:01 0.10 0.02 1.870 0.00
01Jan2000 01:02 0.10 0.02 1.885 0.00
01Jan2000 01:03 0.10 0.02 1.900 0.00
01Jan2000 01:04 0.10 0.02 1.915 0.00
01Jan2000 01:05 0.10 0.02 1.930 0.00
01Jan2000 01:06 0.10 0.02 1.945 0.00
01Jan2000 01:07 0.10 0.02 1.960 0.00
01Jan2000 01:08 0.10 0.02 1.975 0.00
01Jan2000 01:09 0.10 0.02 1.990 0.00
01Jan2000 01:10 0.10 0.02 2.005 0.00
01Jan2000 01:11 0.10 0.02 2.020 0.00
01Jan2000 01:12 0.10 0.02 2.035 0.00
01Jan2000 01:13 0.10 0.02 2.050 0.00
01Jan2000 01:14 0.10 0.02 2.065 0.00
01Jan2000 01:15 0.10 0.02 2.079 0.00
01Jan2000 01:16 0.10 0.02 2.094 0.00
01Jan2000 01:17 0.10 0.02 2.109 0.00
01Jan2000 01:18 0.10 0.02 2.124 0.00
01Jan2000 01:19 0.10 0.02 2.138 0.00
01Jan2000 01:20 0.10 0.02 2.153 0.00
01Jan2000 01:21 0.10 0.02 2.167 0.00
01Jan2000 01:22 0.10 0.02 2.182 0.00
01Jan2000 01:23 0.10 0.02 2.196 0.00
01Jan2000 01:24 0.10 0.02 2.211 0.00
01Jan2000 01:25 0.10 0.02 2.225 0.00
01Jan2000 01:26 0.10 0.02 2.239 0.00
01Jan2000 01:27 0.10 0.02 2.254 0.00

Page 3 ends

Date Time Inflow
(CFS)
Storage
(ACRE-FT)
Elevation
(FT)
Outflow
(CFS)
01Jan2000 01:28 0.10 0.02 2.268 0.01
01Jan2000 01:29 0.10 0.02 2.282 0.01
01Jan2000 01:30 0.10 0.02 2.296 0.01
01Jan2000 01:31 0.10 0.02 2.310 0.01
01Jan2000 01:32 0.10 0.02 2.325 0.01
01Jan2000 01:33 0.10 0.02 2.339 0.01
01Jan2000 01:34 0.10 0.02 2.353 0.01
01Jan2000 01:35 0.10 0.02 2.367 0.01
01Jan2000 01:36 0.10 0.02 2.381 0.01
01Jan2000 01:37 0.10 0.02 2.394 0.01
01Jan2000 01:38 0.10 0.02 2.408 0.01
01Jan2000 01:39 0.10 0.02 2.422 0.01
01Jan2000 01:40 0.10 0.02 2.436 0.01
01Jan2000 01:41 0.10 0.02 2.450 0.01
01Jan2000 01:42 0.10 0.02 2.463 0.01
01Jan2000 01:43 0.10 0.02 2.477 0.01
01Jan2000 01:44 0.10 0.02 2.491 0.01
01Jan2000 01:45 0.10 0.02 2.504 0.01
01Jan2000 01:46 0.10 0.02 2.518 0.01
01Jan2000 01:47 0.10 0.02 2.531 0.01
01Jan2000 01:48 0.10 0.02 2.545 0.01
01Jan2000 01:49 0.12 0.02 2.560 0.01
01Jan2000 01:50 0.13 0.02 2.577 0.01
01Jan2000 01:51 0.15 0.02 2.596 0.01
01Jan2000 01:52 0.17 0.02 2.618 0.01
01Jan2000 01:53 0.18 0.02 2.643 0.01
01Jan2000 01:54 0.20 0.02 2.669 0.01
01Jan2000 01:55 0.20 0.02 2.697 0.01
01Jan2000 01:56 0.20 0.03 2.725 0.01
01Jan2000 01:57 0.20 0.03 2.753 0.01
01Jan2000 01:58 0.20 0.03 2.781 0.01

Page 4 ends

Date Time Inflow
(CFS)
Storage
(ACRE-FT)
Elevation
(FT)
Outflow
(CFS)
01Jan2000 01:59 0.20 0.03 2.809 0.02
01Jan2000 02:00 0.20 0.03 2.837 0.02
01Jan2000 02:01 0.20 0.03 2.864 0.02
01Jan2000 02:02 0.20 0.03 2.892 0.02
01Jan2000 02:03 0.20 0.03 2.919 0.02
01Jan2000 02:04 0.20 0.03 2.946 0.02
01Jan2000 02:05 0.20 0.03 2.974 0.02
01Jan2000 02:06 0.20 0.03 3.001 0.02
01Jan2000 02:07 0.20 0.03 3.028 0.02
01Jan2000 02:08 0.20 0.03 3.055 0.02
01Jan2000 02:09 0.20 0.03 3.082 0.02
01Jan2000 02:10 0.20 0.03 3.109 0.02
01Jan2000 02:11 0.20 0.03 3.137 0.02
01Jan2000 02:12 0.20 0.03 3.164 0.02
01Jan2000 02:13 0.20 0.03 3.191 0.02
01Jan2000 02:14 0.20 0.03 3.218 0.02
01Jan2000 02:15 0.20 0.03 3.245 0.02
01Jan2000 02:16 0.20 0.03 3.272 0.02
01Jan2000 02:17 0.20 0.03 3.299 0.02
01Jan2000 02:18 0.20 0.03 3.327 0.02
01Jan2000 02:19 0.20 0.03 3.354 0.02
01Jan2000 02:20 0.20 0.03 3.381 0.02
01Jan2000 02:21 0.20 0.03 3.408 0.02
01Jan2000 02:22 0.20 0.03 3.435 0.02
01Jan2000 02:23 0.20 0.03 3.462 0.02
01Jan2000 02:24 0.20 0.03 3.490 0.02
01Jan2000 02:25 0.20 0.03 3.517 0.02
01Jan2000 02:26 0.20 0.03 3.544 0.02
01Jan2000 02:27 0.20 0.03 3.571 0.02
01Jan2000 02:28 0.20 0.03 3.598 0.02
01Jan2000 02:29 0.20 0.03 3.625 0.02

Page 5 ends

Date Time Inflow
(CFS)
Storage
(ACRE-FT)
Elevation
(FT)
Outflow
(CFS)
01Jan2000 02:30 0.20 0.03 3.652 0.02
01Jan2000 02:31 0.20 0.03 3.680 0.02
01Jan2000 02:32 0.20 0.03 3.707 0.02
01Jan2000 02:33 0.20 0.03 3.734 0.02
01Jan2000 02:34 0.20 0.03 3.761 0.02
01Jan2000 02:35 0.20 0.03 3.788 0.02
01Jan2000 02:36 0.20 0.04 3.815 0.02
01Jan2000 02:37 0.20 0.04 3.842 0.02
01Jan2000 02:38 0.20 0.04 3.870 0.02
01Jan2000 02:39 0.20 0.04 3.897 0.02
01Jan2000 02:40 0.20 0.04 3.924 0.02
01Jan2000 02:41 0.20 0.04 3.951 0.02
01Jan2000 02:42 0.20 0.04 3.978 0.02
01Jan2000 02:43 0.20 0.04 4.005 0.02
01Jan2000 02:44 0.20 0.04 4.033 0.02
01Jan2000 02:45 0.20 0.04 4.060 0.02
01Jan2000 02:46 0.20 0.04 4.087 0.02
01Jan2000 02:47 0.20 0.04 4.114 0.02
01Jan2000 02:48 0.20 0.04 4.141 0.02
01Jan2000 02:49 0.20 0.04 4.168 0.02
01Jan2000 02:50 0.20 0.04 4.195 0.02
01Jan2000 02:51 0.20 0.04 4.223 0.02
01Jan2000 02:52 0.20 0.04 4.250 0.02
01Jan2000 02:53 0.20 0.04 4.277 0.02
01Jan2000 02:54 0.20 0.04 4.304 0.02
01Jan2000 02:55 0.20 0.04 4.331 0.02
01Jan2000 02:56 0.20 0.04 4.358 0.02
01Jan2000 02:57 0.20 0.04 4.385 0.02
01Jan2000 02:58 0.20 0.04 4.413 0.02
01Jan2000 02:59 0.20 0.04 4.440 0.02
01Jan2000 03:00 0.20 0.04 4.467 0.02

Page 6 ends

Date Time Inflow
(CFS)
Storage
(ACRE-FT)
Elevation
(FT)
Outflow
(CFS)
01Jan2000 03:01 0.22 0.04 4.496 0.02
01Jan2000 03:02 0.23 0.04 4.526 0.02
01Jan2000 03:03 0.25 0.04 4.560 0.02
01Jan2000 03:04 0.27 0.04 4.596 0.02
01Jan2000 03:05 0.28 0.04 4.634 0.02
01Jan2000 03:06 0.30 0.04 4.675 0.02
01Jan2000 03:07 0.30 0.04 4.717 0.02
01Jan2000 03:08 0.30 0.04 4.759 0.02
01Jan2000 03:09 0.30 0.04 4.801 0.02
01Jan2000 03:10 0.30 0.04 4.843 0.02
01Jan2000 03:11 0.30 0.04 4.886 0.02
01Jan2000 03:12 0.30 0.05 4.928 0.02
01Jan2000 03:13 0.30 0.05 4.970 0.02
01Jan2000 03:14 0.30 0.05 5.012 0.02
01Jan2000 03:15 0.30 0.05 5.054 0.02
01Jan2000 03:16 0.30 0.05 5.096 0.02
01Jan2000 03:17 0.30 0.05 5.138 0.02
01Jan2000 03:18 0.30 0.05 5.181 0.02
01Jan2000 03:19 0.30 0.05 5.223 0.02
01Jan2000 03:20 0.30 0.05 5.265 0.02
01Jan2000 03:21 0.30 0.05 5.307 0.02
01Jan2000 03:22 0.30 0.05 5.349 0.02
01Jan2000 03:23 0.30 0.05 5.391 0.02
01Jan2000 03:24 0.30 0.05 5.434 0.02
01Jan2000 03:25 0.32 0.05 5.477 0.02
01Jan2000 03:26 0.33 0.05 5.523 0.02
01Jan2000 03:27 0.35 0.05 5.571 0.02
01Jan2000 03:28 0.37 0.05 5.622 0.02
01Jan2000 03:29 0.38 0.05 5.676 0.02
01Jan2000 03:30 0.40 0.05 5.731 0.02
01Jan2000 03:31 0.40 0.05 5.789 0.02

Page 7 ends

Date Time Inflow
(CFS)
Storage
(ACRE-FT)
Elevation
(FT)
Outflow
(CFS)
01Jan2000 03:32 0.40 0.05 5.846 0.02
01Jan2000 03:33 0.40 0.05 5.903 0.02
01Jan2000 03:34 0.40 0.05 5.960 0.02
01Jan2000 03:35 0.40 0.06 6.017 0.02
01Jan2000 03:36 0.40 0.06 6.074 0.02
01Jan2000 03:37 0.42 0.06 6.133 0.02
01Jan2000 03:38 0.43 0.06 6.194 0.02
01Jan2000 03:39 0.45 0.06 6.257 0.02
01Jan2000 03:40 0.47 0.06 6.323 0.02
01Jan2000 03:41 0.48 0.06 6.392 0.02
01Jan2000 03:42 0.50 0.06 6.462 0.02
01Jan2000 03:43 0.50 0.06 6.534 0.02
01Jan2000 03:44 0.50 0.06 6.607 0.02
01Jan2000 03:45 0.50 0.06 6.679 0.02
01Jan2000 03:46 0.50 0.06 6.751 0.02
01Jan2000 03:47 0.50 0.06 6.823 0.02
01Jan2000 03:48 0.50 0.06 6.895 0.02
01Jan2000 03:49 0.55 0.06 6.971 0.02
01Jan2000 03:50 0.60 0.06 7.038 0.24
01Jan2000 03:51 0.65 0.06 7.077 0.48
01Jan2000 03:52 0.70 0.07 7.098 0.60
01Jan2000 03:53 0.75 0.07 7.111 0.68
01Jan2000 03:54 0.80 0.07 7.121 0.74
01Jan2000 03:55 0.87 0.07 7.131 0.80
01Jan2000 03:56 0.93 0.07 7.142 0.86
01Jan2000 03:57 1.00 0.07 7.153 0.92
01Jan2000 03:58 1.07 0.07 7.164 0.99
01Jan2000 03:59 1.13 0.07 7.175 1.06
01Jan2000 04:00 1.20 0.07 7.186 1.12
01Jan2000 04:01 1.65 0.07 7.218 1.31
01Jan2000 04:02 2.10 0.07 7.288 1.50

Page 8 ends

Date Time Inflow
(CFS)
Storage
(ACRE-FT)
Elevation
(FT)
Outflow
(CFS)
01Jan2000 04:03 2.55 0.07 7.411 1.50
01Jan2000 04:04 3.00 0.07 7.602 1.50
01Jan2000 04:05 3.45 0.07 7.861 1.50
01Jan2000 04:06 3.90 0.08 8.186 1.50
01Jan2000 04:07 3.35 0.08 8.505 1.50
01Jan2000 04:08 2.80 0.08 8.740 1.50
01Jan2000 04:09 2.25 0.08 8.894 1.50
01Jan2000 04:10 1.70 0.08 8.964 1.50
01Jan2000 04:11 1.15 0.08 8.952 1.50
01Jan2000 04:12 0.60 0.08 8.858 1.50
01Jan2000 04:13 0.57 0.08 8.720 1.50
01Jan2000 04:14 0.53 0.08 8.577 1.50
01Jan2000 04:15 0.50 0.08 8.429 1.50
01Jan2000 04:16 0.47 0.08 8.276 1.50
01Jan2000 04:17 0.43 0.07 8.118 1.50
01Jan2000 04:18 0.40 0.07 7.955 1.50
01Jan2000 04:19 0.38 0.07 7.788 1.50
01Jan2000 04:20 0.37 0.07 7.619 1.50
01Jan2000 04:21 0.35 0.07 7.448 1.50
01Jan2000 04:22 0.33 0.07 7.273 1.50
01Jan2000 04:23 0.32 0.07 7.144 0.87
01Jan2000 04:24 0.30 0.07 7.085 0.53
01Jan2000 04:25 0.30 0.06 7.062 0.39
01Jan2000 04:26 0.30 0.06 7.053 0.33
01Jan2000 04:27 0.30 0.06 7.050 0.31
01Jan2000 04:28 0.30 0.06 7.048 0.30
01Jan2000 04:29 0.30 0.06 7.048 0.30
01Jan2000 04:30 0.30 0.06 7.047 0.30
01Jan2000 04:31 0.28 0.06 7.046 0.29
01Jan2000 04:32 0.27 0.06 7.044 0.28
01Jan2000 04:33 0.25 0.06 7.042 0.27

Page 9 ends

Date Time Inflow
(CFS)
Storage
(ACRE-FT)
Elevation
(FT)
Outflow
(CFS)
01Jan2000 04:34 0.23 0.06 7.039 0.25
01Jan2000 04:35 0.22 0.06 7.036 0.23
01Jan2000 04:36 0.20 0.06 7.034 0.22
01Jan2000 04:37 0.20 0.06 7.032 0.21
01Jan2000 04:38 0.20 0.06 7.031 0.20
01Jan2000 04:39 0.20 0.06 7.031 0.20
01Jan2000 04:40 0.20 0.06 7.031 0.20
01Jan2000 04:41 0.20 0.06 7.031 0.20
01Jan2000 04:42 0.20 0.06 7.031 0.20
01Jan2000 04:43 0.20 0.06 7.031 0.20
01Jan2000 04:44 0.20 0.06 7.031 0.20
01Jan2000 04:45 0.20 0.06 7.031 0.20
01Jan2000 04:46 0.20 0.06 7.031 0.20
01Jan2000 04:47 0.20 0.06 7.031 0.20
01Jan2000 04:48 0.20 0.06 7.031 0.20
01Jan2000 04:49 0.20 0.06 7.031 0.20
01Jan2000 04:50 0.20 0.06 7.031 0.20
01Jan2000 04:51 0.20 0.06 7.031 0.20
01Jan2000 04:52 0.20 0.06 7.031 0.20
01Jan2000 04:53 0.20 0.06 7.031 0.20
01Jan2000 04:54 0.20 0.06 7.031 0.20
01Jan2000 04:55 0.20 0.06 7.031 0.20
01Jan2000 04:56 0.20 0.06 7.031 0.20
01Jan2000 04:57 0.20 0.06 7.031 0.20
01Jan2000 04:58 0.20 0.06 7.031 0.20
01Jan2000 04:59 0.20 0.06 7.031 0.20
01Jan2000 05:00 0.20 0.06 7.031 0.20
01Jan2000 05:01 0.20 0.06 7.031 0.20
01Jan2000 05:02 0.20 0.06 7.031 0.20
01Jan2000 05:03 0.20 0.06 7.031 0.20
01Jan2000 05:04 0.20 0.06 7.031 0.20

Page 10 ends

Date Time Inflow
(CFS)
Storage
(ACRE-FT)
Elevation
(FT)
Outflow
(CFS)
01Jan2000 05:05 0.20 0.06 7.031 0.20
01Jan2000 05:06 0.20 0.06 7.031 0.20
01Jan2000 05:07 0.18 0.06 7.029 0.19
01Jan2000 05:08 0.17 0.06 7.028 0.18
01Jan2000 05:09 0.15 0.06 7.025 0.17
01Jan2000 05:10 0.13 0.06 7.022 0.15
01Jan2000 05:11 0.12 0.06 7.020 0.13
01Jan2000 05:12 0.10 0.06 7.017 0.12
01Jan2000 05:13 0.10 0.06 7.015 0.11
01Jan2000 05:14 0.10 0.06 7.014 0.10
01Jan2000 05:15 0.10 0.06 7.014 0.10
01Jan2000 05:16 0.10 0.06 7.014 0.10
01Jan2000 05:17 0.10 0.06 7.014 0.10
01Jan2000 05:18 0.10 0.06 7.014 0.10
01Jan2000 05:19 0.10 0.06 7.014 0.10
01Jan2000 05:20 0.10 0.06 7.014 0.10
01Jan2000 05:21 0.10 0.06 7.014 0.10
01Jan2000 05:22 0.10 0.06 7.014 0.10
01Jan2000 05:23 0.10 0.06 7.014 0.10
01Jan2000 05:24 0.10 0.06 7.014 0.10
01Jan2000 05:25 0.10 0.06 7.014 0.10
01Jan2000 05:26 0.10 0.06 7.014 0.10
01Jan2000 05:27 0.10 0.06 7.014 0.10
01Jan2000 05:28 0.10 0.06 7.014 0.10
01Jan2000 05:29 0.10 0.06 7.014 0.10
01Jan2000 05:30 0.10 0.06 7.014 0.10
01Jan2000 05:31 0.10 0.06 7.014 0.10
01Jan2000 05:32 0.10 0.06 7.014 0.10
01Jan2000 05:33 0.10 0.06 7.014 0.10
01Jan2000 05:34 0.10 0.06 7.014 0.10
01Jan2000 05:35 0.10 0.06 7.014 0.10

Page 11 ends

Date Time Inflow
(CFS)
Storage
(ACRE-FT)
Elevation
(FT)
Outflow
(CFS)
01Jan2000 05:36 0.10 0.06 7.014 0.10
01Jan2000 05:37 0.10 0.06 7.014 0.10
01Jan2000 05:38 0.10 0.06 7.014 0.10
01Jan2000 05:39 0.10 0.06 7.014 0.10
01Jan2000 05:40 0.10 0.06 7.014 0.10
01Jan2000 05:41 0.10 0.06 7.014 0.10
01Jan2000 05:42 0.10 0.06 7.014 0.10
01Jan2000 05:43 0.10 0.06 7.014 0.10
01Jan2000 05:44 0.10 0.06 7.014 0.10
01Jan2000 05:45 0.10 0.06 7.014 0.10
01Jan2000 05:46 0.10 0.06 7.014 0.10
01Jan2000 05:47 0.10 0.06 7.014 0.10
01Jan2000 05:48 0.10 0.06 7.014 0.10
01Jan2000 05:49 0.10 0.06 7.014 0.10
01Jan2000 05:50 0.10 0.06 7.014 0.10
01Jan2000 05:51 0.10 0.06 7.014 0.10
01Jan2000 05:52 0.10 0.06 7.014 0.10
01Jan2000 05:53 0.10 0.06 7.014 0.10
01Jan2000 05:54 0.10 0.06 7.014 0.10
01Jan2000 05:55 0.10 0.06 7.014 0.10
01Jan2000 05:56 0.10 0.06 7.014 0.10
01Jan2000 05:57 0.10 0.06 7.014 0.10
01Jan2000 05:58 0.10 0.06 7.014 0.10
01Jan2000 05:59 0.10 0.06 7.014 0.10
01Jan2000 06:00 0.10 0.06 7.014 0.10
01Jan2000 06:01 0.08 0.06 7.013 0.09
01Jan2000 06:02 0.07 0.06 7.011 0.08
01Jan2000 06:03 0.05 0.06 7.008 0.07
01Jan2000 06:04 0.03 0.06 7.005 0.05
01Jan2000 06:05 0.02 0.06 7.003 0.03
01Jan2000 06:06 0.00 0.06 7.000 0.02

Page 12 ends

Date Time Inflow
(CFS)
Storage
(ACRE-FT)
Elevation
(FT)
Outflow
(CFS)
01Jan2000 06:07 0.00 0.06 6.997 0.02
01Jan2000 06:08 0.00 0.06 6.994 0.02
01Jan2000 06:09 0.00 0.06 6.992 0.02
01Jan2000 06:10 0.00 0.06 6.989 0.02
01Jan2000 06:11 0.00 0.06 6.986 0.02
01Jan2000 06:12 0.00 0.06 6.983 0.02
01Jan2000 06:13 0.00 0.06 6.980 0.02
01Jan2000 06:14 0.00 0.06 6.977 0.02
01Jan2000 06:15 0.00 0.06 6.974 0.02
01Jan2000 06:16 0.00 0.06 6.972 0.02
01Jan2000 06:17 0.00 0.06 6.969 0.02
01Jan2000 06:18 0.00 0.06 6.966 0.02
01Jan2000 06:19 0.00 0.06 6.963 0.02
01Jan2000 06:20 0.00 0.06 6.960 0.02
01Jan2000 06:21 0.00 0.06 6.957 0.02
01Jan2000 06:22 0.00 0.06 6.954 0.02
01Jan2000 06:23 0.00 0.06 6.952 0.02
01Jan2000 06:24 0.00 0.06 6.949 0.02
01Jan2000 06:25 0.00 0.06 6.946 0.02
01Jan2000 06:26 0.00 0.06 6.943 0.02
01Jan2000 06:27 0.00 0.06 6.940 0.02
01Jan2000 06:28 0.00 0.06 6.937 0.02
01Jan2000 06:29 0.00 0.06 6.935 0.02
01Jan2000 06:30 0.00 0.06 6.932 0.02
01Jan2000 06:31 0.00 0.06 6.929 0.02
01Jan2000 06:32 0.00 0.06 6.926 0.02
01Jan2000 06:33 0.00 0.06 6.923 0.02
01Jan2000 06:34 0.00 0.06 6.920 0.02
01Jan2000 06:35 0.00 0.06 6.917 0.02
01Jan2000 06:36 0.00 0.06 6.915 0.02
01Jan2000 06:37 0.00 0.06 6.912 0.02

Page 13 ends

Date Time Inflow
(CFS)
Storage
(ACRE-FT)
Elevation
(FT)
Outflow
(CFS)
01Jan2000 06:38 0.00 0.06 6.909 0.02
01Jan2000 06:39 0.00 0.06 6.906 0.02
01Jan2000 06:40 0.00 0.06 6.903 0.02
01Jan2000 06:41 0.00 0.06 6.900 0.02
01Jan2000 06:42 0.00 0.06 6.897 0.02
01Jan2000 06:43 0.00 0.06 6.895 0.02
01Jan2000 06:44 0.00 0.06 6.892 0.02
01Jan2000 06:45 0.00 0.06 6.889 0.02
01Jan2000 06:46 0.00 0.06 6.886 0.02
01Jan2000 06:47 0.00 0.06 6.883 0.02
01Jan2000 06:48 0.00 0.06 6.880 0.02
01Jan2000 06:49 0.00 0.06 6.878 0.02
01Jan2000 06:50 0.00 0.06 6.875 0.02
01Jan2000 06:51 0.00 0.06 6.872 0.02
01Jan2000 06:52 0.00 0.06 6.869 0.02
01Jan2000 06:53 0.00 0.06 6.866 0.02
01Jan2000 06:54 0.00 0.06 6.863 0.02
01Jan2000 06:55 0.00 0.06 6.860 0.02
01Jan2000 06:56 0.00 0.06 6.858 0.02
01Jan2000 06:57 0.00 0.06 6.855 0.02
01Jan2000 06:58 0.00 0.06 6.852 0.02
01Jan2000 06:59 0.00 0.06 6.849 0.02
01Jan2000 07:00 0.00 0.06 6.846 0.02

Page 14 ends

Pico Place
TM Drainage Study
CHAPTER 4 – STORM DRAIN HYDRAULIC ANALYSIS

Label ‐Node‐ Upstream Downstream ‐Depth‐ Upstream Downstream (ft) ‐EGL‐ Upstream Downstream (ft) ‐Ground‐ Upstream Downstream (ft) ‐HGL‐ Upstream Downstream (ft) ‐Invert‐ Upstream Downstream (ft) Section Discharge Capacity (cfs) Flow (cfs) Velocity (In) (ft/s) Velocity (Out) (ft/s) EX 15"‐RCP JUNCTION 1.25 577.89 580 577.31 576.4 5.02 5.02 5.25 4.09 OUTLET (N/A) (N/A) 578.87 576.9 575.65 9.32
PR‐12"‐RCP NEW CONNECTION 1.47 578.46 580.25 578.36 576.93 1.8 1.8 2.29 2.29 JUNCTION 1.06 578.08 580 578.03 576.4 2.28
EX 15"‐RCP EX INLET 1.49 578.27 578.71 578.08 576.63 3.97 3.97 3.24 3.24 JUNCTION 1.06 578.08 580 577.98 576.4 6.1

Pico Place
TM Drainage Study
CHAPTER 5 - 100 YEAR HYDROLOGIC ANALYSIS FOR

EXISTING CONDITIONS
____________________________________________________________________________ ****************************************************************************

RATIONAL METHOD HYDROLOGY COMPUTER PROGRAM PACKAGE
Reference: SAN DIEGO COUNTY FLOOD CONTROL DISTRICT
2003,1985,1981 HYDROLOGY MANUAL
(c) Copyright 1982-2015 Advanced Engineering Software (aes) Ver. 22.0 Release Date: 07/01/2015 License ID 1643
Analysis prepared by:

************************** DESCRIPTION OF STUDY ************************** * PICO VILLAGE *
* 100 YEAR EXISTING CONDITIONS HYDROLOGIC ANALYSIS *
* *
************************************************************************** FILE NAME: PIEXREV.DAT
TIME/DATE OF STUDY: 08:43 04/14/2023
---------------------------------------------------------------------------- USER SPECIFIED HYDROLOGY AND HYDRAULIC MODEL INFORMATION:
---------------------------------------------------------------------------- 2003 SAN DIEGO MANUAL CRITERIA
USER SPECIFIED STORM EVENT(YEAR) = 100.00
6-HOUR DURATION PRECIPITATION (INCHES) = 3.400
SPECIFIED MINIMUM PIPE SIZE(INCH) = 18.00
SPECIFIED PERCENT OF GRADIENTS(DECIMAL) TO USE FOR FRICTION SLOPE = 0.95 SAN DIEGO HYDROLOGY MANUAL "C"-VALUES USED FOR RATIONAL METHOD NOTE: USE MODIFIED RATIONAL METHOD PROCEDURES FOR CONFLUENCE ANALYSIS *USER-DEFINED STREET-SECTIONS FOR COUPLED PIPEFLOW AND STREETFLOW MODEL* HALF- CROWN TO STREET-CROSSFALL: CURB GUTTER-GEOMETRIES: MANNING

WIDTH CROSSFALL IN- / OUT-/PARK- HEIGHT WIDTH LIP HIKE FACTOR NO. (FT) (FT) SIDE / SIDE/ WAY (FT) (FT) (FT) (FT) (n)
=== ===== ========= ================= ====== ===== ====== ===== ======= 1 30.0 20.0 0.018/0.018/0.020 0.67 2.00 0.0312 0.167 0.0150 GLOBAL STREET FLOW-DEPTH CONSTRAINTS:

1. Relative Flow-Depth = 0.00 FEET
as (Maximum Allowable Street Flow Depth) - (Top-of-Curb)

2. (Depth)*(Velocity) Constraint = 6.0 (FT*FT/S)
*SIZE PIPE WITH A FLOW CAPACITY GREATER THAN
OR EQUAL TO THE UPSTREAM TRIBUTARY PIPE.*
**************************************************************************** FLOW PROCESS FROM NODE 1.00 TO NODE 2.00 IS CODE = 21
---------------------------------------------------------------------------- >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<<
============================================================================ *USER SPECIFIED(SUBAREA):

GENERAL COMMERCIAL RUNOFF COEFFICIENT = .7500
S.C.S. CURVE NUMBER (AMC II) = 0
INITIAL SUBAREA FLOW-LENGTH(FEET) = 60.00
UPSTREAM ELEVATION(FEET) = 581.50
DOWNSTREAM ELEVATION(FEET) = 580.35
ELEVATION DIFFERENCE(FEET) = 1.15
SUBAREA OVERLAND TIME OF FLOW(MIN.) = 3.929
100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 8.958
NOTE: RAINFALL INTENSITY IS BASED ON Tc = 5-MINUTE.

SUBAREA RUNOFF(CFS) = 1.05
TOTAL AREA(ACRES) = 0.16 TOTAL RUNOFF(CFS) = 1.05
**************************************************************************** FLOW PROCESS FROM NODE 2.00 TO NODE 3.00 IS CODE = 51
---------------------------------------------------------------------------- >>>>>COMPUTE TRAPEZOIDAL CHANNEL FLOW<<<<<
>>>>>TRAVELTIME THRU SUBAREA (EXISTING ELEMENT)<<<<<
============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 580.35 DOWNSTREAM(FEET) = 580.20 CHANNEL LENGTH THRU SUBAREA(FEET) = 28.00 CHANNEL SLOPE = 0.0054 CHANNEL BASE(FEET) = 5.00 "Z" FACTOR = 2.000
MANNING'S FACTOR = 0.015 MAXIMUM DEPTH(FEET) = 1.00
100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 8.958
NOTE: RAINFALL INTENSITY IS BASED ON Tc = 5-MINUTE.
*USER SPECIFIED(SUBAREA):

GENERAL COMMERCIAL RUNOFF COEFFICIENT = .7500
S.C.S. CURVE NUMBER (AMC II) = 0
TRAVEL TIME COMPUTED USING ESTIMATED FLOW(CFS) = 1.31
TRAVEL TIME THRU SUBAREA BASED ON VELOCITY(FEET/SEC.) = 1.85 AVERAGE FLOW DEPTH(FEET) = 0.13 TRAVEL TIME(MIN.) = 0.25 Tc(MIN.) = 4.18
SUBAREA AREA(ACRES) = 0.08 SUBAREA RUNOFF(CFS) = 0.52
AREA-AVERAGE RUNOFF COEFFICIENT = 0.750
TOTAL AREA(ACRES) = 0.2 PEAK FLOW RATE(CFS) = 1.57
END OF SUBAREA CHANNEL FLOW HYDRAULICS:

DEPTH(FEET) = 0.15 FLOW VELOCITY(FEET/SEC.) = 1.98
LONGEST FLOWPATH FROM NODE 1.00 TO NODE 3.00 = 88.00 FEET. +--------------------------------------------------------------------------+ | END ANALYSIS TO PICO AVE |
| BEGIN ANALYSIS TO WESTERN BOUNDARY |
| |
+--------------------------------------------------------------------------+ **************************************************************************** FLOW PROCESS FROM NODE 4.00 TO NODE 5.00 IS CODE = 21
---------------------------------------------------------------------------- >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<<
============================================================================ *USER SPECIFIED(SUBAREA):

GENERAL COMMERCIAL RUNOFF COEFFICIENT = .3400
S.C.S. CURVE NUMBER (AMC II) = 0
INITIAL SUBAREA FLOW-LENGTH(FEET) = 60.00
UPSTREAM ELEVATION(FEET) = 580.00
DOWNSTREAM ELEVATION(FEET) = 579.50
ELEVATION DIFFERENCE(FEET) = 0.50
SUBAREA OVERLAND TIME OF FLOW(MIN.) = 10.943
WARNING: INITIAL SUBAREA FLOW PATH LENGTH IS GREATER THAN THE MAXIMUM OVERLAND FLOW LENGTH = 56.67
(Reference: Table 3-1B of Hydrology Manual)
THE MAXIMUM OVERLAND FLOW LENGTH IS USED IN Tc CALCULATION! 100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 5.405
SUBAREA RUNOFF(CFS) = 0.10
TOTAL AREA(ACRES) = 0.05 TOTAL RUNOFF(CFS) = 0.10
**************************************************************************** FLOW PROCESS FROM NODE 5.00 TO NODE 6.00 IS CODE = 51
---------------------------------------------------------------------------- >>>>>COMPUTE TRAPEZOIDAL CHANNEL FLOW<<<<<
>>>>>TRAVELTIME THRU SUBAREA (EXISTING ELEMENT)<<<<<
============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 579.50 DOWNSTREAM(FEET) = 578.50 CHANNEL LENGTH THRU SUBAREA(FEET) = 179.00 CHANNEL SLOPE = 0.0056 CHANNEL BASE(FEET) = 5.00 "Z" FACTOR = 2.000
MANNING'S FACTOR = 0.030 MAXIMUM DEPTH(FEET) = 2.00
100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 4.461
*USER SPECIFIED(SUBAREA):

GENERAL COMMERCIAL RUNOFF COEFFICIENT = .3400
S.C.S. CURVE NUMBER (AMC II) = 0
TRAVEL TIME COMPUTED USING ESTIMATED FLOW(CFS) = 0.39
TRAVEL TIME THRU SUBAREA BASED ON VELOCITY(FEET/SEC.) = 0.79 AVERAGE FLOW DEPTH(FEET) = 0.10 TRAVEL TIME(MIN.) = 3.79 Tc(MIN.) = 14.73
SUBAREA AREA(ACRES) = 0.38 SUBAREA RUNOFF(CFS) = 0.58
AREA-AVERAGE RUNOFF COEFFICIENT = 0.340
TOTAL AREA(ACRES) = 0.4 PEAK FLOW RATE(CFS) = 0.67
END OF SUBAREA CHANNEL FLOW HYDRAULICS:

DEPTH(FEET) = 0.13 FLOW VELOCITY(FEET/SEC.) = 0.94
LONGEST FLOWPATH FROM NODE 4.00 TO NODE 6.00 = 239.00 FEET. **************************************************************************** FLOW PROCESS FROM NODE 7.00 TO NODE 7.00 IS CODE = 81
---------------------------------------------------------------------------- >>>>>ADDITION OF SUBAREA TO MAINLINE PEAK FLOW<<<<<
============================================================================ 100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 4.461
*USER SPECIFIED(SUBAREA):

GENERAL COMMERCIAL RUNOFF COEFFICIENT = .8100
S.C.S. CURVE NUMBER (AMC II) = 0
AREA-AVERAGE RUNOFF COEFFICIENT = 0.4029
SUBAREA AREA(ACRES) = 0.07 SUBAREA RUNOFF(CFS) = 0.25
TOTAL AREA(ACRES) = 0.5 TOTAL RUNOFF(CFS) = 0.91
TC(MIN.) = 14.73
============================================================================ END OF STUDY SUMMARY:

TOTAL AREA(ACRES) = 0.5 TC(MIN.) = 14.73
PEAK FLOW RATE(CFS) = 0.91
============================================================================ ============================================================================

END OF RATIONAL METHOD ANALYSIS

Pico Place
TM Drainage Study
CHAPTER 6 - 100 YEAR HYDROLOGIC ANALYSIS FOR

DEVELOPED CONDITIONS
____________________________________________________________________________ ****************************************************************************

************************** DESCRIPTION OF STUDY ************************** * PICO VILLAGE *
* 100 YEAR DEVELOPED CONDITION HYDROLOGIC ANALYSIS *
* *
************************************************************************** FILE NAME: PIDEV.DAT
TIME/DATE OF STUDY: 14:07 04/14/2023
---------------------------------------------------------------------------- USER SPECIFIED HYDROLOGY AND HYDRAULIC MODEL INFORMATION:
---------------------------------------------------------------------------- 2003 SAN DIEGO MANUAL CRITERIA
USER SPECIFIED STORM EVENT(YEAR) = 100.00
6-HOUR DURATION PRECIPITATION (INCHES) = 3.400
SPECIFIED MINIMUM PIPE SIZE(INCH) = 18.00
SPECIFIED PERCENT OF GRADIENTS(DECIMAL) TO USE FOR FRICTION SLOPE = 0.95 SAN DIEGO HYDROLOGY MANUAL "C"-VALUES USED FOR RATIONAL METHOD NOTE: USE MODIFIED RATIONAL METHOD PROCEDURES FOR CONFLUENCE ANALYSIS *USER-DEFINED STREET-SECTIONS FOR COUPLED PIPEFLOW AND STREETFLOW MODEL* HALF- CROWN TO STREET-CROSSFALL: CURB GUTTER-GEOMETRIES: MANNING

1. Relative Flow-Depth = 0.00 FEET
as (Maximum Allowable Street Flow Depth) - (Top-of-Curb)

RESIDENTIAL (7.3 DU/AC OR LESS) RUNOFF COEFFICIENT = .7500 S.C.S. CURVE NUMBER (AMC II) = 0
INITIAL SUBAREA FLOW-LENGTH(FEET) = 60.00
UPSTREAM ELEVATION(FEET) = 580.50
DOWNSTREAM ELEVATION(FEET) = 579.90
ELEVATION DIFFERENCE(FEET) = 0.60
SUBAREA OVERLAND TIME OF FLOW(MIN.) = 4.880
100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 8.958
NOTE: RAINFALL INTENSITY IS BASED ON Tc = 5-MINUTE.

SUBAREA RUNOFF(CFS) = 0.44
TOTAL AREA(ACRES) = 0.06 TOTAL RUNOFF(CFS) = 0.44
**************************************************************************** FLOW PROCESS FROM NODE 2.00 TO NODE 3.00 IS CODE = 51
---------------------------------------------------------------------------- >>>>>COMPUTE TRAPEZOIDAL CHANNEL FLOW<<<<<
>>>>>TRAVELTIME THRU SUBAREA (EXISTING ELEMENT)<<<<<
============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 579.90 DOWNSTREAM(FEET) = 579.00 CHANNEL LENGTH THRU SUBAREA(FEET) = 218.00 CHANNEL SLOPE = 0.0041 CHANNEL BASE(FEET) = 2.00 "Z" FACTOR = 2.000
MANNING'S FACTOR = 0.015 MAXIMUM DEPTH(FEET) = 1.00
100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 7.696
*USER SPECIFIED(SUBAREA):

RESIDENTIAL (7.3 DU/AC OR LESS) RUNOFF COEFFICIENT = .7500 S.C.S. CURVE NUMBER (AMC II) = 0
TRAVEL TIME COMPUTED USING ESTIMATED FLOW(CFS) = 2.21
TRAVEL TIME THRU SUBAREA BASED ON VELOCITY(FEET/SEC.) = 2.51 AVERAGE FLOW DEPTH(FEET) = 0.33 TRAVEL TIME(MIN.) = 1.45 Tc(MIN.) = 6.33
SUBAREA AREA(ACRES) = 0.61 SUBAREA RUNOFF(CFS) = 3.52
AREA-AVERAGE RUNOFF COEFFICIENT = 0.750
TOTAL AREA(ACRES) = 0.7 PEAK FLOW RATE(CFS) = 3.90
END OF SUBAREA CHANNEL FLOW HYDRAULICS:

DEPTH(FEET) = 0.45 FLOW VELOCITY(FEET/SEC.) = 3.01
LONGEST FLOWPATH FROM NODE 1.00 TO NODE 3.00 = 278.00 FEET. +--------------------------------------------------------------------------+ | INFLOW TO DETENTION BASIN |
| ROUTED FLOW VIA HMS MODEL |
| |
+--------------------------------------------------------------------------+ **************************************************************************** FLOW PROCESS FROM NODE 3.00 TO NODE 3.00 IS CODE = 7
---------------------------------------------------------------------------- >>>>>USER SPECIFIED HYDROLOGY INFORMATION AT NODE<<<<<
============================================================================ USER-SPECIFIED VALUES ARE AS FOLLOWS:

TC(MIN) = 10.63 RAIN INTENSITY(INCH/HOUR) = 5.51
TOTAL AREA(ACRES) = 0.67 TOTAL RUNOFF(CFS) = 1.50
**************************************************************************** FLOW PROCESS FROM NODE 3.00 TO NODE 4.00 IS CODE = 31
---------------------------------------------------------------------------- >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<< ============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 578.00 DOWNSTREAM(FEET) = 577.00 FLOW LENGTH(FEET) = 107.00 MANNING'S N = 0.013
ESTIMATED PIPE DIAMETER(INCH) INCREASED TO 18.000
DEPTH OF FLOW IN 18.0 INCH PIPE IS 4.7 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 4.04
ESTIMATED PIPE DIAMETER(INCH) = 18.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 1.50
PIPE TRAVEL TIME(MIN.) = 0.44 Tc(MIN.) = 11.07
LONGEST FLOWPATH FROM NODE 1.00 TO NODE 4.00 = 385.00 FEET. **************************************************************************** FLOW PROCESS FROM NODE 4.00 TO NODE 4.00 IS CODE = 1
---------------------------------------------------------------------------- >>>>>DESIGNATE INDEPENDENT STREAM FOR CONFLUENCE<<<<<
============================================================================ TOTAL NUMBER OF STREAMS = 2
CONFLUENCE VALUES USED FOR INDEPENDENT STREAM 1 ARE:

TIME OF CONCENTRATION(MIN.) = 11.07
RAINFALL INTENSITY(INCH/HR) = 5.36
TOTAL STREAM AREA(ACRES) = 0.67
PEAK FLOW RATE(CFS) AT CONFLUENCE = 1.50
+--------------------------------------------------------------------------+ | END ANALYSIS FOR PICO PROJECT SITE |
| BEGIN ANALYSIS FOR OFFSITE RUNON INTERCEPT CALCULATION | | |
+--------------------------------------------------------------------------+ **************************************************************************** FLOW PROCESS FROM NODE 10.00 TO NODE 11.00 IS CODE = 21 ---------------------------------------------------------------------------- >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<<
============================================================================ *USER SPECIFIED(SUBAREA):

GENERAL COMMERCIAL RUNOFF COEFFICIENT = .8100
S.C.S. CURVE NUMBER (AMC II) = 0
INITIAL SUBAREA FLOW-LENGTH(FEET) = 60.00
UPSTREAM ELEVATION(FEET) = 581.00
DOWNSTREAM ELEVATION(FEET) = 580.40
ELEVATION DIFFERENCE(FEET) = 0.60
SUBAREA OVERLAND TIME OF FLOW(MIN.) = 4.043
WARNING: INITIAL SUBAREA FLOW PATH LENGTH IS GREATER THAN THE MAXIMUM OVERLAND FLOW LENGTH = 60.00
(Reference: Table 3-1B of Hydrology Manual)
THE MAXIMUM OVERLAND FLOW LENGTH IS USED IN Tc CALCULATION! 100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 8.958
NOTE: RAINFALL INTENSITY IS BASED ON Tc = 5-MINUTE.

SUBAREA RUNOFF(CFS) = 0.25
TOTAL AREA(ACRES) = 0.04 TOTAL RUNOFF(CFS) = 0.25
**************************************************************************** FLOW PROCESS FROM NODE 11.00 TO NODE 12.00 IS CODE = 51 ---------------------------------------------------------------------------- >>>>>COMPUTE TRAPEZOIDAL CHANNEL FLOW<<<<<
>>>>>TRAVELTIME THRU SUBAREA (EXISTING ELEMENT)<<<<<
============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 580.40 DOWNSTREAM(FEET) = 580.00 CHANNEL LENGTH THRU SUBAREA(FEET) = 37.00 CHANNEL SLOPE = 0.0108 CHANNEL BASE(FEET) = 5.00 "Z" FACTOR = 2.000
MANNING'S FACTOR = 0.030 MAXIMUM DEPTH(FEET) = 2.00
100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 8.958
NOTE: RAINFALL INTENSITY IS BASED ON Tc = 5-MINUTE.
*USER SPECIFIED(SUBAREA):

GENERAL COMMERCIAL RUNOFF COEFFICIENT = .8100
S.C.S. CURVE NUMBER (AMC II) = 0
TRAVEL TIME COMPUTED USING ESTIMATED FLOW(CFS) = 0.38
TRAVEL TIME THRU SUBAREA BASED ON VELOCITY(FEET/SEC.) = 0.92 AVERAGE FLOW DEPTH(FEET) = 0.08 TRAVEL TIME(MIN.) = 0.67 Tc(MIN.) = 4.71
SUBAREA AREA(ACRES) = 0.03 SUBAREA RUNOFF(CFS) = 0.25
AREA-AVERAGE RUNOFF COEFFICIENT = 0.810
TOTAL AREA(ACRES) = 0.1 PEAK FLOW RATE(CFS) = 0.50
END OF SUBAREA CHANNEL FLOW HYDRAULICS:

DEPTH(FEET) = 0.09 FLOW VELOCITY(FEET/SEC.) = 1.02
LONGEST FLOWPATH FROM NODE 10.00 TO NODE 12.00 = 97.00 FEET. **************************************************************************** FLOW PROCESS FROM NODE 4.00 TO NODE 4.00 IS CODE = 1
---------------------------------------------------------------------------- >>>>>DESIGNATE INDEPENDENT STREAM FOR CONFLUENCE<<<<<
>>>>>AND COMPUTE VARIOUS CONFLUENCED STREAM VALUES<<<<< ============================================================================ TOTAL NUMBER OF STREAMS = 2
CONFLUENCE VALUES USED FOR INDEPENDENT STREAM 2 ARE:

TIME OF CONCENTRATION(MIN.) = 4.71
RAINFALL INTENSITY(INCH/HR) = 8.96
TOTAL STREAM AREA(ACRES) = 0.07
PEAK FLOW RATE(CFS) AT CONFLUENCE = 0.50
** CONFLUENCE DATA **
STREAM RUNOFF Tc INTENSITY AREA
NUMBER (CFS) (MIN.) (INCH/HOUR) (ACRE)
1 1.50 11.07 5.365 0.67
2 0.50 4.71 8.958 0.07

RAINFALL INTENSITY AND TIME OF CONCENTRATION RATIO
CONFLUENCE FORMULA USED FOR 2 STREAMS.
** PEAK FLOW RATE TABLE **
STREAM RUNOFF Tc INTENSITY
NUMBER (CFS) (MIN.) (INCH/HOUR)
1 1.14 4.71 8.958
2 1.80 11.07 5.365
COMPUTED CONFLUENCE ESTIMATES ARE AS FOLLOWS:

PEAK FLOW RATE(CFS) = 1.80 Tc(MIN.) = 11.07
TOTAL AREA(ACRES) = 0.7
LONGEST FLOWPATH FROM NODE 1.00 TO NODE 4.00 = 385.00 FEET. **************************************************************************** FLOW PROCESS FROM NODE 4.00 TO NODE 102.00 IS CODE = 31 ---------------------------------------------------------------------------- >>>>>COMPUTE PIPE-FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>USING COMPUTER-ESTIMATED PIPESIZE (NON-PRESSURE FLOW)<<<<< ============================================================================ ELEVATION DATA: UPSTREAM(FEET) = 576.93 DOWNSTREAM(FEET) = 576.40 FLOW LENGTH(FEET) = 129.00 MANNING'S N = 0.013
ESTIMATED PIPE DIAMETER(INCH) INCREASED TO 18.000
DEPTH OF FLOW IN 18.0 INCH PIPE IS 6.4 INCHES
PIPE-FLOW VELOCITY(FEET/SEC.) = 3.17
ESTIMATED PIPE DIAMETER(INCH) = 18.00 NUMBER OF PIPES = 1 PIPE-FLOW(CFS) = 1.80
PIPE TRAVEL TIME(MIN.) = 0.68 Tc(MIN.) = 11.75
LONGEST FLOWPATH FROM NODE 1.00 TO NODE 102.00 = 514.00 FEET. **************************************************************************** FLOW PROCESS FROM NODE 102.00 TO NODE 102.00 IS CODE = 1 ---------------------------------------------------------------------------- >>>>>DESIGNATE INDEPENDENT STREAM FOR CONFLUENCE<<<<<
============================================================================ TOTAL NUMBER OF STREAMS = 2
CONFLUENCE VALUES USED FOR INDEPENDENT STREAM 1 ARE:

TIME OF CONCENTRATION(MIN.) = 11.75
RAINFALL INTENSITY(INCH/HR) = 5.16
TOTAL STREAM AREA(ACRES) = 0.74
PEAK FLOW RATE(CFS) AT CONFLUENCE = 1.80
+--------------------------------------------------------------------------+ | END ANALYSIS FOR ONSITE HYDROLOGY |
| BEGIN ANALYSIS FOR EXISTING 15-INCH SD IN PICO AVE |
| |
+--------------------------------------------------------------------------+ **************************************************************************** FLOW PROCESS FROM NODE 100.00 TO NODE 101.00 IS CODE = 21 ---------------------------------------------------------------------------- >>>>>RATIONAL METHOD INITIAL SUBAREA ANALYSIS<<<<<
============================================================================ *USER SPECIFIED(SUBAREA):

RESIDENTIAL (1. DU/AC OR LESS) RUNOFF COEFFICIENT = .9000 S.C.S. CURVE NUMBER (AMC II) = 0
INITIAL SUBAREA FLOW-LENGTH(FEET) = 70.00
UPSTREAM ELEVATION(FEET) = 582.67
DOWNSTREAM ELEVATION(FEET) = 581.97
ELEVATION DIFFERENCE(FEET) = 0.70
SUBAREA OVERLAND TIME OF FLOW(MIN.) = 3.012
100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 8.958
NOTE: RAINFALL INTENSITY IS BASED ON Tc = 5-MINUTE.

SUBAREA RUNOFF(CFS) = 0.43
TOTAL AREA(ACRES) = 0.05 TOTAL RUNOFF(CFS) = 0.43
**************************************************************************** FLOW PROCESS FROM NODE 101.00 TO NODE 102.00 IS CODE = 62 ---------------------------------------------------------------------------- >>>>>COMPUTE STREET FLOW TRAVEL TIME THRU SUBAREA<<<<<
>>>>>(STREET TABLE SECTION # 1 USED)<<<<<
============================================================================ UPSTREAM ELEVATION(FEET) = 581.97 DOWNSTREAM ELEVATION(FEET) = 578.99 STREET LENGTH(FEET) = 281.00 CURB HEIGHT(INCHES) = 8.0
STREET HALFWIDTH(FEET) = 30.00
DISTANCE FROM CROWN TO CROSSFALL GRADEBREAK(FEET) = 20.00 INSIDE STREET CROSSFALL(DECIMAL) = 0.018
OUTSIDE STREET CROSSFALL(DECIMAL) = 0.018
SPECIFIED NUMBER OF HALFSTREETS CARRYING RUNOFF = 1
STREET PARKWAY CROSSFALL(DECIMAL) = 0.020
Manning's FRICTION FACTOR for Streetflow Section(curb-to-curb) = 0.0150 Manning's FRICTION FACTOR for Back-of-Walk Flow Section = 0.0200 **TRAVEL TIME COMPUTED USING ESTIMATED FLOW(CFS) = 2.20 STREETFLOW MODEL RESULTS USING ESTIMATED FLOW:

STREET FLOW DEPTH(FEET) = 0.33
HALFSTREET FLOOD WIDTH(FEET) = 9.47
AVERAGE FLOW VELOCITY(FEET/SEC.) = 2.21
PRODUCT OF DEPTH&VELOCITY(FT*FT/SEC.) = 0.73
STREET FLOW TRAVEL TIME(MIN.) = 2.12 Tc(MIN.) = 5.13
100 YEAR RAINFALL INTENSITY(INCH/HOUR) = 8.813
*USER SPECIFIED(SUBAREA):

STREETS & ROADS (CURBS/STORM DRAINS) RUNOFF COEFFICIENT = .9000 S.C.S. CURVE NUMBER (AMC II) = 0
AREA-AVERAGE RUNOFF COEFFICIENT = 0.900
SUBAREA AREA(ACRES) = 0.45 SUBAREA RUNOFF(CFS) = 3.55
TOTAL AREA(ACRES) = 0.5 PEAK FLOW RATE(CFS) = 3.97
END OF SUBAREA STREET FLOW HYDRAULICS:

DEPTH(FEET) = 0.39 HALFSTREET FLOOD WIDTH(FEET) = 12.46 FLOW VELOCITY(FEET/SEC.) = 2.51 DEPTH*VELOCITY(FT*FT/SEC.) = 0.97 LONGEST FLOWPATH FROM NODE 100.00 TO NODE 102.00 = 351.00 FEET. **************************************************************************** FLOW PROCESS FROM NODE 102.00 TO NODE 102.00 IS CODE = 1 ---------------------------------------------------------------------------- >>>>>DESIGNATE INDEPENDENT STREAM FOR CONFLUENCE<<<<<
>>>>>AND COMPUTE VARIOUS CONFLUENCED STREAM VALUES<<<<< ============================================================================ TOTAL NUMBER OF STREAMS = 2
CONFLUENCE VALUES USED FOR INDEPENDENT STREAM 2 ARE:

TIME OF CONCENTRATION(MIN.) = 5.13
RAINFALL INTENSITY(INCH/HR) = 8.81
TOTAL STREAM AREA(ACRES) = 0.50
PEAK FLOW RATE(CFS) AT CONFLUENCE = 3.97
** CONFLUENCE DATA **
STREAM RUNOFF Tc INTENSITY AREA
NUMBER (CFS) (MIN.) (INCH/HOUR) (ACRE)
1 1.80 11.75 5.163 0.74
2 3.97 5.13 8.813 0.50

RAINFALL INTENSITY AND TIME OF CONCENTRATION RATIO
CONFLUENCE FORMULA USED FOR 2 STREAMS.
** PEAK FLOW RATE TABLE **
STREAM RUNOFF Tc INTENSITY
NUMBER (CFS) (MIN.) (INCH/HOUR)
1 5.02 5.13 8.813
2 4.12 11.75 5.163
COMPUTED CONFLUENCE ESTIMATES ARE AS FOLLOWS:

PEAK FLOW RATE(CFS) = 5.02 Tc(MIN.) = 5.13
TOTAL AREA(ACRES) = 1.2
LONGEST FLOWPATH FROM NODE 1.00 TO NODE 102.00 = 514.00 FEET. +--------------------------------------------------------------------------+ | CONFLUENCE WITH DETAINED ONSITE FLOW AT JUNCTION OF 12-INCH and 15-INCH | | |
| |
+--------------------------------------------------------------------------+ ============================================================================ END OF STUDY SUMMARY:

TOTAL AREA(ACRES) = 1.2 TC(MIN.) = 5.13
PEAK FLOW RATE(CFS) = 5.02
============================================================================ ============================================================================

END OF RATIONAL METHOD ANALYSIS

Pico Place
TM Drainage Study
CHAPTER 7 - HYDROLOGY MAPS
1 EX CONDITIONS - Q100 EXHIBIT

PICO PLACE
236-244 SAN MARCOS PICO AVENUE
SAN MARCOS, CA 92069
1 DMA/BMP PLAN - PROPOSED

PICO VILLAGE
236-244 SAN MARCOS PICO AVENUE
SAN MARCOS, CA 92069

Appendix I. RCNM Results, FHWA Traffic Noise Modeling Results, and Distance Attenuation Calculations
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Roadway Construction Noise Model (RCNM),Version 1.1
Report date:             03/12/2023
Case Description:        Pico Residential
**** Receptor #1 ****
Baselines (dBA)
Description   Land Use        Daytime    Evening    Night ‐‐‐‐‐‐‐‐‐‐‐   ‐‐‐‐‐‐‐‐        ‐‐‐‐‐‐‐    ‐‐‐‐‐‐‐    ‐‐‐‐‐ Residences    Residential        60.0       60.0     60.0 Equipment
‐‐‐‐‐‐‐‐‐
Spec    Actual    Receptor    Estimated
Impact  Usage    Lmax    Lmax      Distance    Shielding Description     Device   (%)     (dBA)   (dBA)      (feet)       (dBA) ‐‐‐‐‐‐‐‐‐‐‐     ‐‐‐‐‐‐  ‐‐‐‐‐    ‐‐‐‐‐   ‐‐‐‐‐     ‐‐‐‐‐‐‐‐    ‐‐‐‐‐‐‐‐‐ Concrete Saw        No     20             89.6         50.0          0.0 Crane               No     16             80.6         50.0          0.0 Excavator           No     40             80.7         50.0          0.0 Dozer               No     40             81.7         50.0          0.0 Scraper             No     40             83.6         50.0          0.0

Results
‐‐‐‐‐‐‐
Noise Limits (dBA)
Noise Limit Exceedance (dBA)

‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐
‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐
Calculated (dBA)         Day           Evening
Night              Day           Evening          Night ‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐   ‐‐‐‐‐‐‐‐‐‐‐‐‐‐   ‐‐‐‐‐‐‐‐‐‐‐‐‐
‐‐‐‐‐‐‐‐‐‐‐‐‐‐    ‐‐‐‐‐‐‐‐‐‐‐‐‐‐  ‐‐‐‐‐‐‐‐‐‐‐‐‐‐  ‐‐‐‐‐‐‐‐‐‐‐‐‐‐ Equipment                  Lmax    Leq        Lmax    Leq     Lmax    Leq     Lmax Leq       Lmax    Leq     Lmax    Leq     Lmax    Leq
‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐  ‐‐‐‐‐‐  ‐‐‐‐‐‐     ‐‐‐‐‐‐  ‐‐‐‐‐‐  ‐‐‐‐‐‐  ‐‐‐‐‐‐  ‐‐‐‐‐‐ ‐‐‐‐‐‐    ‐‐‐‐‐‐  ‐‐‐‐‐‐  ‐‐‐‐‐‐  ‐‐‐‐‐‐  ‐‐‐‐‐‐  ‐‐‐‐‐‐ Concrete Saw              89.6    82.6        N/A     N/A     N/A     N/A     N/A N/A       N/A     N/A     N/A     N/A     N/A     N/A
Crane                     80.6    72.6        N/A     N/A     N/A     N/A     N/A N/A       N/A     N/A     N/A     N/A     N/A     N/A
Excavator                 80.7    76.7        N/A     N/A     N/A     N/A     N/A N/A       N/A     N/A     N/A     N/A     N/A     N/A
Dozer                     81.7    77.7        N/A     N/A     N/A     N/A     N/A N/A       N/A     N/A     N/A     N/A     N/A     N/A
Scraper                   83.6    79.6        N/A     N/A     N/A     N/A     N/A N/A       N/A     N/A     N/A     N/A     N/A     N/A
Total      89.6    86.0        N/A     N/A     N/A     N/A     N/A N/A       N/A     N/A     N/A     N/A     N/A     N/A

TRAFFIC NOISE LEVELS AND NOISE CONTOURS
Project Number:

Project Name: Pico Avenue Residential
Background InformationModel Description: FHWA Highway Noise Prediction Model (FHWA-RD-77-108) with California Vehicle Noise (CALVENO) Emission Levels.Source of Traffic Volumes: Linscott, Law, and Greenspan, February 2023 Community Noise Descriptor: Ldn: CNEL: X
"-" = contour is located within the roadway right-of-way.

Assumed 24-Hour Traffic Distribution: Day Evening Night Distance is from the centerline of the roadway segmentTotal ADT Volumes 77.70% 12.70% 9.60% to the receptor location.Medium-Duty Trucks 87.43% 5.05% 7.52%Heavy-Duty Trucks 89.10% 2.84% 8.06% Design Vehicle Mix Distance from Centerline of Roadway
Analysis Condition Median ADT Speed Alpha Medium Heavy CNEL at Distance to Contour Roadway, Segment Lanes Width Volume (mph) Factor Trucks Trucks 50 Feet 70 CNEL 65 CNEL 60 CNEL 55 CNEL Mission Road
Knoll Road to Pico Avenue, existing 4 12 14,510 45 0.5 3.0% 2.0% 69.6 - 102 219 472Knoll Road to Pico Avenue, existing + project 4 12 14,536 45 0.5 3.0% 2.0% 69.6 - 102 219 473 San Marcos Boulevard
Pico Avenue to TOV Road, existing 4 12 5,860 40 0.5 3.0% 2.0% 64.6 - - 102 220Pico Avenue to TOV Road, existing + project 4 12 5,956 40 0.5 3.0% 2.0% 64.7 - - 103 222 Pico Avenue
Mission Road to San Marcos Boulevard, existing 3 12 31,200 25 0.5 2.0% 1.0% 66.7 - 65 140 301Mission Road to San Marcos Boulevard, existing + project 3 12 31,277 25 0.5 2.0% 1.0% 66.7 - 65 140 301 122-0283
Pico Traffic Noise Worksheet.xls Harris Associates 3/16/2023

Sound Point Source Dependence on Distance
Attenuation Rate: 6 dBA/doubling of distance L1 = Reference sound level D1 = Reference distance L2 = Target sound level D2 = Target distance
L2 = L1 - 20 * log(D2/D1)
L2
L1 D1 D2 D2/D1 log (D2/D1) L1-20*log(D2/D1)
For L(eq)t 86 50 230 4.6 0.6628 72.7 Construction
86 50 180 3.6 0.5563 74.9 Construction 79 3 15 5 0.6990 65.0 HVAC

Appendix J. Will Serve Letters
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\T7 AkI AAAIfFC
3IiI IVIft’.’.d3 Business Services T 760.752.1299
UNIFIED SCHOOL DISTRICT 255 Pico Avenue, Suite 250 F 760.471.4928 engaging students...inspiring futures San Marcos, CA 92069 www.smusd.org May 12, 2023
State of California
Department of Real Estate
320 West Fourth St, Ste 350
Los Angeles, CA 90013-1105
Re: Name: Pico Apartments
Type of Project: Planned DevelopmentDeveloper: Anthony Sfreddo for Pico Investments 7, LLC Cross Streets: Mission Rd and Pico Avenue
No. of Units/Lots: 16
To Whom It May Concern:

This letter is to provide comments from San Marcos Unified School District (District) for the PicoApartments (Project). The Project resides entirely within the District attendance area and the Project’s students will be served by the District.

However, as the District makes known to all potential developments being planned within the District, most of the District’s existing schools are over capacity based on 2018-19 capacityutilization. Additional residential development projects approved or proposed throughout the District’s attendance boundary are projected to add to the current overcrowding for many yearsinto the future.

The Project area is currently served by the following schools:

School Grade Level Distance
San Marcos Elementary K-S .5 Miles
Woodland Park Middle 6-8 2.5 Miles
Mission Hills High School 9-12 1.5 Miles
With regard to the potential facilities which might serve the Project, there are currently no plans for facility improvements, renovations, or additions at San Marcos Elementary, Woodland Park Middle or Mission Hills High School. In addition, the District has no current plans for newelementary, middle, or high schools within the Project area.

While the District has established various programs to levy and collect developer fees, as authorized by State statue and local ordinances such fees are not sufficient to fully mitigate the Governing Board: Sarah Ahmad Stacy Carison Jaime Chamberlin Andrës Martin Carlos Ulloa, Ed. D.

Andrew S. Johnsen. Ed,D.. Superintendent
substantial costs of the acquisition and/or construction of new/additional school facilities to accommodate the increased enrollment associated with new residential development such as theProject.

Accordingly, the District attempts to engage with all new residential developments in a fair and equitable manner by seeking to enter into one or more mutually agreeable school facilitiesmitigation type agreements that would allow developers to demonstrate adequate mitigation ofthe individual developments potential impact on the District’s school facilities. Such agreements mayinclude the formation of a Community Facilities District (CFD) comparable to other similar CFDs for similar development which would help potential cost impacts to providing adequate classrooms and core facilities necessary for the students that will be generated by the Project. The developermay also have the option of annexing into an existing CFD. The District is also open to discussionother mitigation options/ideas proposed by the developer.

The District looks forward to working with you on the Project. Should you have any additional questions, please do not hesitate to contact me.

Sincerely,
Erin Garcia
Assistant Superintendent
Business Services
EG/ar

Appendix K. Water and Sewer Study
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Appendix L. Responses to Comments Received on the
Draft Initial Study/Mitigated Negative Declaration
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IS/MND RTC-1-1 August 2023
Pico Avenue Residential Project
Comment Letter 1: San Diego County Archaeological Society, Inc., August 17, 2023 1-1: This comment states that the commenter agrees with the inclusion of Mitigation Measures CUL-1 through CUL-4
in the Initial Study/Mitigated Negative Declaration
(IS/MND) and appreciates receiving notification of the
availability of the Pico Avenue Residential Project’s
(project’s) documents. The City of San Marcos (City)
appreciates the San Diego County Archaeological
Society’s review of the IS/MND. This comment does not
raise a significant environmental issue regarding the
adequacy or accuracy of information provided in the
IS/MND. Therefore, no further response is required.

IS/MND RTC
-1-2 August 2023
Pico Avenue Residential Project
IS/MND RTC-2-1 August 2023
Pico Avenue Residential Project
Comment Letter 2: California Department of Transportation, August 22, 2023 2-1: This comment discusses the California Department of Transportation’s (Caltrans’) mission, goals, and priorities and states that Caltrans looks forward to working with the City of San Marcos (City) in areas of joint jurisdiction.

The City appreciates Caltrans’ review of the Initial
Study/Mitigated Negative Declaration (IS/MND). This
comment does not raise a significant environmental issue regarding the adequacy or accuracy of information
provided in the IS/MND. Therefore, no further response
is required.

IS/MND RTC-2-2 August 2023
Pico Avenue Residential Project
2-2: This comment states that Caltrans supports enhancements that promote a complete and integrated transportation
network and that bicycle, pedestrian, and public transit access during construction should be maintained in
accordance with Caltrans’ goals and policies to reduce
greenhouse gas emissions. This comment further states
that bicycle, pedestrian, and public transit access during construction is important. As discussed in IS/MND
Section 2.4.17, Transportation, the Pico Avenue
Residential Project (project) is within a half-mile of a major transit stop, including the bus and light-rail system, and would improve pedestrian access to the transit
system. The project would improve the sidewalk on Pico
Avenue along the project frontage to increase pedestrian connections to off-site areas. Development of the project site would allow future residents to walk or bike to
adjacent retail stores and restaurants. During short-term construction activities, the project is not anticipated to result in any substantial traffic queuing on nearby streets, and all construction equipment would be staged on or
directly adjacent to the project site to not hinder access. 2-3: This comment states that Caltrans has some discretionary authority over a portion of the project that is proposed in a Caltrans right-of-way (ROW) and asks for a meeting to discuss the elements of the environmental document that Caltrans will use for subsequent environmental
compliance. This comment also states that an
encroachment permit will be required for any work within a Caltrans ROW before construction and that approved
IS/MND RTC-2-3 August 2023
Pico Avenue Residential Project
final environmental documentation for the project must
be provided. This comment also states that Caltrans is
interested in any additional mitigation measures
identified for the IS/MND. The City concurs that Caltrans has authority over its ROW. However, the ROW Caltrans
is referring to is State Route 78, which is approximately

0.3 mile south of the project site. Regarding
encroachment permits, as discussed in the IS/MND, the
project does not propose any off-site improvements and
would not encroach into Caltrans’ ROW. Regarding
Caltrans’ request for consideration of additional
mitigation measures, as demonstrated in IS/MND Section

2.4.17, all traffic impacts from the project have been
determined to be less than significant, and no mitigation measures would be required.
2-4: This comment provides background information related to land use and Smart Growth, discussing how the pattern of land use can affect local vehicle miles traveled and the number of trips. The comment further states that the City should continue to coordinate with Caltrans to implement necessary transportation improvements. The City will
continue to coordinate with Caltrans on improvements in areas of joint jurisdiction. This comment does not raise a significant environmental issue regarding the adequacy
or accuracy of information provided in the IS/MND.

Therefore, no further response is required.
2-5: This comment discusses the benefits of teleworking in reducing the number of vehicle miles traveled and the
amount of greenhouse gas emissions and the importance
IS/MND RTC-2-4 August 2023
Pico Avenue Residential Project
of the availability of reliable broadband. This comment further provides contact information for the commenter.

This is a closing comment and does not raise a significant environmental issue regarding the adequacy or accuracy
of information provided in the IS/MND. Therefore, no
further response is required.

San Marcos City CouncilOctober 24, 2023

San Marcos City Council
October 24, 2023