Agenda packet, regular meeting — Coachella City Council, December 17, 2025 (part 3 of 7)

The purpose of an EIR is to provide State and local agencies and the general public with detailed information on the potentially significant environmental effects which a proposed project is likely to have and to list ways in which the significant environmental effects may be minimized and indicate alternatives to the project.
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3.3.3 Section 2081 of the State Fish and Game Code
Under Section 2081 of the California Fish and Game Code (FGC), the California Department of Fish and Wildlife (CDFW) authorizes individuals or public agencies to import, export, take, or possess state endangered, threatened, or candidate species in California through permits or memoranda of understanding. These acts, which are otherwise prohibited, may be authorized through permits or “memoranda of understanding” if (1) the take is incidental to otherwise lawful activities, (2) impacts of the take are minimized and fully mitigated, (3) the permit is consistent with regulations adopted in accordance with any recovery plan for the species in question, and (4) the applicant ensures suitable funding to implement the measures required by the CDFW. The CDFW shall make this determination based on the best scientific information reasonably available and shall include consideration of the species’ capability to survive and reproduce.

3.3.4 Sections 3503, 3505.5, & 3513 of the State Fish and Game Code Section 3503 of the FGC makes it unlawful to take, possess, or needlessly destroy the nest or eggs of any bird. Section 3505.5 makes it unlawful to take, possess, or destroy any birds in the order Falconiformes or Strigiformes (birds-of-prey, i.e.: owls, hawks, eagles, etc.) or to take, possess, or destroy the nest or eggs of any bird-of-prey. Section 3513 makes it unlawful to take or possess any migratory nongame bird as designated in the MBTA.

3.4 Regional

3.4.1 Coachella Valley Multiple Species Habitat Conservation Plan Finalized in October 2008, the CVMSHCP is a comprehensive, regional plan that addresses the conservation needs of 27 species of native flora and fauna and 24 natural vegetation communities occurring throughout the Coachella Valley region of western Riverside County, California. Permits for the CVMSHCP were issued by the CDFW on September 9, 2008 and the United States Fish and Wildlife Service (USFWS) on October 1, 2008 (TE104604-0). The CVMSHCP serves two primary purposes: Balancing environmental protection and economic development objectives in the CVMSHCP area and simplifying compliance with endangered species related laws. The CVMSHCP accomplishes this by conserving unfragmented habitat to permanently protect and secure viable populations of the covered species. The covered species include those plants and animals that are either currently listed as threatened or endangered, are proposed for listing, or are believed by an appointed Scientific Advisory Committee, USFWS and CDFW, to have a high probability of being proposed for listing in the future if not provided protection by the CVMSHCP. The goal of the CVMSHCP is to meet the requirements of the state and federal endangered species acts, while at the same time allowing for the economic growth (land development) within the plan area without significant delay or hidden costs. Under the CVMSHCP, land development/mitigation fees are 529
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Biological Resources Assessment & CVMSHCP Consistency Analysis Report Calhoun Street & Avenue 49 Residential Development Project March 2024
Calhoun Street & Avenue 49 Residential Development Project BRAR Page 6 collected from all new development projects occurring in the plan area. The purpose of this fee is to support the assembly of a preserve system for the covered species and natural vegetation communities within areas identified as having high conservation value.

4.0 METHODS

4.1 Literature Review
In preparation for the field surveys, a literature search was conducted to identify special status biological resources known from the vicinity of the project site. In the context of this report, and for the purpose of this assessment, vicinity is defined as areas within a 5-mile radius of the project site.

The literature search included a review of the following documents:
• California Natural Diversity Data Base (CNDDB) RareFind 5 (CDFW 2024a) • Special Animals List (CDFW 2024b)
• California Native Plant Society's (CNPS) Inventory of Rare, Threatened, and Endangered Plants of California (CNPS 2024a)
• Information for Planning and Consultation (IPaC) Resources List (USFWS 2024) • CVMSHCP (Coachella Valley Conservation Commission “CVCC” 2024) • United States Department of Agriculture (USDA), Natural Resources Conservation Service (NRCS). 2024. Web Soil Survey
• USGS 7.5’ Indio, La Quinta, Myoma, Valerie and West Berdoo Canyon, Calif. quadrangles (USGS 2015a, USGS 2015b, USGS 2015c, USGS 2015d, USGS 2021) Scientific nomenclature for this document follows standard reference sources: For plant communities, CVMSHCP (CVCC 2024); for flora, Jepson eFlora (2024) and the USDA NRCS PLANTS Database (2024); for amphibians, reptiles, and mammals, CDFW (2016); and for birds, California Bird Records Committee (2024).

4.2 Field Assessment
The field assessment was conducted between the hours of 1040 and 1240 on 29 February 2024 by WSP senior biologist Michael D. Wilcox. Onsite suitable habitat was assessed based on the presence of constituent habitat elements (e.g., soils, vegetation and topography) characteristic of the potentially occurring special status biological resources determined by the literature review.

The entire site and adjacent properties (where accessible) were assessed on foot to record pertinent field data and current site conditions. Where present, adjacent undeveloped areas within an approximate 150-meter (m) (~500-foot [ft]) buffer zone were also assessed visually, from the project site, for burrowing owl (Athene cunicularia). All onsite flora and fauna observed or otherwise detected (e.g., vocalizations, presence of scat, tracks, and/or bones) during the 530
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Calhoun Street & Avenue 49 Residential Development Project BRAR Page 7 assessment were recorded in field notes and are included in Appendices A and B. General weather and site conditions were also recorded at the beginning and end of the survey. Temperatures and wind speeds were recorded with a handheld Kestrel 3500 anemometer. Percent cloud cover was visually estimated.

5.0 RESULTS
The fenced, 38.8-acre project site currently consists of a combination of an abandoned, remnant date palm farm, intermittent disturbed/ruderal areas and a largely barren area that has been cleared of nearly all vegetation and graded/scraped. With the exception of a few areas, primarily along the western edge of the site, vegetation is relatively sparse. Soils are largely stabilized, compacted and disturbed. Existing site disturbances observed onsite included abandoned, fallow agricultural practices (rows of remnant date palms and associated irrigation and/or farming structures), vegetation clearance, grading/scraping, dumping, offroad vehicular activity (minor), minor dumping and accumulation of roadside trash (minor).

Existing residential (tract home) developments occur to the north and south. The lands to the west are fenced and currently being graded and under construction, likely for future residential development (tract homes), while the lands to the east are largely vacant, undeveloped and disturbed.

5.1 Coachella Valley Multiple Species Habitat Conservation Plan The project site is located within Coachella, which is a signatory to the CVMSHCP. The site is not within any CVMSHCP-designated conservation areas. The closest is the East Indio Hills Conservation Area which is located approximately 5.5 kilometers (km) (3.4 mi) to the northeast and the Santa Rosa and San Jacinto Mountains Conservation Area, which is located approximately

7.4 km (4.6 mi) to the southwest of the site (Figure 3). The site does not contain CVMSHCP modeled habitats for any covered or special status species. The site is not within a fluvial sand transport area as illustrated on CVMSHCP Figure 4-5: Essential Ecological Processes Conserved Through General Plan Land Use Designations and Flood Control Standards (CVCC 2024). The site is not within any of the Coachella Valley Fringe-toed Lizard Preserves as illustrated on CVMSHCP Figure 6-2 (CVCC 2024). No CVMSHCP-designated wildlife corridors or biological linkages are mapped on the project site.

5.2 Weather Conditions
Weather conditions during the assessment included clear skies with no cloud cover. The temperatures ranged from 72 to 78 degrees Fahrenheit (°F). Winds were calm with speeds ranging 0 to 2 miles per hour (mph).
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5.3 Topography, Soils and Waters
Existing topography is largely flat, sloping slightly to the south. Slight relief occurs only in the form of a manufactured linear embankment (edge of dirt perimeter road) along the northern site boundary and around a small, currently dry irrigation pond located in the northwestern corner of the site. Mapped soils (USDA NRCS 2024) include: Coachella fine sand, 0-2% slopes (CpA); Gilman fine sandy loam, 0-2% slopes (GbA) and Indio fine sandy loam (Ip) (Figure 4).

Coachella series soils are well-drained soils that are moderately rapidly permeable and occur in lacustrine basins at elevations from 230 feet below sea level to 800 feet above sea level. Although well drained, perched water tables are common in areas that are irrigated. Sediments originate largely from igneous rocks. Slopes are nearly level to gently sloping. The climate is arid with average annual rainfall ranging from 2 to 4 inches, occurring in light winter rains and/or high intensity summer monsoon thunderstorms (USDA NRCS 2024).

Gilman series soils are very deep, well drained soils with slow runoff and moderate permeability that were formed in stratified stream alluvium. This series generally occur at elevations from 75 to 2,500 feet above sea level. They are known to occur on flood plains and alluvial fans and have slopes of 0 to 3 percent. Gilman series soils generally range from non-saline to strongly saline.

Mean annual rainfall is 2 to 10 inches (USDA NRCS 2024).

Indio series soils are very deep, well to moderately well drained soils that were formed in alluvium and are derived from mixed rock sources. Runoff is generally slow and permeability is moderate.

This soil series generally occur at elevations from 230 feet below sea level to 1,400 feet above sea level on alluvial fans, lacustrine basins and flood plains. Slopes are usually gentle at 0 to 3 percent with the exception of where they occur on low stream or wash embankments. Mean annual precipitation ranges from 3 to 10 inches (USDA NRCS 2024).

Onsite soils are highly disturbed, a result of past date farming practices and grading in at least one area (the northeastern ¼ of the site). Prior to the planting of the date palms, the entire site was very likely scraped, cleared and graded. A former irrigation pond; evident by manufactured embankments, dried cracked substrates and remnant cement/concrete irrigation structures; is located in the northwest corner of the site. This irrigation pond was completely dry at the time of the assessment and exhibited no evidence of having recently held water or contained moisture (other than the dried, cracked substrate observed in the bottom). Irrigation furrows and underground piping is evident throughout the southern and western 2/3 of the site. No streams, washes, springs, active drifts, sand dunes, rock outcrops, rocky areas, or natural clay lenses were observed.
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5.4 Vegetation
According to CVMSHCP Figure 3-1: Natural Communities and Development, onsite vegetation community is mapped as “ruderal” (CVCC 2023). Historic aerial imagery indicates that by 2002, the southern and western ¾ of the site was being used to grow dates. The northeastern ¼ of the site appears to have been cleared of vegetation and has remained vacant, undeveloped and not used to grow dates since 2002 at least. Although Sawyer et. al. (2009) does not provide a description for agricultural and/or disturbed areas, perhaps the best way to describe the current vegetation present onsite would likely be abandoned/fallow agricultural lands with sparse, remnant patches of Atriplex lentiformis shrubland alliance (quailbush scrub), ruderal/disturbed and largely barren areas (primarily in the northeastern ¼ of the site) occurring intermittently throughout (Figure 5). The dominant plant species onsite is the formerly cultivated date palm (Phoenix dactylifera) that intermittently remain in east/west linear rows throughout the western and southern ¾ of the site. Although relatively sparse and primarily located along the perimeter and in linear rows, in between and beneath the rows of date palms, native perennial plant species observed included quailbush (Atriplex lentiformis), arrow-weed (Pluchea sericea), common sunflower (Helianthus annuus) and blue palo verde (Parkinsonia florida). Other plant species observed primarily included a mixture of non-native, invasive and/or ruderal species. These included puncture vine (Tribulus terrestris), amaranth (Amaranthus sp.), cheeseweed (Malva parviflora), Sahara mustard (Brassica tournefortii), Mexican palo verde (Parkinsonia aculeata), saltcedar (Tamarisk ramosissima) and Bermuda grass (Cynodon dactylon). A complete list of the plant species observed onsite is included in Appendix A.

No natural wetland, riparian or otherwise special-status vegetation communities were observed on-site. A full list of the plant species observed during the surveys, including common and scientific names, is appended to this report (Appendix A).

5.5 Wildlife
Vertebrate wildlife directly observed and/or detected otherwise (e.g., scat, bones, tracks, feathers, burrows, etc.) during the surveys was not diverse or abundant, limited to 17 species common to the region. This included one reptile, 14 birds and two mammals (Appendix B).

The one reptile species observed onsite include the side-blotched lizard (Uta stansburiana).

Representative bird species observed onsite included but were not limited to: Eurasian collared dove (Streptopelia decaocto), mourning dove (Zenaida macroura), red-shouldered hawk (Buteo lineatus), red-tailed hawk (Buteo jamaicensis), American kestrel (Falco sparverius), common raven (Corvus corax), verdin (Auriparus flaviceps), northern mockingbird (Mimus polyglottos), house finch (Haemorhous mexicanus) and white-crowned sparrow (Zonotrichia leucophrys). The two mammals observed and/or detected onsite included Botta’s pocket gopher (Thomomys bottae) and 533
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Biological Resources Assessment & CVMSHCP Consistency Analysis Report Calhoun Street & Avenue 49 Residential Development Project March 2024
Calhoun Street & Avenue 49 Residential Development Project BRAR Page 10 California ground squirrel (Otospermophilus beecheyi). A complete list of the vertebrate species observed or detected onsite is included as Appendix B.

It should be noted that relatively short-term biological studies of this nature are often limited by the seasonality of annual plants, the migratory habits of many birds, the fossorial and nocturnal habits of many mammals and reptiles, as well as the timing of field visit. A complete inventory of the wildlife on the site would require extensive year-round surveys for birds, amphibians, and reptiles, and additional surveys, such as placement of scent stations or tracking stations, for the detection of nocturnal mammals. Knowledge of habitat associations, natural history, seasonality, and distribution is essential in the assessment of the potential for occurrence of the various special status plants and animals known to occur throughout the Coachella Valley. For these reasons, other common and special status species that were not observed onsite may also have the potential to occur based on their geographic distribution, habitat preferences and the regional location of the site. The following section summarizes information on special status biological resources known to occur in the vicinity of the project site.

5.6 Special Status Biological Resources
Plant or animal taxa may be considered "sensitive" or as having “special status” due to declining populations, vulnerability to habitat change, or because they have restricted ranges. Some are listed as threatened or endangered by the USFWS or by the CDFW and are protected by the federal and state Endangered Species acts. Others have been identified as sensitive or as specialstatus species by the USFWS, the CDFW, or by private conservation organizations, including the CNPS. Unlisted sensitive species do not have formal state or federal status but may nevertheless be considered significant under the CEQA. The CVMSHCP provides conservation for twenty-seven (27) imperiled plant and animal species (5 plants, 2 insects, 1 amphibian, 3 reptiles, 11 birds, and 5 mammals). These include federal and state-listed species, federal and California Species of Concern, and species on the CNPS sensitive species lists. CVMSHCP covered species are designated on the tables below. The site is not within designated critical habitat for any special status plants or wildlife.

The review of the CNDDB, CNPS Online Inventory of Rare Plants and IPaC Resources List resulted in the identification of 68 special status biological resources known to occur in the vicinity (within an approximate 5-mile radius) of the project site. The 68 special status biological resources known from the vicinity included 33 plants, one vegetation communities, five invertebrates, one fish, four reptiles, 14 birds and 10 mammals. Tables 1 through 7 provide a complete list of the special status biological resources, their associated legal status, and their respective onsite occurrence potentials.
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Biological Resources Assessment & CVMSHCP Consistency Analysis Report Calhoun Street & Avenue 49 Residential Development Project March 2024
Calhoun Street & Avenue 49 Residential Development Project BRAR Page 11 Tables 1 through 7 summarize information on all special status species that have been reported within the vicinity (5-mile radius) or that occur or are considered to have some potential to occur onsite based on geographic distribution, elevational parameters and/or presence of potentially suitable habitat. Occurrence probability is based on the best available information and the collective expertise of WSP biologists. These tables provide the names, legal or conservation status, general habitat associations, and the probability of occurrence for each of these species.

Table 1. Special Status Plants
Species Status Habitat Probability
Abronia villosa var. aurita
chaparral sand-verbena
F: None
C: None
CNPS: List 1B.1
State Rank: S2
CVMSHCP: No
Sandy areas in chaparral,
coastal sage scrub & desert
dune habitats. 80-1,600 m.
(262-5,249 ft.); B: (Jan) MarSept.

Absent
Suitable habitat lacking. Site
below known elevational range
of species.

Astragalus lentiginosus var.
borreganus
Borrego milk-vetch
F: None
C: None
CNPS List: 4.3
State Rank: S4
CVMSHCP: No
Mojavean desert scrub,
Sonoran Desert scrub; sandy.
30-895 m. (100-2,935 ft.); B:

Feb-May.

Absent
Suitable habitat lacking. Site
below known elevational range
of species.

Astragalus lentiginosus var.
coachellae
Coachella Valley milk-vetch
F: END
C: None
CNPS: 1B.2
State Rank: S1
CVMSHCP: Yes
Sonoran desert scrub; sandy
flats, washes, outwash fans,
sometimes on dunes. 40-665
m. (131-2,182 ft.); B: Jan–Sept.

Absent
Suitable habitat lacking. Site
below known elevational range
of species. Site is not within
designated critical habitat or
CVMSHCP modeled habitat for
this species.

Astragalus preussii var. laxiflorus
Lancaster milk-vetch
F: None
C: None
CNPS: 1B.1
State Rank: S1
CVMSHCP: No
Chenopod scrub. 700 m. (2,295
ft.); B: Mar–May.

Absent
Suitable habitat lacking. Site
below known elevational range
of species.

Astragalus subulonum
gravel milk-vetch
F: None
C: None
CNPS: 2B.2
State Rank: S2
CVMSHCP: No
Mojavean desert scrub,
Sonoran desert scrub; dunes; -
60-930 m. (195-3,050 ft.); B:

Feb–Jun.

Absent
Suitable habitat lacking. Site
below known elevational range
of species.

Astragalus tricarinatus
triple-ribbed milk-vetch
F: END
C: None
CNPS: 1B.2
State Rank: S2
CVMSHCP: Yes
Joshua tree woodland &
Sonoran desert scrub on hot,
rocky slopes in canyons &
along edge of boulder-strewn
desert washes with
Larrea and Encelia. 455-1,525
m. (1,492-5,000 ft.); B: Feb–
May.

Absent
Suitable habitat lacking. Site
below known elevational range
of species.

Bursera microphylla
little-leaf elephant tree
F: None
C: None
CNPS: 2B.3
State Rank: S3
Sonoran desert scrub, hillsides,
canyon sides and washes;
rocky. 195-700 m. (640-2,297
ft.); B: Jun-Jul.

Absent
Suitable habitat lacking. Site
below known elevational range
of species.
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Calhoun Street & Avenue 49 Residential Development Project BRAR Page 12 Table 1. Special Status Plants
Species Status Habitat Probability
CVMSHCP: No
Chorizanthe leptotheca
Peninsular spineflower
F: None
C: None
CNPS: 4.2
State Rank: S3
CVMSHCP: No
Chaparral, coastal scrub, lower
montane coniferous forest.
300-1,900 m. (985-6,230 ft.); B:

May-Aug.

Absent
Suitable habitat lacking. Site
below known elevation range of
species.

Ditaxis claryana
glandular ditaxis
F: None
C: None
CNPS: 2B.2
State Rank: S2
CVMSHCP: No
Mojavean & Sonoran desert
scrub. 0-465 m. (0-1,526 ft.); B:

Oct–Mar.

Absent
Suitable habitat lacking. Site
below known elevational range
of species.

Ditaxis serrata var. californica
California ditaxis
F: None
C: None
CNPS: 3.2
State Rank: S2?
CVMSHCP: No
Sonoran desert scrub. 30 to
1,000 m. (98-3,281 ft.); B: MarDec.

Absent
Suitable habitat lacking. Site
below known elevational range
of species.

Eremothera boothii var. boothii
Booth’s evening primrose
F: None
C: None
CNPS: 2B.3
State Rank: S3
CVMSHCP: No
Joshua tree woodland, pinyon
& juniper woodland. 815-2,400
m. (2,674-7,874 ft.); B: Apr-Sep.

Absent
Suitable habitat lacking. Site
below known elevational range
of species.

Eschscholtzia androuxii
Joshua Tree poppy
F: None
C: None
CNPS: 4.3
State Rank: S3
CVMSHCP: No
Mojavean desert scrub, Joshua
tree woodland. 585-1,685 m.
(1,920-5,530 ft.); B: Feb-May
(Jun).

Absent
Suitable habitat lacking. Site
below known elevational range
of species.

Euphorbia abramsiana
Abrams’ spurge
F: None
C: None
CNPS: 2B.2
State Rank: S2
CVMSHCP: No
Sandy sites in Mojave and
Sonoran desert scrub. -5–1,450
m. (-16-4,757 ft.). B: (Aug)
Sept- Nov.

Very Low
Remnant marginally suitable
habitat very limited, disturbed
and largely stabilized. Only
small, insignificant pockets of
sandy soils present. Site just
below/at edge of elevational
range of species.

Euphorbia arizonica
Arizona spurge
F: None
C: None
CNPS: 2B.3
State Rank: S3
CVMSHCP: No
Sandy soils in Sonoran desert
scrub; 50-300 m. (200-1,000 ft);
B: Mar-Apr.

Absent
Suitable habitat lacking. Site
below known elevational range
of species.

Euphorbia platysperma
flat-seeded spurge
F: None
C: None
CNPS: 1B.2
State Rank: S1
CVMSHCP: No
Sandy Sonoran desert scrub,
shifting dunes. In CA,
potentially a waif; more
common in AZ and MX. 65-100
m. (215-330 ft.); B: Feb-Sep.

Absent
Suitable habitat lacking. Site
below known elevational range
of species.

Horsfordia alata
pink velvet-mallow
F: None
C: None
CNPS: 4.3
State Rank: S4
Sonoran desert scrub (rocky).
100-500 m. (330-1,640 ft); B:

Feb-Dec.

Absent
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Calhoun Street & Avenue 49 Residential Development Project BRAR Page 13 Table 1. Special Status Plants
Species Status Habitat Probability
CVMSHCP: No Suitable habitat lacking. Site
below known elevational range
of species.

Horsfordia newberryi
Newberry's velvet-mallow
F: None
C: None
CNPS: 4.3
State Rank: S4
CVMSHCP: No
Sonoran desert scrub (rocky).
8-300 m. (26-984 ft); B: FebDec.

Absent
Suitable habitat lacking. Site
below known elevational range
of species.

Johnstonella costata
ribbed cryptantha
F: None
C: None
CNPS: 4.3
State Rank: S4
CVMSHCP: No
Desert dunes, Mojavean desert
scrub, Sonoran desert scrub; -
60-500 m (-195-1,640 ft); B:

Feb-May.

Very Low
Remnant marginally suitable
habitat very limited, disturbed
and largely stabilized. Only
small, insignificant pockets of
sandy soils present.

Johnstonella holoptera
winged cryptantha
F: None
C: None
CNPS: 4.3
State Rank: S4
CVMSHCP: No
Sonoran desert scrub,
Mojavean desert scrub; sandy
or rocky canyons. 100-1,690 m.
(328-5,545 ft); B: Mar-Apr.

Absent
Suitable habitat lacking. Site
below known elevational range
of species.

Juncus acutus ssp. leopoldii
southwestern spiny rush
F: None
C: None
CNPS: 4.2
State Rank: S4
CVMSHCP: No
Coastal dunes (mesic), coastal
scrub, meadows & seeps
(alkaline), marshes & swamps
(coastal salt) Mojavean desert
scrub, Sonoran desert scrub; -
3-900 m (-10-2,955 ft). B: MarJun.

Absent
Suitable habitat lacking. Former
irrigation pond located in NW
corner of site and irrigation
rows for date palms currently
dry. Site just below/at edge of
elevational range of species.

Juncus cooperi
Cooper’s rush
F: None
C: None
CNPS: 4.3
State Rank: S3
CVMSHCP: No
Meadows & seeps (mesic,
alkaline or saline). -260-1,700
m (-855-5,805 ft); B: Apr-Aug.

Absent
Suitable habitat lacking. Former
irrigation pond located in NW
corner of site and irrigation
rows for date palms currently
dry.

Leptosiphon floribundus
Santa Rosa Mountains
leptosiphon
F: None
C: None
CNPS: 1B.3
State Rank: S1S2
CVMSHCP: No
Sonoran desert scrub, pinyon
juniper woodland; 1,000-2,000
m (3,280–6,560 ft); B: May-Jul
(Nov).

Absent
Suitable habitat lacking. Site
below known elevational range
of species.

Lycium torreyi
Torrey's box-thorn
F: None
C: None
CNPS: 4.2
State Rank: S3
CVMSHCP: No
Mojavean desert scrub,
Sonoran desert scrub; -50 -
1220 m (-165–4,005 ft); B: (JanFeb) Mar-Jun (Sep-Nov).

Absent
Remnant marginally suitable
habitat very limited and
disturbed. Conspicuous
perennial species would likely
have been detected if present.

Marina orcuttii var. orcuttii
California marina
F: None
C: None
CNPS: 1B.3
Chaparral, pinyon and juniper
woodland, Sonoran desert
scrub, rocky. 1,050-1,160 m
(3,445–3,806 ft); B: May-Oct.

Absent
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Calhoun Street & Avenue 49 Residential Development Project BRAR Page 14 Table 1. Special Status Plants
Species Status Habitat Probability
State Rank: S2?
CVMSHCP: No
Suitable habitat lacking. Site
below known elevational range
of species.

Matelea parvifolia
spear-leaf matelea
F: None
C: None
CNPS: 2B.3
State Rank: S3
CVMSHCP: No
Mojavean desert scrub,
Sonoran desert scrub, rocky.
440-1,095 m. (1,445–3,595 ft.);
B: Mar-May (Jul).

Absent
Suitable habitat lacking. Site
below known elevational range
of species.

Nemacaulis denudata var. gracilis
slender cottonheads
F: None
C: None
CNPS: 2B.2
State Rank: S2
CVMSHCP: No
Sandy places in coastal dunes,
desert dunes & Sonoran desert
scrub. 50-400 m. (164-1,315
ft.); B: Mar–May.

Absent
Suitable habitat lacking. Site
below known elevational range
of species.

Petalonyx linearis
narrow-leaf sandpaper-plant
F: None
C: None
CNPS: 2B.3
State Rank: S3?
CVMSHCP: No
Sandy or rocky canyons in
Mojavean desert scrub and
Sonoran desert scrub; -25-1115
m. (-80-3,660 ft.); B: Mar-May
(sometimes Jan-Dec).

Absent
Suitable habitat lacking.

Perennial sandpaper-plant
(Petalonyx spp.) not observed.

Phaseolis filiformis
slender-stem bean
F: None
C: None
CNPS: 2B.1
State Rank: S1
CVMSHCP: No
Sonoran desert scrub. 125 m
(410 ft.); B: Apr.

Absent
Suitable habitat lacking. Site
below known elevational range
of species.

Pseudorontium cyanthiferum
Deep Canyon snapdragon
F: None
C: None
CNPS: 2B.3
State Rank: S1
CVMSHCP: No
Sonoran desert scrub in rocky
washes and on rocky slopes in
the immediate vicinity of Deep
Canyon. 0-800 m. (0-2,625 ft.);
B: Feb-Apr.

Absent
Suitable habitat lacking. Site
below known elevational range
of species.

Selaginella eremophila
desert spike-moss
F: None
C: None
CNPS: 2B.2
State Rank: S2S3
CVMSHCP: No
Chaparral, Sonoran Desert
scrub; shaded sites, gravelly
soils, crevices or among rocks.
200-900 m. (656-2,953 ft.); B:

May–Jul.

Absent
Suitable habitat lacking. Site
below known elevational range
of species.

Senna covesii
Cove’s cassia
F: None
C: None
CNPS: 2B.2
State Rank: S3
CVMSHCP: No
Sonoran Desert scrub, dry,
sandy desert washes & slopes.
225-1,295 m. (740-4,250 ft.); B:

Mar–Jun (Aug).

Absent
Suitable habitat lacking. Site
below known elevational range
of species.

Stemodia durantifolia
purple stemodia
F: None
C: None
CNPS: List 2B.1
State Rank: S2.1?
CVMSHCP: No
Mesic sites on sandy soils in
Sonoran desert scrub. 180-300
m. (590–980 ft.); B: (Jan) AprDec.

Absent
Suitable habitat lacking. Site
below known elevational range
of species.

Xylorhiza cognata
Mecca-aster
F: None
C: None
CNPS: List 1B.2
State Rank: S2
CVMSHCP: Yes
Grows on steep canyon slopes
on sandstone and clay
substrates, 20-305 m (65–1,000
ft); B: Jan-Jun.

Absent
Suitable habitat lacking. Site
below known elevational range
of species.
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Biological Resources Assessment & CVMSHCP Consistency Analysis Report Calhoun Street & Avenue 49 Residential Development Project March 2024
Calhoun Street & Avenue 49 Residential Development Project BRAR Page 15 Table 2. Special Status Vegetation Communities
Community Status Habitat Probability
desert fan palm oasis woodland
F: None
C: S3.2
State Rank: S3.2
CVMSHCP: Yes
Natural California fan palm
(Washingtonia filifera) stands
Absent
Only small, sapling fan
palms and cultivated
date palms (Phoenix
dactilifera) observed
onsite.

Table 3. Special Status Invertebrates
Community Status Habitat Probability
Dinacoma caseyi
Casey’s June beetle
F: END
C: None
State Rank: S1
CVMSHCP: No
Appears to be entirely
restricted to the mouth and
alluvial floodplain of Palm
Canyon Wash and Tahquitz
Creek in Palm Springs, in
association with deposits of
fine silts, sands and gravels
Absent
Suitable habitat lacking.

Site outside of known
range of species. Site is
not within designated
critical habitat or USFWS
recommended survey
area for this species.

Danaus plexippus
monarch butterfly
F: FC
C: None
State Rank: S2S3
CVMSHCP: No
Western winter roost sites
primarily occur along the
coast from northern
Mendocino to Baja
California, Mexico, located in
wind-protected tree groves
(Eucalyptus species,
Monterey pine (Pinus
radiata), cypress), with nectar
and water sources nearby.

During breeding season,
adults widespread but scarce
in the desert. Larvae require
milkweed
Absent
Suitable habitat lacking.

Larval host plants
(milkweeds) not observed.

Winter roost sites not
present. Adults may,
however, occasionally fly
through site.

Macrobaenetes valgum
Coachella giant sand treader
cricket
F: None
C: None
State Rank: S1S2
CVMSHCP: Yes
Active sand dune hummocks
and ridges, sites favorable to
permanent habitation
include spring-moistened
sand.

Absent
Suitable habitat lacking.

Sand dunes and
hummocks not present.

Site is not within
CVMSHCP modeled
habitat for this species.

Oliarces clara
cheeseweed owlfly
F: None
C: None
State Rank: S2
CVMSHCP: No
Known from lower Colorado
River drainage, associated
with creosote bush (Larrea
tridentata) in desert scrub;
creosote is suspected larval
host. Found under rocks or
in flight over streams.

Absent
Suitable habitat lacking.

No drainages or washes
on the site.
539
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Biological Resources Assessment & CVMSHCP Consistency Analysis Report Calhoun Street & Avenue 49 Residential Development Project March 2024
Calhoun Street & Avenue 49 Residential Development Project BRAR Page 16 Table 3. Special Status Invertebrates
Euparagia unidentate
Algodones Dunes Euparagia
F: None
C: None
State Rank: S1S2
CVMSHCP: No
Desert dunes.

Absent
Suitable habitat lacking.

Dune habitats not
present.

Table 4. Special Status Fish
Community Status Habitat Probability
Cyprinodon macularius
desert pupfish
F: END
C: END
State Rank: S1
CVMSHCP: Yes
Desert ponds, springs,
marshes and streams.

Absent
Suitable aquatic habitat
lacking. Former
irrigation pond in NW
corner of site currently
dry. Site is not within
designated critical
habitat or CVMSHCP
modeled habitat for this
species.

Table 5. Special Status Reptiles
Species Status Habitat Probability
Crotalus ruber ruber
northern red diamond
rattlesnake
F: ND
C: SSC
State Rank: S2?
CVMSHCP: No
Favors rocky areas and
dense vegetation, shelters in
rodent burrows, rock cracks,
or surface cover. Known
from the eastern slopes of
the Peninsular Ranges,
desert floor up to 5,000 feet
Absent
Suitable habitat lacking.

Gopherus agassizi
desert tortoise
F: THR
C: THR
State Rank: S2
CVMSHCP: Yes
Creosote bush scrub, Joshua
tree woodland, saltbush
scrub); washes, arroyos,
bajadas, rocky hillsides, open
flat desert.

Absent
Suitable habitat lacking.

Site formerly agricultural
(date palm farm). Sign
(burrows, scat, remains,
etc.) not observed. Site is
not within designated
critical habitat or
CVMSHCP modeled
habitat for this species.

Phrynosoma mcallii
flat-tailed horned lizard
F: None
C: SSC
State Rank: S2
CVMSHCP: Yes
Sandy and gravelly areas in
desert washes, edges of
dunes and desert flats;
requires vegetative cover,
ants & fine sand.

Absent
Suitable habitat lacking.

Site disturbed with only
small, remnant patches of
sandy soils and native
plant species. Site not
within CVMSHCP modeled
habitat for this species.
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Biological Resources Assessment & CVMSHCP Consistency Analysis Report Calhoun Street & Avenue 49 Residential Development Project March 2024
Calhoun Street & Avenue 49 Residential Development Project BRAR Page 17 Table 4. Special Status Fish
Community Status Habitat Probability
Cyprinodon macularius
desert pupfish
F: END
C: END
State Rank: S1
CVMSHCP: Yes
Desert ponds, springs,
marshes and streams.

Absent
Suitable aquatic habitat
lacking. Former
irrigation pond in NW
corner of site currently
dry. Site is not within
designated critical
habitat or CVMSHCP
modeled habitat for this
species.

Table 5. Special Status Reptiles
Species Status Habitat Probability
Uma inornata
Coachella Valley fringe-toed
lizard
F: THR
C: END
State Rank: S1
CVMSHCP: Yes
Requires fine, loose,
windblown sand (dunes)
interspersed with hardpan &
widely spaced desert shrubs.

Known only from the
Coachella Valley.

Absent
Suitable habitat lacking.

Site disturbed, primarily
stabilized with only small,
remnant patches of sandy
soils and native plant
species. Site is not within
designated critical habitat
or CVMSHCP modeled
habitat for this species.

Table 6. Special Status Birds
Species Status Habitat Probability
Accipiter cooperii
Cooper’s hawk
F: MBTA
C: Watch List
State Rank: S4
CVMSHCP: No
Woodland, chiefly of open,
interrupted or marginal type,
including residential areas.

Nests in trees.

Nesting: Absent
Suitable nesting habitat
lacking.

Foraging: Occurs
Observed.

Aquila chrysaetos
golden eagle
F: BGEPA, MBTA, BCC
C: FP, WL
State Rank: S3
CVMSHCP: No
Forages over rolling foothills,
mountain areas, sage-juniper
flats, and desert. Cliff-walled
canyons used for nesting,
sometimes large trees in
open areas.

Nesting: Absent
Suitable habitat lacking.

Foraging: Low
Marginally suitable
habitat present.
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Biological Resources Assessment & CVMSHCP Consistency Analysis Report Calhoun Street & Avenue 49 Residential Development Project March 2024
Calhoun Street & Avenue 49 Residential Development Project BRAR Page 18 Table 6. Special Status Birds
Species Status Habitat Probability
Athene cunicularia
burrowing owl
F: MBTA, BCC
C: SSC (burrows), FGC
State Rank: S2
CVMSHCP: Yes*
Open, dry annual or perennial
grassland, deserts &
scrublands characterized by
low-growing vegetation.

Burrow sites essential.

Nesting: Low
Marginally suitable
habitat intermittently
present. Suitable
California ground
squirrel burrows
detected.

Foraging: Low
If present onsite or on
other suitable lands to
the east of the site.

Buteo regalis
ferruginous hawk
F: MBTA, BCC
C: WL
State Rank: S3S4
CVMSHCP: No
Great Basin grassland, Great
Basin scrub, pinon & juniper
woodland, valley & foothill
grassland.

Nesting: Absent
Suitable habitat lacking.

Foraging: Low
During winter and
migration only.

Calypte costae
Costa’s hummingbird
F: MBTA, BCC
C: None
State Rank: S4
CVMSHCP: No
Desert and semi-desert, arid
brushy foothills and chaparral,
in migration and winter also
in adjacent mountains and in
open meadows and gardens
Nesting: Moderate
Suitable nesting habitat
(sparse palo verde)
present.

Foraging: Occurs
Observed.

Empidonax traillii extimus
southwestern willow flycatcher
F: END, MBTA
C: END
State Rank: S1
CVMSHCP: Yes*
Breeds in dense riparian
areas.

Nesting: Absent
Suitable habitat lacking.

Foraging: Very Low
Occurs in many habitats
during migration.

Site is not within
designated critical
habitat for this species.

Falco mexicanus
prairie falcon
F: MBTA, BCC
C: SSC (nesting), FGC
State Rank: S3
CVMSHCP: No
Inhabits dry, open terrain,
either level or hilly. Breeding
sites located on cliffs, but
forages far afield.

Nesting: Absent
Suitable habitat lacking.

Foraging: Moderate
May nest or winter
nearby & forage over
site.

Haliaeetus leucocephalus
bald eagle
F: BGEPA, MBTA, BCC
C: END, FP
State: S3
CVMSHCP: No
Margins of lakes, rivers, and
other bodies of water. In
Southern California, nests at
Big Bear Lake and Lake
Silverwood in the San
Bernardino Mountains and
Lake Hemet in the San Jacinto
Mountains.

Nesting: Absent
Suitable habitat lacking.

Foraging: Absent
Suitable habitat lacking.
542
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Biological Resources Assessment & CVMSHCP Consistency Analysis Report Calhoun Street & Avenue 49 Residential Development Project March 2024
Calhoun Street & Avenue 49 Residential Development Project BRAR Page 19 Table 6. Special Status Birds
Species Status Habitat Probability
Lanius ludovicianus
loggerhead shrike
F: MBTA, BCC
C: SSC (nesting), FGC
State Rank: S4
CVMSHCP: No
Open fields with scattered
trees or shrubs, open country
with short vegetation,
pastures, old orchards,
cemeteries, golf courses,
riparian areas & open
woodlands.

Nesting: Very Low
Suitable nesting habitat
very limited.

Foraging: Moderate
May nest or winter
nearby & forage onsite.

Polioptila melanura
black-tailed gnatcatcher
F: ND
C: ND
State rank: S3S4
CVMSHCP: No
Nests in wooded desert wash
habitat containing mesquite,
palo verde, ironwood, and
acacia. May also occur in
areas with salt cedar,
especially when adjacent to
native wooded desert wash
habitat. Also occurs in desert
scrub habitat in winter.

Nesting: Very Low
Suitable nesting habitat
(palo verde) limited.

Foraging: Low
May forage or move
through site from nearby
areas.

Pyrocephalus rubinus
vermilion flycatcher
F: MBTA
C: SSC (nesting)
State Rank: S2S3
CVMSHCP: No
During nesting, inhabits
desert riparian adjacent to
irrigated fields, irrigation
ditches, pastures, & other
open, mesic areas with nests
in cottonwood, willow,
mesquite, or other large
desert riparian trees. Also
known to nest in landscaped
areas such as commercial and
residential developments, golf
courses and parks.

Nesting: Absent
Suitable nesting habitat
lacking.

Foraging: Low
If nesting nearby.

Toxostoma crissale
crissal thrasher
F: None
C: SSC
State Rank: S3
CVMSHCP: Yes*
Resident of SE deserts in
desert riparian and wash
habitats, nests in dense
mesquite, ironwood, catclaw,
arrowweed.

Nesting: Absent
Suitable nesting habitat
lacking.

Foraging: Very low
If nesting nearby.

Site is not within
CVMSHCP modeled
habitat for this species.
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Biological Resources Assessment & CVMSHCP Consistency Analysis Report Calhoun Street & Avenue 49 Residential Development Project March 2024
Calhoun Street & Avenue 49 Residential Development Project BRAR Page 20 Table 6. Special Status Birds
Species Status Habitat Probability
Toxostoma lecontei
Le Conte’s thrasher
F: MBTA, BCC
C: SSC (nesting), FGC
State Rank: S3
CVMSHCP: Yes*
Desert resident; primarily of
open desert wash, desert
scrub, alkali desert scrub, and
desert succulent scrub
habitats. Nest in dense, spiny
shrub or densely branched
cactus in desert wash habitat,
usually 2-8 feet above
ground.

Nesting: Absent
Suitable nesting habitat
lacking.

Foraging: Very Low
If nesting nearby.

Suitable habitat not
observed on adjacent
lands, however.

Site is not within
CVMSHCP modeled
habitat for this species.

Vireo bellii pusillus
least Bell’s vireo
F: END
C: END
State rank: S2
CVMSHCP: Yes
Riparian woodland habitats
along the riverine systems of
Southern California, primarily
in San Diego, Santa Barbara,
and Riverside Counties.

Needs dense shrub cover
within 1 to 2 meters (3 to 6
feet) off the ground for
nesting, and stratified canopy
for foraging
Nesting: Absent
Suitable habitat lacking.

Foraging: Low
Migration only
Site is not within
designated critical
habitat for this species.
* Species conserved under the CVMSHCP, but is still protected by the MBTA and FGC Table 7. Special Status Mammals
Species Status Habitat Probability
Chaetodipus fallax pallidus
pallid San Diego pocket mouse
F: None
C: SSC
State Rank: S3S4
CVMSHCP: No
Desert border areas in
desert wash, desert scrub,
desert succulent scrub,
pinon-juniper, etc. Sandy
herbaceous areas usually in
association with rocks or
coarse gravel.

Absent
Suitable habitat lacking.

Site largely disturbed
former date palm farm.

Dipodomys merriami collinus
Earthquake Merriam's
(Aguanga) kangaroo rat
F: None
C: SSC
State Rank: S1S2
CVMSHCP: No
Known only from San Diego
& Riverside Counties.

Associated with Riversidean
sage scrub, chaparral, &
non-native grassland. Needs
sandy loam substrates for
digging of burrows.

Absent
The CNDDB records near
site out of range and
habitat for this
subspecies. Presumably
these records are in error
and refer to a different
subspecies.
544
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Biological Resources Assessment & CVMSHCP Consistency Analysis Report Calhoun Street & Avenue 49 Residential Development Project March 2024
Calhoun Street & Avenue 49 Residential Development Project BRAR Page 21 Table 7. Special Status Mammals
Species Status Habitat Probability
Eumops perotis californicus
western mastiff bat
F: ND
C: CSC
State Rank: S3S4
CVMSHCP: No
WBWG: M (Region 8)
Many open, semi-arid to arid
areas including conifer and
deciduous forests,
grasslands, chaparral, and
coastal scrubs. Roosts in
crevices in cliff faces,
buildings, trees, and tunnels.

Roosting: Absent
Roosting habitat lacking.

Foraging: Low
May forage over site if
roosting nearby.

Lasiurus xanthinus
western yellow bat
F: None
C: SSC
State Rank: S3
WBWG: H
CVMSHCP: Yes
Found in a variety of
habitats: Valley foothill
riparian, desert riparian,
desert wash, and palm oasis
habitats
Roosting: Absent
Roosting habitat lacking.

Foraging: Low
May forage over site if
roosting nearby.

Neotoma lepida intermedia
San Diego desert woodrat
F: None
C: SSC
State Rank: S3S4
CVMSHCP: No
Coastal scrub of southern
California. Moderate to
dense canopies preferred.

Particularly abundant in rock
outcrops & rocky cliffs &
slopes.

Absent
Habitat lacking. Middens
not detected. Site heavily
disturbed.

Nyctinomops femorosaccus
pocketed free-tailed bat
F: None
C: SSC
State Rank: S2S3
WBWG: M
CVMSHCP: No
Rocky areas with high cliffs
in a variety of arid areas in
southern California.

Roosting: Absent
Suitable habitat lacking
Foraging: Low
May roost in vicinity and
forage over site.

Peninsular bighorn sheep DPS
Ovis canadensis nelsoni (Pop. 2)
F: END
C: THR
State Rank: S1
MSHCP: Yes
Eastern slopes of the
Peninsular Ranges below
4,600 feet. Optimal habitat
includes steep-walled
canyons/ridges bisected by
rocky or sandy washes w/
available water
Absent
Suitable habitat lacking.

Site is not within
designated critical habitat
or CVMSHCP modeled
habitat for this species.

Perognathus longimembris bangsi
Palm Springs pocket mouse
F: None
C: SSC
State Rank: S2
CVMSHCP: Yes
Inhabits flat or gently
sloping areas with sparse
vegetative cover and packed
or sandy soils.

Very Low
Only small, remnant
patches of marginal
potentially suitable
habitat present. Site
disturbance and past
agricultural practices
further reduce the
likelihood of occurrence.

Site not within CVMSHCP
modeled habitat for this
species.

Taxidea taxus
American badger
F: ND
C: CSC
State Rank: S3
CVMSHCP: No
Widespread, occurring in a
wide variety of usually open
habitats.

Very Low
Although disturbed, site
potentially suitable. No
burrows or sign observed.
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Biological Resources Assessment & CVMSHCP Consistency Analysis Report Calhoun Street & Avenue 49 Residential Development Project March 2024
Calhoun Street & Avenue 49 Residential Development Project BRAR Page 22 Table 7. Special Status Mammals
Species Status Habitat Probability
Xerospermophilus tereticaudus
chlorus
Coachella Valley (Palm Springs)
round-tailed ground squirrel
F: None
C: SSC
State Rank: S1S2
CVMSHCP: Yes
Prefers open, flat, grassy
areas in fine-textured, sandy
soil in desert succulent
scrub, desert wash, desert
scrub, alkali scrub, & levees.

Very Low
Preferred habitat lacking.

Species has been known
to occur in disturbed and
converted habitats.

Site not within CVMSHCP
modeled habitat for this
species.

Definitions of status designations and occurrence probabilities for Tables 1-7 Definitions for Species
Italics – Scientific name (i.e., Genus species subspecies) Bold – Standard common name
[Genus] – Previous genus, relatively recent taxonomic revision var. – variety (plants only)
DPS – Distinct Population Segment
Definitions of occurrence probability:

Occurs: Observed or detected onsite by WSP or recently reported by another reliable source.

High: Observed in similar habitat in region by qualified biologists, or habitat onsite is a type often utilized by the species and the site is within the known range of the species.

Moderate: Reported sightings in surrounding region, or site is within the known range of the species and habitat onsite is a type occasionally used by the species.

Low: Site is within the known range of the species but habitat onsite is rarely used by the species Very Low: Habitat is of marginal suitability and/or site is at the edge of species known range or distribution.

Absent:A focused study failed to detect the species, suitable habitat not present, or site is outside the geographic distribution of the species.

Unknown: No focused surveys have been performed in the region, & the species' distribution & habitat are poorly known.

CVMSHCP designations
Yes: Conserved by the CVMSHCP
No: Not Specifically Conserved by the CVMSHCP
Federal designations: (F = federal Endangered Species Act or USFWS designations) END: Federally listed, Endangered
THR: Federally listed, Threatened
CAN: Candidate for Federal listing
MBTA: Migratory Bird Treat
BEPA: Bald Eagle Protection Act (also protects Golden Eagles) BCC: Birds of Conservation Concern
None: No designation
State designations: (C = California Endangered Species Act or CDFG designations) END: State listed, Endangered
THR: State listed, Threatened
CAN: Candidate for State listing
RARE: State listed, Rare
FP: Fully Protected Species
SSC: Species of Special Concern
FGC: Fish and Game Code
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Biological Resources Assessment & CVMSHCP Consistency Analysis Report Calhoun Street & Avenue 49 Residential Development Project March 2024
Calhoun Street & Avenue 49 Residential Development Project BRAR Page 23 WL: Watch List Species
CDFW state rankings are a reflection of the overall condition of an element throughout its California range. The number after the decimal point represents a threat designation attached to the rank:

S1 = Critically Imperiled. Less than (<) 6 Element Occurrences (EOs) OR < 1,000 individuals OR < 2,000 acres S1.1 = very threatened
S1.2 = threatened
S1.3 = no current threats known
S2 = Imperiled. 6-20 EOs OR 1,000-3,000 individuals OR 2,000-10,000 acres S2.1 = very threatened
S2.2 = threatened
S2.3 = no current threats known
S3 = Vulnerable. 21-80 EOs OR 3,000-10,000 individuals OR 10,000-50,000 acres S3.1 = very threatened
S3.2 = threatened
S3.3 = no current threats known
S4 =
S5 = Secure. Common, widespread, and abundant in the state.

SH = All known California sites are historical, not extant ? = Qualifier: Inexact or Uncertain - A question mark represents a rank qualifier, denoting an inexact or uncertain numeric rank.

California Native Plant Society (CNPS) designations:

Primary Categories
LIST 1A: Plants Presumed Extirpated in California and Either Rare or Extinct Elsewhere LIST 1B: Plants Rare, Threatened, or Endangered in California and Elsewhere LIST 2A: Plants Presumed Extirpated in California, But Common Elsewhere LIST 2B: Plants Rare, Threatened, or Endangered in California, But More Common Elsewhere LIST 3: Plants About Which More Information is Needed - A Review List LIST 4: Plants of Limited Distribution - A Watch List
Subdivisions within Categories

0.1: Seriously threatened in California

0.2: Moderately threatened in California

0.3: Not very threatened in California
Western Bat Working Group (WBWG) designations:

The Western Bat Working Group is comprised of agencies, organizations and individuals interested in bat research, management and conservation from the 13 western states and provinces. Its goals are (1) to facilitate communication among interested parties and reduce risks of species decline or extinction; (2) to provide a mechanism by which current information on bat ecology, distribution and research techniques can be readily accessed; and (3) to develop a forum to discuss conservation strategies, provide technical assistance and encourage education programs.

H: High: Species which are imperiled or are at high risk of imperilment based on available information on distribution, status, ecology and known threats.

M: Medium: Species which warrant a medium level of concern and need closer evaluation, more research, and conservation actions of both the species and possible threats. A lack of meaningful information is a major obstacle in adequately assessing these species' status and should be considered a threat.

L: Low: Species for which most of the existing data support stable populations, and for which the potential for major changes in status in the near future is considered unlikely. There may be localized concerns, but the overall status of the species is believed to be secure. Conservation actions would still apply for these bats, but limited resources are best used on High and Medium status species.

P: Periphery: This designation indicates a species on the edge of its range, for which no other designation has been determined.
547
Item 2.

6.0 DISCUSSION
The proposed development of the project site would result in the loss/conversion of 38.8 acres of fallow, vacant, abandoned agricultural lands (date palm farm) and the biological resources, sensitive and otherwise, that occur, or potentially occur, onsite. The likelihood of occurrence for the special status species reported from the vicinity has either been eliminated or significantly reduced by the former conversion of the site to agricultural uses and past farming practices, which included removal of nearly all native vegetation, grading and may have also included use of herbicides and/or pesticides. Small, unmapped, remnant or successional patches of what is best described as quailbush scrub are, however, present intermittently throughout portions of the site, primarily along the western and southern-most areas. Other existing site disturbance (i.e., compaction of soils, offroad vehicular activity, dumping and accumulation of roadside trash) also reduces the likelihood of occurrence of many special status species. Furthermore, the presence of existing adjacent residential development to the north and south of the site and the vegetation removal, active grading of the lands to the west have largely isolated the site from other undeveloped open space. The only undeveloped, vacant open space occurs to the east. The adjacent vacant lands appear to the east appear to have also been rough graded and cleared of most native vegetation in the past. As a result, connectivity of the site to other undeveloped open space has been eliminated, or at least significantly diminished, for many terrestrial species.

The CVMSHCP was designed to streamline the permitting process and to mitigate potential impacts resulting from covered projects and the lawful activities of permittees through payment of the requisite development fee and participation in plan’s requirements. A few species, which are not covered by the CVMSHCP and/or are not yet adequately conserved by the CVMSHCP (e.g., burrowing owl, nesting birds) require additional consideration and/or actions, which are detailed below.

6.1 Discussion of the Special Status Biological Resources Tables A review of the CNDDB, CNPS and IPaC Resources List resulted in a total of 68 special status biological resources that have been reported from the vicinity (Tables 1-7). These include: 33 plants, one vegetation communities, five invertebrates, one fish, four reptiles, 14 birds and 10 mammals. Of these, 59 are considered to be absent from the site due to a combination of factors including a lack of suitable habitat, the elevation of the site outside of elevational parameters and/or in the case of flying animals (birds and bats), they may only occur onsite to forage and will therefore not be directly impacted. The special status biological resources that are considered to be absent from the site include: chaparral sand-verbena (Abronia villosa var. aurita), Borrego milkvetch (Astragalus lentiginosus var. borreganus), Coachella Valley milk-vetch (Astragalus lentiginosus var. coachellae), Lancaster milk-vetch (Astragalus preussii var. laxiflorus), gravel milkvetch (Astragalus subulonum), triple-ribbed milk-vetch (Astragalus tricarinatus), little-leaf elephant 548
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Calhoun Street & Avenue 49 Residential Development Project BRAR Page 25 tree (Bursera microphylla), Peninsular spineflower (Chorizanthe leptotheca), glandular ditaxis (Ditaxis claryana), California ditaxis (Ditaxis serrata var. californica), Booth’s evening primrose (Eremothera boothii var. boothii), Joshua Tree poppy (Eschscholtzia androuxii), Arizona spurge (Euphorbia arizonica), flat-seeded spurge (Euphorbia platysperma), pink velvet-mallow (Horsfordia alata), Newberry’s velvet-mallow (Horsfordia newberryi), winged cryptantha (Johnstonella holoptera), southwestern spiny rush (Juncus acutus ssp. leopoldii), Cooper’s rush (Juncus cooperi), Santa Rosa Mountains leptosiphon (Leptosiphon floribundus), Torrey’s box-thorn (Lycium torreyi), California marina (Marina orcuttii var. orcuttii), spear-leaf matelea (Matelea parvifolia), slender cottonheads (Nemacaulis denudate var. gracilis), narrow-leaf sandpaper-plant (Petalonyx linearis), slender-stem bean (Phaseolis filiformis), Deep Canyon snapdragon (Pseudorontium cyanthiferum), desert spike-moss (Selaginella eremophila), Cove’s cassia (Senna covesii), purple stemodia (Stemodia durantifolia), Mecca-aster (Xylorhiza cognata), desert fan palm oasis woodland, Casey’s June beetle (Dinacoma caseyi), monarch butterfly (Danaus plexippus), Coachella giant sand treader cricket (Macrobaenetes valgum), cheeseweed owlfly (Oliarces clara), Algodunes Dunes Euparagia (Euparagia unidentate), desert pupfish (Cyprinodon macularius), northern red diamond rattlesnake (Crotalus ruber ruber), desert tortoise (Gopherus agassizi), flat-tailed horned lizard (Phrynosoma mcallii), Coachella Valley fringe-toed lizard (Uma inornata), nesting Cooper’s hawk (Accipiter cooperii), nesting golden eagle (Aquila chrysaetos), nesting ferruginous hawk (Buteo regalis), nesting southwestern willow flycatcher (Empidonax traillii extimus), nesting prairie falcon (Falco mexicanus), nesting bald eagle (Haliaeetus leucocephalus), nesting vermilion flycatcher (Pyrocephalus rubinus), nesting crissal thrasher (Toxostoma crissale), nesting Le Conte’s thrasher (Toxostoma lecontei), nesting least Bell’s vireo (Vireo bellii pusillus), pallid San Diego pocket mouse (Chaetodipus fallax pallidus), Earthquake Merriam's (Aguanga) kangaroo rat (Dipodomys merriami collinus), roosting western mastiff bat (Eumops perotis californicus), roosting western yellow bat (Lasiurus xanthinus), San Diego desert woodrat (Neotoma lepida intermedia), roosting pocketed free-tailed bat (Nyctinomops femorosaccus) and Peninsular bighorn sheep DPS (Ovis canadensis nelsoni [Pop. 2]). These special status biological resources will not be discussed further.

Three of the remaining nine species are fully (or partially) covered, conserved (or partially conserved) under the CVMSHCP. Participation in the CVMSHPS and payment of the requisite CVMSHCP development fee and participation in the plan is expected to fully mitigate project related impacts (if any) to these species. These include burrowing owl (Athene cunicularia), Palm Springs pocket mouse (Perognathus longimembris bangsi) and Coachella Valley (Palm Springs) round-tailed ground squirrel (Xerospermophilus tereticaudus chlorus). The site is not within CVMSHCP modeled habitat for Coachella Valley milk-vetch, Coachella giant sand-treader cricket, flat-tailed horned lizard, Coachella Valley fringe-toed lizard, Palm Springs pocket mouse and Coachella Valley (Palm Springs) round-tailed ground squirrel. It should be noted that due to the current, highly disturbed condition and/or past agricultural conversion of the site, the likelihood for the occurrence for these species is considered to be very low to low. Regardless of whether 549
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Calhoun Street & Avenue 49 Residential Development Project BRAR Page 26 these species occur on the project site or not, participation in the CVMSHCP and payment of the development fee is designed and intended to provide full coverage of potential project-related impacts. One of these species, burrowing owl, however, requires additional considerations and/or actions for full CVMSHCP compliance, which is discussed below. Although desert tortoise is considered to be absent from the site, due to an overall lack of suitable habitat, it will also be discussed below for further clarification.

6.1.1 Species Covered Under the CVMSHCP
The desert tortoise is federally and state listed as threatened by the CDFW and USFWS. Although desert tortoise is covered under the CVMSHCP, further actions are required (where suitable habitat is present) to ensure that take is entirely avoided and/or minimized to the greatest extent possible.

No live desert tortoises or sign thereof (i.e., burrows, scat, tracks, carcass remains, courtship rings, drinking depressions) were observed onsite during the assessment. Furthermore, the site is the location of a former date palm farm/plantation and contains very little remnant and sparse native vegetation (i.e., quailbush scrub). The site is not located within designated critical habitat or CVMSHCP modeled habitat for desert tortoise. For these reasons, habitat suitable for desert tortoise is not present onsite. Additionally, surrounding lands (with the exception of lands to the east) have been developed or are currently in the process of being developed. The land to the east is vacant, undeveloped and disturbed but also does not appear to support habitat suitable for desert tortoise. For these reasons, although a very limited amount of remnant vegetation community (i.e., quailbush scrub) that might otherwise technically be suitable for the desert tortoise, existing site conditions (i.e., nearly 100% conversion to former agricultural practices, existing and past site disturbance, existing adjacent development, etc.) have resulted in an area that is currently unsuitable for this conspicuous and wide-ranging species. For these reasons, it is the opinion of WSP that desert tortoise is absent from the project site and that focused surveys are not warranted or recommended. Project implementation is anticipated to have no impact on the desert tortoise.

The burrowing owl is not listed as threatened or endangered by the USFWS or CDFW. It is, however, managed as a BCC by the USFWS and designated as a SSC by the CDFW. It is also protected from take by the MBTA and FGC. The burrowing owl is a covered species under the CVMSHCP, however the federal permit for the CVMSHCP does not allow take of this species under the MBTA. Any impacts to burrowing owl would be considered significant under the CEQA.

Although no burrowing owls, or sign thereof, were observed or detected onsite during the assessment, potentially suitable habitat (i.e., sparsely vegetated vacant lands; disturbed, remnant and sparse saltbush scrub) is, however, present on the site (Appendix D). California ground squirrel burrows of sufficient size to be suitable for burrowing owl were also observed onsite (Appendix D). The CNDDB reported burrowing owl occurring in the vicinity of the site, including a 2004 record 550
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Calhoun Street & Avenue 49 Residential Development Project BRAR Page 27 from 0.5 mile north of the site (CDFW 2024a). For these reasons, WSP considers there to be at least a low potential for the occurrence of burrowing owl onsite. Because the site is not located within or adjacent to a CVMSHCP conservation area, it is the opinion of WSP that at a minimum, a preconstruction (take avoidance) survey for burrowing owl is warranted and is therefore recommended to be conducted immediately prior to initial site clearance to ensure that burrowing owl does not occur on the site and that no direct take of burrowing owl result from project implementation. If burrowing owl is found to be present onsite, scheduled project activities would need to be temporarily halted or delayed and the CVCC and other resource agencies contact for further guidance.

Although there is a very low potential for Palm Springs pocket mouse and/or Coachella Valley (Palm Springs) round-tailed ground squirrel to occur onsite, both are fully covered species under the CVMSHCP, therefore payment of the development fee and participation in the plan is expected to fully mitigate any potential impacts to these species. Neither of these species are listed by USFWS or CDFW but are designated as SSCs by the CDFW. The site is not within CVMSHCP modeled habitat for either of these species.

The remaining six species, which are not covered, or not fully covered, under the CVMSHCP are discussed separately below.

6.1.2 Plant Species Not Covered Under the CVMSHCP
Abram’s spurge is considered to have a very low potential of occurrence as it is associated with sandy soils in Mojavean and Sonoran desert scrub within the elevational parameters of the site and is known from the vicinity. It should be noted that due to the sparse and disturbed nature of the remnant native vegetation remaining and soils onsite, the potential occurrence of this species is considered highly unlikely, however, not impossible. This species was not detected during the field assessment as the assessment was conducted outside of this species blooming period (September-November). Abram’s spurge is not listed as threatened or endangered but is designated as S2 by the CDFW and List 2B.2 by the CNPS meaning that it is considered to be “imperiled” by the CDFW and “rare, threated or endangered in California but more common elsewhere” and “moderately threatened in California”. Abram’s spurge is not covered under the CVMSHCP; thus, development fees and participation offer no mitigation for impacts (if any).

Impacts (if any) to Abrams spurge potentially resulting from the implementation of the proposed project would not likely be considered significant, as there is almost no potential for the occurrence of a significant population of this species onsite. If present, this species would very likely only be in the form of a very limited number of individual plants. The site offers little to no conservation value for this, or any other special status species. For these reasons, unmitigated impacts to Abram’s spurge (if any) would not likely be considered significant under the CEQA. For 551
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Calhoun Street & Avenue 49 Residential Development Project BRAR Page 28 these reasons, a focused survey for Abram’s spurge is not considered to be warranted and thus is not recommended for this site.

Ribbed cryptantha is considered to have a very low potential of occurrence onsite as it is associated with sandy soils in Sonoran desert scrub, has been reported from the Cathedral City quadrangle. This species was not detected during the field assessment as the assessment was conducted outside of this species blooming period (February-May), however the sparse, remnant and disturbed quailbush scrub and somewhat sandy soils that are intermittently remnant onsite may nevertheless provide potentially suitable (albeit low quality) habitat for the occurrence of this species. Ribbed cryptantha is not listed as threatened or endangered but is designated as S4 by the CDFW and List 4.3 by the CNPS meaning that it is considered to be “Apparently Secure; but some cause for long-term concern” by the CDFW and “Plant of limited distribution, a Watch List species” and “not very threatened in California”. Ribbed cryptantha is not covered under the CVMSHCP, thus development fees and participation offer no mitigation for impacts to this species.

Impacts (if any) to ribbed cryptantha potentially resulting from the implementation of the proposed project would not likely be considered significant, as there is almost no potential for the occurrence of a significant population onsite. If present, this species would very likely only be in the form of a very limited number of individual plants. The site offers little to no conservation value for this, or any other special status species. Potential impacts to a few individuals (again, in the unlikely event that this species was present) would not be expected to cause the population to drop to a less than self-sustaining level. For these reasons, unmitigated impacts to ribbed cryptantha (if any) would not likely be considered significant under the CEQA. For these reasons, a focused survey for ribbed cryptantha on this site is not considered to be warranted and thus is not recommended.

6.1.3 Wildlife Species Not Covered Under the CVMSHCP
A single Cooper’s hawk was observed onsite during the assessment. This species is not federally or state listed by the USFWS or CDFW. It is, however, managed as a Bird of Conservation Concern (BCC) and protected by Fish and Game Code (FGC) and the MBTA while nesting. Although observed occurring onsite, nesting habitat (i.e., riparian and/or deciduous communities, live oaks, etc.) is not present onsite. For these reasons, despite the detection of Cooper’s hawk onsite, impacts to nesting Cooper’s hawk are not anticipated to occur as a result of project implementation. As a result, surveys for nesting Coopers hawk are not considered to be warranted and are therefore not recommended for this site.

Costa’s hummingbird was observed onsite during the assessment. This species is not federally or state listed by the USFWS or CDFW, however is managed as a BCC and protected by FGC and the MBTA while nesting. Limited nesting habitat for Costa’s hummingbird is present onsite in the blue palo verde trees, Mexican palo verde trees and saltcedar trees intermittently present throughout 552
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Calhoun Street & Avenue 49 Residential Development Project BRAR Page 29 the site. In order to avoid potentially impacting nesting Costa’s hummingbird, avoidance of any project-related disturbance (i.e., grading, vegetation removal, landscaping, operation of heavy equipment, construction, etc.) during the nesting season (1 February through 31 August) is recommended. If initial project disturbance cannot be scheduled to occur outside of the nesting season, a clearance survey for nesting Costa’s hummingbird conducted by a qualified ornithologist or biologist immediately prior to onsite disturbance is recommended. If nesting Costa’s hummingbirds are found, 100% avoidance of impacts is required and no work buffer zones would need to be established and observed where no work would be permitted until young have fledged. While there is no established protocol for nest avoidance, when consulted the CDFW generally recommends avoidance buffers of about 100–300 feet for unlisted songbirds.

American badger was not observed or detected on-site during the assessment. This species is not listed as threatened or endangered by either the USFWS or CDFW, however, it is designated as a SSC by the CDFW. American badger is a wide-ranging species and occurs in many habitats from below sea level to alpine habitats in the western and midwestern US, southcentral Canada and much of Mexico. No potential badger burrows were observed on-site, however lands on and adjacent to (to the east of) the site are otherwise potentially suitable. The American badger is known from the vicinity (CDFW 2024a). For these reasons, WSP considers there to be at least a low potential for American badger to occur on-site. Project-related impacts (if any) to American badger would not likely be considered significant under the CEQA as implementation of the proposed project is not anticipated to result in: 1) a substantial reduction of habitat for these this species, 2) a drop in self-sustaining population levels, 3) an elimination of these this species population levels, or 4) substantially reduce these this species numbers or reduce their its geographic range. For these reasons, despite considered to have a low potential of occurrence, presence/absence survey(s) for American badger are not recommended for this site.

6.1.4 Additional Bird Species Protected by the Migratory Bird Treaty Act Excluded from coverage under the CVMSHCP are a variety of common bird species that are protected by the MBTA and FGC. This includes virtually all native migratory and resident bird species, including birds observed onsite and/or known to occur in the vicinity. Avoidance of impacts to these nesting migratory and resident birds is a requirement of the federal permit issued for the CVMSHCP. In order to avoid potentially impacting nesting birds, avoidance of any projectrelated disturbance (i.e., grading, vegetation removal, landscaping, operation of heavy equipment, construction, etc.) during the nesting season (1 February through 31 August) is recommended. If initial project disturbance cannot be scheduled to occur outside of the nesting season, a nesting bird clearance survey conducted by a qualified ornithologist or biologist immediately prior to onsite disturbance is recommended. If nesting birds are found, no work buffer zones would need to be established and observed where no work would be permitted until young have fledged. 553
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Calhoun Street & Avenue 49 Residential Development Project BRAR Page 30 While there is no established protocol for nest avoidance, when consulted the CDFW generally recommends avoidance buffers of about 100–300 feet for unlisted songbirds and 500 feet for listed songbirds and raptors.

6.1.5 Jurisdictional Areas
No natural streams, creeks, rivers, lakes, ponds or pools are located on the project site. A manmade, abandoned and dry irrigation pond and old irrigation structures (i.e., presumed derelict pumps, machinery, cement or concrete pipes and linear earthen furrows) are present in the approximate western and southern 2/3 of the site. These irrigation features, including the dry irrigation pond, are not anticipated to fall under the jurisdiction of either the USACE or CDFW.

7.0 CONCLUSION
The City of Coachella is a signatory to the CVMSHCP (CVCC 2024). Therefore, payment of the required development fees for approved projects are anticipated to mitigate the impacts and/or potential impacts (if any) to covered species potentially resulting from the development of the site, whether those covered species occur there or not. Covered species that are considered to have at least some (very low to low) potential of onsite occurrence include: burrowing owl, Palm Springs pocket mouse and Coachella Valley (Palm Springs) round-tailed ground squirrel. Impacts to these species (if any) and their respective habitat, would be fully covered and mitigated under the CVMSHCP with the payment of the requisite development fee and participation in the requirements of the plan.

Because the site contains suitable habitat and burrows suitable for burrowing owl were observed onsite, WSP recommends a preconstruction (take avoidance) survey for burrowing owl to ensure that burrowing owls do not occur onsite immediately prior to initial site clearance and or construction activities. Conducting a preconstruction (take avoidance) survey immediately prior to the commencement of proposed construction would ensure that impacts to burrowing owl do not result from project implementation. If burrowing owls are detected onsite, the CDFW would need to be contacted for guidance. If burrowing owls are detected onsite, relocation may be required, in coordination with the CVCC and CDFW.

Impacts to other bird species protected by the MBTA and FGC, including but not limited to Costa’s hummingbird, mourning dove (Zenaida macroura), killdeer (Charadrius vociferus) and lesser nighthawk (Chordeiles acutipennis), require avoidance. If project activities (i.e., site grading, vegetation removal/trimming, earthwork in undisturbed areas, etc.) are conducted during the nesting season (i.e., generally between 1 February and 31 August), a nesting bird clearance survey is recommended to ensure impacts to nesting birds are avoided. If project activities are conducted outside of the nesting season, a nesting bird clearance survey could likely be avoided. If active 554
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Calhoun Street & Avenue 49 Residential Development Project BRAR Page 31 bird nests are found, at any time, proposed project activities would need to be halted and postponed until young have fledged the nest and impacts to nesting birds are entirely avoided.

With participation in and compliance with the requirements of the CVMSHC and implementation of the recommendations above, impacts to special status biological resources are anticipated to be mitigated to a less than significant level.
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8.0 LITERATURE CITED AND REFERENCES
Association of Environmental Professionals. 2022. 2022 CEQA California Environmental Quality Act Statute and Guidelines. Accessed online at:
https://www.califaep.org/docs/2022_CEQA_Statue_and_Guidelines.pdf California Bird Records Committee. 2024. Official California Checklist. Accessed online at:
http://californiabirds.org/ca_list.asp.

California Department of Fish and Wildlife (CDFW). 2024a. California Natural Diversity Data Base, Rarefind 5. Report for the Indio, La Quinta, Myoma, Valerie and West Berdoo Canyon, Calif. quadrangles. Accessed at: dfg.ca.gov/biogeodata/cnddb/mapsanddata.asp CDFW. 2024b. Special Animals List. January. Periodic publication. Sacramento, CA. Accessed online at: https://nrm.dfg.ca.gov/FileHandler.ashx?DocumentID=109406&inline=1 CDFW. 2016. Complete List of Amphibian, Reptile, Bird and Mammal Species in California.

Accessed online at: https://nrm.dfg.ca.gov/FileHandler.ashx?DocumentID=87155&inline California Native Plant Society (CNPS). 2024a. CNPS Rare Plant Inventory. Report for the Indio, La Quinta, Myoma, Valerie and West Berdoo Canyon Calif. quadrangles. Accessed online at:
http://www.rareplants.cnps.org
CNPS. 2024b. California Rare Plant Ranks. Accessed online at: https://www.cnps.org/rareplants/california-rare-plant-ranks Coachella Valley Conservation Commission (CVCC). 2024. Coachella Valley Multiple Species Habitat Conservation Plan. Accessed plan documents online at: cvmshcp.org Holland, R.F. 1986. Preliminary Descriptions of the Terrestrial Natural Communities of California.

Prepared for the California Department of Fish and Game.

Jepson Flora Project (2nd ed.). 2024. Jepson eFlora. Accessed online at: [13 Mar 2024] Riverside County Information Technology. 2024. Map My County. Accessed online at:
http://mmc.rivcoit.org/MMC_Public/Custom/disclaimer/Default.htm Sawyer, J.O., T. Keeler-Wolf, and J.M. Evens. 2009. A manual of California vegetation (2nd ed.).

California Native Plant Society, Sacramento, CA.

USDA, NRCS. 2024. Web Soil Survey. Accessed online at: http://websoilsurvey.nrcs.usda.gov/app/ USDA, NRCS. 2024. The PLANTS Database. National Plant Data Team. Accessed online at:
plants.usda.gov
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Calhoun Street & Avenue 49 Residential Development Project BRAR Page 33 USFWS. 2024. Migratory Bird Treaty Act of 1918. Accessed online at:
https://www.fws.gov/law/migratory-bird-treaty-act-1918
USGS. 2021. West Berdoo Canyon, Calif. 7.5-Minute Topographic Quadrangle.

USGS. 2015a. Indio, Calif. 7.5-Minute Topographic Quadrangle.

USGS. 2015b. La Quinta, Calif. 7.5-Minute Topographic Quadrangle.

USGS. 2015c. Myoma, Calif. 7.5-Minute Topographic Quadrangle.

USGS. 2015d. Valerie, Calif. 7.5-Minute Topographic Quadrangle. 557
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APPENDIX A
SPECIES LIST: VASCULAR PLANTS
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APPENDIX A
Species List: Vascular Plants
This list reports only plants observed by WSP on the site during the field assessment. Other species may have been overlooked or undetectable due to their growing season. [†= special status species, * = non-native species, sp. = identified only to genus, cf= compares favorably with] Amaranthaceae Amaranth family
Amaranthis cf. albus* tumbleweed*
Asteraceae Sunflower family
Dicoria canescens desert dicoria
Helianthus annuus common sunflower
Lactuca serriola* prickly lettuce*
cf. Lepidospartum squamatum scalebroom
Palafoxia arida Spanish needles
Pluchea sericea arrow-weed
Brassicaceae Mustard family
Brassica tournefortii* Saraha mustard*
Sisymbrium irio* London rocket*
Chenopodaceae Goosefoot family
Atriplex canescens four-wing saltbush
Atriplex lentiformis quailbush
Salsola tragus* Russian thistle*
Fabaceae Pea family
cf. Acacia sp.* Unidentified non-native acacia*
Parkinsonia aculeata* Mexican palo verde*
Parkinsonia florida Mexican palo verde*
Malvaceae Saltcedar family
Malva parviflora* cheeseweed*
Solanaceae Nightshade family
Datura wrightii jimsonweed
Solanum cf. xanti purple nightshade
Tamaricaceae Saltcedar family
Tamarix cf. ramosissima cf. saltcedar
Zygophyllaceace Caltrop family
Tribulus terrestris* Puncture vine*
Arecaceae Palm family
Phoenix dactylifera* (remnant agriculture) date palm (remnant agriculture) Washingtonia sp. (sapling) fan palm (sapling)
Poaceae Grass family
Cynodon dactylon* Bermuda grass*
Schismus cf. barbatus* Mediterranean grass*
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APPENDIX B
SPECIES LIST: VERTEBRATE ANIMALS
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APPENDIX B
Species List: Vertebrate Animals
This list reports only the vertebrate animals observed or detected by WSP during the field assessment. Other species may have been overlooked or undetectable due to their activity patterns or weather conditions. [†= special status species, * = non-native species, sp. = identified only to genus, cf = compares favorably with]

VERTEBRATES

REPTILIA REPTILES
Phrynosomatidae Spiny Lizards & Allies
Uta stansburiana side-blotched lizard

AVES BIRDS
Columbidae Pigeons & Doves
Columba livia* rock pigeon*
Streptopelia decaocto* Eurasian collared dove*
Zenaida macroura mourning dove
Trochilidae Hummingbirds
Calypte costae† Costa’s hummingbird†
Accipitridae Hawks, Kites, Eagles & Allies
Accipiter cooperii† Cooper’s hawk†
Buteo lineatus red-shouldered hawk
Buteo jamaicensis red-tailed hawk
Falconidae Caracaras & Falcons
Falco sparverius American kestrel
Remizidae Penduline Tits & Verdins
Auriparus flaviceps verdin
Mimidae Mockingbirds & Thrashers
Mimus polyglottos northern mockingbird
Corvidae Crows & Ravens
Corvus corax common raven
Fringillidae Fringilline & Cardueline Finches
Haemorhous mexicanus house finch
Passerellidae New World Sparrows
Zonotrichia leucophrys white-crowned sparrow

MAMMALIA MAMMALS
Geomyidae Pocket Gophers
Thomomys bottae (burrows & tailings) Botta’s pocket gopher Scuiridae Squirrels
Otospermophilus beecheyi California ground squirrel
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APPENDIX C

FIGURES
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APPENDIX D

PHOTOGRAPHIC EXHIBITS
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PHOTOGRAPHIC LOG
Photo 1: Representative condition of the largely barren, highly disturbed area of the site. Boundary of existing residential development visible to right (perimeter wall). View facing west-southwest from the northeastern corner of the site.

Photo 2: Representative condition of some of the remnant quailbush scrub onsite. Dry, abandoned irrigation pond visible to left. View facing south-southeast from northwestern corner of site. 570
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PHOTOGRAPHIC LOG
Photo 3: Representative condition of a remnant quailbush scrub portion of the site. Dry, abandoned irrigation pond visible in center. View facing east-southeast from northeast corner of site.

Photo 4: Representative condition of the remnant, fallow date palm farm portion of the site. View facing north from vicinity of the southwestern corner of site. 571
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PHOTOGRAPHIC LOG
Photo 5: Representative condition of the remnant, fallow date palm farm portion of the site.

Existing adjacent residential development visible to right. View facing east from a south-central portion of site.

Photo 6: View of highly disturbed portion of site. Off-road vehicular activity and dumping evident.

Calhoun Street and adjacent undeveloped open space visible to right. View facing north from southeastern corner of site.
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PHOTOGRAPHIC LOG

Photo 7: Representative example of burrows suitable for burrowing owl present onsite. View facing south from north-central portion of site.

Photo 8: Another representative example of an onsite burrow suitable for burrowing owl. View facing south from north-central potion of site.
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PHOTOGRAPHIC LOG
Photo 9: Another representative example of burrow suitable for burrowing owl present onsite.

View facing south from south-central portion of site.

Photo 10: Another representative example of an onsite burrow suitable for burrowing owl. View facing south-southwest from a central location of site. 574
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Initial Study/Mitigated Negative Declaration
City of Coachella Calhoun Street Housing Development/TTM 39051 November 2025 Initial Study/Mitigated Negative Declaration C
Appendix C
Calhoun Street Housing Development
Historical/Archaeological Resources Survey Report

CONFIDENTIAL
Available upon request to qualified professionals
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Initial Study/Mitigated Negative Declaration
City of Coachella Calhoun Street Housing Development/TTM 39051 November 2025 Initial Study/Mitigated Negative Declaration D
Appendix D
Calhoun Street Housing Development Preliminary Hydrology Report 576
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SW CORNER – CALHOUN ATREET AT 49TH AVENUE

SUBDIVISION

PRELIMINARY HYDROLOGY REPORT
TABLE OF CONTENTS:

I PURPOSE AND SCOPE

II DESIGN METHODOLOGY

III RCFCD SYNTHETIC UNIT HYDROGRAPH CALCULATIONS

IV STREET FLOWRATE CAPACITY
V APPENDIX – REFERENCE MATERIAL
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I. PURPOSE AND SCOPE
This report was prepared in support of the Calhoun Street at 49th Avenue Subdivision entitlement package submittal. The purpose of this preliminary report is to analyze the existing and proposed drainage patterns, discuss the on-site drainage design and size the proposed on-site drainage facilities to meet the City of Coachella drainage ordinance requirements.

The existing project site is an undeveloped lot at the southwesterly corner of the intersection of Calhoun Street and 49th Avenue in Coachella, CA. The proposed project improvements include the addition of residential lots with an interior access drive serving the lots on a

38.76 acre parcel. The site is bound to the north and east with fully improved public streets, to the east by a residential subdivision under development and to the south by an existing residential subdivision. The project proposes to obtain access to the site from Calhoun Street to the east, and from 49th Avenue to the north. The site will be drain via street surface flow to a series of on-site retention basins designed to capture and and store the storm run off generated during the 100 year design storm event. In general, the existing site is not subject to offsite storm flows.

II. DESIGN METHODOLOGY AND CALCULATIONS
The Calhoun Street project will provide five (5) on-site storm drain infiltration retention basin systems designed to capture and store the runoff generated from the “worst case” 100 year design storm based on City of Coachella requirements. The five retention basins have a combined volume capacity designed to store the runoff generated on-site during the 100 year design storm as well as runoff from the Calhoun Street half street project frontage and the 49 Avenue full width street frontage within the public right of way. The low point on the existing project site occurs on the project’s easterly frontage. Runoff that exceeds the capacity of the on-site retention basin storage systems in an emergency overflow condition is designed to overflow onto interior surface streets and exit via surface flow onto Calhoun Street following the historical drainage pattern toward the south.

Riverside County Flood Control District Synthetic Unit Hydrograph methods are used to quantify the runoff volume generated and stored on-site during the 100 year “worst case” design storm return period. The program data and results prepared for this project are included in the Appendix of this report. The program model typically accounts for the volume of runoff lost due to infiltration in the basins and the allowable design retention basin infiltration rate of 10 gal./s.f./day (0.67 in/hr) established by City of Coachella will be applied over the surface area of the basin bottoms. The combined capacity of all five on-site basins will be compared to the total design runoff volume calculated for the Calhoun Street project to show that runoff generated during the 100 year design storm can be stored within the basins at a depth not to exceed 3ft and the runoff generated during the 10 year storm event can be stored within the on-site basins at a depth not to exceed 1.5 feet in accordance with City of Coachella retention basin criteria.

City of Coachella requires that runoff water stored on-site must be evacuated completely via infiltration within a period of 72 hours in order to comply with vector control concerns. In order to help facilitate this requirement, City of Coachella has limited the maximum depth of 579
Item 2.
stored runoff within any basin to 1.5’ during the 10 year storm event and the maximum depth of any on-site retention basin must not exceed 3.5 feet.

On-site street curb and gutter systems will be designed to convey runoff to the on-site retention basin systems via surface flow. The project site will be designed to ensure that surface runoff generated during the 10 year storm is contained below the top of the proposed street curbs and runoff generated during the 100 year storm event is contained within street right of way. Street flowrates (Q) will be calculated by applying the Rational Method using CivilD software.

DESIGN CRITERIA
The following Riverside County Flood Control District (RCFCD) parameters were used in the preparation of the analyses:

 2 year – 1 hour Precipitation 0.35” (NOAA)
 10 year – 1 hour Precipitation 0.70” (NOAA)
 10 year – 3 hour Precipitation 1.04” (NOAA)
 10 year – 6 hour Precipitation 1.36” (NOAA)
 10 year – 24 hour Precipitation 1.04” (NOAA)
 100 year – 1 hour Precipitation 1.37” (NOAA)
 100 year – 3 hour Precipitation 2.12” (NOAA)
 100 year – 6 hour Precipitation 2.78” (NOAA)
 100 year – 24 hour Precipitation 4.47” (NOAA)
 Hydrologic Soil Type “B” US Dept. of Agriculture, SCS  Runoff Index Number 56 (RCFC&WCD Plate E-6.1)
 Assumed Design Percolation Rate 0.67 in/hr
 Slope Intensity Duration Curve 0.59 (RCFC&WCD Plate D-4.6)

580
Item 2.

III RCFCD SYNTHETIC UNIT HYDROGRAPH CALCULATED RETENTION

VOLUMES

SUBAREA
100 YR.

VOLUME

REQUIRED
(CU.FT.)
BASIN
VOLUME

PROVIDED
(CU.FT.)
100 YR.

BASIN

STORAGE
DEPTH
10 YR. BASIN

STORAGE
DEPTH
1 9,580 12,250 2.45 0.72
2 57,661 64,193 3.19’ 0.99’
3 53,709 62,528 3.07’ 0.94’
4 51,654 57,236 3.20 0.99
5 41,999 72,828 2.14’ 0.54
581
Item 2.
1 2
3 4
5 6
7 8
9 10
11 12
13 14
15 16
17 18
19 20
21 22
23 24
25 26
27 28
29 30
31 32
33 34
35 36
37 38
39 40
41 42
43 44
45 46
47 48
49 50
51 52
53 54
55 56
AB C D

RCFCD SYNTHETIC UNIT HYDROGRAPH

DATA INPUT SHEET
WORKSHEET PREPARED BY: JAMES R. BAZUA, P.E.

PROJECT NAME CALHOUN AT AVENUE 49 - 10 YEAR EVENT
JOB #
CONCENTRATION POINT DESIGNATION 1
AREA DESIGNATION SUBAREA 1

TRIBUTARY AREAS ACRES

COMMERCIAL
PAVING/HARDSCAPE 1.18
SF - 1 ACRE
SF - 1/2 ACRE
SF - 1/4 ACRE

MF - CONDOMINIUMS

MF - APARTMENTS

MOBILE HOME PARK
LANDSCAPING 0.83

RETENTION BASIN

GOLF COURSE

MOUNTAINOUS
LOW LOSS RATE (PERCENT) 90%
LENGTH OF WATERCOURSE (L) 1000
LENGTH TO POINT OPPOSITE CENTROID (Lca) 15
ELEVATION OF HEADWATER 471.5
ELEVATION OF CONCENTRATION POINT 468.8
AVERAGE MANNINGS 'N' VALUE 0.02
STORM FREQUENCY (YEAR) 100

POINT RAIN
3-HOUR 1.04
6-HOUR 1.36
24-HOUR 2.23
BASIN CHARACTERISTICS: ELEVATION AREA
465 3025
466 3700
467 4430
468 5215
468.5 5630
PERCOLATION RATE (in/hr) 0.67

DRYWELL DATA

NUMBER USED
PERCOLATION RATE (cfs)
582
Item 2.

RCFCD SYNTHETIC UNIT HYDROGRAPH METHOD PROJECT: CALHOUN AT AVENUE 49 - 10 YEAR EVENT BASIC DATA CALCULATION FORM JOB # 0
SHORTCUT METHOD BY ES R. BAZUA, P.E. DATE 1/17/2025
[1] SOURCE
[2] FREQUENCY-YEARS 100
[3] DURATION:
[4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] [15]

POINT AREA AVERAGE POINT AREA AVERAGE POINT AREA AVERAGE

RAIN POINT RAIN POINT RAIN POINT

INCHES RAIN INCHES RAIN INCHES RAIN
(Plate E-5.2) INCHES (Plate E-5.4) INCHES (Plate E-5.6) INCHES

1.04 2.010 1.00 1.04 1.36 2.010 1.00 1.36 2.23 2.010 1.00 2.23

0.00 0.00 0.00 0.00 0.00 0.00

0.00 0.00 0.00 0.00 0.00 0.00
SUM [5] 2.01 SUM [7] 1.04 SUM [9] 2.01 SUM [11] 1.36 SUM [13] 2.01 SUM [15] 2.23 [16] AREA ADJ FACTOR 1.000 1.000 1.000
[17] ADJ AVG POINT RAIN 1.04 1.36 2.23
DURATION 3-HOUR 6-HOUR 24-HOUR
EFFECTIVE RAIN (in) 0.40 0.39 0.26
FLOOD VOLUME (cu-ft) 2,906 2,880 1,903
(acre-ft) 0.07 0.07 0.04
REQUIRED STORAGE (cu-ft) 2,439 2,140 370
(acre-ft) 0.06 0.05 0.01
PEAK FLOW (cfs) 1.56 1.34 0.19
MAXIMUM WSEL (ft) 465.72 465.64 465.10

0.189

15.00 0.000
[12] S^0.5
[13] L*LCA/S^0.5
[14] AVERAGE MANNINGS 'N'
[10] H-FEET 2.7
[11] S-FEET/MILE

PHYSICAL DATA

RAINFALL DATA
[1] CONCENTRATION POINT 1
SUBAREA 1

2.010
1000

0.003
471.5
468.8

0.02 1.0

1.0 2.0

14.3 3.78

0.02 6-HOURS
[6] La-FEET
[7] La-MILES
[8] ELEVATION OF HEADWATER
[9] ELEVATION OF CONCENTRATION POINT
[2] AREA DESIGNATION
[3] AREA - ACRES
[4] L-FEET
[5] L-MILES
5 24-HOURS
[15] LAG TIME-HOURS
[16] LAG TIME-MINUTES

0.05 STORM EVENT SUMMARY
[17] 100% OF LAG-MINUTES
[18] 200% OF LAG-MINUTES
[24] TOTAL PERCOLATION RATE (cfs)
[19] UNIT TIME-MINUTES (100%-200% OF LAG)
3-HOURS
Plate E-2.1

Page 2 of 14 ends

Item 2.

RCFCD SYNTHETIC UNIT HYDROGRAPH METHOD PROJECT CALHOUN AT AVENUE 49 - 10 YEAR EVENT CONCENTRATION POINT: 1BY MES R. BAZUA, P.E. DATE 1/17/2025

ADJUSTED LOSS RATE

SOIL RI PERVIOUS DECIMAL ADJUSTED AREA AVERAGE

GROUP NUMBER AREA PERCENT INFILTRATION ADJUSTED

INFILTRATION OF AREA RATE INFILTRATION

RATE IMPERVIOUS RATE
(in/hr) (in/hr) (in/hr)
[Plate C-1] [Plate E-6.1] [Plate E-6.2] [Plate E-6.3]
B 56 0.52 90% 0.10 0.00 0.000 0.0000
B 56 0.52 100% 0.05 1.18 0.587 0.0305
B 56 0.52 20% 0.43 0.00 0.000 0.0000B 56 0.52 40% 0.33 0.00 0.000 0.0000B 56 0.52 50% 0.29 0.00 0.000 0.0000B 56 0.52 65% 0.22 0.00 0.000 0.0000B 56 0.52 80% 0.15 0.00 0.000 0.0000B 56 0.52 75% 0.17 0.00 0.000 0.0000B 56 0.52 0% 0.52 0.83 0.413 0.2147B 56 0.52 0% 0.52 0.00 0.000 0.0000B 56 0.52 0% 0.52 0.00 0.000 0.0000 D 93 0.95 90% 0.18 0.00 0.000 0.0000

0.00 0.000 0.0000

0.00 0.000 0.0000
SUM 2.01 SUM 0.2453
VARIABLE LOSS RATE CURVE (24-HOUR STORM ONLY)Fm= 0.122626866C= 0.00227Ft=C(24-(T/60))^1.55 = 0.00227 0.12 in/hr LOW LOSS RATE (80-90 PERCENT) = 90%Where:T=Time in minutes. To get an average value for each unit time period, Use T=1/2 the unit time for the first time period,T=1 1/2 unit time for the second period, etc. (24-(T/60))^1.55 +

LAND USE

COMMERCIAL

PAVING/HARDSCAPE
SF - 1 ACRE
SF - 1/2 ACRESF - 1/4 ACRE
MF - COND0MINIUMS

MF - APARTMENTS

MOBILE HOME PARKS

LANDSCAPING

RETENTION BASINS

GOLF COURSE

MOUNTAINOUS
Plate E-2.1

Page 3 of 14 ends

Item 2.

RCFCD SYNTHETIC UNIT HYDROGRAPH METHOD PROJECT: CALHOUN AT AVENUE 49 - 10 YEAR EVENT 100 YEAR - 3 HOUR STORM EVENT CONCENTRATION POINT: 1
BY: MES R. BAZUA, DATE 1/17/2025
DRAINAGE AREA-ACRES 2.01
UNIT TIME-MINUTES 5
LAG TIME - MINUTES 1.00
UNIT TIME-PERCENT OF LAG 502.5
TOTAL ADJUSTED STORM RAIN-INCHES 1.04
CONSTANT LOSS RATE-in/hr 0.25
LOW LOSS RATE - PERCENT 90% TOTAL PERCOLATION RATE (cfs) 0.05 cfs Unit Time Pattern Storm Effective Flood Required
Period Minutes Hours Percent Rain Rain Hydrograph Storage in/hr Flow
(Plate E-5.9) Max Low in/hr cfs cf
1 5 0.08 1.3 0.162 0.25 0.15 0.02 0.03 0.00
2 10 0.17 1.3 0.162 0.25 0.15 0.02 0.03 0.00
3 15 0.25 1.1 0.137 0.25 0.12 0.01 0.03 0.00
4 20 0.33 1.5 0.187 0.25 0.17 0.02 0.04 0.00
5 25 0.42 1.5 0.187 0.25 0.17 0.02 0.04 0.00
6 30 0.50 1.8 0.225 0.25 0.20 0.02 0.05 0.00
7 35 0.58 1.5 0.187 0.25 0.17 0.02 0.04 0.00
8 40 0.67 1.8 0.225 0.25 0.20 0.02 0.05 0.00
9 45 0.75 1.8 0.225 0.25 0.20 0.02 0.05 0.00
10 50 0.83 1.5 0.187 0.25 0.17 0.02 0.04 0.00
11 55 0.92 1.6 0.200 0.25 0.18 0.02 0.04 0.00
12 60 1.00 1.8 0.225 0.25 0.20 0.02 0.05 0.00
13 65 1.08 2.2 0.275 0.25 0.25 0.03 0.06 3.60
14 70 1.17 2.2 0.275 0.25 0.25 0.03 0.06 3.60
15 75 1.25 2.2 0.275 0.25 0.25 0.03 0.06 3.60
16 80 1.33 2.0 0.250 0.25 0.22 0.00 0.01 0.00
17 85 1.42 2.6 0.324 0.25 0.29 0.08 0.16 33.70
18 90 1.50 2.7 0.337 0.25 0.30 0.09 0.18 41.22
19 95 1.58 2.4 0.300 0.25 0.27 0.05 0.11 18.65
20 100 1.67 2.7 0.337 0.25 0.30 0.09 0.18 41.22
21 105 1.75 3.3 0.412 0.25 0.37 0.17 0.33 86.38
22 110 1.83 3.1 0.387 0.25 0.35 0.14 0.28 71.33
23 115 1.92 2.9 0.362 0.25 0.33 0.12 0.23 56.28
24 120 2.00 3.0 0.374 0.25 0.34 0.13 0.26 63.80
25 125 2.08 3.1 0.387 0.25 0.35 0.14 0.28 71.33
26 130 2.17 4.2 0.524 0.25 0.47 0.28 0.56 154.11
27 135 2.25 5.0 0.624 0.25 0.56 0.38 0.76 214.31
28 140 2.33 3.5 0.437 0.25 0.39 0.19 0.39 101.43
29 145 2.42 6.8 0.849 0.25 0.76 0.60 1.21 349.77
30 150 2.50 7.3 0.911 0.25 0.82 0.67 1.34 387.39
31 155 2.58 8.2 1.023 0.25 0.92 0.78 1.56 455.12
32 160 2.67 5.9 0.736 0.25 0.66 0.49 0.99 282.04
33 165 2.75 2.0 0.250 0.25 0.22 0.00 0.01 0.00
34 170 2.83 1.8 0.225 0.25 0.20 0.02 0.05 0.00
35 175 2.92 1.8 0.225 0.25 0.20 0.02 0.05 0.00
36 180 3.00 0.6 0.075 0.25 0.07 0.01 0.02 0.00

EFFECTIVE RAIN & FLOOD VOLUMES SUMMARY
EFFECTIVE RAIN (in) 0.40
FLOOD VOLUME (acft) 0.07
FLOOD VOLUME (cuft) 2906.38
REQUIRED STORAGE (acft) 0.06
REQUIRED STORAGE (cuft) 2438.86
PEAK FLOW RATE (cfs) 1.56
Loss Rate
in/hr
Time

EFFECTIVE RAIN CALCULATION FORM
Plate E-2.2

Page 4 of 14 ends

Item 2.

RCFCD SYNTHETIC UNIT HYDROGRAPH METHOD PROJECT: CALHOUN AT AVENUE 49 - 10 YEAR EVENT 100 YEAR - 6 HOUR STORM EVENT CONCENTRATION POINT: 1
BY: JAMES R. BAZ DATE: 1/17/2025
DRAINAGE AREA-ACRES 2.01
UNIT TIME-MINUTES 5
LAG TIME - MINUTES 1.00
UNIT TIME-PERCENT OF LAG 502.5
TOTAL ADJUSTED STORM RAIN-INCHES 1.36
CONSTANT LOSS RATE-in/hr 0.245
LOW LOSS RATE - PERCENT 90% TOTAL PERCOLATION RATE (cfs) 0.05 cfs Unit Time Pattern Storm Effective Flood Required
Period Minutes Hours Percent Rain Rain Hydrograph Storage in/hr Flow
(Plate E-5.9) Max Low in/hr cfs cf
1 5 0.08 0.5 0.082 0.25 0.07 0.01 0.02 0.00
2 10 0.17 0.6 0.098 0.25 0.09 0.01 0.02 0.00
3 15 0.25 0.6 0.098 0.25 0.09 0.01 0.02 0.00
4 20 0.33 0.6 0.098 0.25 0.09 0.01 0.02 0.00
5 25 0.42 0.6 0.098 0.25 0.09 0.01 0.02 0.00
6 30 0.50 0.7 0.114 0.25 0.10 0.01 0.02 0.00
7 35 0.58 0.7 0.114 0.25 0.10 0.01 0.02 0.00
8 40 0.67 0.7 0.114 0.25 0.10 0.01 0.02 0.00
9 45 0.75 0.7 0.114 0.25 0.10 0.01 0.02 0.00
10 50 0.83 0.7 0.114 0.25 0.10 0.01 0.02 0.00
11 55 0.92 0.7 0.114 0.25 0.10 0.01 0.02 0.00
12 60 1.00 0.8 0.131 0.25 0.12 0.01 0.03 0.00
13 65 1.08 0.8 0.131 0.25 0.12 0.01 0.03 0.00
14 70 1.17 0.8 0.131 0.25 0.12 0.01 0.03 0.00
15 75 1.25 0.8 0.131 0.25 0.12 0.01 0.03 0.00
16 80 1.33 0.8 0.131 0.25 0.12 0.01 0.03 0.00
17 85 1.42 0.8 0.131 0.25 0.12 0.01 0.03 0.00
18 90 1.50 0.8 0.131 0.25 0.12 0.01 0.03 0.00
19 95 1.58 0.8 0.131 0.25 0.12 0.01 0.03 0.00
20 100 1.67 0.8 0.131 0.25 0.12 0.01 0.03 0.00
21 105 1.75 0.8 0.131 0.25 0.12 0.01 0.03 0.00
22 110 1.83 0.8 0.131 0.25 0.12 0.01 0.03 0.00
23 115 1.92 0.8 0.131 0.25 0.12 0.01 0.03 0.00
24 120 2.00 0.9 0.147 0.25 0.13 0.01 0.03 0.00
25 125 2.08 0.8 0.131 0.25 0.12 0.01 0.03 0.00
26 130 2.17 0.9 0.147 0.25 0.13 0.01 0.03 0.00
27 135 2.25 0.9 0.147 0.25 0.13 0.01 0.03 0.00
28 140 2.33 0.9 0.147 0.25 0.13 0.01 0.03 0.00
29 145 2.42 0.9 0.147 0.25 0.13 0.01 0.03 0.00
30 150 2.50 0.9 0.147 0.25 0.13 0.01 0.03 0.00
31 155 2.58 0.9 0.147 0.25 0.13 0.01 0.03 0.00
32 160 2.67 0.9 0.147 0.25 0.13 0.01 0.03 0.00
33 165 2.75 1.0 0.163 0.25 0.15 0.02 0.03 0.00
34 170 2.83 1.0 0.163 0.25 0.15 0.02 0.03 0.00
35 175 2.92 1.0 0.163 0.25 0.15 0.02 0.03 0.00
36 180 3.00 1.0 0.163 0.25 0.15 0.02 0.03 0.00
37 185 3.08 1.0 0.163 0.25 0.15 0.02 0.03 0.00
38 190 3.17 1.1 0.180 0.25 0.16 0.02 0.04 0.00
39 195 3.25 1.1 0.180 0.25 0.16 0.02 0.04 0.00
40 200 3.33 1.1 0.180 0.25 0.16 0.02 0.04 0.00
41 205 3.42 1.2 0.196 0.25 0.18 0.02 0.04 0.00
42 210 3.50 1.3 0.212 0.25 0.19 0.02 0.04 0.00
43 215 3.58 1.4 0.228 0.25 0.21 0.02 0.05 0.00
44 220 3.67 1.4 0.228 0.25 0.21 0.02 0.05 0.00
45 225 3.75 1.5 0.245 0.25 0.22 0.02 0.05 0.69
46 230 3.83 1.5 0.245 0.25 0.22 0.02 0.05 0.69
47 235 3.92 1.6 0.261 0.25 0.24 0.02 0.03 0.00
48 240 4.00 1.6 0.261 0.25 0.24 0.02 0.03 0.00
49 245 4.08 1.7 0.277 0.25 0.25 0.03 0.06 5.33
50 250 4.17 1.8 0.294 0.25 0.26 0.05 0.10 15.17
51 255 4.25 1.9 0.310 0.25 0.28 0.06 0.13 25.02
52 260 4.33 2.0 0.326 0.25 0.29 0.08 0.16 34.86
53 265 4.42 2.1 0.343 0.25 0.31 0.10 0.20 44.70
54 270 4.50 2.1 0.343 0.25 0.31 0.10 0.20 44.70
55 275 4.58 2.2 0.359 0.25 0.32 0.11 0.23 54.54
56 280 4.67 2.3 0.375 0.25 0.34 0.13 0.26 64.38

EFFECTIVE RAIN CALCULATION FORM
Time Loss Rate
in/hr
Plate E-2.2

Page 5 of 14 ends

Item 2.

EFFECTIVE RAIN CALCULATION FORM
Time Loss Rate
in/hr
57 285 4.75 2.4 0.392 0.25 0.35 0.15 0.29 74.22
58 290 4.83 2.4 0.392 0.25 0.35 0.15 0.29 74.22
59 295 4.92 2.5 0.408 0.25 0.37 0.16 0.33 84.06
60 300 5.00 2.6 0.424 0.25 0.38 0.18 0.36 93.90
61 305 5.08 3.1 0.506 0.25 0.46 0.26 0.52 143.11
62 310 5.17 3.6 0.588 0.25 0.53 0.34 0.69 192.31
63 315 5.25 3.9 0.636 0.25 0.57 0.39 0.79 221.83
64 320 5.33 4.2 0.685 0.25 0.62 0.44 0.88 251.36
65 325 5.42 4.7 0.767 0.25 0.69 0.52 1.05 300.56
66 330 5.50 5.6 0.914 0.25 0.82 0.67 1.34 389.13
67 335 5.58 1.9 0.310 0.25 0.28 0.06 0.13 25.02
68 340 5.67 0.9 0.147 0.25 0.13 0.01 0.03 0.00
69 345 5.75 0.6 0.098 0.25 0.09 0.01 0.02 0.00
70 350 5.83 0.5 0.082 0.25 0.07 0.01 0.02 0.00
71 355 5.92 0.3 0.049 0.25 0.04 0.00 0.01 0.00
72 360 6.00 0.2 0.033 0.25 0.03 0.00 0.01 0.00

EFFECTIVE RAIN & FLOOD VOLUMES SUMMARY
EFFECTIVE RAIN (in) 0.39
FLOOD VOLUME (acft) 0.07
FLOOD VOLUME (cuft) 2879.82
REQUIRED STORAGE (acft) 0.05
REQUIRED STORAGE (cuft) 2139.79
PEAK FLOW RATE (cfs) 1.34
Plate E-2.2

Page 6 of 14 ends

Item 2.

RCFCD SYNTHETIC UNIT HYDROGRAPH METHOD PROJECT: CALHOUN AT AVENUE 49 - 10 YEAR EVENT 100 YEAR - 24 HOUR STORM EVENT CONCENTRATION POINT: 1
BY: JAMES R. BAZ DATE: 1/17/2025
DRAINAGE AREA-ACRES 2.010 CONSTANT LOSS RATE-in/hr n/a
UNIT TIME-MINUTES 15 VARIABLE LOSS RATE (AVG) in/hr 0.2453 LAG TIME - MINUTES 1.00 MINIMUM LOSS RATE (for var. loss) - in/hr 0.123 UNIT TIME-PERCENT OF LAG 1507.5 LOW LOSS RATE - DECIMAL 0.90 TOTAL ADJUSTED STORM RAIN-INCHES 2.23 C 0.00227
PERCOLATION RATE (cfs) 0.05
Unit Time Pattern Storm Effective Flood Required
Period Minutes Hours Percent Rain Rain Hydrograph Storage in/hr Flow
(Plate E-5.9) Max Low in/hr cfs cf
1 15 0.25 0.2 0.018 0.433 0.016 0.002 0.00 0.00
2 30 0.50 0.3 0.027 0.428 0.024 0.003 0.01 0.00
3 45 0.75 0.3 0.027 0.423 0.024 0.003 0.01 0.00
4 60 1.00 0.4 0.036 0.418 0.032 0.004 0.01 0.00
5 75 1.25 0.3 0.027 0.413 0.024 0.003 0.01 0.00
6 90 1.50 0.3 0.027 0.408 0.024 0.003 0.01 0.00
7 105 1.75 0.3 0.027 0.403 0.024 0.003 0.01 0.00
8 120 2.00 0.4 0.036 0.399 0.032 0.004 0.01 0.00
9 135 2.25 0.4 0.036 0.394 0.032 0.004 0.01 0.00
10 150 2.50 0.4 0.036 0.389 0.032 0.004 0.01 0.00
11 165 2.75 0.5 0.045 0.384 0.040 0.004 0.01 0.00
12 180 3.00 0.5 0.045 0.379 0.040 0.004 0.01 0.00
13 195 3.25 0.5 0.045 0.375 0.040 0.004 0.01 0.00
14 210 3.50 0.5 0.045 0.370 0.040 0.004 0.01 0.00
15 225 3.75 0.5 0.045 0.365 0.040 0.004 0.01 0.00
16 240 4.00 0.6 0.054 0.361 0.048 0.005 0.01 0.00
17 255 4.25 0.6 0.054 0.356 0.048 0.005 0.01 0.00
18 270 4.50 0.7 0.062 0.352 0.056 0.006 0.01 0.00
19 285 4.75 0.7 0.062 0.347 0.056 0.006 0.01 0.00
20 300 5.00 0.8 0.071 0.343 0.064 0.007 0.01 0.00
21 315 5.25 0.6 0.054 0.338 0.048 0.005 0.01 0.00
22 330 5.50 0.7 0.062 0.334 0.056 0.006 0.01 0.00
23 345 5.75 0.8 0.071 0.330 0.064 0.007 0.01 0.00
24 360 6.00 0.8 0.071 0.325 0.064 0.007 0.01 0.00
25 375 6.25 0.9 0.080 0.321 0.072 0.008 0.02 0.00
26 390 6.50 0.9 0.080 0.317 0.072 0.008 0.02 0.00
27 405 6.75 1.0 0.089 0.312 0.080 0.009 0.02 0.00
28 420 7.00 1.0 0.089 0.308 0.080 0.009 0.02 0.00
29 435 7.25 1.0 0.089 0.304 0.080 0.009 0.02 0.00
30 450 7.50 1.1 0.098 0.300 0.088 0.010 0.02 0.00
31 465 7.75 1.2 0.107 0.296 0.096 0.011 0.02 0.00
32 480 8.00 1.3 0.116 0.292 0.104 0.012 0.02 0.00
33 495 8.25 1.5 0.134 0.288 0.120 0.013 0.03 0.00
34 510 8.50 1.5 0.134 0.284 0.120 0.013 0.03 0.00
35 525 8.75 1.6 0.143 0.280 0.128 0.014 0.03 0.00
36 540 9.00 1.7 0.152 0.276 0.136 0.015 0.03 0.00
37 555 9.25 1.9 0.169 0.272 0.153 0.017 0.03 0.00
38 570 9.50 2.0 0.178 0.268 0.161 0.018 0.04 0.00
39 585 9.75 2.1 0.187 0.264 0.169 0.019 0.04 0.00
40 600 10.00 2.2 0.196 0.260 0.177 0.020 0.04 0.00
41 615 10.25 1.5 0.134 0.256 0.120 0.013 0.03 0.00
42 630 10.50 1.5 0.134 0.253 0.120 0.013 0.03 0.00
43 645 10.75 2.0 0.178 0.249 0.161 0.018 0.04 0.00
44 660 11.00 2.0 0.178 0.245 0.161 0.018 0.04 0.00
45 675 11.25 1.9 0.169 0.242 0.153 0.017 0.03 0.00
46 690 11.50 1.9 0.169 0.238 0.153 0.017 0.03 0.00
47 705 11.75 1.7 0.152 0.235 0.136 0.015 0.03 0.00
48 720 12.00 1.8 0.161 0.231 0.145 0.016 0.03 0.00
49 735 12.25 2.5 0.223 0.228 0.201 0.022 0.04 0.00
50 750 12.50 2.6 0.232 0.224 0.209 0.008 0.02 0.00
51 765 12.75 2.8 0.250 0.221 0.225 0.029 0.06 9.79
52 780 13.00 2.9 0.259 0.218 0.233 0.041 0.08 31.95
53 795 13.25 3.4 0.303 0.214 0.273 0.089 0.18 118.58
54 810 13.50 3.4 0.303 0.211 0.273 0.092 0.19 124.46
55 825 13.75 2.3 0.205 0.208 0.185 0.021 0.04 0.00
56 840 14.00 2.3 0.205 0.205 0.185 0.000 0.00 0.00
57 855 14.25 2.7 0.241 0.202 0.217 0.039 0.08 28.68
58 870 14.50 2.6 0.232 0.199 0.209 0.033 0.07 18.11
59 885 14.75 2.6 0.232 0.196 0.209 0.036 0.07 23.61
60 900 15.00 2.5 0.223 0.193 0.201 0.030 0.06 12.88
61 915 15.25 2.4 0.214 0.190 0.193 0.024 0.05 2.07
Time Loss Rate
in/hr

EFFECTIVE RAIN CALCULATION FORM
Plate E-2.2

Page 7 of 14 ends

Item 2.

EFFECTIVE RAIN CALCULATION FORM
62 930 15.50 2.3 0.205 0.187 0.185 0.018 0.04 0.00
63 945 15.75 1.9 0.169 0.184 0.153 0.017 0.03 0.00
64 960 16.00 1.9 0.169 0.181 0.153 0.017 0.03 0.00
65 975 16.25 0.4 0.036 0.178 0.032 0.004 0.01 0.00
66 990 16.50 0.4 0.036 0.176 0.032 0.004 0.01 0.00
67 1005 16.75 0.3 0.027 0.173 0.024 0.003 0.01 0.00
68 1020 17.00 0.3 0.027 0.170 0.024 0.003 0.01 0.00
69 1035 17.25 0.5 0.045 0.168 0.040 0.004 0.01 0.00
70 1050 17.50 0.5 0.045 0.165 0.040 0.004 0.01 0.00
71 1065 17.75 0.5 0.045 0.163 0.040 0.004 0.01 0.00
72 1080 18.00 0.4 0.036 0.160 0.032 0.004 0.01 0.00
73 1095 18.25 0.4 0.036 0.158 0.032 0.004 0.01 0.00
74 1110 18.50 0.4 0.036 0.156 0.032 0.004 0.01 0.00
75 1125 18.75 0.3 0.027 0.153 0.024 0.003 0.01 0.00
76 1140 19.00 0.2 0.018 0.151 0.016 0.002 0.00 0.00
77 1155 19.25 0.3 0.027 0.149 0.024 0.003 0.01 0.00
78 1170 19.50 0.4 0.036 0.147 0.032 0.004 0.01 0.00
79 1185 19.75 0.3 0.027 0.145 0.024 0.003 0.01 0.00
80 1200 20.00 0.2 0.018 0.143 0.016 0.002 0.00 0.00
81 1215 20.25 0.3 0.027 0.141 0.024 0.003 0.01 0.00
82 1230 20.50 0.3 0.027 0.139 0.024 0.003 0.01 0.00
83 1245 20.75 0.3 0.027 0.138 0.024 0.003 0.01 0.00
84 1260 21.00 0.2 0.018 0.136 0.016 0.002 0.00 0.00
85 1275 21.25 0.3 0.027 0.134 0.024 0.003 0.01 0.00
86 1290 21.50 0.2 0.018 0.133 0.016 0.002 0.00 0.00
87 1305 21.75 0.3 0.027 0.131 0.024 0.003 0.01 0.00
88 1320 22.00 0.2 0.018 0.130 0.016 0.002 0.00 0.00
89 1335 22.25 0.3 0.027 0.129 0.024 0.003 0.01 0.00
90 1350 22.50 0.2 0.018 0.127 0.016 0.002 0.00 0.00
91 1365 22.75 0.2 0.018 0.126 0.016 0.002 0.00 0.00
92 1380 23.00 0.2 0.018 0.125 0.016 0.002 0.00 0.00
93 1395 23.25 0.2 0.018 0.124 0.016 0.002 0.00 0.00
94 1410 23.50 0.2 0.018 0.124 0.016 0.002 0.00 0.00
95 1425 23.75 0.2 0.018 0.123 0.016 0.002 0.00 0.00
96 1440 24.00 0.2 0.018 0.123 0.016 0.002 0.00 0.00

EFFECTIVE RAIN & FLOOD VOLUMES SUMMARY
EFFECTIVE RAIN (in) 0.26
FLOOD VOLUME (acft) 0.04
FLOOD VOLUME (cuft) 1902.84
REQUIRED STORAGE (acft) 0.01
REQUIRED STORAGE (cuft) 370.13
PEAK FLOW (cfs) 0.19
Plate E-2.2

Page 8 of 14 ends

Item 2.

PROJECT: CALHOUN AT AVENUE 49 - 10 YEAR EVENT
JOB # 0
1 BASIN CHARACTERISTICS

CONTOUR DEPTH AREA VOLUME

INCR TOTAL INCR TOTAL INCR TOTAL
(ft) (ft) (sf) (sf) (cuft) (cuft) (acre-ft)
465 0 0 3025 0 0 0.00
466 1 1 675 3700 3363 3363 0.08
467 1 2 730 4430 4065 7428 0.17
468 1 3 785 5215 4823 12250 0.28
468.5 0.5 3.5 415 5630 2711 14961 0.34

PERCOLATION CALCULATIONS
PERCOLATION RATE 0.67 in/hr 0.05 cfs

MAXWELL IV DRYWELLS
NUMBER USED 0
RATE/DRYWELL 0 cfs
TOTAL DISSIPATED 0 cfs
TOTAL PERCOLATION RATE 0.05 cfs
Basin Characteristics

Page 9 of 14 ends

Item 2.
1 JOB # 0
100 YEAR - 3 HOUR STORM EVENT

FLOW VOLUME TOTAL IN PERC TOTAL IN BASIN
UNIT (min) IN IN BASIN OUT BASIN DEPTH
PERIOD (cfs) (cuft) (cuft) (cuft) (cuft) (ft) (cuft) (acre-ft) 1 5 0.03 10 10 14 - 465.00 - 0.00
2 10 0.03 10 10 14 - 465.00 - 0.00
3 15 0.03 8 8 14 - 465.00 - 0.00
4 20 0.04 11 11 14 - 465.00 - 0.00
5 25 0.04 11 11 14 - 465.00 - 0.00
6 30 0.05 14 14 14 - 465.00 - 0.00
7 35 0.04 11 11 14 - 465.00 - 0.00
8 40 0.05 14 14 14 - 465.00 - 0.00
9 45 0.05 14 14 14 - 465.00 - 0.00
10 50 0.04 11 11 14 - 465.00 - 0.00
11 55 0.04 12 12 14 - 465.00 - 0.00
12 60 0.05 14 14 14 - 465.00 - 0.00
13 65 0.06 18 18 14 4 465.00 0.00 4
14 70 0.06 18 21 14 7 465.00 0.00 7
15 75 0.06 18 25 14 11 465.00 11 0.00
16 80 0.01 3 13 14 - 465.00 - 0.00
17 85 0.16 48 48 14 34 465.01 34 0.00
18 90 0.18 55 89 14 75 465.02 75 0.00
19 95 0.11 33 108 14 94 465.03 94 0.00
20 100 0.18 55 149 14 135 465.04 135 0.00
21 105 0.33 100 235 14 221 465.07 221 0.01
22 110 0.28 85 307 14 292 465.09 292 0.01
23 115 0.23 70 363 14 349 465.10 349 0.01
24 120 0.26 78 427 14 413 465.12 413 0.01
25 125 0.28 85 498 14 484 465.14 484 0.01
26 130 0.56 168 652 14 638 465.19 638 0.01
27 135 0.76 228 866 14 852 465.25 852 0.02
28 140 0.39 116 968 14 954 465.28 954 0.02
29 145 1.21 364 1,318 14 1,304 465.39 1,304 0.03
30 150 1.34 401 1,705 14 1,691 465.50 1,691 0.04
31 155 1.56 469 2,160 14 2,146 465.64 2,146 0.05
32 160 0.99 296 2,442 14 2,428 465.72 2,428 0.06
33 165 0.01 3 2,431 14 2,417 465.72 2,417 0.06
34 170 0.05 14 2,430 14 2,416 465.72 2,416 0.06
35 175 0.05 14 2,430 14 2,416 465.72 2,416 0.06
36 180 0.02 5 2,420 14 2,406 465.72 2,406 0.06

BALANCE IN
BASIN
TIME
Basin Depth Analysis

Page 10 of 14 ends

Item 2.
1 JOB # 0
100 YEAR - 6 HOUR STORM EVENT

FLOW VOLUME TOTAL IN PERC TOTAL IN BASIN
UNIT (min) IN IN BASIN OUT BASIN DEPTH
PERIOD (cfs) (cuft) (cuft) (cuft) (cuft) (ft) (cuft) (acre-ft) 1 5 0.02 5 5 14 - 465.00 - 0.00
2 10 0.02 6 6 14 - 465.00 - 0.00
3 15 0.02 6 6 14 - 465.00 - 0.00
4 20 0.02 6 6 14 - 465.00 - 0.00
5 25 0.02 6 6 14 - 465.00 - 0.00
6 30 0.02 7 7 14 - 465.00 - 0.00
7 35 0.02 7 7 14 - 465.00 - 0.00
8 40 0.02 7 7 14 - 465.00 - 0.00
9 45 0.02 7 7 14 - 465.00 - 0.00
10 50 0.02 7 7 14 - 465.00 - 0.00
11 55 0.02 7 7 14 - 465.00 - 0.00
12 60 0.03 8 8 14 - 465.00 - 0.00
13 65 0.03 8 8 14 - 465.00 - 0.00
14 70 0.03 8 8 14 - 465.00 - 0.00
15 75 0.03 8 8 14 - 465.00 - 0.00
16 80 0.03 8 8 14 - 465.00 - 0.00
17 85 0.03 8 8 14 - 465.00 - 0.00
18 90 0.03 8 8 14 - 465.00 - 0.00
19 95 0.03 8 8 14 - 465.00 - 0.00
20 100 0.03 8 8 14 - 465.00 - 0.00
21 105 0.03 8 8 14 - 465.00 - 0.00
22 110 0.03 8 8 14 - 465.00 - 0.00
23 115 0.03 8 8 14 - 465.00 - 0.00
24 120 0.03 9 9 14 - 465.00 - 0.00
25 125 0.03 8 8 14 - 465.00 - 0.00
26 130 0.03 9 9 14 - 465.00 - 0.00
27 135 0.03 9 9 14 - 465.00 - 0.00
28 140 0.03 9 9 14 - 465.00 - 0.00
29 145 0.03 9 9 14 - 465.00 - 0.00
30 150 0.03 9 9 14 - 465.00 - 0.00
31 155 0.03 9 9 14 - 465.00 - 0.00
32 160 0.03 9 9 14 - 465.00 - 0.00
33 165 0.03 10 10 14 - 465.00 - 0.00
34 170 0.03 10 10 14 - 465.00 - 0.00
35 175 0.03 10 10 14 - 465.00 - 0.00
36 180 0.03 10 10 14 - 465.00 - 0.00
37 185 0.03 10 10 14 - 465.00 - 0.00
38 190 0.04 11 11 14 - 465.00 - 0.00
39 195 0.04 11 11 14 - 465.00 - 0.00
40 200 0.04 11 11 14 - 465.00 - 0.00
41 205 0.04 12 12 14 - 465.00 - 0.00
42 210 0.04 13 13 14 - 465.00 - 0.00
43 215 0.05 14 14 14 - 465.00 - 0.00
44 220 0.05 14 14 14 - 465.00 - 0.00
45 225 0.05 15 15 14 1 465.00 0.00 1
46 230 0.05 15 15 14 1 465.00 0.00 1
47 235 0.03 10 11 14 - 465.00 - 0.00
48 240 0.03 10 10 14 - 465.00 - 0.00
49 245 0.06 19 19 14 5 465.00 0.00 5
50 250 0.10 29 35 14 21 465.01 21 0.00
51 255 0.13 39 60 14 46 465.01 46 0.00
52 260 0.16 49 94 14 80 465.02 80 0.00
53 265 0.20 59 139 14 125 465.04 125 0.00
54 270 0.20 59 184 14 170 465.05 170 0.00
55 275 0.23 69 238 14 224 465.07 224 0.01

TIME BALANCE IN
BASIN
Basin Depth Analysis

Page 11 of 14 ends

Item 2.
1 JOB # 0
100 YEAR - 6 HOUR STORM EVENT

FLOW VOLUME TOTAL IN PERC TOTAL IN BASIN
UNIT (min) IN IN BASIN OUT BASIN DEPTH
PERIOD (cfs) (cuft) (cuft) (cuft) (cuft) (ft) (cuft) (acre-ft)

TIME BALANCE IN
BASIN
56 280 0.26 78 303 14 289 465.09 289 0.01
57 285 0.29 88 377 14 363 465.11 363 0.01
58 290 0.29 88 451 14 437 465.13 437 0.01
59 295 0.33 98 535 14 521 465.16 521 0.01
60 300 0.36 108 629 14 615 465.18 615 0.01
61 305 0.52 157 772 14 758 465.23 758 0.02
62 310 0.69 206 965 14 951 465.28 951 0.02
63 315 0.79 236 1,186 14 1,172 465.35 1,172 0.03
64 320 0.88 265 1,438 14 1,424 465.42 1,424 0.03
65 325 1.05 315 1,738 14 1,724 465.51 1,724 0.04
66 330 1.34 403 2,127 14 2,113 465.63 2,113 0.05
67 335 0.13 39 2,152 14 2,138 465.64 2,138 0.05
68 340 0.03 9 2,147 14 2,133 465.63 2,133 0.05
69 345 0.02 6 2,139 14 2,125 465.63 2,125 0.05
70 350 0.02 5 2,130 14 2,116 465.63 2,116 0.05
71 355 0.01 3 2,119 14 2,105 465.63 2,105 0.05
72 360 0.01 2 2,107 14 2,093 465.62 2,093 0.05
Basin Depth Analysis

Page 12 of 14 ends

Item 2.
1 JOB # 0
100 YEAR - 24 HOUR STORM EVENT

FLOW VOLUME TOTAL IN PERC TOTAL IN BASIN
UNIT (min) IN IN BASIN OUT BASIN DEPTH
PERIOD (cfs) (cuft) (cuft) (cuft) (cuft) (ft) (cuft) (acre-ft) 1 15 0.00 3 3 42 - 465.00 - 0.00
2 30 0.01 5 5 42 - 465.00 - 0.00
3 45 0.01 5 5 42 - 465.00 - 0.00
4 60 0.01 6 6 42 - 465.00 - 0.00
5 75 0.01 5 5 42 - 465.00 - 0.00
6 90 0.01 5 5 42 - 465.00 - 0.00
7 105 0.01 5 5 42 - 465.00 - 0.00
8 120 0.01 6 6 42 - 465.00 - 0.00
9 135 0.01 6 6 42 - 465.00 - 0.00
10 150 0.01 6 6 42 - 465.00 - 0.00
11 165 0.01 8 8 42 - 465.00 - 0.00
12 180 0.01 8 8 42 - 465.00 - 0.00
13 195 0.01 8 8 42 - 465.00 - 0.00
14 210 0.01 8 8 42 - 465.00 - 0.00
15 225 0.01 8 8 42 - 465.00 - 0.00
16 240 0.01 10 10 42 - 465.00 - 0.00
17 255 0.01 10 10 42 - 465.00 - 0.00
18 270 0.01 11 11 42 - 465.00 - 0.00
19 285 0.01 11 11 42 - 465.00 - 0.00
20 300 0.01 13 13 42 - 465.00 - 0.00
21 315 0.01 10 10 42 - 465.00 - 0.00
22 330 0.01 11 11 42 - 465.00 - 0.00
23 345 0.01 13 13 42 - 465.00 - 0.00
24 360 0.01 13 13 42 - 465.00 - 0.00
25 375 0.02 15 15 42 - 465.00 - 0.00
26 390 0.02 15 15 42 - 465.00 - 0.00
27 405 0.02 16 16 42 - 465.00 - 0.00
28 420 0.02 16 16 42 - 465.00 - 0.00
29 435 0.02 16 16 42 - 465.00 - 0.00
30 450 0.02 18 18 42 - 465.00 - 0.00
31 465 0.02 19 19 42 - 465.00 - 0.00
32 480 0.02 21 21 42 - 465.00 - 0.00
33 495 0.03 24 24 42 - 465.00 - 0.00
34 510 0.03 24 24 42 - 465.00 - 0.00
35 525 0.03 26 26 42 - 465.00 - 0.00
36 540 0.03 27 27 42 - 465.00 - 0.00
37 555 0.03 31 31 42 - 465.00 - 0.00
38 570 0.04 32 32 42 - 465.00 - 0.00
39 585 0.04 34 34 42 - 465.00 - 0.00
40 600 0.04 35 35 42 - 465.00 - 0.00
41 615 0.03 24 24 42 - 465.00 - 0.00
42 630 0.03 24 24 42 - 465.00 - 0.00
43 645 0.04 32 32 42 - 465.00 - 0.00
44 660 0.04 32 32 42 - 465.00 - 0.00
45 675 0.03 31 31 42 - 465.00 - 0.00
46 690 0.03 31 31 42 - 465.00 - 0.00
47 705 0.03 27 27 42 - 465.00 - 0.00
48 720 0.03 29 29 42 - 465.00 - 0.00
49 735 0.04 40 40 42 - 465.00 - 0.00
50 750 0.02 14 14 42 - 465.00 - 0.00
51 765 0.06 52 52 42 10 465.00 10 0.00
52 780 0.08 74 84 42 42 465.01 42 0.00
53 795 0.18 161 203 42 160 465.05 160 0.00
54 810 0.19 167 327 42 285 465.08 285 0.01
55 825 0.04 37 322 42 280 465.08 280 0.01
56 840 0.00 1 280 42 238 465.07 238 0.01
57 855 0.08 71 309 42 267 465.08 267 0.01
58 870 0.07 60 327 42 285 465.08 285 0.01

TIME BALANCE IN
BASIN
Basin Depth Analysis

Page 13 of 14 ends

Item 2.
1 JOB # 0
100 YEAR - 24 HOUR STORM EVENT

FLOW VOLUME TOTAL IN PERC TOTAL IN BASIN
UNIT (min) IN IN BASIN OUT BASIN DEPTH
PERIOD (cfs) (cuft) (cuft) (cuft) (cuft) (ft) (cuft) (acre-ft)

TIME BALANCE IN
BASIN
59 885 0.07 66 351 42 309 465.09 309 0.01
60 900 0.06 55 364 42 321 465.10 321 0.01
61 915 0.05 44 366 42 324 465.10 324 0.01
62 930 0.04 33 357 42 315 465.09 315 0.01
63 945 0.03 31 345 42 303 465.09 303 0.01
64 960 0.03 31 334 42 292 465.09 292 0.01
65 975 0.01 6 298 42 256 465.08 256 0.01
66 990 0.01 6 262 42 220 465.07 220 0.01
67 1005 0.01 5 225 42 183 465.05 183 0.00
68 1020 0.01 5 187 42 145 465.04 145 0.00
69 1035 0.01 8 153 42 111 465.03 111 0.00
70 1050 0.01 8 119 42 77 465.02 77 0.00
71 1065 0.01 8 85 42 43 465.01 43 0.00
72 1080 0.01 6 49 42 7 465.00 7 0.00
73 1095 0.01 6 13 42 - 465.00 - 0.00
74 1110 0.01 6 6 42 - 465.00 - 0.00
75 1125 0.01 5 5 42 - 465.00 - 0.00
76 1140 0.00 3 3 42 - 465.00 - 0.00
77 1155 0.01 5 5 42 - 465.00 - 0.00
78 1170 0.01 6 6 42 - 465.00 - 0.00
79 1185 0.01 5 5 42 - 465.00 - 0.00
80 1200 0.00 3 3 42 - 465.00 - 0.00
81 1215 0.01 5 5 42 - 465.00 - 0.00
82 1230 0.01 5 5 42 - 465.00 - 0.00
83 1245 0.01 5 5 42 - 465.00 - 0.00
84 1260 0.00 3 3 42 - 465.00 - 0.00
85 1275 0.01 5 5 42 - 465.00 - 0.00
86 1290 0.00 3 3 42 - 465.00 - 0.00
87 1305 0.01 5 5 42 - 465.00 - 0.00
88 1320 0.00 3 3 42 - 465.00 - 0.00
89 1335 0.01 5 5 42 - 465.00 - 0.00
90 1350 0.00 3 3 42 - 465.00 - 0.00
91 1365 0.00 3 3 42 - 465.00 - 0.00
92 1380 0.00 3 3 42 - 465.00 - 0.00
93 1395 0.00 3 3 42 - 465.00 - 0.00
94 1410 0.00 3 3 42 - 465.00 - 0.00
95 1425 0.00 3 3 42 - 465.00 - 0.00
96 1440 0.00 3 3 42 - 465.00 - 0.00
Basin Depth Analysis

Page 14 of 14 ends

Item 2.
1 2
3 4
5 6
7 8
9 10
11 12
13 14
15 16
17 18
19 20
21 22
23 24
25 26
27 28
29 30
31 32
33 34
35 36
37 38
39 40
41 42
43 44
45 46
47 48
49 50
51 52
53 54
55 56
AB C D

RCFCD SYNTHETIC UNIT HYDROGRAPH

DATA INPUT SHEET
WORKSHEET PREPARED BY: JAMES R. BAZUA, P.E.

PROJECT NAME CALHOUN AT AVENUE 49 - 10 YEAR EVENT
JOB #
CONCENTRATION POINT DESIGNATION 1
AREA DESIGNATION SUBAREA 2

TRIBUTARY AREAS ACRES

COMMERCIAL
PAVING/HARDSCAPE 2.51
SF - 1 ACRE
SF - 1/2 ACRE
SF - 1/4 ACRE
MF - CONDOMINIUMS 7.46

MF - APARTMENTS

MOBILE HOME PARK
LANDSCAPING 0.6

RETENTION BASIN

GOLF COURSE

MOUNTAINOUS
LOW LOSS RATE (PERCENT) 90%
LENGTH OF WATERCOURSE (L) 724
LENGTH TO POINT OPPOSITE CENTROID (Lca) 100
ELEVATION OF HEADWATER 472
ELEVATION OF CONCENTRATION POINT 468.5
AVERAGE MANNINGS 'N' VALUE 0.02
STORM FREQUENCY (YEAR) 100

POINT RAIN
3-HOUR 1.04
6-HOUR 1.36
24-HOUR 2.23
BASIN CHARACTERISTICS: ELEVATION AREA
465 15600
466 17120
467 18710
468 20350
468.5 21200
PERCOLATION RATE (in/hr) 0.67

DRYWELL DATA

NUMBER USED
PERCOLATION RATE (cfs)
596
Item 2.

POINT AREA AVERAGE POINT AREA AVERAGE POINT AREA AVERAGE

RAIN POINT RAIN POINT RAIN POINT

INCHES RAIN INCHES RAIN INCHES RAIN
(Plate E-5.2) INCHES (Plate E-5.4) INCHES (Plate E-5.6) INCHES

1.04 10.570 1.00 1.04 1.36 10.570 1.00 1.36 2.23 10.570 1.00 2.23

0.00 0.00 0.00 0.00 0.00 0.00

0.00 0.00 0.00 0.00 0.00 0.00
SUM [5] 10.57 SUM [7] 1.04 SUM [9] 10.57 SUM [11] 1.36 SUM [13] 10.57 SUM [15] 2.23 [16] AREA ADJ FACTOR 1.000 1.000 1.000
[17] ADJ AVG POINT RAIN 1.04 1.36 2.23
DURATION 3-HOUR 6-HOUR 24-HOUR
EFFECTIVE RAIN (in) 0.49 0.49 0.40
FLOOD VOLUME (cu-ft) 18,821 18,747 15,460
(acre-ft) 0.43 0.43 0.35
REQUIRED STORAGE (cu-ft) 16,281 14,878 6,850
(acre-ft) 0.37 0.34 0.16
PEAK FLOW (cfs) 8.76 7.61 1.44
MAXIMUM WSEL (ft) 465.99 465.91 465.42
24-HOURS
[15] LAG TIME-HOURS
[16] LAG TIME-MINUTES

0.24 STORM EVENT SUMMARY
[17] 100% OF LAG-MINUTES
[18] 200% OF LAG-MINUTES
[24] TOTAL PERCOLATION RATE (cfs)
[19] UNIT TIME-MINUTES (100%-200% OF LAG)
3-HOURS 6-HOURS
[6] La-FEET
[7] La-MILES
[8] ELEVATION OF HEADWATER
[9] ELEVATION OF CONCENTRATION POINT
[2] AREA DESIGNATION
[3] AREA - ACRES
[4] L-FEET
[5] L-MILES
5 0.03

1.6 1.6

3.2 25.5

5.05 0.02

PHYSICAL DATA

RAINFALL DATA
[1] CONCENTRATION POINT 1
SUBAREA 2

10.570
724

0.019
472
468.5

0.137
100.00

0.001
[12] S^0.5
[13] L*LCA/S^0.5
[14] AVERAGE MANNINGS 'N'
[10] H-FEET 3.5
[11] S-FEET/MILE
Plate E-2.1

Page 2 of 14 ends

Item 2.

RCFCD SYNTHETIC UNIT HYDROGRAPH METHOD PROJECT CALHOUN AT AVENUE 49 - 10 YEAR EVENT CONCENTRATION POINT: 1BY MES R. BAZUA, P.E. DATE 1/17/2025

ADJUSTED LOSS RATE

SOIL RI PERVIOUS DECIMAL ADJUSTED AREA AVERAGE

GROUP NUMBER AREA PERCENT INFILTRATION ADJUSTED

INFILTRATION OF AREA RATE INFILTRATION

RATE IMPERVIOUS RATE
(in/hr) (in/hr) (in/hr)
[Plate C-1] [Plate E-6.1] [Plate E-6.2] [Plate E-6.3]
B 56 0.52 90% 0.10 0.00 0.000 0.0000
B 56 0.52 100% 0.05 2.51 0.237 0.0123
B 56 0.52 20% 0.43 0.00 0.000 0.0000B 56 0.52 40% 0.33 0.00 0.000 0.0000B 56 0.52 50% 0.29 0.00 0.000 0.0000B 56 0.52 65% 0.22 7.46 0.706 0.1523B 56 0.52 80% 0.15 0.00 0.000 0.0000B 56 0.52 75% 0.17 0.00 0.000 0.0000B 56 0.52 0% 0.52 0.60 0.057 0.0295B 56 0.52 0% 0.52 0.00 0.000 0.0000B 56 0.52 0% 0.52 0.00 0.000 0.0000 D 93 0.95 90% 0.18 0.00 0.000 0.0000

0.00 0.000 0.0000

0.00 0.000 0.0000
SUM 10.57 SUM 0.1942
VARIABLE LOSS RATE CURVE (24-HOUR STORM ONLY)Fm= 0.097085525C= 0.00180Ft=C(24-(T/60))^1.55 = 0.00180 0.10 in/hr LOW LOSS RATE (80-90 PERCENT) = 90%Where:T=Time in minutes. To get an average value for each unit time period, Use T=1/2 the unit time for the first time period,T=1 1/2 unit time for the second period, etc.

LANDSCAPING

RETENTION BASINS

GOLF COURSE

MOUNTAINOUS
SF - 1 ACRE
SF - 1/2 ACRESF - 1/4 ACRE
MF - COND0MINIUMS

MF - APARTMENTS

MOBILE HOME PARKS
(24-(T/60))^1.55 +

LAND USE

COMMERCIAL

PAVING/HARDSCAPE
Plate E-2.1

Page 3 of 14 ends

Item 2.

RCFCD SYNTHETIC UNIT HYDROGRAPH METHOD PROJECT: CALHOUN AT AVENUE 49 - 10 YEAR EVENT 100 YEAR - 3 HOUR STORM EVENT CONCENTRATION POINT: 1
BY: MES R. BAZUA, DATE 1/17/2025
DRAINAGE AREA-ACRES 10.57
UNIT TIME-MINUTES 5
LAG TIME - MINUTES 1.62
UNIT TIME-PERCENT OF LAG 308.6
TOTAL ADJUSTED STORM RAIN-INCHES 1.04
CONSTANT LOSS RATE-in/hr 0.19
LOW LOSS RATE - PERCENT 90% TOTAL PERCOLATION RATE (cfs) 0.24 cfs Unit Time Pattern Storm Effective Flood Required
Period Minutes Hours Percent Rain Rain Hydrograph Storage in/hr Flow
(Plate E-5.9) Max Low in/hr cfs cf
1 5 0.08 1.3 0.162 0.19 0.15 0.02 0.17 0.00
2 10 0.17 1.3 0.162 0.19 0.15 0.02 0.17 0.00
3 15 0.25 1.1 0.137 0.19 0.12 0.01 0.15 0.00
4 20 0.33 1.5 0.187 0.19 0.17 0.02 0.20 0.00
5 25 0.42 1.5 0.187 0.19 0.17 0.02 0.20 0.00
6 30 0.50 1.8 0.225 0.19 0.20 0.03 0.32 24.03
7 35 0.58 1.5 0.187 0.19 0.17 0.02 0.20 0.00
8 40 0.67 1.8 0.225 0.19 0.20 0.03 0.32 24.03
9 45 0.75 1.8 0.225 0.19 0.20 0.03 0.32 24.03
10 50 0.83 1.5 0.187 0.19 0.17 0.02 0.20 0.00
11 55 0.92 1.6 0.200 0.19 0.18 0.01 0.06 0.00
12 60 1.00 1.8 0.225 0.19 0.20 0.03 0.32 24.03
13 65 1.08 2.2 0.275 0.19 0.25 0.08 0.85 182.33
14 70 1.17 2.2 0.275 0.19 0.25 0.08 0.85 182.33
15 75 1.25 2.2 0.275 0.19 0.25 0.08 0.85 182.33
16 80 1.33 2.0 0.250 0.19 0.22 0.06 0.59 103.18
17 85 1.42 2.6 0.324 0.19 0.29 0.13 1.38 340.63
18 90 1.50 2.7 0.337 0.19 0.30 0.14 1.51 380.20
19 95 1.58 2.4 0.300 0.19 0.27 0.11 1.11 261.48
20 100 1.67 2.7 0.337 0.19 0.30 0.14 1.51 380.20
21 105 1.75 3.3 0.412 0.19 0.37 0.22 2.30 617.64
22 110 1.83 3.1 0.387 0.19 0.35 0.19 2.04 538.50
23 115 1.92 2.9 0.362 0.19 0.33 0.17 1.77 459.35
24 120 2.00 3.0 0.374 0.19 0.34 0.18 1.91 498.92
25 125 2.08 3.1 0.387 0.19 0.35 0.19 2.04 538.50
26 130 2.17 4.2 0.524 0.19 0.47 0.33 3.49 973.81
27 135 2.25 5.0 0.624 0.19 0.56 0.43 4.54 1290.40
28 140 2.33 3.5 0.437 0.19 0.39 0.24 2.56 696.79
29 145 2.42 6.8 0.849 0.19 0.76 0.65 6.92 2002.74
30 150 2.50 7.3 0.911 0.19 0.82 0.72 7.58 2200.61
31 155 2.58 8.2 1.023 0.19 0.92 0.83 8.76 2556.77
32 160 2.67 5.9 0.736 0.19 0.66 0.54 5.73 1646.57
33 165 2.75 2.0 0.250 0.19 0.22 0.06 0.59 103.18
34 170 2.83 1.8 0.225 0.19 0.20 0.03 0.32 24.03
35 175 2.92 1.8 0.225 0.19 0.20 0.03 0.32 24.03
36 180 3.00 0.6 0.075 0.19 0.07 0.01 0.08 0.00

EFFECTIVE RAIN & FLOOD VOLUMES SUMMARY
EFFECTIVE RAIN (in) 0.49
FLOOD VOLUME (acft) 0.43
FLOOD VOLUME (cuft) 18821.12
REQUIRED STORAGE (acft) 0.37
REQUIRED STORAGE (cuft) 16280.67
PEAK FLOW RATE (cfs) 8.76
Loss Rate
in/hr
Time

EFFECTIVE RAIN CALCULATION FORM
Plate E-2.2

Page 4 of 14 ends

Item 2.

RCFCD SYNTHETIC UNIT HYDROGRAPH METHOD PROJECT: CALHOUN AT AVENUE 49 - 10 YEAR EVENT 100 YEAR - 6 HOUR STORM EVENT CONCENTRATION POINT: 1
BY: JAMES R. BAZ DATE: 1/17/2025
DRAINAGE AREA-ACRES 10.57
UNIT TIME-MINUTES 5
LAG TIME - MINUTES 1.62
UNIT TIME-PERCENT OF LAG 308.6
TOTAL ADJUSTED STORM RAIN-INCHES 1.36
CONSTANT LOSS RATE-in/hr 0.194
LOW LOSS RATE - PERCENT 90% TOTAL PERCOLATION RATE (cfs) 0.24 cfs Unit Time Pattern Storm Effective Flood Required
Period Minutes Hours Percent Rain Rain Hydrograph Storage in/hr Flow
(Plate E-5.9) Max Low in/hr cfs cf
1 5 0.08 0.5 0.082 0.19 0.07 0.01 0.09 0.00
2 10 0.17 0.6 0.098 0.19 0.09 0.01 0.10 0.00
3 15 0.25 0.6 0.098 0.19 0.09 0.01 0.10 0.00
4 20 0.33 0.6 0.098 0.19 0.09 0.01 0.10 0.00
5 25 0.42 0.6 0.098 0.19 0.09 0.01 0.10 0.00
6 30 0.50 0.7 0.114 0.19 0.10 0.01 0.12 0.00
7 35 0.58 0.7 0.114 0.19 0.10 0.01 0.12 0.00
8 40 0.67 0.7 0.114 0.19 0.10 0.01 0.12 0.00
9 45 0.75 0.7 0.114 0.19 0.10 0.01 0.12 0.00
10 50 0.83 0.7 0.114 0.19 0.10 0.01 0.12 0.00
11 55 0.92 0.7 0.114 0.19 0.10 0.01 0.12 0.00
12 60 1.00 0.8 0.131 0.19 0.12 0.01 0.14 0.00
13 65 1.08 0.8 0.131 0.19 0.12 0.01 0.14 0.00
14 70 1.17 0.8 0.131 0.19 0.12 0.01 0.14 0.00
15 75 1.25 0.8 0.131 0.19 0.12 0.01 0.14 0.00
16 80 1.33 0.8 0.131 0.19 0.12 0.01 0.14 0.00
17 85 1.42 0.8 0.131 0.19 0.12 0.01 0.14 0.00
18 90 1.50 0.8 0.131 0.19 0.12 0.01 0.14 0.00
19 95 1.58 0.8 0.131 0.19 0.12 0.01 0.14 0.00
20 100 1.67 0.8 0.131 0.19 0.12 0.01 0.14 0.00
21 105 1.75 0.8 0.131 0.19 0.12 0.01 0.14 0.00
22 110 1.83 0.8 0.131 0.19 0.12 0.01 0.14 0.00
23 115 1.92 0.8 0.131 0.19 0.12 0.01 0.14 0.00
24 120 2.00 0.9 0.147 0.19 0.13 0.01 0.16 0.00
25 125 2.08 0.8 0.131 0.19 0.12 0.01 0.14 0.00
26 130 2.17 0.9 0.147 0.19 0.13 0.01 0.16 0.00
27 135 2.25 0.9 0.147 0.19 0.13 0.01 0.16 0.00
28 140 2.33 0.9 0.147 0.19 0.13 0.01 0.16 0.00
29 145 2.42 0.9 0.147 0.19 0.13 0.01 0.16 0.00
30 150 2.50 0.9 0.147 0.19 0.13 0.01 0.16 0.00
31 155 2.58 0.9 0.147 0.19 0.13 0.01 0.16 0.00
32 160 2.67 0.9 0.147 0.19 0.13 0.01 0.16 0.00
33 165 2.75 1.0 0.163 0.19 0.15 0.02 0.17 0.00
34 170 2.83 1.0 0.163 0.19 0.15 0.02 0.17 0.00
35 175 2.92 1.0 0.163 0.19 0.15 0.02 0.17 0.00
36 180 3.00 1.0 0.163 0.19 0.15 0.02 0.17 0.00
37 185 3.08 1.0 0.163 0.19 0.15 0.02 0.17 0.00
38 190 3.17 1.1 0.180 0.19 0.16 0.02 0.19 0.00
39 195 3.25 1.1 0.180 0.19 0.16 0.02 0.19 0.00
40 200 3.33 1.1 0.180 0.19 0.16 0.02 0.19 0.00
41 205 3.42 1.2 0.196 0.19 0.18 0.00 0.02 0.00
42 210 3.50 1.3 0.212 0.19 0.19 0.02 0.19 0.00
43 215 3.58 1.4 0.228 0.19 0.21 0.03 0.36 36.21
44 220 3.67 1.4 0.228 0.19 0.21 0.03 0.36 36.21
45 225 3.75 1.5 0.245 0.19 0.22 0.05 0.54 87.96
46 230 3.83 1.5 0.245 0.19 0.22 0.05 0.54 87.96
47 235 3.92 1.6 0.261 0.19 0.24 0.07 0.71 139.71
48 240 4.00 1.6 0.261 0.19 0.24 0.07 0.71 139.71
49 245 4.08 1.7 0.277 0.19 0.25 0.08 0.88 191.46
50 250 4.17 1.8 0.294 0.19 0.26 0.10 1.05 243.21
51 255 4.25 1.9 0.310 0.19 0.28 0.12 1.23 294.96
52 260 4.33 2.0 0.326 0.19 0.29 0.13 1.40 346.71
53 265 4.42 2.1 0.343 0.19 0.31 0.15 1.57 398.47
54 270 4.50 2.1 0.343 0.19 0.31 0.15 1.57 398.47
55 275 4.58 2.2 0.359 0.19 0.32 0.16 1.74 450.22
56 280 4.67 2.3 0.375 0.19 0.34 0.18 1.92 501.97

EFFECTIVE RAIN CALCULATION FORM
Time Loss Rate
in/hr
Plate E-2.2

Page 5 of 14 ends

Item 2.

EFFECTIVE RAIN CALCULATION FORM
Time Loss Rate
in/hr
57 285 4.75 2.4 0.392 0.19 0.35 0.20 2.09 553.72
58 290 4.83 2.4 0.392 0.19 0.35 0.20 2.09 553.72
59 295 4.92 2.5 0.408 0.19 0.37 0.21 2.26 605.47
60 300 5.00 2.6 0.424 0.19 0.38 0.23 2.43 657.22
61 305 5.08 3.1 0.506 0.19 0.46 0.31 3.30 915.97
62 310 5.17 3.6 0.588 0.19 0.53 0.39 4.16 1174.73
63 315 5.25 3.9 0.636 0.19 0.57 0.44 4.68 1329.98
64 320 5.33 4.2 0.685 0.19 0.62 0.49 5.19 1485.23
65 325 5.42 4.7 0.767 0.19 0.69 0.57 6.06 1743.98
66 330 5.50 5.6 0.914 0.19 0.82 0.72 7.61 2209.74
67 335 5.58 1.9 0.310 0.19 0.28 0.12 1.23 294.96
68 340 5.67 0.9 0.147 0.19 0.13 0.01 0.16 0.00
69 345 5.75 0.6 0.098 0.19 0.09 0.01 0.10 0.00
70 350 5.83 0.5 0.082 0.19 0.07 0.01 0.09 0.00
71 355 5.92 0.3 0.049 0.19 0.04 0.00 0.05 0.00
72 360 6.00 0.2 0.033 0.19 0.03 0.00 0.03 0.00

EFFECTIVE RAIN & FLOOD VOLUMES SUMMARY
EFFECTIVE RAIN (in) 0.49
FLOOD VOLUME (acft) 0.43
FLOOD VOLUME (cuft) 18747.03
REQUIRED STORAGE (acft) 0.34
REQUIRED STORAGE (cuft) 14877.95
PEAK FLOW RATE (cfs) 7.61
Plate E-2.2

Page 6 of 14 ends

Item 2.

RCFCD SYNTHETIC UNIT HYDROGRAPH METHOD PROJECT: CALHOUN AT AVENUE 49 - 10 YEAR EVENT 100 YEAR - 24 HOUR STORM EVENT CONCENTRATION POINT: 1
BY: JAMES R. BAZ DATE: 1/17/2025
DRAINAGE AREA-ACRES 10.570 CONSTANT LOSS RATE-in/hr n/a UNIT TIME-MINUTES 15 VARIABLE LOSS RATE (AVG) in/hr 0.1942 LAG TIME - MINUTES 1.62 MINIMUM LOSS RATE (for var. loss) - in/hr 0.097 UNIT TIME-PERCENT OF LAG 925.8 LOW LOSS RATE - DECIMAL 0.90 TOTAL ADJUSTED STORM RAIN-INCHES 2.23 C 0.00180
PERCOLATION RATE (cfs) 0.24
Unit Time Pattern Storm Effective Flood Required
Period Minutes Hours Percent Rain Rain Hydrograph Storage in/hr Flow
(Plate E-5.9) Max Low in/hr cfs cf
1 15 0.25 0.2 0.018 0.343 0.016 0.002 0.02 0.00
2 30 0.50 0.3 0.027 0.339 0.024 0.003 0.03 0.00
3 45 0.75 0.3 0.027 0.335 0.024 0.003 0.03 0.00
4 60 1.00 0.4 0.036 0.331 0.032 0.004 0.04 0.00
5 75 1.25 0.3 0.027 0.327 0.024 0.003 0.03 0.00
6 90 1.50 0.3 0.027 0.323 0.024 0.003 0.03 0.00
7 105 1.75 0.3 0.027 0.319 0.024 0.003 0.03 0.00
8 120 2.00 0.4 0.036 0.316 0.032 0.004 0.04 0.00
9 135 2.25 0.4 0.036 0.312 0.032 0.004 0.04 0.00
10 150 2.50 0.4 0.036 0.308 0.032 0.004 0.04 0.00
11 165 2.75 0.5 0.045 0.304 0.040 0.004 0.05 0.00
12 180 3.00 0.5 0.045 0.300 0.040 0.004 0.05 0.00
13 195 3.25 0.5 0.045 0.297 0.040 0.004 0.05 0.00
14 210 3.50 0.5 0.045 0.293 0.040 0.004 0.05 0.00
15 225 3.75 0.5 0.045 0.289 0.040 0.004 0.05 0.00
16 240 4.00 0.6 0.054 0.286 0.048 0.005 0.06 0.00
17 255 4.25 0.6 0.054 0.282 0.048 0.005 0.06 0.00
18 270 4.50 0.7 0.062 0.278 0.056 0.006 0.07 0.00
19 285 4.75 0.7 0.062 0.275 0.056 0.006 0.07 0.00
20 300 5.00 0.8 0.071 0.271 0.064 0.007 0.08 0.00
21 315 5.25 0.6 0.054 0.268 0.048 0.005 0.06 0.00
22 330 5.50 0.7 0.062 0.264 0.056 0.006 0.07 0.00
23 345 5.75 0.8 0.071 0.261 0.064 0.007 0.08 0.00
24 360 6.00 0.8 0.071 0.257 0.064 0.007 0.08 0.00
25 375 6.25 0.9 0.080 0.254 0.072 0.008 0.08 0.00
26 390 6.50 0.9 0.080 0.251 0.072 0.008 0.08 0.00
27 405 6.75 1.0 0.089 0.247 0.080 0.009 0.09 0.00
28 420 7.00 1.0 0.089 0.244 0.080 0.009 0.09 0.00
29 435 7.25 1.0 0.089 0.241 0.080 0.009 0.09 0.00
30 450 7.50 1.1 0.098 0.237 0.088 0.010 0.10 0.00
31 465 7.75 1.2 0.107 0.234 0.096 0.011 0.11 0.00
32 480 8.00 1.3 0.116 0.231 0.104 0.012 0.12 0.00
33 495 8.25 1.5 0.134 0.228 0.120 0.013 0.14 0.00
34 510 8.50 1.5 0.134 0.224 0.120 0.013 0.14 0.00
35 525 8.75 1.6 0.143 0.221 0.128 0.014 0.15 0.00
36 540 9.00 1.7 0.152 0.218 0.136 0.015 0.16 0.00
37 555 9.25 1.9 0.169 0.215 0.153 0.017 0.18 0.00
38 570 9.50 2.0 0.178 0.212 0.161 0.018 0.19 0.00
39 585 9.75 2.1 0.187 0.209 0.169 0.019 0.20 0.00
40 600 10.00 2.2 0.196 0.206 0.177 0.020 0.21 0.00
41 615 10.25 1.5 0.134 0.203 0.120 0.013 0.14 0.00
42 630 10.50 1.5 0.134 0.200 0.120 0.013 0.14 0.00
43 645 10.75 2.0 0.178 0.197 0.161 0.018 0.19 0.00
44 660 11.00 2.0 0.178 0.194 0.161 0.018 0.19 0.00
45 675 11.25 1.9 0.169 0.191 0.153 0.017 0.18 0.00
46 690 11.50 1.9 0.169 0.189 0.153 0.017 0.18 0.00
47 705 11.75 1.7 0.152 0.186 0.136 0.015 0.16 0.00
48 720 12.00 1.8 0.161 0.183 0.145 0.016 0.17 0.00
49 735 12.25 2.5 0.223 0.180 0.201 0.043 0.45 188.01
50 750 12.50 2.6 0.232 0.178 0.209 0.054 0.57 298.56
51 765 12.75 2.8 0.250 0.175 0.225 0.075 0.79 493.67
52 780 13.00 2.9 0.259 0.172 0.233 0.086 0.91 603.61
53 795 13.25 3.4 0.303 0.170 0.273 0.134 1.41 1052.67
54 810 13.50 3.4 0.303 0.167 0.273 0.136 1.44 1077.14
55 825 13.75 2.3 0.205 0.165 0.185 0.041 0.43 167.88
56 840 14.00 2.3 0.205 0.162 0.185 0.043 0.45 191.72
57 855 14.25 2.7 0.241 0.160 0.217 0.081 0.86 554.66
58 870 14.50 2.6 0.232 0.157 0.209 0.075 0.79 492.99
59 885 14.75 2.6 0.232 0.155 0.209 0.077 0.82 515.85
60 900 15.00 2.5 0.223 0.152 0.201 0.071 0.75 453.52
61 915 15.25 2.4 0.214 0.150 0.193 0.064 0.68 390.86
Time Loss Rate
in/hr

EFFECTIVE RAIN CALCULATION FORM
Plate E-2.2

Page 7 of 14 ends

Item 2.

EFFECTIVE RAIN CALCULATION FORM
62 930 15.50 2.3 0.205 0.148 0.185 0.057 0.61 327.85
63 945 15.75 1.9 0.169 0.146 0.153 0.024 0.25 9.93
64 960 16.00 1.9 0.169 0.143 0.153 0.026 0.28 31.09
65 975 16.25 0.4 0.036 0.141 0.032 0.004 0.04 0.00
66 990 16.50 0.4 0.036 0.139 0.032 0.004 0.04 0.00
67 1005 16.75 0.3 0.027 0.137 0.024 0.003 0.03 0.00
68 1020 17.00 0.3 0.027 0.135 0.024 0.003 0.03 0.00
69 1035 17.25 0.5 0.045 0.133 0.040 0.004 0.05 0.00
70 1050 17.50 0.5 0.045 0.131 0.040 0.004 0.05 0.00
71 1065 17.75 0.5 0.045 0.129 0.040 0.004 0.05 0.00
72 1080 18.00 0.4 0.036 0.127 0.032 0.004 0.04 0.00
73 1095 18.25 0.4 0.036 0.125 0.032 0.004 0.04 0.00
74 1110 18.50 0.4 0.036 0.123 0.032 0.004 0.04 0.00
75 1125 18.75 0.3 0.027 0.121 0.024 0.003 0.03 0.00
76 1140 19.00 0.2 0.018 0.120 0.016 0.002 0.02 0.00
77 1155 19.25 0.3 0.027 0.118 0.024 0.003 0.03 0.00
78 1170 19.50 0.4 0.036 0.116 0.032 0.004 0.04 0.00
79 1185 19.75 0.3 0.027 0.115 0.024 0.003 0.03 0.00
80 1200 20.00 0.2 0.018 0.113 0.016 0.002 0.02 0.00
81 1215 20.25 0.3 0.027 0.112 0.024 0.003 0.03 0.00
82 1230 20.50 0.3 0.027 0.110 0.024 0.003 0.03 0.00
83 1245 20.75 0.3 0.027 0.109 0.024 0.003 0.03 0.00
84 1260 21.00 0.2 0.018 0.108 0.016 0.002 0.02 0.00
85 1275 21.25 0.3 0.027 0.106 0.024 0.003 0.03 0.00
86 1290 21.50 0.2 0.018 0.105 0.016 0.002 0.02 0.00
87 1305 21.75 0.3 0.027 0.104 0.024 0.003 0.03 0.00
88 1320 22.00 0.2 0.018 0.103 0.016 0.002 0.02 0.00
89 1335 22.25 0.3 0.027 0.102 0.024 0.003 0.03 0.00
90 1350 22.50 0.2 0.018 0.101 0.016 0.002 0.02 0.00
91 1365 22.75 0.2 0.018 0.100 0.016 0.002 0.02 0.00
92 1380 23.00 0.2 0.018 0.099 0.016 0.002 0.02 0.00
93 1395 23.25 0.2 0.018 0.099 0.016 0.002 0.02 0.00
94 1410 23.50 0.2 0.018 0.098 0.016 0.002 0.02 0.00
95 1425 23.75 0.2 0.018 0.097 0.016 0.002 0.02 0.00
96 1440 24.00 0.2 0.018 0.097 0.016 0.002 0.02 0.00

EFFECTIVE RAIN & FLOOD VOLUMES SUMMARY
EFFECTIVE RAIN (in) 0.40
FLOOD VOLUME (acft) 0.35
FLOOD VOLUME (cuft) 15459.88
REQUIRED STORAGE (acft) 0.16
REQUIRED STORAGE (cuft) 6850.04
PEAK FLOW (cfs) 1.44
Plate E-2.2

Page 8 of 14 ends

Item 2.

PROJECT: CALHOUN AT AVENUE 49 - 10 YEAR EVENT
JOB # 0
1 BASIN CHARACTERISTICS

CONTOUR DEPTH AREA VOLUME

INCR TOTAL INCR TOTAL INCR TOTAL
(ft) (ft) (sf) (sf) (cuft) (cuft) (acre-ft)
465 0 0 15600 0 0 0.00
466 1 1 1520 17120 16360 16360 0.38
467 1 2 1590 18710 17915 34275 0.79
468 1 3 1640 20350 19530 53805 1.24
468.5 0.5 3.5 850 21200 10388 64193 1.47

PERCOLATION CALCULATIONS
PERCOLATION RATE 0.67 in/hr 0.24 cfs

MAXWELL IV DRYWELLS
NUMBER USED 0
RATE/DRYWELL 0 cfs
TOTAL DISSIPATED 0 cfs
TOTAL PERCOLATION RATE 0.24 cfs
Basin Characteristics

Page 9 of 14 ends

Item 2.
1 JOB # 0
100 YEAR - 3 HOUR STORM EVENT

FLOW VOLUME TOTAL IN PERC TOTAL IN BASIN
UNIT (min) IN IN BASIN OUT BASIN DEPTH
PERIOD (cfs) (cuft) (cuft) (cuft) (cuft) (ft) (cuft) (acre-ft) 1 5 0.17 51 51 73 - 465.00 - 0.00
2 10 0.17 51 51 73 - 465.00 - 0.00
3 15 0.15 44 44 73 - 465.00 - 0.00
4 20 0.20 59 59 73 - 465.00 - 0.00
5 25 0.20 59 59 73 - 465.00 - 0.00
6 30 0.32 97 97 73 24 465.00 24 0.00
7 35 0.20 59 83 73 11 465.00 11 0.00
8 40 0.32 97 107 73 35 465.00 35 0.00
9 45 0.32 97 131 73 59 465.00 59 0.00
10 50 0.20 59 118 73 46 465.00 46 0.00
11 55 0.06 17 63 73 - 465.00 - 0.00
12 60 0.32 97 97 73 24 465.00 24 0.00
13 65 0.85 255 279 73 206 465.01 206 0.00
14 70 0.85 255 461 73 389 465.02 389 0.01
15 75 0.85 255 644 73 571 465.03 571 0.01
16 80 0.59 176 747 73 674 465.04 674 0.02
17 85 1.38 413 1,087 73 1,015 465.06 1,015 0.02
18 90 1.51 453 1,468 73 1,395 465.09 1,395 0.03
19 95 1.11 334 1,729 73 1,657 465.10 1,657 0.04
20 100 1.51 453 2,109 73 2,037 465.12 2,037 0.05
21 105 2.30 690 2,727 73 2,654 465.16 2,654 0.06
22 110 2.04 611 3,265 73 3,193 465.20 3,193 0.07
23 115 1.77 532 3,725 73 3,652 465.22 3,652 0.08
24 120 1.91 572 4,224 73 4,151 465.25 4,151 0.10
25 125 2.04 611 4,762 73 4,690 465.29 4,690 0.11
26 130 3.49 1,046 5,736 73 5,663 465.35 5,663 0.13
27 135 4.54 1,363 7,026 73 6,954 465.43 6,954 0.16
28 140 2.56 769 7,723 73 7,651 465.47 7,651 0.18
29 145 6.92 2,075 9,726 73 9,653 465.59 9,653 0.22
30 150 7.58 2,273 11,927 73 11,854 465.72 11,854 0.27
31 155 8.76 2,629 14,483 73 14,411 465.88 14,411 0.33
32 160 5.73 1,719 16,130 73 16,057 465.98 16,057 0.37
33 165 0.59 176 16,233 73 16,161 465.99 16,161 0.37
34 170 0.32 97 16,257 73 16,185 465.99 16,185 0.37
35 175 0.32 97 16,281 73 16,209 465.99 16,209 0.37
36 180 0.08 24 16,232 73 16,160 465.99 16,160 0.37

BALANCE IN
BASIN
TIME
Basin Depth Analysis

Page 10 of 14 ends

Item 2.
1 JOB # 0
100 YEAR - 6 HOUR STORM EVENT

FLOW VOLUME TOTAL IN PERC TOTAL IN BASIN
UNIT (min) IN IN BASIN OUT BASIN DEPTH
PERIOD (cfs) (cuft) (cuft) (cuft) (cuft) (ft) (cuft) (acre-ft) 1 5 0.09 26 26 73 - 465.00 - 0.00
2 10 0.10 31 31 73 - 465.00 - 0.00
3 15 0.10 31 31 73 - 465.00 - 0.00
4 20 0.10 31 31 73 - 465.00 - 0.00
5 25 0.10 31 31 73 - 465.00 - 0.00
6 30 0.12 36 36 73 - 465.00 - 0.00
7 35 0.12 36 36 73 - 465.00 - 0.00
8 40 0.12 36 36 73 - 465.00 - 0.00
9 45 0.12 36 36 73 - 465.00 - 0.00
10 50 0.12 36 36 73 - 465.00 - 0.00
11 55 0.12 36 36 73 - 465.00 - 0.00
12 60 0.14 41 41 73 - 465.00 - 0.00
13 65 0.14 41 41 73 - 465.00 - 0.00
14 70 0.14 41 41 73 - 465.00 - 0.00
15 75 0.14 41 41 73 - 465.00 - 0.00
16 80 0.14 41 41 73 - 465.00 - 0.00
17 85 0.14 41 41 73 - 465.00 - 0.00
18 90 0.14 41 41 73 - 465.00 - 0.00
19 95 0.14 41 41 73 - 465.00 - 0.00
20 100 0.14 41 41 73 - 465.00 - 0.00
21 105 0.14 41 41 73 - 465.00 - 0.00
22 110 0.14 41 41 73 - 465.00 - 0.00
23 115 0.14 41 41 73 - 465.00 - 0.00
24 120 0.16 47 47 73 - 465.00 - 0.00
25 125 0.14 41 41 73 - 465.00 - 0.00
26 130 0.16 47 47 73 - 465.00 - 0.00
27 135 0.16 47 47 73 - 465.00 - 0.00
28 140 0.16 47 47 73 - 465.00 - 0.00
29 145 0.16 47 47 73 - 465.00 - 0.00
30 150 0.16 47 47 73 - 465.00 - 0.00
31 155 0.16 47 47 73 - 465.00 - 0.00
32 160 0.16 47 47 73 - 465.00 - 0.00
33 165 0.17 52 52 73 - 465.00 - 0.00
34 170 0.17 52 52 73 - 465.00 - 0.00
35 175 0.17 52 52 73 - 465.00 - 0.00
36 180 0.17 52 52 73 - 465.00 - 0.00
37 185 0.17 52 52 73 - 465.00 - 0.00
38 190 0.19 57 57 73 - 465.00 - 0.00
39 195 0.19 57 57 73 - 465.00 - 0.00
40 200 0.19 57 57 73 - 465.00 - 0.00
41 205 0.02 5 5 73 - 465.00 - 0.00
42 210 0.19 57 57 73 - 465.00 - 0.00
43 215 0.36 109 109 73 36 465.00 36 0.00
44 220 0.36 109 145 73 72 465.00 72 0.00
45 225 0.54 161 233 73 160 465.01 160 0.00
46 230 0.54 161 321 73 248 465.02 248 0.01
47 235 0.71 212 461 73 388 465.02 388 0.01
48 240 0.71 212 600 73 528 465.03 528 0.01
49 245 0.88 264 792 73 719 465.04 719 0.02
50 250 1.05 316 1,035 73 962 465.06 962 0.02
51 255 1.23 368 1,330 73 1,257 465.08 1,257 0.03
52 260 1.40 419 1,677 73 1,604 465.10 1,604 0.04
53 265 1.57 471 2,075 73 2,003 465.12 2,003 0.05
54 270 1.57 471 2,474 73 2,401 465.15 2,401 0.06
55 275 1.74 523 2,924 73 2,851 465.17 2,851 0.07

TIME BALANCE IN
BASIN
Basin Depth Analysis

Page 11 of 14 ends

Item 2.
1 JOB # 0
100 YEAR - 6 HOUR STORM EVENT

FLOW VOLUME TOTAL IN PERC TOTAL IN BASIN
UNIT (min) IN IN BASIN OUT BASIN DEPTH
PERIOD (cfs) (cuft) (cuft) (cuft) (cuft) (ft) (cuft) (acre-ft)

TIME BALANCE IN
BASIN
56 280 1.92 575 3,426 73 3,353 465.20 3,353 0.08
57 285 2.09 626 3,980 73 3,907 465.24 3,907 0.09
58 290 2.09 626 4,533 73 4,461 465.27 4,461 0.10
59 295 2.26 678 5,139 73 5,066 465.31 5,066 0.12
60 300 2.43 730 5,796 73 5,723 465.35 5,723 0.13
61 305 3.30 989 6,712 73 6,639 465.41 6,639 0.15
62 310 4.16 1,247 7,887 73 7,814 465.48 7,814 0.18
63 315 4.68 1,403 9,217 73 9,144 465.56 9,144 0.21
64 320 5.19 1,558 10,702 73 10,629 465.65 10,629 0.24
65 325 6.06 1,817 12,446 73 12,373 465.76 12,373 0.28
66 330 7.61 2,282 14,656 73 14,583 465.89 14,583 0.33
67 335 1.23 368 14,951 73 14,878 465.91 14,878 0.34
68 340 0.16 47 14,925 73 14,852 465.91 14,852 0.34
69 345 0.10 31 14,883 73 14,810 465.91 14,810 0.34
70 350 0.09 26 14,836 73 14,764 465.90 14,764 0.34
71 355 0.05 16 14,779 73 14,707 465.90 14,707 0.34
72 360 0.03 10 14,717 73 14,644 465.90 14,644 0.34
Basin Depth Analysis

Page 12 of 14 ends

Item 2.
1 JOB # 0
100 YEAR - 24 HOUR STORM EVENT

FLOW VOLUME TOTAL IN PERC TOTAL IN BASIN
UNIT (min) IN IN BASIN OUT BASIN DEPTH
PERIOD (cfs) (cuft) (cuft) (cuft) (cuft) (ft) (cuft) (acre-ft) 1 15 0.02 17 17 218 - 465.00 - 0.00
2 30 0.03 25 25 218 - 465.00 - 0.00
3 45 0.03 25 25 218 - 465.00 - 0.00
4 60 0.04 34 34 218 - 465.00 - 0.00
5 75 0.03 25 25 218 - 465.00 - 0.00
6 90 0.03 25 25 218 - 465.00 - 0.00
7 105 0.03 25 25 218 - 465.00 - 0.00
8 120 0.04 34 34 218 - 465.00 - 0.00
9 135 0.04 34 34 218 - 465.00 - 0.00
10 150 0.04 34 34 218 - 465.00 - 0.00
11 165 0.05 42 42 218 - 465.00 - 0.00
12 180 0.05 42 42 218 - 465.00 - 0.00
13 195 0.05 42 42 218 - 465.00 - 0.00
14 210 0.05 42 42 218 - 465.00 - 0.00
15 225 0.05 42 42 218 - 465.00 - 0.00
16 240 0.06 51 51 218 - 465.00 - 0.00
17 255 0.06 51 51 218 - 465.00 - 0.00
18 270 0.07 59 59 218 - 465.00 - 0.00
19 285 0.07 59 59 218 - 465.00 - 0.00
20 300 0.08 68 68 218 - 465.00 - 0.00
21 315 0.06 51 51 218 - 465.00 - 0.00
22 330 0.07 59 59 218 - 465.00 - 0.00
23 345 0.08 68 68 218 - 465.00 - 0.00
24 360 0.08 68 68 218 - 465.00 - 0.00
25 375 0.08 76 76 218 - 465.00 - 0.00
26 390 0.08 76 76 218 - 465.00 - 0.00
27 405 0.09 85 85 218 - 465.00 - 0.00
28 420 0.09 85 85 218 - 465.00 - 0.00
29 435 0.09 85 85 218 - 465.00 - 0.00
30 450 0.10 93 93 218 - 465.00 - 0.00
31 465 0.11 102 102 218 - 465.00 - 0.00
32 480 0.12 110 110 218 - 465.00 - 0.00
33 495 0.14 127 127 218 - 465.00 - 0.00
34 510 0.14 127 127 218 - 465.00 - 0.00
35 525 0.15 136 136 218 - 465.00 - 0.00
36 540 0.16 144 144 218 - 465.00 - 0.00
37 555 0.18 161 161 218 - 465.00 - 0.00
38 570 0.19 170 170 218 - 465.00 - 0.00
39 585 0.20 178 178 218 - 465.00 - 0.00
40 600 0.21 187 187 218 - 465.00 - 0.00
41 615 0.14 127 127 218 - 465.00 - 0.00
42 630 0.14 127 127 218 - 465.00 - 0.00
43 645 0.19 170 170 218 - 465.00 - 0.00
44 660 0.19 170 170 218 - 465.00 - 0.00
45 675 0.18 161 161 218 - 465.00 - 0.00
46 690 0.18 161 161 218 - 465.00 - 0.00
47 705 0.16 144 144 218 - 465.00 - 0.00
48 720 0.17 153 153 218 - 465.00 - 0.00
49 735 0.45 406 406 218 188 465.01 188 0.00
50 750 0.57 516 704 218 487 465.03 487 0.01
51 765 0.79 711 1,198 218 980 465.06 980 0.02
52 780 0.91 821 1,802 218 1,584 465.10 1,584 0.04
53 795 1.41 1,270 2,854 218 2,637 465.16 2,637 0.06
54 810 1.44 1,295 3,931 218 3,714 465.23 3,714 0.09
55 825 0.43 386 4,099 218 3,882 465.24 3,882 0.09
56 840 0.45 409 4,291 218 4,073 465.25 4,073 0.09
57 855 0.86 772 4,846 218 4,628 465.28 4,628 0.11
58 870 0.79 711 5,339 218 5,121 465.31 5,121 0.12

TIME BALANCE IN
BASIN
Basin Depth Analysis

Page 13 of 14 ends

Item 2.
1 JOB # 0
100 YEAR - 24 HOUR STORM EVENT

FLOW VOLUME TOTAL IN PERC TOTAL IN BASIN
UNIT (min) IN IN BASIN OUT BASIN DEPTH
PERIOD (cfs) (cuft) (cuft) (cuft) (cuft) (ft) (cuft) (acre-ft)

TIME BALANCE IN
BASIN
59 885 0.82 734 5,855 218 5,637 465.34 5,637 0.13
60 900 0.75 671 6,308 218 6,090 465.37 6,090 0.14
61 915 0.68 609 6,699 218 6,481 465.40 6,481 0.15
62 930 0.61 546 7,027 218 6,809 465.42 6,809 0.16
63 945 0.25 228 7,037 218 6,819 465.42 6,819 0.16
64 960 0.28 249 7,068 218 6,850 465.42 6,850 0.16
65 975 0.04 34 6,884 218 6,666 465.41 6,666 0.15
66 990 0.04 34 6,700 218 6,482 465.40 6,482 0.15
67 1005 0.03 25 6,508 218 6,290 465.38 6,290 0.14
68 1020 0.03 25 6,316 218 6,098 465.37 6,098 0.14
69 1035 0.05 42 6,140 218 5,923 465.36 5,923 0.14
70 1050 0.05 42 5,965 218 5,747 465.35 5,747 0.13
71 1065 0.05 42 5,790 218 5,572 465.34 5,572 0.13
72 1080 0.04 34 5,606 218 5,388 465.33 5,388 0.12
73 1095 0.04 34 5,422 218 5,204 465.32 5,204 0.12
74 1110 0.04 34 5,238 218 5,020 465.31 5,020 0.12
75 1125 0.03 25 5,046 218 4,828 465.30 4,828 0.11
76 1140 0.02 4,845 17 218 4,627 465.28 4,627 0.11
77 1155 0.03 25 4,653 218 4,435 465.27 4,435 0.10
78 1170 0.04 34 4,469 218 4,251 465.26 4,251 0.10
79 1185 0.03 25 4,277 218 4,059 465.25 4,059 0.09
80 1200 0.02 17 4,076 218 3,858 465.24 3,858 0.09
81 1215 0.03 25 3,884 218 3,666 465.22 3,666 0.08
82 1230 0.03 25 3,691 218 3,474 465.21 3,474 0.08
83 1245 0.03 25 3,499 218 3,281 465.20 3,281 0.08
84 1260 0.02 17 3,298 218 3,081 465.19 3,081 0.07
85 1275 0.03 25 3,106 218 2,888 465.18 2,888 0.07
86 1290 0.02 17 2,905 218 2,687 465.16 2,687 0.06
87 1305 0.03 25 2,713 218 2,495 465.15 2,495 0.06
88 1320 0.02 17 2,512 218 2,294 465.14 2,294 0.05
89 1335 0.03 25 2,320 218 2,102 465.13 2,102 0.05
90 1350 0.02 17 2,119 218 1,901 465.12 1,901 0.04
91 1365 0.02 17 1,918 218 1,701 465.10 1,701 0.04
92 1380 0.02 17 1,718 218 1,500 465.09 1,500 0.03
93 1395 0.02 17 1,517 218 1,299 465.08 1,299 0.03
94 1410 0.02 17 1,316 218 1,098 465.07 1,098 0.03
95 1425 0.02 17 1,115 218 897 465.05 897 0.02
96 1440 0.02 17 914 218 697 465.04 697 0.02
Basin Depth Analysis

Page 14 of 14 ends

Item 2.
1 2
3 4
5 6
7 8
9 10
11 12
13 14
15 16
17 18
19 20
21 22
23 24
25 26
27 28
29 30
31 32
33 34
35 36
37 38
39 40
41 42
43 44
45 46
47 48
49 50
51 52
53 54
55 56
AB C D

RCFCD SYNTHETIC UNIT HYDROGRAPH

DATA INPUT SHEET
WORKSHEET PREPARED BY: JAMES R. BAZUA, P.E.

PROJECT NAME CALHOUN AT AVENUE 49 - 10 YEAR EVENT
JOB #
CONCENTRATION POINT DESIGNATION 1
AREA DESIGNATION SUBAREA 3

TRIBUTARY AREAS ACRES

COMMERCIAL
PAVING/HARDSCAPE 2.56
SF - 1 ACRE
SF - 1/2 ACRE
SF - 1/4 ACRE
MF - CONDOMINIUMS 6.65

MF - APARTMENTS

MOBILE HOME PARK
LANDSCAPING 1.04

RETENTION BASIN

GOLF COURSE

MOUNTAINOUS
LOW LOSS RATE (PERCENT) 90%
LENGTH OF WATERCOURSE (L) 750
LENGTH TO POINT OPPOSITE CENTROID (Lca) 170
ELEVATION OF HEADWATER 471.8
ELEVATION OF CONCENTRATION POINT 468.5
AVERAGE MANNINGS 'N' VALUE 0.02
STORM FREQUENCY (YEAR) 100

POINT RAIN
3-HOUR 1.04
6-HOUR 1.36
24-HOUR 2.23
BASIN CHARACTERISTICS: ELEVATION AREA
465 15000
466 16600
467 18250
468 19960
468.5 20831
PERCOLATION RATE (in/hr) 0.67

DRYWELL DATA

NUMBER USED
PERCOLATION RATE (cfs)
610
Item 2.

POINT AREA AVERAGE POINT AREA AVERAGE POINT AREA AVERAGE

RAIN POINT RAIN POINT RAIN POINT

INCHES RAIN INCHES RAIN INCHES RAIN
(Plate E-5.2) INCHES (Plate E-5.4) INCHES (Plate E-5.6) INCHES

1.04 10.250 1.00 1.04 1.36 10.250 1.00 1.36 2.23 10.250 1.00 2.23

0.00 0.00 0.00 0.00 0.00 0.00

0.00 0.00 0.00 0.00 0.00 0.00
SUM [5] 10.25 SUM [7] 1.04 SUM [9] 10.25 SUM [11] 1.36 SUM [13] 10.25 SUM [15] 2.23 [16] AREA ADJ FACTOR 1.000 1.000 1.000
[17] ADJ AVG POINT RAIN 1.04 1.36 2.23
DURATION 3-HOUR 6-HOUR 24-HOUR
EFFECTIVE RAIN (in) 0.47 0.46 0.36
FLOOD VOLUME (cu-ft) 17,326 17,301 13,560
(acre-ft) 0.40 0.40 0.31
REQUIRED STORAGE (cu-ft) 14,912 13,552 5,367
(acre-ft) 0.34 0.31 0.12
PEAK FLOW (cfs) 8.38 7.26 1.29
MAXIMUM WSEL (ft) 465.94 465.86 465.34

0.142
170.00

0.001
[12] S^0.5
[13] L*LCA/S^0.5
[14] AVERAGE MANNINGS 'N'
[10] H-FEET 3.3
[11] S-FEET/MILE

PHYSICAL DATA

RAINFALL DATA
[1] CONCENTRATION POINT 1
SUBAREA 3

10.250
750

0.032
471.8
468.5

0.03 2.0

2.0 4.1

23.2 4.82

0.23 STORM EVENT SUMMARY
[17] 100% OF LAG-MINUTES
[18] 200% OF LAG-MINUTES
[24] TOTAL PERCOLATION RATE (cfs)
[19] UNIT TIME-MINUTES (100%-200% OF LAG)
3-HOURS
Plate E-2.1

Page 2 of 14 ends

Item 2.

RCFCD SYNTHETIC UNIT HYDROGRAPH METHOD PROJECT CALHOUN AT AVENUE 49 - 10 YEAR EVENT CONCENTRATION POINT: 1BY MES R. BAZUA, P.E. DATE 1/17/2025

ADJUSTED LOSS RATE

SOIL RI PERVIOUS DECIMAL ADJUSTED AREA AVERAGE

GROUP NUMBER AREA PERCENT INFILTRATION ADJUSTED

INFILTRATION OF AREA RATE INFILTRATION

RATE IMPERVIOUS RATE
(in/hr) (in/hr) (in/hr)
[Plate C-1] [Plate E-6.1] [Plate E-6.2] [Plate E-6.3]
B 56 0.52 90% 0.10 0.00 0.000 0.0000
B 56 0.52 100% 0.05 2.56 0.250 0.0130
B 56 0.52 20% 0.43 0.00 0.000 0.0000B 56 0.52 40% 0.33 0.00 0.000 0.0000B 56 0.52 50% 0.29 0.00 0.000 0.0000B 56 0.52 65% 0.22 6.65 0.649 0.1400B 56 0.52 80% 0.15 0.00 0.000 0.0000B 56 0.52 75% 0.17 0.00 0.000 0.0000B 56 0.52 0% 0.52 1.04 0.101 0.0528B 56 0.52 0% 0.52 0.00 0.000 0.0000B 56 0.52 0% 0.52 0.00 0.000 0.0000 D 93 0.95 90% 0.18 0.00 0.000 0.0000

0.00 0.000 0.0000

0.00 0.000 0.0000
SUM 10.25 SUM 0.2058
VARIABLE LOSS RATE CURVE (24-HOUR STORM ONLY)Fm= 0.102877561C= 0.00191Ft=C(24-(T/60))^1.55 = 0.00191 0.10 in/hr LOW LOSS RATE (80-90 PERCENT) = 90%Where:T=Time in minutes. To get an average value for each unit time period, Use T=1/2 the unit time for the first time period,T=1 1/2 unit time for the second period, etc. (24-(T/60))^1.55 +

LAND USE

COMMERCIAL

PAVING/HARDSCAPE
SF - 1 ACRE
SF - 1/2 ACRESF - 1/4 ACRE
MF - COND0MINIUMS

MF - APARTMENTS

MOBILE HOME PARKS

LANDSCAPING

RETENTION BASINS

GOLF COURSE

MOUNTAINOUS
Plate E-2.1

Page 3 of 14 ends

Item 2.

RCFCD SYNTHETIC UNIT HYDROGRAPH METHOD PROJECT: CALHOUN AT AVENUE 49 - 10 YEAR EVENT 100 YEAR - 3 HOUR STORM EVENT CONCENTRATION POINT: 1
BY: MES R. BAZUA, DATE 1/17/2025
DRAINAGE AREA-ACRES 10.25
UNIT TIME-MINUTES 5
LAG TIME - MINUTES 2.05
UNIT TIME-PERCENT OF LAG 244.5
TOTAL ADJUSTED STORM RAIN-INCHES 1.04
CONSTANT LOSS RATE-in/hr 0.21
LOW LOSS RATE - PERCENT 90% TOTAL PERCOLATION RATE (cfs) 0.23 cfs Unit Time Pattern Storm Effective Flood Required
Period Minutes Hours Percent Rain Rain Hydrograph Storage in/hr Flow
(Plate E-5.9) Max Low in/hr cfs cf
1 5 0.08 1.3 0.162 0.21 0.15 0.02 0.17 0.00
2 10 0.17 1.3 0.162 0.21 0.15 0.02 0.17 0.00
3 15 0.25 1.1 0.137 0.21 0.12 0.01 0.14 0.00
4 20 0.33 1.5 0.187 0.21 0.17 0.02 0.19 0.00
5 25 0.42 1.5 0.187 0.21 0.17 0.02 0.19 0.00
6 30 0.50 1.8 0.225 0.21 0.20 0.02 0.19 0.00
7 35 0.58 1.5 0.187 0.21 0.17 0.02 0.19 0.00
8 40 0.67 1.8 0.225 0.21 0.20 0.02 0.19 0.00
9 45 0.75 1.8 0.225 0.21 0.20 0.02 0.19 0.00
10 50 0.83 1.5 0.187 0.21 0.17 0.02 0.19 0.00
11 55 0.92 1.6 0.200 0.21 0.18 0.02 0.20 0.00
12 60 1.00 1.8 0.225 0.21 0.20 0.02 0.19 0.00
13 65 1.08 2.2 0.275 0.21 0.25 0.07 0.71 141.78
14 70 1.17 2.2 0.275 0.21 0.25 0.07 0.71 141.78
15 75 1.25 2.2 0.275 0.21 0.25 0.07 0.71 141.78
16 80 1.33 2.0 0.250 0.21 0.22 0.04 0.45 65.03
17 85 1.42 2.6 0.324 0.21 0.29 0.12 1.22 295.29
18 90 1.50 2.7 0.337 0.21 0.30 0.13 1.34 333.66
19 95 1.58 2.4 0.300 0.21 0.27 0.09 0.96 218.54
20 100 1.67 2.7 0.337 0.21 0.30 0.13 1.34 333.66
21 105 1.75 3.3 0.412 0.21 0.37 0.21 2.11 563.92
22 110 1.83 3.1 0.387 0.21 0.35 0.18 1.86 487.17
23 115 1.92 2.9 0.362 0.21 0.33 0.16 1.60 410.42
24 120 2.00 3.0 0.374 0.21 0.34 0.17 1.73 448.79
25 125 2.08 3.1 0.387 0.21 0.35 0.18 1.86 487.17
26 130 2.17 4.2 0.524 0.21 0.47 0.32 3.26 909.30
27 135 2.25 5.0 0.624 0.21 0.56 0.42 4.29 1216.31
28 140 2.33 3.5 0.437 0.21 0.39 0.23 2.37 640.67
29 145 2.42 6.8 0.849 0.21 0.76 0.64 6.59 1907.08
30 150 2.50 7.3 0.911 0.21 0.82 0.71 7.23 2098.96
31 155 2.58 8.2 1.023 0.21 0.92 0.82 8.38 2444.34
32 160 2.67 5.9 0.736 0.21 0.66 0.53 5.44 1561.70
33 165 2.75 2.0 0.250 0.21 0.22 0.04 0.45 65.03
34 170 2.83 1.8 0.225 0.21 0.20 0.02 0.19 0.00
35 175 2.92 1.8 0.225 0.21 0.20 0.02 0.19 0.00
36 180 3.00 0.6 0.075 0.21 0.07 0.01 0.08 0.00

EFFECTIVE RAIN & FLOOD VOLUMES SUMMARY
EFFECTIVE RAIN (in) 0.47
FLOOD VOLUME (acft) 0.40
FLOOD VOLUME (cuft) 17326.37
REQUIRED STORAGE (acft) 0.34
REQUIRED STORAGE (cuft) 14912.39
PEAK FLOW RATE (cfs) 8.38
Loss Rate
in/hr
Time

EFFECTIVE RAIN CALCULATION FORM
Plate E-2.2

Page 4 of 14 ends

Item 2.

RCFCD SYNTHETIC UNIT HYDROGRAPH METHOD PROJECT: CALHOUN AT AVENUE 49 - 10 YEAR EVENT 100 YEAR - 6 HOUR STORM EVENT CONCENTRATION POINT: 1
BY: JAMES R. BAZ DATE: 1/17/2025
DRAINAGE AREA-ACRES 10.25
UNIT TIME-MINUTES 5
LAG TIME - MINUTES 2.05
UNIT TIME-PERCENT OF LAG 244.5
TOTAL ADJUSTED STORM RAIN-INCHES 1.36
CONSTANT LOSS RATE-in/hr 0.206
LOW LOSS RATE - PERCENT 90% TOTAL PERCOLATION RATE (cfs) 0.23 cfs Unit Time Pattern Storm Effective Flood Required
Period Minutes Hours Percent Rain Rain Hydrograph Storage in/hr Flow
(Plate E-5.9) Max Low in/hr cfs cf
1 5 0.08 0.5 0.082 0.21 0.07 0.01 0.08 0.00
2 10 0.17 0.6 0.098 0.21 0.09 0.01 0.10 0.00
3 15 0.25 0.6 0.098 0.21 0.09 0.01 0.10 0.00
4 20 0.33 0.6 0.098 0.21 0.09 0.01 0.10 0.00
5 25 0.42 0.6 0.098 0.21 0.09 0.01 0.10 0.00
6 30 0.50 0.7 0.114 0.21 0.10 0.01 0.12 0.00
7 35 0.58 0.7 0.114 0.21 0.10 0.01 0.12 0.00
8 40 0.67 0.7 0.114 0.21 0.10 0.01 0.12 0.00
9 45 0.75 0.7 0.114 0.21 0.10 0.01 0.12 0.00
10 50 0.83 0.7 0.114 0.21 0.10 0.01 0.12 0.00
11 55 0.92 0.7 0.114 0.21 0.10 0.01 0.12 0.00
12 60 1.00 0.8 0.131 0.21 0.12 0.01 0.13 0.00
13 65 1.08 0.8 0.131 0.21 0.12 0.01 0.13 0.00
14 70 1.17 0.8 0.131 0.21 0.12 0.01 0.13 0.00
15 75 1.25 0.8 0.131 0.21 0.12 0.01 0.13 0.00
16 80 1.33 0.8 0.131 0.21 0.12 0.01 0.13 0.00
17 85 1.42 0.8 0.131 0.21 0.12 0.01 0.13 0.00
18 90 1.50 0.8 0.131 0.21 0.12 0.01 0.13 0.00
19 95 1.58 0.8 0.131 0.21 0.12 0.01 0.13 0.00
20 100 1.67 0.8 0.131 0.21 0.12 0.01 0.13 0.00
21 105 1.75 0.8 0.131 0.21 0.12 0.01 0.13 0.00
22 110 1.83 0.8 0.131 0.21 0.12 0.01 0.13 0.00
23 115 1.92 0.8 0.131 0.21 0.12 0.01 0.13 0.00
24 120 2.00 0.9 0.147 0.21 0.13 0.01 0.15 0.00
25 125 2.08 0.8 0.131 0.21 0.12 0.01 0.13 0.00
26 130 2.17 0.9 0.147 0.21 0.13 0.01 0.15 0.00
27 135 2.25 0.9 0.147 0.21 0.13 0.01 0.15 0.00
28 140 2.33 0.9 0.147 0.21 0.13 0.01 0.15 0.00
29 145 2.42 0.9 0.147 0.21 0.13 0.01 0.15 0.00
30 150 2.50 0.9 0.147 0.21 0.13 0.01 0.15 0.00
31 155 2.58 0.9 0.147 0.21 0.13 0.01 0.15 0.00
32 160 2.67 0.9 0.147 0.21 0.13 0.01 0.15 0.00
33 165 2.75 1.0 0.163 0.21 0.15 0.02 0.17 0.00
34 170 2.83 1.0 0.163 0.21 0.15 0.02 0.17 0.00
35 175 2.92 1.0 0.163 0.21 0.15 0.02 0.17 0.00
36 180 3.00 1.0 0.163 0.21 0.15 0.02 0.17 0.00
37 185 3.08 1.0 0.163 0.21 0.15 0.02 0.17 0.00
38 190 3.17 1.1 0.180 0.21 0.16 0.02 0.18 0.00
39 195 3.25 1.1 0.180 0.21 0.16 0.02 0.18 0.00
40 200 3.33 1.1 0.180 0.21 0.16 0.02 0.18 0.00
41 205 3.42 1.2 0.196 0.21 0.18 0.02 0.20 0.00
42 210 3.50 1.3 0.212 0.21 0.19 0.01 0.07 0.00
43 215 3.58 1.4 0.228 0.21 0.21 0.02 0.23 0.09
44 220 3.67 1.4 0.228 0.21 0.21 0.02 0.23 0.09
45 225 3.75 1.5 0.245 0.21 0.22 0.04 0.40 50.27
46 230 3.83 1.5 0.245 0.21 0.22 0.04 0.40 50.27
47 235 3.92 1.6 0.261 0.21 0.24 0.06 0.57 100.46
48 240 4.00 1.6 0.261 0.21 0.24 0.06 0.57 100.46
49 245 4.08 1.7 0.277 0.21 0.25 0.07 0.73 150.64
50 250 4.17 1.8 0.294 0.21 0.26 0.09 0.90 200.82
51 255 4.25 1.9 0.310 0.21 0.28 0.10 1.07 251.01
52 260 4.33 2.0 0.326 0.21 0.29 0.12 1.24 301.19
53 265 4.42 2.1 0.343 0.21 0.31 0.14 1.40 351.38
54 270 4.50 2.1 0.343 0.21 0.31 0.14 1.40 351.38
55 275 4.58 2.2 0.359 0.21 0.32 0.15 1.57 401.56
56 280 4.67 2.3 0.375 0.21 0.34 0.17 1.74 451.74

EFFECTIVE RAIN CALCULATION FORM
Time Loss Rate
in/hr
Plate E-2.2

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Item 2.

EFFECTIVE RAIN CALCULATION FORM
Time Loss Rate
in/hr
57 285 4.75 2.4 0.392 0.21 0.35 0.19 1.91 501.93
58 290 4.83 2.4 0.392 0.21 0.35 0.19 1.91 501.93
59 295 4.92 2.5 0.408 0.21 0.37 0.20 2.07 552.11
60 300 5.00 2.6 0.424 0.21 0.38 0.22 2.24 602.30
61 305 5.08 3.1 0.506 0.21 0.46 0.30 3.08 853.22
62 310 5.17 3.6 0.588 0.21 0.53 0.38 3.91 1104.14
63 315 5.25 3.9 0.636 0.21 0.57 0.43 4.41 1254.69
64 320 5.33 4.2 0.685 0.21 0.62 0.48 4.92 1405.24
65 325 5.42 4.7 0.767 0.21 0.69 0.56 5.75 1656.16
66 330 5.50 5.6 0.914 0.21 0.82 0.71 7.26 2107.82
67 335 5.58 1.9 0.310 0.21 0.28 0.10 1.07 251.01
68 340 5.67 0.9 0.147 0.21 0.13 0.01 0.15 0.00
69 345 5.75 0.6 0.098 0.21 0.09 0.01 0.10 0.00
70 350 5.83 0.5 0.082 0.21 0.07 0.01 0.08 0.00
71 355 5.92 0.3 0.049 0.21 0.04 0.00 0.05 0.00
72 360 6.00 0.2 0.033 0.21 0.03 0.00 0.03 0.00

EFFECTIVE RAIN & FLOOD VOLUMES SUMMARY
EFFECTIVE RAIN (in) 0.46
FLOOD VOLUME (acft) 0.40
FLOOD VOLUME (cuft) 17301.15
REQUIRED STORAGE (acft) 0.31
REQUIRED STORAGE (cuft) 13551.86
PEAK FLOW RATE (cfs) 7.26
Plate E-2.2

Page 6 of 14 ends

Item 2.

RCFCD SYNTHETIC UNIT HYDROGRAPH METHOD PROJECT: CALHOUN AT AVENUE 49 - 10 YEAR EVENT 100 YEAR - 24 HOUR STORM EVENT CONCENTRATION POINT: 1
BY: JAMES R. BAZ DATE: 1/17/2025
DRAINAGE AREA-ACRES 10.250 CONSTANT LOSS RATE-in/hr n/a UNIT TIME-MINUTES 15 VARIABLE LOSS RATE (AVG) in/hr 0.2058 LAG TIME - MINUTES 2.05 MINIMUM LOSS RATE (for var. loss) - in/hr 0.103 UNIT TIME-PERCENT OF LAG 733.4 LOW LOSS RATE - DECIMAL 0.90 TOTAL ADJUSTED STORM RAIN-INCHES 2.23 C 0.00191
PERCOLATION RATE (cfs) 0.23
Unit Time Pattern Storm Effective Flood Required
Period Minutes Hours Percent Rain Rain Hydrograph Storage in/hr Flow
(Plate E-5.9) Max Low in/hr cfs cf
1 15 0.25 0.2 0.018 0.363 0.016 0.002 0.02 0.00
2 30 0.50 0.3 0.027 0.359 0.024 0.003 0.03 0.00
3 45 0.75 0.3 0.027 0.355 0.024 0.003 0.03 0.00
4 60 1.00 0.4 0.036 0.351 0.032 0.004 0.04 0.00
5 75 1.25 0.3 0.027 0.347 0.024 0.003 0.03 0.00
6 90 1.50 0.3 0.027 0.343 0.024 0.003 0.03 0.00
7 105 1.75 0.3 0.027 0.338 0.024 0.003 0.03 0.00
8 120 2.00 0.4 0.036 0.334 0.032 0.004 0.04 0.00
9 135 2.25 0.4 0.036 0.330 0.032 0.004 0.04 0.00
10 150 2.50 0.4 0.036 0.326 0.032 0.004 0.04 0.00
11 165 2.75 0.5 0.045 0.322 0.040 0.004 0.05 0.00
12 180 3.00 0.5 0.045 0.318 0.040 0.004 0.05 0.00
13 195 3.25 0.5 0.045 0.314 0.040 0.004 0.05 0.00
14 210 3.50 0.5 0.045 0.310 0.040 0.004 0.05 0.00
15 225 3.75 0.5 0.045 0.307 0.040 0.004 0.05 0.00
16 240 4.00 0.6 0.054 0.303 0.048 0.005 0.05 0.00
17 255 4.25 0.6 0.054 0.299 0.048 0.005 0.05 0.00
18 270 4.50 0.7 0.062 0.295 0.056 0.006 0.06 0.00
19 285 4.75 0.7 0.062 0.291 0.056 0.006 0.06 0.00
20 300 5.00 0.8 0.071 0.288 0.064 0.007 0.07 0.00
21 315 5.25 0.6 0.054 0.284 0.048 0.005 0.05 0.00
22 330 5.50 0.7 0.062 0.280 0.056 0.006 0.06 0.00
23 345 5.75 0.8 0.071 0.276 0.064 0.007 0.07 0.00
24 360 6.00 0.8 0.071 0.273 0.064 0.007 0.07 0.00
25 375 6.25 0.9 0.080 0.269 0.072 0.008 0.08 0.00
26 390 6.50 0.9 0.080 0.266 0.072 0.008 0.08 0.00
27 405 6.75 1.0 0.089 0.262 0.080 0.009 0.09 0.00
28 420 7.00 1.0 0.089 0.258 0.080 0.009 0.09 0.00
29 435 7.25 1.0 0.089 0.255 0.080 0.009 0.09 0.00
30 450 7.50 1.1 0.098 0.252 0.088 0.010 0.10 0.00
31 465 7.75 1.2 0.107 0.248 0.096 0.011 0.11 0.00
32 480 8.00 1.3 0.116 0.245 0.104 0.012 0.12 0.00
33 495 8.25 1.5 0.134 0.241 0.120 0.013 0.14 0.00
34 510 8.50 1.5 0.134 0.238 0.120 0.013 0.14 0.00
35 525 8.75 1.6 0.143 0.235 0.128 0.014 0.15 0.00
36 540 9.00 1.7 0.152 0.231 0.136 0.015 0.16 0.00
37 555 9.25 1.9 0.169 0.228 0.153 0.017 0.17 0.00
38 570 9.50 2.0 0.178 0.225 0.161 0.018 0.18 0.00
39 585 9.75 2.1 0.187 0.222 0.169 0.019 0.19 0.00
40 600 10.00 2.2 0.196 0.218 0.177 0.020 0.20 0.00
41 615 10.25 1.5 0.134 0.215 0.120 0.013 0.14 0.00
42 630 10.50 1.5 0.134 0.212 0.120 0.013 0.14 0.00
43 645 10.75 2.0 0.178 0.209 0.161 0.018 0.18 0.00
44 660 11.00 2.0 0.178 0.206 0.161 0.018 0.18 0.00
45 675 11.25 1.9 0.169 0.203 0.153 0.017 0.17 0.00
46 690 11.50 1.9 0.169 0.200 0.153 0.017 0.17 0.00
47 705 11.75 1.7 0.152 0.197 0.136 0.015 0.16 0.00
48 720 12.00 1.8 0.161 0.194 0.145 0.016 0.16 0.00
49 735 12.25 2.5 0.223 0.191 0.201 0.032 0.33 84.85
50 750 12.50 2.6 0.232 0.188 0.209 0.044 0.45 193.54
51 765 12.75 2.8 0.250 0.185 0.225 0.064 0.66 384.21
52 780 13.00 2.9 0.259 0.183 0.233 0.076 0.78 492.27
53 795 13.25 3.4 0.303 0.180 0.273 0.123 1.27 929.17
54 810 13.50 3.4 0.303 0.177 0.273 0.126 1.29 954.32
55 825 13.75 2.3 0.205 0.174 0.185 0.031 0.31 73.98
56 840 14.00 2.3 0.205 0.172 0.185 0.033 0.34 98.48
57 855 14.25 2.7 0.241 0.169 0.217 0.072 0.73 451.79
58 870 14.50 2.6 0.232 0.167 0.209 0.065 0.67 393.33
59 885 14.75 2.6 0.232 0.164 0.209 0.068 0.70 416.82
60 900 15.00 2.5 0.223 0.162 0.201 0.061 0.63 357.68
61 915 15.25 2.4 0.214 0.159 0.193 0.055 0.56 298.20
Time Loss Rate
in/hr

EFFECTIVE RAIN CALCULATION FORM
Plate E-2.2

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Item 2.

EFFECTIVE RAIN CALCULATION FORM
62 930 15.50 2.3 0.205 0.157 0.185 0.049 0.50 238.37
63 945 15.75 1.9 0.169 0.154 0.153 0.015 0.16 0.00
64 960 16.00 1.9 0.169 0.152 0.153 0.018 0.18 0.00
65 975 16.25 0.4 0.036 0.150 0.032 0.004 0.04 0.00
66 990 16.50 0.4 0.036 0.147 0.032 0.004 0.04 0.00
67 1005 16.75 0.3 0.027 0.145 0.024 0.003 0.03 0.00
68 1020 17.00 0.3 0.027 0.143 0.024 0.003 0.03 0.00
69 1035 17.25 0.5 0.045 0.141 0.040 0.004 0.05 0.00
70 1050 17.50 0.5 0.045 0.139 0.040 0.004 0.05 0.00
71 1065 17.75 0.5 0.045 0.137 0.040 0.004 0.05 0.00
72 1080 18.00 0.4 0.036 0.134 0.032 0.004 0.04 0.00
73 1095 18.25 0.4 0.036 0.133 0.032 0.004 0.04 0.00
74 1110 18.50 0.4 0.036 0.131 0.032 0.004 0.04 0.00
75 1125 18.75 0.3 0.027 0.129 0.024 0.003 0.03 0.00
76 1140 19.00 0.2 0.018 0.127 0.016 0.002 0.02 0.00
77 1155 19.25 0.3 0.027 0.125 0.024 0.003 0.03 0.00
78 1170 19.50 0.4 0.036 0.123 0.032 0.004 0.04 0.00
79 1185 19.75 0.3 0.027 0.122 0.024 0.003 0.03 0.00
80 1200 20.00 0.2 0.018 0.120 0.016 0.002 0.02 0.00
81 1215 20.25 0.3 0.027 0.118 0.024 0.003 0.03 0.00
82 1230 20.50 0.3 0.027 0.117 0.024 0.003 0.03 0.00
83 1245 20.75 0.3 0.027 0.115 0.024 0.003 0.03 0.00
84 1260 21.00 0.2 0.018 0.114 0.016 0.002 0.02 0.00
85 1275 21.25 0.3 0.027 0.113 0.024 0.003 0.03 0.00
86 1290 21.50 0.2 0.018 0.111 0.016 0.002 0.02 0.00
87 1305 21.75 0.3 0.027 0.110 0.024 0.003 0.03 0.00
88 1320 22.00 0.2 0.018 0.109 0.016 0.002 0.02 0.00
89 1335 22.25 0.3 0.027 0.108 0.024 0.003 0.03 0.00
90 1350 22.50 0.2 0.018 0.107 0.016 0.002 0.02 0.00
91 1365 22.75 0.2 0.018 0.106 0.016 0.002 0.02 0.00
92 1380 23.00 0.2 0.018 0.105 0.016 0.002 0.02 0.00
93 1395 23.25 0.2 0.018 0.104 0.016 0.002 0.02 0.00
94 1410 23.50 0.2 0.018 0.104 0.016 0.002 0.02 0.00
95 1425 23.75 0.2 0.018 0.103 0.016 0.002 0.02 0.00
96 1440 24.00 0.2 0.018 0.103 0.016 0.002 0.02 0.00

EFFECTIVE RAIN & FLOOD VOLUMES SUMMARY
EFFECTIVE RAIN (in) 0.36
FLOOD VOLUME (acft) 0.31
FLOOD VOLUME (cuft) 13560.19
REQUIRED STORAGE (acft) 0.12
REQUIRED STORAGE (cuft) 5367.00
PEAK FLOW (cfs) 1.29
Plate E-2.2

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Item 2.

PROJECT: CALHOUN AT AVENUE 49 - 10 YEAR EVENT
JOB # 0
1 BASIN CHARACTERISTICS

CONTOUR DEPTH AREA VOLUME

INCR TOTAL INCR TOTAL INCR TOTAL
(ft) (ft) (sf) (sf) (cuft) (cuft) (acre-ft)
465 0 0 15000 0 0 0.00
466 1 1 1600 16600 15800 15800 0.36
467 1 2 1650 18250 17425 33225 0.76
468 1 3 1710 19960 19105 52330 1.20
468.5 0.5 3.5 871 20831 10198 62528 1.44

PERCOLATION CALCULATIONS
PERCOLATION RATE 0.67 in/hr 0.23 cfs

MAXWELL IV DRYWELLS
NUMBER USED 0
RATE/DRYWELL 0 cfs
TOTAL DISSIPATED 0 cfs
TOTAL PERCOLATION RATE 0.23 cfs
Basin Characteristics

Page 9 of 14 ends

Item 2.
1 JOB # 0
100 YEAR - 3 HOUR STORM EVENT

FLOW VOLUME TOTAL IN PERC TOTAL IN BASIN
UNIT (min) IN IN BASIN OUT BASIN DEPTH
PERIOD (cfs) (cuft) (cuft) (cuft) (cuft) (ft) (cuft) (acre-ft) 1 5 0.17 50 50 70 - 465.00 - 0.00
2 10 0.17 50 50 70 - 465.00 - 0.00
3 15 0.14 42 42 70 - 465.00 - 0.00
4 20 0.19 58 58 70 - 465.00 - 0.00
5 25 0.19 58 58 70 - 465.00 - 0.00
6 30 0.19 58 58 70 - 465.00 - 0.00
7 35 0.19 58 58 70 - 465.00 - 0.00
8 40 0.19 58 58 70 - 465.00 - 0.00
9 45 0.19 58 58 70 - 465.00 - 0.00
10 50 0.19 58 58 70 - 465.00 - 0.00
11 55 0.20 61 61 70 - 465.00 - 0.00
12 60 0.19 58 58 70 - 465.00 - 0.00
13 65 0.71 212 212 70 142 465.01 142 0.00
14 70 0.71 212 353 70 284 465.02 284 0.01
15 75 0.71 212 495 70 425 465.03 425 0.01
16 80 0.45 135 560 70 490 465.03 490 0.01
17 85 1.22 365 855 70 786 465.05 786 0.02
18 90 1.34 403 1,189 70 1,119 465.07 1,119 0.03
19 95 0.96 288 1,408 70 1,338 465.08 1,338 0.03
20 100 1.34 403 1,741 70 1,672 465.11 1,672 0.04
21 105 2.11 634 2,305 70 2,235 465.14 2,235 0.05
22 110 1.86 557 2,792 70 2,723 465.17 2,723 0.06
23 115 1.60 480 3,203 70 3,133 465.20 3,133 0.07
24 120 1.73 519 3,652 70 3,582 465.23 3,582 0.08
25 125 1.86 557 4,139 70 4,069 465.26 4,069 0.09
26 130 3.26 979 5,048 70 4,978 465.32 4,978 0.11
27 135 4.29 1,286 6,264 70 6,195 465.39 6,195 0.14
28 140 2.37 710 6,905 70 6,835 465.43 6,835 0.16
29 145 6.59 1,977 8,812 70 8,742 465.55 8,742 0.20
30 150 7.23 2,169 10,911 70 10,841 465.69 10,841 0.25
31 155 8.38 2,514 13,355 70 13,286 465.84 13,286 0.30
32 160 5.44 1,631 14,917 70 14,847 465.94 14,847 0.34
33 165 0.45 135 14,982 70 14,912 465.94 14,912 0.34
34 170 0.19 58 14,970 70 14,901 465.94 14,901 0.34
35 175 0.19 58 14,959 70 14,889 465.94 14,889 0.34
36 180 0.08 23 14,912 70 14,842 465.94 14,842 0.34

BALANCE IN
BASIN
TIME
Basin Depth Analysis

Page 10 of 14 ends

Item 2.
1 JOB # 0
100 YEAR - 6 HOUR STORM EVENT

FLOW VOLUME TOTAL IN PERC TOTAL IN BASIN
UNIT (min) IN IN BASIN OUT BASIN DEPTH
PERIOD (cfs) (cuft) (cuft) (cuft) (cuft) (ft) (cuft) (acre-ft) 1 5 0.08 25 25 70 - 465.00 - 0.00
2 10 0.10 30 30 70 - 465.00 - 0.00
3 15 0.10 30 30 70 - 465.00 - 0.00
4 20 0.10 30 30 70 - 465.00 - 0.00
5 25 0.10 30 30 70 - 465.00 - 0.00
6 30 0.12 35 35 70 - 465.00 - 0.00
7 35 0.12 35 35 70 - 465.00 - 0.00
8 40 0.12 35 35 70 - 465.00 - 0.00
9 45 0.12 35 35 70 - 465.00 - 0.00
10 50 0.12 35 35 70 - 465.00 - 0.00
11 55 0.12 35 35 70 - 465.00 - 0.00
12 60 0.13 40 40 70 - 465.00 - 0.00
13 65 0.13 40 40 70 - 465.00 - 0.00
14 70 0.13 40 40 70 - 465.00 - 0.00
15 75 0.13 40 40 70 - 465.00 - 0.00
16 80 0.13 40 40 70 - 465.00 - 0.00
17 85 0.13 40 40 70 - 465.00 - 0.00
18 90 0.13 40 40 70 - 465.00 - 0.00
19 95 0.13 40 40 70 - 465.00 - 0.00
20 100 0.13 40 40 70 - 465.00 - 0.00
21 105 0.13 40 40 70 - 465.00 - 0.00
22 110 0.13 40 40 70 - 465.00 - 0.00
23 115 0.13 40 40 70 - 465.00 - 0.00
24 120 0.15 45 45 70 - 465.00 - 0.00
25 125 0.13 40 40 70 - 465.00 - 0.00
26 130 0.15 45 45 70 - 465.00 - 0.00
27 135 0.15 45 45 70 - 465.00 - 0.00
28 140 0.15 45 45 70 - 465.00 - 0.00
29 145 0.15 45 45 70 - 465.00 - 0.00
30 150 0.15 45 45 70 - 465.00 - 0.00
31 155 0.15 45 45 70 - 465.00 - 0.00
32 160 0.15 45 45 70 - 465.00 - 0.00
33 165 0.17 50 50 70 - 465.00 - 0.00
34 170 0.17 50 50 70 - 465.00 - 0.00
35 175 0.17 50 50 70 - 465.00 - 0.00
36 180 0.17 50 50 70 - 465.00 - 0.00
37 185 0.17 50 50 70 - 465.00 - 0.00
38 190 0.18 55 55 70 - 465.00 - 0.00
39 195 0.18 55 55 70 - 465.00 - 0.00
40 200 0.18 55 55 70 - 465.00 - 0.00
41 205 0.20 60 60 70 - 465.00 - 0.00
42 210 0.07 20 20 70 - 465.00 - 0.00
43 215 0.23 70 70 70 0 465.00 0.00 0
44 220 0.23 70 70 70 0 465.00 0.00 0
45 225 0.40 120 120 70 50 465.00 50 0.00
46 230 0.40 120 171 70 101 465.01 101 0.00
47 235 0.57 170 271 70 201 465.01 201 0.00
48 240 0.57 170 371 70 302 465.02 302 0.01
49 245 0.73 220 522 70 452 465.03 452 0.01
50 250 0.90 271 723 70 653 465.04 653 0.01
51 255 1.07 321 974 70 904 465.06 904 0.02
52 260 1.24 371 1,275 70 1,205 465.08 1,205 0.03
53 265 1.40 421 1,626 70 1,557 465.10 1,557 0.04
54 270 1.40 421 1,978 70 1,908 465.12 1,908 0.04
55 275 1.57 471 2,379 70 2,310 465.15 2,310 0.05

TIME BALANCE IN
BASIN
Basin Depth Analysis

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Item 2.
1 JOB # 0
100 YEAR - 6 HOUR STORM EVENT

FLOW VOLUME TOTAL IN PERC TOTAL IN BASIN
UNIT (min) IN IN BASIN OUT BASIN DEPTH
PERIOD (cfs) (cuft) (cuft) (cuft) (cuft) (ft) (cuft) (acre-ft)

TIME BALANCE IN
BASIN
56 280 1.74 522 2,831 70 2,761 465.17 2,761 0.06
57 285 1.91 572 3,333 70 3,263 465.21 3,263 0.07
58 290 1.91 572 3,835 70 3,765 465.24 3,765 0.09
59 295 2.07 622 4,387 70 4,317 465.27 4,317 0.10
60 300 2.24 672 4,989 70 4,920 465.31 4,920 0.11
61 305 3.08 923 5,843 70 5,773 465.37 5,773 0.13
62 310 3.91 1,174 6,947 70 6,877 465.44 6,877 0.16
63 315 4.41 1,324 8,201 70 8,132 465.51 8,132 0.19
64 320 4.92 1,475 9,607 70 9,537 465.60 9,537 0.22
65 325 5.75 1,726 11,263 70 11,193 465.71 11,193 0.26
66 330 7.26 2,178 13,371 70 13,301 465.84 13,301 0.31
67 335 1.07 321 13,622 70 13,552 465.86 13,552 0.31
68 340 0.15 45 13,597 70 13,527 465.86 13,527 0.31
69 345 0.10 30 13,557 70 13,488 465.85 13,488 0.31
70 350 0.08 25 13,513 70 13,443 465.85 13,443 0.31
71 355 0.05 15 13,458 70 13,388 465.85 13,388 0.31
72 360 0.03 10 13,398 70 13,328 465.84 13,328 0.31
Basin Depth Analysis

Page 12 of 14 ends

Item 2.
1 JOB # 0
100 YEAR - 24 HOUR STORM EVENT

FLOW VOLUME TOTAL IN PERC TOTAL IN BASIN
UNIT (min) IN IN BASIN OUT BASIN DEPTH
PERIOD (cfs) (cuft) (cuft) (cuft) (cuft) (ft) (cuft) (acre-ft) 1 15 0.02 16 16 209 - 465.00 - 0.00
2 30 0.03 25 25 209 - 465.00 - 0.00
3 45 0.03 25 25 209 - 465.00 - 0.00
4 60 0.04 33 33 209 - 465.00 - 0.00
5 75 0.03 25 25 209 - 465.00 - 0.00
6 90 0.03 25 25 209 - 465.00 - 0.00
7 105 0.03 25 25 209 - 465.00 - 0.00
8 120 0.04 33 33 209 - 465.00 - 0.00
9 135 0.04 33 33 209 - 465.00 - 0.00
10 150 0.04 33 33 209 - 465.00 - 0.00
11 165 0.05 41 41 209 - 465.00 - 0.00
12 180 0.05 41 41 209 - 465.00 - 0.00
13 195 0.05 41 41 209 - 465.00 - 0.00
14 210 0.05 41 41 209 - 465.00 - 0.00
15 225 0.05 41 41 209 - 465.00 - 0.00
16 240 0.05 49 49 209 - 465.00 - 0.00
17 255 0.05 49 49 209 - 465.00 - 0.00
18 270 0.06 58 58 209 - 465.00 - 0.00
19 285 0.06 58 58 209 - 465.00 - 0.00
20 300 0.07 66 66 209 - 465.00 - 0.00
21 315 0.05 49 49 209 - 465.00 - 0.00
22 330 0.06 58 58 209 - 465.00 - 0.00
23 345 0.07 66 66 209 - 465.00 - 0.00
24 360 0.07 66 66 209 - 465.00 - 0.00
25 375 0.08 74 74 209 - 465.00 - 0.00
26 390 0.08 74 74 209 - 465.00 - 0.00
27 405 0.09 82 82 209 - 465.00 - 0.00
28 420 0.09 82 82 209 - 465.00 - 0.00
29 435 0.09 82 82 209 - 465.00 - 0.00
30 450 0.10 91 91 209 - 465.00 - 0.00
31 465 0.11 99 99 209 - 465.00 - 0.00
32 480 0.12 107 107 209 - 465.00 - 0.00
33 495 0.14 123 123 209 - 465.00 - 0.00
34 510 0.14 123 123 209 - 465.00 - 0.00
35 525 0.15 132 132 209 - 465.00 - 0.00
36 540 0.16 140 140 209 - 465.00 - 0.00
37 555 0.17 156 156 209 - 465.00 - 0.00
38 570 0.18 165 165 209 - 465.00 - 0.00
39 585 0.19 173 173 209 - 465.00 - 0.00
40 600 0.20 181 181 209 - 465.00 - 0.00
41 615 0.14 123 123 209 - 465.00 - 0.00
42 630 0.14 123 123 209 - 465.00 - 0.00
43 645 0.18 165 165 209 - 465.00 - 0.00
44 660 0.18 165 165 209 - 465.00 - 0.00
45 675 0.17 156 156 209 - 465.00 - 0.00
46 690 0.17 156 156 209 - 465.00 - 0.00
47 705 0.16 140 140 209 - 465.00 - 0.00
48 720 0.16 148 148 209 - 465.00 - 0.00
49 735 0.33 294 294 209 85 465.01 85 0.00
50 750 0.45 403 488 209 278 465.02 278 0.01
51 765 0.66 594 872 209 663 465.04 663 0.02
52 780 0.78 702 1,364 209 1,155 465.07 1,155 0.03
53 795 1.27 1,139 2,293 209 2,084 465.13 2,084 0.05
54 810 1.29 1,164 3,248 209 3,038 465.19 3,038 0.07
55 825 0.31 283 3,322 209 3,112 465.20 3,112 0.07
56 840 0.34 308 3,420 209 3,211 465.20 3,211 0.07
57 855 0.73 661 3,872 209 3,663 465.23 3,663 0.08
58 870 0.67 603 4,265 209 4,056 465.26 4,056 0.09

TIME BALANCE IN
BASIN
Basin Depth Analysis

Page 13 of 14 ends

Item 2.
1 JOB # 0
100 YEAR - 24 HOUR STORM EVENT

FLOW VOLUME TOTAL IN PERC TOTAL IN BASIN
UNIT (min) IN IN BASIN OUT BASIN DEPTH
PERIOD (cfs) (cuft) (cuft) (cuft) (cuft) (ft) (cuft) (acre-ft)

TIME BALANCE IN
BASIN
59 885 0.70 626 4,682 209 4,473 465.28 4,473 0.10
60 900 0.63 567 5,040 209 4,830 465.31 4,830 0.11
61 915 0.56 508 5,338 209 5,129 465.32 5,129 0.12
62 930 0.50 448 5,576 209 5,367 465.34 5,367 0.12
63 945 0.16 141 5,508 209 5,298 465.34 5,298 0.12
64 960 0.18 162 5,461 209 5,251 465.33 5,251 0.12
65 975 0.04 33 5,284 209 5,075 465.32 5,075 0.12
66 990 0.04 33 5,108 209 4,898 465.31 4,898 0.11
67 1005 0.03 25 4,923 209 4,714 465.30 4,714 0.11
68 1020 0.03 25 4,738 209 4,529 465.29 4,529 0.10
69 1035 0.05 41 4,570 209 4,361 465.28 4,361 0.10
70 1050 0.05 41 4,402 209 4,193 465.27 4,193 0.10
71 1065 0.05 41 4,234 209 4,024 465.25 4,024 0.09
72 1080 0.04 33 4,057 209 3,848 465.24 3,848 0.09
73 1095 0.04 33 3,881 209 3,671 465.23 3,671 0.08
74 1110 0.04 33 3,704 209 3,495 465.22 3,495 0.08
75 1125 0.03 25 3,520 209 3,310 465.21 3,310 0.08
76 1140 0.02 3,327 16 209 3,117 465.20 3,117 0.07
77 1155 0.03 25 3,142 209 2,933 465.19 2,933 0.07
78 1170 0.04 33 2,966 209 2,756 465.17 2,756 0.06
79 1185 0.03 25 2,781 209 2,572 465.16 2,572 0.06
80 1200 0.02 16 2,588 209 2,379 465.15 2,379 0.05
81 1215 0.03 25 2,403 209 2,194 465.14 2,194 0.05
82 1230 0.03 25 2,219 209 2,009 465.13 2,009 0.05
83 1245 0.03 25 2,034 209 1,825 465.12 1,825 0.04
84 1260 0.02 16 1,841 209 1,632 465.10 1,632 0.04
85 1275 0.03 25 1,656 209 1,447 465.09 1,447 0.03
86 1290 0.02 16 1,463 209 1,254 465.08 1,254 0.03
87 1305 0.03 25 1,279 209 1,069 465.07 1,069 0.02
88 1320 0.02 16 1,086 209 876 465.06 876 0.02
89 1335 0.03 25 901 209 692 465.04 692 0.02
90 1350 0.02 16 708 209 499 465.03 499 0.01
91 1365 0.02 16 515 209 306 465.02 306 0.01
92 1380 0.02 16 322 209 113 465.01 113 0.00
93 1395 0.02 16 129 209 - 465.00 - 0.00
94 1410 0.02 16 16 209 - 465.00 - 0.00
95 1425 0.02 16 16 209 - 465.00 - 0.00
96 1440 0.02 16 16 209 - 465.00 - 0.00
Basin Depth Analysis

Page 14 of 14 ends

Item 2.
1 2
3 4
5 6
7 8
9 10
11 12
13 14
15 16
17 18
19 20
21 22
23 24
25 26
27 28
29 30
31 32
33 34
35 36
37 38
39 40
41 42
43 44
45 46
47 48
49 50
51 52
53 54
55 56
AB C D

RCFCD SYNTHETIC UNIT HYDROGRAPH

DATA INPUT SHEET
WORKSHEET PREPARED BY: JAMES R. BAZUA, P.E.

PROJECT NAME CALHOUN AT AVENUE 49 - 10 YEAR EVENT
JOB #
CONCENTRATION POINT DESIGNATION 1
AREA DESIGNATION SUBAREA 4

TRIBUTARY AREAS ACRES

COMMERCIAL
PAVING/HARDSCAPE 2.33
SF - 1 ACRE
SF - 1/2 ACRE
SF - 1/4 ACRE
MF - CONDOMINIUMS 6.56

MF - APARTMENTS

MOBILE HOME PARK
LANDSCAPING 0.9

RETENTION BASIN

GOLF COURSE

MOUNTAINOUS
LOW LOSS RATE (PERCENT) 90%
LENGTH OF WATERCOURSE (L) 620
LENGTH TO POINT OPPOSITE CENTROID (Lca) 70
ELEVATION OF HEADWATER 470.5
ELEVATION OF CONCENTRATION POINT 468
AVERAGE MANNINGS 'N' VALUE 0.02
STORM FREQUENCY (YEAR) 100

POINT RAIN
3-HOUR 1.04
6-HOUR 1.36
24-HOUR 2.23
BASIN CHARACTERISTICS: ELEVATION AREA
464.5 13730
465.5 15200
466.5 16700
467.5 18270
468 19075
PERCOLATION RATE (in/hr) 0.67

DRYWELL DATA

NUMBER USED
PERCOLATION RATE (cfs)
624
Item 2.

POINT AREA AVERAGE POINT AREA AVERAGE POINT AREA AVERAGE

RAIN POINT RAIN POINT RAIN POINT

INCHES RAIN INCHES RAIN INCHES RAIN
(Plate E-5.2) INCHES (Plate E-5.4) INCHES (Plate E-5.6) INCHES

1.04 9.790 1.00 1.04 1.36 9.790 1.00 1.36 2.23 9.790 1.00 2.23

0.00 0.00 0.00 0.00 0.00 0.00

0.00 0.00 0.00 0.00 0.00 0.00
SUM [5] 9.79 SUM [7] 1.04 SUM [9] 9.79 SUM [11] 1.36 SUM [13] 9.79 SUM [15] 2.23 [16] AREA ADJ FACTOR 1.000 1.000 1.000
[17] ADJ AVG POINT RAIN 1.04 1.36 2.23
DURATION 3-HOUR 6-HOUR 24-HOUR
EFFECTIVE RAIN (in) 0.47 0.47 0.37
FLOOD VOLUME (cu-ft) 16,627 16,600 13,067
(acre-ft) 0.38 0.38 0.30
REQUIRED STORAGE (cu-ft) 14,362 13,085 5,344
(acre-ft) 0.33 0.30 0.12
PEAK FLOW (cfs) 8.01 6.94 1.24
MAXIMUM WSEL (ft) 465.49 465.40 464.87
24-HOURS
[15] LAG TIME-HOURS
[16] LAG TIME-MINUTES

0.21 STORM EVENT SUMMARY
[17] 100% OF LAG-MINUTES
[18] 200% OF LAG-MINUTES
[24] TOTAL PERCOLATION RATE (cfs)
[19] UNIT TIME-MINUTES (100%-200% OF LAG)
3-HOURS 6-HOURS
[6] La-FEET
[7] La-MILES
[8] ELEVATION OF HEADWATER
[9] ELEVATION OF CONCENTRATION POINT
[2] AREA DESIGNATION
[3] AREA - ACRES
[4] L-FEET
[5] L-MILES
5 0.02

1.4 1.4

2.8 21.3

4.61 0.02

PHYSICAL DATA

RAINFALL DATA
[1] CONCENTRATION POINT 1
SUBAREA 4

9.790
620

0.013
470.5
468

0.117

70.00 0.000
[12] S^0.5
[13] L*LCA/S^0.5
[14] AVERAGE MANNINGS 'N'
[10] H-FEET 2.5
[11] S-FEET/MILE
Plate E-2.1

Page 2 of 14 ends

Item 2.

RCFCD SYNTHETIC UNIT HYDROGRAPH METHOD PROJECT CALHOUN AT AVENUE 49 - 10 YEAR EVENT CONCENTRATION POINT: 1BY MES R. BAZUA, P.E. DATE 1/17/2025

ADJUSTED LOSS RATE

SOIL RI PERVIOUS DECIMAL ADJUSTED AREA AVERAGE

GROUP NUMBER AREA PERCENT INFILTRATION ADJUSTED

INFILTRATION OF AREA RATE INFILTRATION

RATE IMPERVIOUS RATE
(in/hr) (in/hr) (in/hr)
[Plate C-1] [Plate E-6.1] [Plate E-6.2] [Plate E-6.3]
B 56 0.52 90% 0.10 0.00 0.000 0.0000
B 56 0.52 100% 0.05 2.33 0.238 0.0124
B 56 0.52 20% 0.43 0.00 0.000 0.0000B 56 0.52 40% 0.33 0.00 0.000 0.0000B 56 0.52 50% 0.29 0.00 0.000 0.0000B 56 0.52 65% 0.22 6.56 0.670 0.1446B 56 0.52 80% 0.15 0.00 0.000 0.0000B 56 0.52 75% 0.17 0.00 0.000 0.0000B 56 0.52 0% 0.52 0.90 0.092 0.0478B 56 0.52 0% 0.52 0.00 0.000 0.0000B 56 0.52 0% 0.52 0.00 0.000 0.0000 D 93 0.95 90% 0.18 0.00 0.000 0.0000

0.00 0.000 0.0000

0.00 0.000 0.0000
SUM 9.79 SUM 0.2048
VARIABLE LOSS RATE CURVE (24-HOUR STORM ONLY)Fm= 0.102390603C= 0.00190Ft=C(24-(T/60))^1.55 = 0.00190 0.10 in/hr LOW LOSS RATE (80-90 PERCENT) = 90%Where:T=Time in minutes. To get an average value for each unit time period, Use T=1/2 the unit time for the first time period,T=1 1/2 unit time for the second period, etc.

LANDSCAPING

RETENTION BASINS

GOLF COURSE

MOUNTAINOUS
SF - 1 ACRE
SF - 1/2 ACRESF - 1/4 ACRE
MF - COND0MINIUMS

MF - APARTMENTS

MOBILE HOME PARKS
(24-(T/60))^1.55 +

LAND USE

COMMERCIAL

PAVING/HARDSCAPE
Plate E-2.1

Page 3 of 14 ends

Item 2.

RCFCD SYNTHETIC UNIT HYDROGRAPH METHOD PROJECT: CALHOUN AT AVENUE 49 - 10 YEAR EVENT 100 YEAR - 3 HOUR STORM EVENT CONCENTRATION POINT: 1
BY: MES R. BAZUA, DATE 1/17/2025
DRAINAGE AREA-ACRES 9.79
UNIT TIME-MINUTES 5
LAG TIME - MINUTES 1.38
UNIT TIME-PERCENT OF LAG 362.1
TOTAL ADJUSTED STORM RAIN-INCHES 1.04
CONSTANT LOSS RATE-in/hr 0.20
LOW LOSS RATE - PERCENT 90% TOTAL PERCOLATION RATE (cfs) 0.21 cfs Unit Time Pattern Storm Effective Flood Required
Period Minutes Hours Percent Rain Rain Hydrograph Storage in/hr Flow
(Plate E-5.9) Max Low in/hr cfs cf
1 5 0.08 1.3 0.162 0.20 0.15 0.02 0.16 0.00
2 10 0.17 1.3 0.162 0.20 0.15 0.02 0.16 0.00
3 15 0.25 1.1 0.137 0.20 0.12 0.01 0.13 0.00
4 20 0.33 1.5 0.187 0.20 0.17 0.02 0.18 0.00
5 25 0.42 1.5 0.187 0.20 0.17 0.02 0.18 0.00
6 30 0.50 1.8 0.225 0.20 0.20 0.02 0.19 0.00
7 35 0.58 1.5 0.187 0.20 0.17 0.02 0.18 0.00
8 40 0.67 1.8 0.225 0.20 0.20 0.02 0.19 0.00
9 45 0.75 1.8 0.225 0.20 0.20 0.02 0.19 0.00
10 50 0.83 1.5 0.187 0.20 0.17 0.02 0.18 0.00
11 55 0.92 1.6 0.200 0.20 0.18 0.02 0.20 0.00
12 60 1.00 1.8 0.225 0.20 0.20 0.02 0.19 0.00
13 65 1.08 2.2 0.275 0.20 0.25 0.07 0.68 141.06
14 70 1.17 2.2 0.275 0.20 0.25 0.07 0.68 141.06
15 75 1.25 2.2 0.275 0.20 0.25 0.07 0.68 141.06
16 80 1.33 2.0 0.250 0.20 0.22 0.04 0.44 67.75
17 85 1.42 2.6 0.324 0.20 0.29 0.12 1.17 287.67
18 90 1.50 2.7 0.337 0.20 0.30 0.13 1.29 324.33
19 95 1.58 2.4 0.300 0.20 0.27 0.09 0.93 214.37
20 100 1.67 2.7 0.337 0.20 0.30 0.13 1.29 324.33
21 105 1.75 3.3 0.412 0.20 0.37 0.21 2.03 544.25
22 110 1.83 3.1 0.387 0.20 0.35 0.18 1.78 470.94
23 115 1.92 2.9 0.362 0.20 0.33 0.16 1.54 397.63
24 120 2.00 3.0 0.374 0.20 0.34 0.17 1.66 434.29
25 125 2.08 3.1 0.387 0.20 0.35 0.18 1.78 470.94
26 130 2.17 4.2 0.524 0.20 0.47 0.32 3.13 874.13
27 135 2.25 5.0 0.624 0.20 0.56 0.42 4.10 1167.36
28 140 2.33 3.5 0.437 0.20 0.39 0.23 2.27 617.56
29 145 2.42 6.8 0.849 0.20 0.76 0.64 6.30 1827.13
30 150 2.50 7.3 0.911 0.20 0.82 0.71 6.91 2010.40
31 155 2.58 8.2 1.023 0.20 0.92 0.82 8.01 2340.28
32 160 2.67 5.9 0.736 0.20 0.66 0.53 5.20 1497.25
33 165 2.75 2.0 0.250 0.20 0.22 0.04 0.44 67.75
34 170 2.83 1.8 0.225 0.20 0.20 0.02 0.19 0.00
35 175 2.92 1.8 0.225 0.20 0.20 0.02 0.19 0.00
36 180 3.00 0.6 0.075 0.20 0.07 0.01 0.07 0.00

EFFECTIVE RAIN & FLOOD VOLUMES SUMMARY
EFFECTIVE RAIN (in) 0.47
FLOOD VOLUME (acft) 0.38
FLOOD VOLUME (cuft) 16626.67
REQUIRED STORAGE (acft) 0.33
REQUIRED STORAGE (cuft) 14361.53
PEAK FLOW RATE (cfs) 8.01
Loss Rate
in/hr
Time

EFFECTIVE RAIN CALCULATION FORM
Plate E-2.2

Page 4 of 14 ends

Item 2.

RCFCD SYNTHETIC UNIT HYDROGRAPH METHOD PROJECT: CALHOUN AT AVENUE 49 - 10 YEAR EVENT 100 YEAR - 6 HOUR STORM EVENT CONCENTRATION POINT: 1
BY: JAMES R. BAZ DATE: 1/17/2025
DRAINAGE AREA-ACRES 9.79
UNIT TIME-MINUTES 5
LAG TIME - MINUTES 1.38
UNIT TIME-PERCENT OF LAG 362.1
TOTAL ADJUSTED STORM RAIN-INCHES 1.36
CONSTANT LOSS RATE-in/hr 0.205
LOW LOSS RATE - PERCENT 90% TOTAL PERCOLATION RATE (cfs) 0.21 cfs Unit Time Pattern Storm Effective Flood Required
Period Minutes Hours Percent Rain Rain Hydrograph Storage in/hr Flow
(Plate E-5.9) Max Low in/hr cfs cf
1 5 0.08 0.5 0.082 0.20 0.07 0.01 0.08 0.00
2 10 0.17 0.6 0.098 0.20 0.09 0.01 0.10 0.00
3 15 0.25 0.6 0.098 0.20 0.09 0.01 0.10 0.00
4 20 0.33 0.6 0.098 0.20 0.09 0.01 0.10 0.00
5 25 0.42 0.6 0.098 0.20 0.09 0.01 0.10 0.00
6 30 0.50 0.7 0.114 0.20 0.10 0.01 0.11 0.00
7 35 0.58 0.7 0.114 0.20 0.10 0.01 0.11 0.00
8 40 0.67 0.7 0.114 0.20 0.10 0.01 0.11 0.00
9 45 0.75 0.7 0.114 0.20 0.10 0.01 0.11 0.00
10 50 0.83 0.7 0.114 0.20 0.10 0.01 0.11 0.00
11 55 0.92 0.7 0.114 0.20 0.10 0.01 0.11 0.00
12 60 1.00 0.8 0.131 0.20 0.12 0.01 0.13 0.00
13 65 1.08 0.8 0.131 0.20 0.12 0.01 0.13 0.00
14 70 1.17 0.8 0.131 0.20 0.12 0.01 0.13 0.00
15 75 1.25 0.8 0.131 0.20 0.12 0.01 0.13 0.00
16 80 1.33 0.8 0.131 0.20 0.12 0.01 0.13 0.00
17 85 1.42 0.8 0.131 0.20 0.12 0.01 0.13 0.00
18 90 1.50 0.8 0.131 0.20 0.12 0.01 0.13 0.00
19 95 1.58 0.8 0.131 0.20 0.12 0.01 0.13 0.00
20 100 1.67 0.8 0.131 0.20 0.12 0.01 0.13 0.00
21 105 1.75 0.8 0.131 0.20 0.12 0.01 0.13 0.00
22 110 1.83 0.8 0.131 0.20 0.12 0.01 0.13 0.00
23 115 1.92 0.8 0.131 0.20 0.12 0.01 0.13 0.00
24 120 2.00 0.9 0.147 0.20 0.13 0.01 0.14 0.00
25 125 2.08 0.8 0.131 0.20 0.12 0.01 0.13 0.00
26 130 2.17 0.9 0.147 0.20 0.13 0.01 0.14 0.00
27 135 2.25 0.9 0.147 0.20 0.13 0.01 0.14 0.00
28 140 2.33 0.9 0.147 0.20 0.13 0.01 0.14 0.00
29 145 2.42 0.9 0.147 0.20 0.13 0.01 0.14 0.00
30 150 2.50 0.9 0.147 0.20 0.13 0.01 0.14 0.00
31 155 2.58 0.9 0.147 0.20 0.13 0.01 0.14 0.00
32 160 2.67 0.9 0.147 0.20 0.13 0.01 0.14 0.00
33 165 2.75 1.0 0.163 0.20 0.15 0.02 0.16 0.00
34 170 2.83 1.0 0.163 0.20 0.15 0.02 0.16 0.00
35 175 2.92 1.0 0.163 0.20 0.15 0.02 0.16 0.00
36 180 3.00 1.0 0.163 0.20 0.15 0.02 0.16 0.00
37 185 3.08 1.0 0.163 0.20 0.15 0.02 0.16 0.00
38 190 3.17 1.1 0.180 0.20 0.16 0.02 0.18 0.00
39 195 3.25 1.1 0.180 0.20 0.16 0.02 0.18 0.00
40 200 3.33 1.1 0.180 0.20 0.16 0.02 0.18 0.00
41 205 3.42 1.2 0.196 0.20 0.18 0.02 0.19 0.00
42 210 3.50 1.3 0.212 0.20 0.19 0.01 0.07 0.00
43 215 3.58 1.4 0.228 0.20 0.21 0.02 0.23 5.72
44 220 3.67 1.4 0.228 0.20 0.21 0.02 0.23 5.72
45 225 3.75 1.5 0.245 0.20 0.22 0.04 0.39 53.65
46 230 3.83 1.5 0.245 0.20 0.22 0.04 0.39 53.65
47 235 3.92 1.6 0.261 0.20 0.24 0.06 0.55 101.58
48 240 4.00 1.6 0.261 0.20 0.24 0.06 0.55 101.58
49 245 4.08 1.7 0.277 0.20 0.25 0.07 0.71 149.52
50 250 4.17 1.8 0.294 0.20 0.26 0.09 0.87 197.45
51 255 4.25 1.9 0.310 0.20 0.28 0.11 1.03 245.38
52 260 4.33 2.0 0.326 0.20 0.29 0.12 1.19 293.31
53 265 4.42 2.1 0.343 0.20 0.31 0.14 1.35 341.24
54 270 4.50 2.1 0.343 0.20 0.31 0.14 1.35 341.24
55 275 4.58 2.2 0.359 0.20 0.32 0.15 1.51 389.18
56 280 4.67 2.3 0.375 0.20 0.34 0.17 1.67 437.11

EFFECTIVE RAIN CALCULATION FORM
Time Loss Rate
in/hr
Plate E-2.2

Page 5 of 14 ends

Item 2.

EFFECTIVE RAIN CALCULATION FORM
Time Loss Rate
in/hr
57 285 4.75 2.4 0.392 0.20 0.35 0.19 1.83 485.04
58 290 4.83 2.4 0.392 0.20 0.35 0.19 1.83 485.04
59 295 4.92 2.5 0.408 0.20 0.37 0.20 1.99 532.97
60 300 5.00 2.6 0.424 0.20 0.38 0.22 2.15 580.90
61 305 5.08 3.1 0.506 0.20 0.46 0.30 2.95 820.56
62 310 5.17 3.6 0.588 0.20 0.53 0.38 3.75 1060.22
63 315 5.25 3.9 0.636 0.20 0.57 0.43 4.23 1204.02
64 320 5.33 4.2 0.685 0.20 0.62 0.48 4.71 1347.81
65 325 5.42 4.7 0.767 0.20 0.69 0.56 5.50 1587.47
66 330 5.50 5.6 0.914 0.20 0.82 0.71 6.94 2018.86
67 335 5.58 1.9 0.310 0.20 0.28 0.11 1.03 245.38
68 340 5.67 0.9 0.147 0.20 0.13 0.01 0.14 0.00
69 345 5.75 0.6 0.098 0.20 0.09 0.01 0.10 0.00
70 350 5.83 0.5 0.082 0.20 0.07 0.01 0.08 0.00
71 355 5.92 0.3 0.049 0.20 0.04 0.00 0.05 0.00
72 360 6.00 0.2 0.033 0.20 0.03 0.00 0.03 0.00

EFFECTIVE RAIN & FLOOD VOLUMES SUMMARY
EFFECTIVE RAIN (in) 0.47
FLOOD VOLUME (acft) 0.38
FLOOD VOLUME (cuft) 16599.70
REQUIRED STORAGE (acft) 0.30
REQUIRED STORAGE (cuft) 13084.61
PEAK FLOW RATE (cfs) 6.94
Plate E-2.2

Page 6 of 14 ends

Item 2.

RCFCD SYNTHETIC UNIT HYDROGRAPH METHOD PROJECT: CALHOUN AT AVENUE 49 - 10 YEAR EVENT 100 YEAR - 24 HOUR STORM EVENT CONCENTRATION POINT: 1
BY: JAMES R. BAZ DATE: 1/17/2025
DRAINAGE AREA-ACRES 9.790 CONSTANT LOSS RATE-in/hr n/a
UNIT TIME-MINUTES 15 VARIABLE LOSS RATE (AVG) in/hr 0.2048 LAG TIME - MINUTES 1.38 MINIMUM LOSS RATE (for var. loss) - in/hr 0.102 UNIT TIME-PERCENT OF LAG 1086.4 LOW LOSS RATE - DECIMAL 0.90 TOTAL ADJUSTED STORM RAIN-INCHES 2.23 C 0.00190
PERCOLATION RATE (cfs) 0.21
Unit Time Pattern Storm Effective Flood Required
Period Minutes Hours Percent Rain Rain Hydrograph Storage in/hr Flow
(Plate E-5.9) Max Low in/hr cfs cf
1 15 0.25 0.2 0.018 0.362 0.016 0.002 0.02 0.00
2 30 0.50 0.3 0.027 0.357 0.024 0.003 0.03 0.00
3 45 0.75 0.3 0.027 0.353 0.024 0.003 0.03 0.00
4 60 1.00 0.4 0.036 0.349 0.032 0.004 0.03 0.00
5 75 1.25 0.3 0.027 0.345 0.024 0.003 0.03 0.00
6 90 1.50 0.3 0.027 0.341 0.024 0.003 0.03 0.00
7 105 1.75 0.3 0.027 0.337 0.024 0.003 0.03 0.00
8 120 2.00 0.4 0.036 0.333 0.032 0.004 0.03 0.00
9 135 2.25 0.4 0.036 0.329 0.032 0.004 0.03 0.00
10 150 2.50 0.4 0.036 0.325 0.032 0.004 0.03 0.00
11 165 2.75 0.5 0.045 0.321 0.040 0.004 0.04 0.00
12 180 3.00 0.5 0.045 0.317 0.040 0.004 0.04 0.00
13 195 3.25 0.5 0.045 0.313 0.040 0.004 0.04 0.00
14 210 3.50 0.5 0.045 0.309 0.040 0.004 0.04 0.00
15 225 3.75 0.5 0.045 0.305 0.040 0.004 0.04 0.00
16 240 4.00 0.6 0.054 0.301 0.048 0.005 0.05 0.00
17 255 4.25 0.6 0.054 0.297 0.048 0.005 0.05 0.00
18 270 4.50 0.7 0.062 0.294 0.056 0.006 0.06 0.00
19 285 4.75 0.7 0.062 0.290 0.056 0.006 0.06 0.00
20 300 5.00 0.8 0.071 0.286 0.064 0.007 0.07 0.00
21 315 5.25 0.6 0.054 0.282 0.048 0.005 0.05 0.00
22 330 5.50 0.7 0.062 0.279 0.056 0.006 0.06 0.00
23 345 5.75 0.8 0.071 0.275 0.064 0.007 0.07 0.00
24 360 6.00 0.8 0.071 0.272 0.064 0.007 0.07 0.00
25 375 6.25 0.9 0.080 0.268 0.072 0.008 0.08 0.00
26 390 6.50 0.9 0.080 0.264 0.072 0.008 0.08 0.00
27 405 6.75 1.0 0.089 0.261 0.080 0.009 0.09 0.00
28 420 7.00 1.0 0.089 0.257 0.080 0.009 0.09 0.00
29 435 7.25 1.0 0.089 0.254 0.080 0.009 0.09 0.00
30 450 7.50 1.1 0.098 0.250 0.088 0.010 0.10 0.00
31 465 7.75 1.2 0.107 0.247 0.096 0.011 0.10 0.00
32 480 8.00 1.3 0.116 0.243 0.104 0.012 0.11 0.00
33 495 8.25 1.5 0.134 0.240 0.120 0.013 0.13 0.00
34 510 8.50 1.5 0.134 0.237 0.120 0.013 0.13 0.00
35 525 8.75 1.6 0.143 0.233 0.128 0.014 0.14 0.00
36 540 9.00 1.7 0.152 0.230 0.136 0.015 0.15 0.00
37 555 9.25 1.9 0.169 0.227 0.153 0.017 0.17 0.00
38 570 9.50 2.0 0.178 0.224 0.161 0.018 0.17 0.00
39 585 9.75 2.1 0.187 0.220 0.169 0.019 0.18 0.00
40 600 10.00 2.2 0.196 0.217 0.177 0.020 0.19 0.00
41 615 10.25 1.5 0.134 0.214 0.120 0.013 0.13 0.00
42 630 10.50 1.5 0.134 0.211 0.120 0.013 0.13 0.00
43 645 10.75 2.0 0.178 0.208 0.161 0.018 0.17 0.00
44 660 11.00 2.0 0.178 0.205 0.161 0.018 0.17 0.00
45 675 11.25 1.9 0.169 0.202 0.153 0.017 0.17 0.00
46 690 11.50 1.9 0.169 0.199 0.153 0.017 0.17 0.00
47 705 11.75 1.7 0.152 0.196 0.136 0.015 0.15 0.00
48 720 12.00 1.8 0.161 0.193 0.145 0.016 0.16 0.00
49 735 12.25 2.5 0.223 0.190 0.201 0.033 0.32 97.34
50 750 12.50 2.6 0.232 0.187 0.209 0.045 0.44 201.03
51 765 12.75 2.8 0.250 0.185 0.225 0.065 0.64 383.03
52 780 13.00 2.9 0.259 0.182 0.233 0.077 0.75 486.13
53 795 13.25 3.4 0.303 0.179 0.273 0.124 1.22 903.31
54 810 13.50 3.4 0.303 0.176 0.273 0.127 1.24 927.21
55 825 13.75 2.3 0.205 0.174 0.185 0.032 0.31 86.27
56 840 14.00 2.3 0.205 0.171 0.185 0.034 0.33 109.55
57 855 14.25 2.7 0.241 0.168 0.217 0.072 0.71 446.90
58 870 14.50 2.6 0.232 0.166 0.209 0.066 0.65 390.96
59 885 14.75 2.6 0.232 0.163 0.209 0.069 0.67 413.29
60 900 15.00 2.5 0.223 0.161 0.201 0.062 0.61 356.70
61 915 15.25 2.4 0.214 0.158 0.193 0.056 0.55 299.78
Time Loss Rate
in/hr

EFFECTIVE RAIN CALCULATION FORM
Plate E-2.2

Page 7 of 14 ends

Item 2.

EFFECTIVE RAIN CALCULATION FORM
62 930 15.50 2.3 0.205 0.156 0.185 0.049 0.48 242.53
63 945 15.75 1.9 0.169 0.153 0.153 0.016 0.16 0.00
64 960 16.00 1.9 0.169 0.151 0.153 0.018 0.18 0.00
65 975 16.25 0.4 0.036 0.149 0.032 0.004 0.03 0.00
66 990 16.50 0.4 0.036 0.147 0.032 0.004 0.03 0.00
67 1005 16.75 0.3 0.027 0.144 0.024 0.003 0.03 0.00
68 1020 17.00 0.3 0.027 0.142 0.024 0.003 0.03 0.00
69 1035 17.25 0.5 0.045 0.140 0.040 0.004 0.04 0.00
70 1050 17.50 0.5 0.045 0.138 0.040 0.004 0.04 0.00
71 1065 17.75 0.5 0.045 0.136 0.040 0.004 0.04 0.00
72 1080 18.00 0.4 0.036 0.134 0.032 0.004 0.03 0.00
73 1095 18.25 0.4 0.036 0.132 0.032 0.004 0.03 0.00
74 1110 18.50 0.4 0.036 0.130 0.032 0.004 0.03 0.00
75 1125 18.75 0.3 0.027 0.128 0.024 0.003 0.03 0.00
76 1140 19.00 0.2 0.018 0.126 0.016 0.002 0.02 0.00
77 1155 19.25 0.3 0.027 0.124 0.024 0.003 0.03 0.00
78 1170 19.50 0.4 0.036 0.123 0.032 0.004 0.03 0.00
79 1185 19.75 0.3 0.027 0.121 0.024 0.003 0.03 0.00
80 1200 20.00 0.2 0.018 0.119 0.016 0.002 0.02 0.00
81 1215 20.25 0.3 0.027 0.118 0.024 0.003 0.03 0.00
82 1230 20.50 0.3 0.027 0.116 0.024 0.003 0.03 0.00
83 1245 20.75 0.3 0.027 0.115 0.024 0.003 0.03 0.00
84 1260 21.00 0.2 0.018 0.113 0.016 0.002 0.02 0.00
85 1275 21.25 0.3 0.027 0.112 0.024 0.003 0.03 0.00
86 1290 21.50 0.2 0.018 0.111 0.016 0.002 0.02 0.00
87 1305 21.75 0.3 0.027 0.110 0.024 0.003 0.03 0.00
88 1320 22.00 0.2 0.018 0.108 0.016 0.002 0.02 0.00
89 1335 22.25 0.3 0.027 0.107 0.024 0.003 0.03 0.00
90 1350 22.50 0.2 0.018 0.106 0.016 0.002 0.02 0.00
91 1365 22.75 0.2 0.018 0.105 0.016 0.002 0.02 0.00
92 1380 23.00 0.2 0.018 0.105 0.016 0.002 0.02 0.00
93 1395 23.25 0.2 0.018 0.104 0.016 0.002 0.02 0.00
94 1410 23.50 0.2 0.018 0.103 0.016 0.002 0.02 0.00
95 1425 23.75 0.2 0.018 0.103 0.016 0.002 0.02 0.00
96 1440 24.00 0.2 0.018 0.102 0.016 0.002 0.02 0.00

EFFECTIVE RAIN & FLOOD VOLUMES SUMMARY
EFFECTIVE RAIN (in) 0.37
FLOOD VOLUME (acft) 0.30
FLOOD VOLUME (cuft) 13066.60
REQUIRED STORAGE (acft) 0.12
REQUIRED STORAGE (cuft) 5344.02
PEAK FLOW (cfs) 1.24
Plate E-2.2

Page 8 of 14 ends

Item 2.

PROJECT: CALHOUN AT AVENUE 49 - 10 YEAR EVENT
JOB # 0
1 BASIN CHARACTERISTICS

CONTOUR DEPTH AREA VOLUME

INCR TOTAL INCR TOTAL INCR TOTAL
(ft) (ft) (sf) (sf) (cuft) (cuft) (acre-ft)
464.5 0 0 13730 0 0 0.00
465.5 1 1 1470 15200 14465 14465 0.33
466.5 1 2 1500 16700 15950 30415 0.70
467.5 1 3 1570 18270 17485 47900 1.10
468 0.5 3.5 805 19075 9336 57236 1.31

PERCOLATION CALCULATIONS
PERCOLATION RATE 0.67 in/hr 0.21 cfs

MAXWELL IV DRYWELLS
NUMBER USED 0
RATE/DRYWELL 0 cfs
TOTAL DISSIPATED 0 cfs
TOTAL PERCOLATION RATE 0.21 cfs
Basin Characteristics

Page 9 of 14 ends

Item 2.
1 JOB # 0
100 YEAR - 3 HOUR STORM EVENT

FLOW VOLUME TOTAL IN PERC TOTAL IN BASIN
UNIT (min) IN IN BASIN OUT BASIN DEPTH
PERIOD (cfs) (cuft) (cuft) (cuft) (cuft) (ft) (cuft) (acre-ft) 1 5 0.16 48 48 64 - 464.50 - 0.00
2 10 0.16 48 48 64 - 464.50 - 0.00
3 15 0.13 40 40 64 - 464.50 - 0.00
4 20 0.18 55 55 64 - 464.50 - 0.00
5 25 0.18 55 55 64 - 464.50 - 0.00
6 30 0.19 58 58 64 - 464.50 - 0.00
7 35 0.18 55 55 64 - 464.50 - 0.00
8 40 0.19 58 58 64 - 464.50 - 0.00
9 45 0.19 58 58 64 - 464.50 - 0.00
10 50 0.18 55 55 64 - 464.50 - 0.00
11 55 0.20 59 59 64 - 464.50 - 0.00
12 60 0.19 58 58 64 - 464.50 - 0.00
13 65 0.68 205 205 64 141 464.51 141 0.00
14 70 0.68 205 346 64 282 464.52 282 0.01
15 75 0.68 205 487 64 423 464.53 423 0.01
16 80 0.44 132 555 64 491 464.53 491 0.01
17 85 1.17 352 842 64 779 464.55 779 0.02
18 90 1.29 388 1,167 64 1,103 464.58 1,103 0.03
19 95 0.93 278 1,381 64 1,317 464.59 1,317 0.03
20 100 1.29 388 1,705 64 1,642 464.61 1,642 0.04
21 105 2.03 608 2,250 64 2,186 464.65 2,186 0.05
22 110 1.78 535 2,721 64 2,657 464.68 2,657 0.06
23 115 1.54 462 3,118 64 3,054 464.71 3,054 0.07
24 120 1.66 498 3,553 64 3,489 464.74 3,489 0.08
25 125 1.78 535 4,024 64 3,960 464.77 3,960 0.09
26 130 3.13 938 4,898 64 4,834 464.83 4,834 0.11
27 135 4.10 1,231 6,065 64 6,001 464.91 6,001 0.14
28 140 2.27 681 6,683 64 6,619 464.96 6,619 0.15
29 145 6.30 1,891 8,510 64 8,446 465.08 8,446 0.19
30 150 6.91 2,074 10,520 64 10,456 465.22 10,456 0.24
31 155 8.01 2,404 12,860 64 12,797 465.38 12,797 0.29
32 160 5.20 1,561 14,358 64 14,294 465.49 14,294 0.33
33 165 0.44 132 14,425 64 14,362 465.49 14,362 0.33
34 170 0.19 58 14,420 64 14,356 465.49 14,356 0.33
35 175 0.19 58 14,414 64 14,350 465.49 14,350 0.33
36 180 0.07 22 14,372 64 14,309 465.49 14,309 0.33

BALANCE IN
BASIN
TIME
Basin Depth Analysis

Page 10 of 14 ends

Item 2.
1 JOB # 0
100 YEAR - 6 HOUR STORM EVENT

FLOW VOLUME TOTAL IN PERC TOTAL IN BASIN
UNIT (min) IN IN BASIN OUT BASIN DEPTH
PERIOD (cfs) (cuft) (cuft) (cuft) (cuft) (ft) (cuft) (acre-ft) 1 5 0.08 24 24 64 - 464.50 - 0.00
2 10 0.10 29 29 64 - 464.50 - 0.00
3 15 0.10 29 29 64 - 464.50 - 0.00
4 20 0.10 29 29 64 - 464.50 - 0.00
5 25 0.10 29 29 64 - 464.50 - 0.00
6 30 0.11 34 34 64 - 464.50 - 0.00
7 35 0.11 34 34 64 - 464.50 - 0.00
8 40 0.11 34 34 64 - 464.50 - 0.00
9 45 0.11 34 34 64 - 464.50 - 0.00
10 50 0.11 34 34 64 - 464.50 - 0.00
11 55 0.11 34 34 64 - 464.50 - 0.00
12 60 0.13 38 38 64 - 464.50 - 0.00
13 65 0.13 38 38 64 - 464.50 - 0.00
14 70 0.13 38 38 64 - 464.50 - 0.00
15 75 0.13 38 38 64 - 464.50 - 0.00
16 80 0.13 38 38 64 - 464.50 - 0.00
17 85 0.13 38 38 64 - 464.50 - 0.00
18 90 0.13 38 38 64 - 464.50 - 0.00
19 95 0.13 38 38 64 - 464.50 - 0.00
20 100 0.13 38 38 64 - 464.50 - 0.00
21 105 0.13 38 38 64 - 464.50 - 0.00
22 110 0.13 38 38 64 - 464.50 - 0.00
23 115 0.13 38 38 64 - 464.50 - 0.00
24 120 0.14 43 43 64 - 464.50 - 0.00
25 125 0.13 38 38 64 - 464.50 - 0.00
26 130 0.14 43 43 64 - 464.50 - 0.00
27 135 0.14 43 43 64 - 464.50 - 0.00
28 140 0.14 43 43 64 - 464.50 - 0.00
29 145 0.14 43 43 64 - 464.50 - 0.00
30 150 0.14 43 43 64 - 464.50 - 0.00
31 155 0.14 43 43 64 - 464.50 - 0.00
32 160 0.14 43 43 64 - 464.50 - 0.00
33 165 0.16 48 48 64 - 464.50 - 0.00
34 170 0.16 48 48 64 - 464.50 - 0.00
35 175 0.16 48 48 64 - 464.50 - 0.00
36 180 0.16 48 48 64 - 464.50 - 0.00
37 185 0.16 48 48 64 - 464.50 - 0.00
38 190 0.18 53 53 64 - 464.50 - 0.00
39 195 0.18 53 53 64 - 464.50 - 0.00
40 200 0.18 53 53 64 - 464.50 - 0.00
41 205 0.19 58 58 64 - 464.50 - 0.00
42 210 0.07 22 22 64 - 464.50 - 0.00
43 215 0.23 70 70 64 6 464.50 0.00 6
44 220 0.23 70 75 64 11 464.50 11 0.00
45 225 0.39 118 129 64 65 464.50 65 0.00
46 230 0.39 118 183 64 119 464.51 119 0.00
47 235 0.55 165 284 64 220 464.52 220 0.01
48 240 0.55 165 386 64 322 464.52 322 0.01
49 245 0.71 213 535 64 471 464.53 471 0.01
50 250 0.87 261 733 64 669 464.55 669 0.02
51 255 1.03 309 978 64 914 464.56 914 0.02
52 260 1.19 357 1,271 64 1,208 464.58 1,208 0.03
53 265 1.35 405 1,613 64 1,549 464.61 1,549 0.04
54 270 1.35 405 1,954 64 1,890 464.63 1,890 0.04
55 275 1.51 453 2,343 64 2,279 464.66 2,279 0.05

TIME BALANCE IN
BASIN
Basin Depth Analysis

Page 11 of 14 ends

Item 2.
1 JOB # 0
100 YEAR - 6 HOUR STORM EVENT

FLOW VOLUME TOTAL IN PERC TOTAL IN BASIN
UNIT (min) IN IN BASIN OUT BASIN DEPTH
PERIOD (cfs) (cuft) (cuft) (cuft) (cuft) (ft) (cuft) (acre-ft)

TIME BALANCE IN
BASIN
56 280 1.67 501 2,780 64 2,716 464.69 2,716 0.06
57 285 1.83 549 3,265 64 3,201 464.72 3,201 0.07
58 290 1.83 549 3,750 64 3,686 464.75 3,686 0.08
59 295 1.99 597 4,283 64 4,219 464.79 4,219 0.10
60 300 2.15 645 4,864 64 4,800 464.83 4,800 0.11
61 305 2.95 884 5,685 64 5,621 464.89 5,621 0.13
62 310 3.75 1,124 6,745 64 6,681 464.96 6,681 0.15
63 315 4.23 1,268 7,949 64 7,885 465.05 7,885 0.18
64 320 4.71 1,412 9,297 64 9,233 465.14 9,233 0.21
65 325 5.50 1,651 10,884 64 10,820 465.25 10,820 0.25
66 330 6.94 2,083 12,903 64 12,839 465.39 12,839 0.29
67 335 1.03 309 13,148 64 13,085 465.40 13,085 0.30
68 340 0.14 43 13,128 64 13,064 465.40 13,064 0.30
69 345 0.10 29 13,093 64 13,029 465.40 13,029 0.30
70 350 0.08 24 13,053 64 12,989 465.40 12,989 0.30
71 355 0.05 14 13,003 64 12,939 465.39 12,939 0.30
72 360 0.03 10 12,949 64 12,885 465.39 12,885 0.30
Basin Depth Analysis

Page 12 of 14 ends

Item 2.
1 JOB # 0
100 YEAR - 24 HOUR STORM EVENT

FLOW VOLUME TOTAL IN PERC TOTAL IN BASIN
UNIT (min) IN IN BASIN OUT BASIN DEPTH
PERIOD (cfs) (cuft) (cuft) (cuft) (cuft) (ft) (cuft) (acre-ft) 1 15 0.02 16 16 192 - 464.50 - 0.00
2 30 0.03 24 24 192 - 464.50 - 0.00
3 45 0.03 24 24 192 - 464.50 - 0.00
4 60 0.03 31 31 192 - 464.50 - 0.00
5 75 0.03 24 24 192 - 464.50 - 0.00
6 90 0.03 24 24 192 - 464.50 - 0.00
7 105 0.03 24 24 192 - 464.50 - 0.00
8 120 0.03 31 31 192 - 464.50 - 0.00
9 135 0.03 31 31 192 - 464.50 - 0.00
10 150 0.03 31 31 192 - 464.50 - 0.00
11 165 0.04 39 39 192 - 464.50 - 0.00
12 180 0.04 39 39 192 - 464.50 - 0.00
13 195 0.04 39 39 192 - 464.50 - 0.00
14 210 0.04 39 39 192 - 464.50 - 0.00
15 225 0.04 39 39 192 - 464.50 - 0.00
16 240 0.05 47 47 192 - 464.50 - 0.00
17 255 0.05 47 47 192 - 464.50 - 0.00
18 270 0.06 55 55 192 - 464.50 - 0.00
19 285 0.06 55 55 192 - 464.50 - 0.00
20 300 0.07 63 63 192 - 464.50 - 0.00
21 315 0.05 47 47 192 - 464.50 - 0.00
22 330 0.06 55 55 192 - 464.50 - 0.00
23 345 0.07 63 63 192 - 464.50 - 0.00
24 360 0.07 63 63 192 - 464.50 - 0.00
25 375 0.08 71 71 192 - 464.50 - 0.00
26 390 0.08 71 71 192 - 464.50 - 0.00
27 405 0.09 79 79 192 - 464.50 - 0.00
28 420 0.09 79 79 192 - 464.50 - 0.00
29 435 0.09 79 79 192 - 464.50 - 0.00
30 450 0.10 86 86 192 - 464.50 - 0.00
31 465 0.10 94 94 192 - 464.50 - 0.00
32 480 0.11 102 102 192 - 464.50 - 0.00
33 495 0.13 118 118 192 - 464.50 - 0.00
34 510 0.13 118 118 192 - 464.50 - 0.00
35 525 0.14 126 126 192 - 464.50 - 0.00
36 540 0.15 134 134 192 - 464.50 - 0.00
37 555 0.17 149 149 192 - 464.50 - 0.00
38 570 0.17 157 157 192 - 464.50 - 0.00
39 585 0.18 165 165 192 - 464.50 - 0.00
40 600 0.19 173 173 192 - 464.50 - 0.00
41 615 0.13 118 118 192 - 464.50 - 0.00
42 630 0.13 118 118 192 - 464.50 - 0.00
43 645 0.17 157 157 192 - 464.50 - 0.00
44 660 0.17 157 157 192 - 464.50 - 0.00
45 675 0.17 149 149 192 - 464.50 - 0.00
46 690 0.17 149 149 192 - 464.50 - 0.00
47 705 0.15 134 134 192 - 464.50 - 0.00
48 720 0.16 141 141 192 - 464.50 - 0.00
49 735 0.32 289 289 192 97 464.51 97 0.00
50 750 0.44 393 490 192 298 464.52 298 0.01
51 765 0.64 575 873 192 681 464.55 681 0.02
52 780 0.75 678 1,359 192 1,168 464.58 1,168 0.03
53 795 1.22 1,095 2,262 192 2,071 464.64 2,071 0.05
54 810 1.24 1,119 3,190 192 2,998 464.71 2,998 0.07
55 825 0.31 278 3,276 192 3,084 464.71 3,084 0.07
56 840 0.33 301 3,386 192 3,194 464.72 3,194 0.07
57 855 0.71 639 3,832 192 3,641 464.75 3,641 0.08
58 870 0.65 583 4,223 192 4,032 464.78 4,032 0.09

TIME BALANCE IN
BASIN
Basin Depth Analysis

Page 13 of 14 ends

Item 2.
1 JOB # 0
100 YEAR - 24 HOUR STORM EVENT

FLOW VOLUME TOTAL IN PERC TOTAL IN BASIN
UNIT (min) IN IN BASIN OUT BASIN DEPTH
PERIOD (cfs) (cuft) (cuft) (cuft) (cuft) (ft) (cuft) (acre-ft)

TIME BALANCE IN
BASIN
59 885 0.67 605 4,637 192 4,445 464.81 4,445 0.10
60 900 0.61 548 4,993 192 4,802 464.83 4,802 0.11
61 915 0.55 491 5,293 192 5,101 464.85 5,101 0.12
62 930 0.48 434 5,536 192 5,344 464.87 5,344 0.12
63 945 0.16 141 5,485 192 5,293 464.87 5,293 0.12
64 960 0.18 161 5,455 192 5,263 464.86 5,263 0.12
65 975 0.03 31 5,294 192 5,103 464.85 5,103 0.12
66 990 0.03 31 5,134 192 4,943 464.84 4,943 0.11
67 1005 0.03 24 4,966 192 4,775 464.83 4,775 0.11
68 1020 0.03 24 4,798 192 4,606 464.82 4,606 0.11
69 1035 0.04 39 4,646 192 4,454 464.81 4,454 0.10
70 1050 0.04 39 4,493 192 4,302 464.80 4,302 0.10
71 1065 0.04 39 4,341 192 4,149 464.79 4,149 0.10
72 1080 0.03 31 4,181 192 3,989 464.78 3,989 0.09
73 1095 0.03 31 4,021 192 3,829 464.76 3,829 0.09
74 1110 0.03 31 3,860 192 3,669 464.75 3,669 0.08
75 1125 0.03 24 3,692 192 3,501 464.74 3,501 0.08
76 1140 0.02 3,516 16 192 3,325 464.73 3,325 0.08
77 1155 0.03 24 3,348 192 3,157 464.72 3,157 0.07
78 1170 0.03 31 3,188 192 2,996 464.71 2,996 0.07
79 1185 0.03 24 3,020 192 2,828 464.70 2,828 0.06
80 1200 0.02 16 2,844 192 2,652 464.68 2,652 0.06
81 1215 0.03 24 2,676 192 2,484 464.67 2,484 0.06
82 1230 0.03 24 2,508 192 2,316 464.66 2,316 0.05
83 1245 0.03 24 2,340 192 2,148 464.65 2,148 0.05
84 1260 0.02 16 2,164 192 1,972 464.64 1,972 0.05
85 1275 0.03 24 1,996 192 1,804 464.62 1,804 0.04
86 1290 0.02 16 1,820 192 1,628 464.61 1,628 0.04
87 1305 0.03 24 1,652 192 1,460 464.60 1,460 0.03
88 1320 0.02 16 1,476 192 1,284 464.59 1,284 0.03
89 1335 0.03 24 1,308 192 1,116 464.58 1,116 0.03
90 1350 0.02 16 1,132 192 940 464.57 940 0.02
91 1365 0.02 16 956 192 764 464.55 764 0.02
92 1380 0.02 16 780 192 588 464.54 588 0.01
93 1395 0.02 16 604 192 413 464.53 413 0.01
94 1410 0.02 16 428 192 237 464.52 237 0.01
95 1425 0.02 16 252 192 61 464.50 61 0.00
96 1440 0.02 16 76 192 - 464.50 - 0.00
Basin Depth Analysis

Page 14 of 14 ends

Item 2.
1 2
3 4
5 6
7 8
9 10
11 12
13 14
15 16
17 18
19 20
21 22
23 24
25 26
27 28
29 30
31 32
33 34
35 36
37 38
39 40
41 42
43 44
45 46
47 48
49 50
51 52
53 54
55 56
AB C D

RCFCD SYNTHETIC UNIT HYDROGRAPH

DATA INPUT SHEET
WORKSHEET PREPARED BY: JAMES R. BAZUA, P.E.

PROJECT NAME CALHOUN AT AVENUE 49 - 10 YEAR EVENT
JOB #
CONCENTRATION POINT DESIGNATION 1
AREA DESIGNATION SUBAREA 5

TRIBUTARY AREAS ACRES

COMMERCIAL
PAVING/HARDSCAPE 1.95
SF - 1 ACRE
SF - 1/2 ACRE
SF - 1/4 ACRE
MF - CONDOMINIUMS 4.71

MF - APARTMENTS

MOBILE HOME PARK
LANDSCAPING 2.83

RETENTION BASIN

GOLF COURSE

MOUNTAINOUS
LOW LOSS RATE (PERCENT) 90%
LENGTH OF WATERCOURSE (L) 950
LENGTH TO POINT OPPOSITE CENTROID (Lca) 310
ELEVATION OF HEADWATER 471
ELEVATION OF CONCENTRATION POINT 467
AVERAGE MANNINGS 'N' VALUE 0.02
STORM FREQUENCY (YEAR) 100

POINT RAIN
3-HOUR 1.04
6-HOUR 1.36
24-HOUR 2.23
BASIN CHARACTERISTICS: ELEVATION AREA
463.5 17610
464.5 19400
465.5 21240
466.5 23140
467 24110
PERCOLATION RATE (in/hr) 0.67

DRYWELL DATA

NUMBER USED
PERCOLATION RATE (cfs)
638
Item 2.

POINT AREA AVERAGE POINT AREA AVERAGE POINT AREA AVERAGE

RAIN POINT RAIN POINT RAIN POINT

INCHES RAIN INCHES RAIN INCHES RAIN
(Plate E-5.2) INCHES (Plate E-5.4) INCHES (Plate E-5.6) INCHES

1.04 9.490 1.00 1.04 1.36 9.490 1.00 1.36 2.23 9.490 1.00 2.23

0.00 0.00 0.00 0.00 0.00 0.00

0.00 0.00 0.00 0.00 0.00 0.00
SUM [5] 9.49 SUM [7] 1.04 SUM [9] 9.49 SUM [11] 1.36 SUM [13] 9.49 SUM [15] 2.23 [16] AREA ADJ FACTOR 1.000 1.000 1.000
[17] ADJ AVG POINT RAIN 1.04 1.36 2.23
DURATION 3-HOUR 6-HOUR 24-HOUR
EFFECTIVE RAIN (in) 0.36 0.35 0.22
FLOOD VOLUME (cu-ft) 12,335 12,150 7,524
(acre-ft) 0.28 0.28 0.17
REQUIRED STORAGE (cu-ft) 9,965 8,400 646
(acre-ft) 0.23 0.19 0.01
PEAK FLOW (cfs) 7.12 6.08 0.65
MAXIMUM WSEL (ft) 464.04 463.95 463.53

0.180
310.00

0.002
[12] S^0.5
[13] L*LCA/S^0.5
[14] AVERAGE MANNINGS 'N'
[10] H-FEET 4
[11] S-FEET/MILE

PHYSICAL DATA

RAINFALL DATA
[1] CONCENTRATION POINT 1
SUBAREA 5

9.490
950

0.059
471
467

0.05 2.8

2.8 5.7

22.2 4.72

0.27 STORM EVENT SUMMARY
[17] 100% OF LAG-MINUTES
[18] 200% OF LAG-MINUTES
[24] TOTAL PERCOLATION RATE (cfs)
[19] UNIT TIME-MINUTES (100%-200% OF LAG)
3-HOURS
Plate E-2.1

Page 2 of 14 ends

Item 2.

RCFCD SYNTHETIC UNIT HYDROGRAPH METHOD PROJECT CALHOUN AT AVENUE 49 - 10 YEAR EVENT CONCENTRATION POINT: 1BY MES R. BAZUA, P.E. DATE 1/17/2025

ADJUSTED LOSS RATE

SOIL RI PERVIOUS DECIMAL ADJUSTED AREA AVERAGE

GROUP NUMBER AREA PERCENT INFILTRATION ADJUSTED

INFILTRATION OF AREA RATE INFILTRATION

RATE IMPERVIOUS RATE
(in/hr) (in/hr) (in/hr)
[Plate C-1] [Plate E-6.1] [Plate E-6.2] [Plate E-6.3]
B 56 0.52 90% 0.10 0.00 0.000 0.0000
B 56 0.52 100% 0.05 1.95 0.205 0.0107
B 56 0.52 20% 0.43 0.00 0.000 0.0000B 56 0.52 40% 0.33 0.00 0.000 0.0000B 56 0.52 50% 0.29 0.00 0.000 0.0000B 56 0.52 65% 0.22 4.71 0.496 0.1071B 56 0.52 80% 0.15 0.00 0.000 0.0000B 56 0.52 75% 0.17 0.00 0.000 0.0000B 56 0.52 0% 0.52 2.83 0.298 0.1551B 56 0.52 0% 0.52 0.00 0.000 0.0000B 56 0.52 0% 0.52 0.00 0.000 0.0000 D 93 0.95 90% 0.18 0.00 0.000 0.0000

0.00 0.000 0.0000

0.00 0.000 0.0000
SUM 9.49 SUM 0.2729
VARIABLE LOSS RATE CURVE (24-HOUR STORM ONLY)Fm= 0.136428767C= 0.00253Ft=C(24-(T/60))^1.55 = 0.00253 0.14 in/hr LOW LOSS RATE (80-90 PERCENT) = 90%Where:T=Time in minutes. To get an average value for each unit time period, Use T=1/2 the unit time for the first time period,T=1 1/2 unit time for the second period, etc. (24-(T/60))^1.55 +

LAND USE

COMMERCIAL

PAVING/HARDSCAPE
SF - 1 ACRE
SF - 1/2 ACRESF - 1/4 ACRE
MF - COND0MINIUMS

MF - APARTMENTS

MOBILE HOME PARKS

LANDSCAPING

RETENTION BASINS

GOLF COURSE

MOUNTAINOUS
Plate E-2.1

Page 3 of 14 ends

Item 2.

RCFCD SYNTHETIC UNIT HYDROGRAPH METHOD PROJECT: CALHOUN AT AVENUE 49 - 10 YEAR EVENT 100 YEAR - 3 HOUR STORM EVENT CONCENTRATION POINT: 1
BY: MES R. BAZUA, DATE 1/17/2025
DRAINAGE AREA-ACRES 9.49
UNIT TIME-MINUTES 5
LAG TIME - MINUTES 2.83
UNIT TIME-PERCENT OF LAG 176.4
TOTAL ADJUSTED STORM RAIN-INCHES 1.04
CONSTANT LOSS RATE-in/hr 0.27
LOW LOSS RATE - PERCENT 90% TOTAL PERCOLATION RATE (cfs) 0.27 cfs Unit Time Pattern Storm Effective Flood Required
Period Minutes Hours Percent Rain Rain Hydrograph Storage in/hr Flow
(Plate E-5.9) Max Low in/hr cfs cf
1 5 0.08 1.3 0.162 0.27 0.15 0.02 0.15 0.00
2 10 0.17 1.3 0.162 0.27 0.15 0.02 0.15 0.00
3 15 0.25 1.1 0.137 0.27 0.12 0.01 0.13 0.00
4 20 0.33 1.5 0.187 0.27 0.17 0.02 0.18 0.00
5 25 0.42 1.5 0.187 0.27 0.17 0.02 0.18 0.00
6 30 0.50 1.8 0.225 0.27 0.20 0.02 0.21 0.00
7 35 0.58 1.5 0.187 0.27 0.17 0.02 0.18 0.00
8 40 0.67 1.8 0.225 0.27 0.20 0.02 0.21 0.00
9 45 0.75 1.8 0.225 0.27 0.20 0.02 0.21 0.00
10 50 0.83 1.5 0.187 0.27 0.17 0.02 0.18 0.00
11 55 0.92 1.6 0.200 0.27 0.18 0.02 0.19 0.00
12 60 1.00 1.8 0.225 0.27 0.20 0.02 0.21 0.00
13 65 1.08 2.2 0.275 0.27 0.25 0.00 0.02 0.00
14 70 1.17 2.2 0.275 0.27 0.25 0.00 0.02 0.00
15 75 1.25 2.2 0.275 0.27 0.25 0.00 0.02 0.00
16 80 1.33 2.0 0.250 0.27 0.22 0.02 0.24 0.00
17 85 1.42 2.6 0.324 0.27 0.29 0.05 0.49 65.03
18 90 1.50 2.7 0.337 0.27 0.30 0.06 0.61 100.56
19 95 1.58 2.4 0.300 0.27 0.27 0.03 0.25 0.00
20 100 1.67 2.7 0.337 0.27 0.30 0.06 0.61 100.56
21 105 1.75 3.3 0.412 0.27 0.37 0.14 1.32 313.75
22 110 1.83 3.1 0.387 0.27 0.35 0.11 1.08 242.69
23 115 1.92 2.9 0.362 0.27 0.33 0.09 0.85 171.63
24 120 2.00 3.0 0.374 0.27 0.34 0.10 0.96 207.16
25 125 2.08 3.1 0.387 0.27 0.35 0.11 1.08 242.69
26 130 2.17 4.2 0.524 0.27 0.47 0.25 2.38 633.52
27 135 2.25 5.0 0.624 0.27 0.56 0.35 3.33 917.77
28 140 2.33 3.5 0.437 0.27 0.39 0.16 1.56 384.81
29 145 2.42 6.8 0.849 0.27 0.76 0.58 5.46 1557.32
30 150 2.50 7.3 0.911 0.27 0.82 0.64 6.06 1734.97
31 155 2.58 8.2 1.023 0.27 0.92 0.75 7.12 2054.75
32 160 2.67 5.9 0.736 0.27 0.66 0.46 4.40 1237.54
33 165 2.75 2.0 0.250 0.27 0.22 0.02 0.24 0.00
34 170 2.83 1.8 0.225 0.27 0.20 0.02 0.21 0.00
35 175 2.92 1.8 0.225 0.27 0.20 0.02 0.21 0.00
36 180 3.00 0.6 0.075 0.27 0.07 0.01 0.07 0.00

EFFECTIVE RAIN & FLOOD VOLUMES SUMMARY
EFFECTIVE RAIN (in) 0.36
FLOOD VOLUME (acft) 0.28
FLOOD VOLUME (cuft) 12334.87
REQUIRED STORAGE (acft) 0.23
REQUIRED STORAGE (cuft) 9964.74
PEAK FLOW RATE (cfs) 7.12
Loss Rate
in/hr
Time

EFFECTIVE RAIN CALCULATION FORM
Plate E-2.2

Page 4 of 14 ends

Item 2.

RCFCD SYNTHETIC UNIT HYDROGRAPH METHOD PROJECT: CALHOUN AT AVENUE 49 - 10 YEAR EVENT 100 YEAR - 6 HOUR STORM EVENT CONCENTRATION POINT: 1
BY: JAMES R. BAZ DATE: 1/17/2025
DRAINAGE AREA-ACRES 9.49
UNIT TIME-MINUTES 5
LAG TIME - MINUTES 2.83
UNIT TIME-PERCENT OF LAG 176.4
TOTAL ADJUSTED STORM RAIN-INCHES 1.36
CONSTANT LOSS RATE-in/hr 0.273
LOW LOSS RATE - PERCENT 90% TOTAL PERCOLATION RATE (cfs) 0.27 cfs Unit Time Pattern Storm Effective Flood Required
Period Minutes Hours Percent Rain Rain Hydrograph Storage in/hr Flow
(Plate E-5.9) Max Low in/hr cfs cf
1 5 0.08 0.5 0.082 0.27 0.07 0.01 0.08 0.00
2 10 0.17 0.6 0.098 0.27 0.09 0.01 0.09 0.00
3 15 0.25 0.6 0.098 0.27 0.09 0.01 0.09 0.00
4 20 0.33 0.6 0.098 0.27 0.09 0.01 0.09 0.00
5 25 0.42 0.6 0.098 0.27 0.09 0.01 0.09 0.00
6 30 0.50 0.7 0.114 0.27 0.10 0.01 0.11 0.00
7 35 0.58 0.7 0.114 0.27 0.10 0.01 0.11 0.00
8 40 0.67 0.7 0.114 0.27 0.10 0.01 0.11 0.00
9 45 0.75 0.7 0.114 0.27 0.10 0.01 0.11 0.00
10 50 0.83 0.7 0.114 0.27 0.10 0.01 0.11 0.00
11 55 0.92 0.7 0.114 0.27 0.10 0.01 0.11 0.00
12 60 1.00 0.8 0.131 0.27 0.12 0.01 0.12 0.00
13 65 1.08 0.8 0.131 0.27 0.12 0.01 0.12 0.00
14 70 1.17 0.8 0.131 0.27 0.12 0.01 0.12 0.00
15 75 1.25 0.8 0.131 0.27 0.12 0.01 0.12 0.00
16 80 1.33 0.8 0.131 0.27 0.12 0.01 0.12 0.00
17 85 1.42 0.8 0.131 0.27 0.12 0.01 0.12 0.00
18 90 1.50 0.8 0.131 0.27 0.12 0.01 0.12 0.00
19 95 1.58 0.8 0.131 0.27 0.12 0.01 0.12 0.00
20 100 1.67 0.8 0.131 0.27 0.12 0.01 0.12 0.00
21 105 1.75 0.8 0.131 0.27 0.12 0.01 0.12 0.00
22 110 1.83 0.8 0.131 0.27 0.12 0.01 0.12 0.00
23 115 1.92 0.8 0.131 0.27 0.12 0.01 0.12 0.00
24 120 2.00 0.9 0.147 0.27 0.13 0.01 0.14 0.00
25 125 2.08 0.8 0.131 0.27 0.12 0.01 0.12 0.00
26 130 2.17 0.9 0.147 0.27 0.13 0.01 0.14 0.00
27 135 2.25 0.9 0.147 0.27 0.13 0.01 0.14 0.00
28 140 2.33 0.9 0.147 0.27 0.13 0.01 0.14 0.00
29 145 2.42 0.9 0.147 0.27 0.13 0.01 0.14 0.00
30 150 2.50 0.9 0.147 0.27 0.13 0.01 0.14 0.00
31 155 2.58 0.9 0.147 0.27 0.13 0.01 0.14 0.00
32 160 2.67 0.9 0.147 0.27 0.13 0.01 0.14 0.00
33 165 2.75 1.0 0.163 0.27 0.15 0.02 0.15 0.00
34 170 2.83 1.0 0.163 0.27 0.15 0.02 0.15 0.00
35 175 2.92 1.0 0.163 0.27 0.15 0.02 0.15 0.00
36 180 3.00 1.0 0.163 0.27 0.15 0.02 0.15 0.00
37 185 3.08 1.0 0.163 0.27 0.15 0.02 0.15 0.00
38 190 3.17 1.1 0.180 0.27 0.16 0.02 0.17 0.00
39 195 3.25 1.1 0.180 0.27 0.16 0.02 0.17 0.00
40 200 3.33 1.1 0.180 0.27 0.16 0.02 0.17 0.00
41 205 3.42 1.2 0.196 0.27 0.18 0.02 0.19 0.00
42 210 3.50 1.3 0.212 0.27 0.19 0.02 0.20 0.00
43 215 3.58 1.4 0.228 0.27 0.21 0.02 0.22 0.00
44 220 3.67 1.4 0.228 0.27 0.21 0.02 0.22 0.00
45 225 3.75 1.5 0.245 0.27 0.22 0.02 0.23 0.00
46 230 3.83 1.5 0.245 0.27 0.22 0.02 0.23 0.00
47 235 3.92 1.6 0.261 0.27 0.24 0.03 0.25 0.00
48 240 4.00 1.6 0.261 0.27 0.24 0.03 0.25 0.00
49 245 4.08 1.7 0.277 0.27 0.25 0.00 0.04 0.00
50 250 4.17 1.8 0.294 0.27 0.26 0.02 0.20 0.00
51 255 4.25 1.9 0.310 0.27 0.28 0.04 0.35 24.04
52 260 4.33 2.0 0.326 0.27 0.29 0.05 0.51 70.50
53 265 4.42 2.1 0.343 0.27 0.31 0.07 0.66 116.96
54 270 4.50 2.1 0.343 0.27 0.31 0.07 0.66 116.96
55 275 4.58 2.2 0.359 0.27 0.32 0.09 0.82 163.43
56 280 4.67 2.3 0.375 0.27 0.34 0.10 0.97 209.89

EFFECTIVE RAIN CALCULATION FORM
Time Loss Rate
in/hr
Plate E-2.2

Page 5 of 14 ends

Item 2.

EFFECTIVE RAIN CALCULATION FORM
Time Loss Rate
in/hr
57 285 4.75 2.4 0.392 0.27 0.35 0.12 1.13 256.35
58 290 4.83 2.4 0.392 0.27 0.35 0.12 1.13 256.35
59 295 4.92 2.5 0.408 0.27 0.37 0.14 1.28 302.82
60 300 5.00 2.6 0.424 0.27 0.38 0.15 1.44 349.28
61 305 5.08 3.1 0.506 0.27 0.46 0.23 2.21 581.59
62 310 5.17 3.6 0.588 0.27 0.53 0.31 2.99 813.91
63 315 5.25 3.9 0.636 0.27 0.57 0.36 3.45 953.30
64 320 5.33 4.2 0.685 0.27 0.62 0.41 3.92 1092.69
65 325 5.42 4.7 0.767 0.27 0.69 0.49 4.69 1325.00
66 330 5.50 5.6 0.914 0.27 0.82 0.64 6.08 1743.17
67 335 5.58 1.9 0.310 0.27 0.28 0.04 0.35 24.04
68 340 5.67 0.9 0.147 0.27 0.13 0.01 0.14 0.00
69 345 5.75 0.6 0.098 0.27 0.09 0.01 0.09 0.00
70 350 5.83 0.5 0.082 0.27 0.07 0.01 0.08 0.00
71 355 5.92 0.3 0.049 0.27 0.04 0.00 0.05 0.00
72 360 6.00 0.2 0.033 0.27 0.03 0.00 0.03 0.00

EFFECTIVE RAIN & FLOOD VOLUMES SUMMARY
EFFECTIVE RAIN (in) 0.35
FLOOD VOLUME (acft) 0.28
FLOOD VOLUME (cuft) 12149.95
REQUIRED STORAGE (acft) 0.19
REQUIRED STORAGE (cuft) 8400.27
PEAK FLOW RATE (cfs) 6.08
Plate E-2.2

Page 6 of 14 ends

Item 2.

RCFCD SYNTHETIC UNIT HYDROGRAPH METHOD PROJECT: CALHOUN AT AVENUE 49 - 10 YEAR EVENT 100 YEAR - 24 HOUR STORM EVENT CONCENTRATION POINT: 1
BY: JAMES R. BAZ DATE: 1/17/2025
DRAINAGE AREA-ACRES 9.490 CONSTANT LOSS RATE-in/hr n/a
UNIT TIME-MINUTES 15 VARIABLE LOSS RATE (AVG) in/hr 0.2729 LAG TIME - MINUTES 2.83 MINIMUM LOSS RATE (for var. loss) - in/hr 0.136 UNIT TIME-PERCENT OF LAG 529.1 LOW LOSS RATE - DECIMAL 0.90 TOTAL ADJUSTED STORM RAIN-INCHES 2.23 C 0.00253
PERCOLATION RATE (cfs) 0.27
Unit Time Pattern Storm Effective Flood Required
Period Minutes Hours Percent Rain Rain Hydrograph Storage in/hr Flow
(Plate E-5.9) Max Low in/hr cfs cf
1 15 0.25 0.2 0.018 0.482 0.016 0.002 0.02 0.00
2 30 0.50 0.3 0.027 0.476 0.024 0.003 0.03 0.00
3 45 0.75 0.3 0.027 0.471 0.024 0.003 0.03 0.00
4 60 1.00 0.4 0.036 0.465 0.032 0.004 0.03 0.00
5 75 1.25 0.3 0.027 0.460 0.024 0.003 0.03 0.00
6 90 1.50 0.3 0.027 0.454 0.024 0.003 0.03 0.00
7 105 1.75 0.3 0.027 0.449 0.024 0.003 0.03 0.00
8 120 2.00 0.4 0.036 0.443 0.032 0.004 0.03 0.00
9 135 2.25 0.4 0.036 0.438 0.032 0.004 0.03 0.00
10 150 2.50 0.4 0.036 0.433 0.032 0.004 0.03 0.00
11 165 2.75 0.5 0.045 0.427 0.040 0.004 0.04 0.00
12 180 3.00 0.5 0.045 0.422 0.040 0.004 0.04 0.00
13 195 3.25 0.5 0.045 0.417 0.040 0.004 0.04 0.00
14 210 3.50 0.5 0.045 0.412 0.040 0.004 0.04 0.00
15 225 3.75 0.5 0.045 0.407 0.040 0.004 0.04 0.00
16 240 4.00 0.6 0.054 0.401 0.048 0.005 0.05 0.00
17 255 4.25 0.6 0.054 0.396 0.048 0.005 0.05 0.00
18 270 4.50 0.7 0.062 0.391 0.056 0.006 0.06 0.00
19 285 4.75 0.7 0.062 0.386 0.056 0.006 0.06 0.00
20 300 5.00 0.8 0.071 0.381 0.064 0.007 0.07 0.00
21 315 5.25 0.6 0.054 0.376 0.048 0.005 0.05 0.00
22 330 5.50 0.7 0.062 0.371 0.056 0.006 0.06 0.00
23 345 5.75 0.8 0.071 0.367 0.064 0.007 0.07 0.00
24 360 6.00 0.8 0.071 0.362 0.064 0.007 0.07 0.00
25 375 6.25 0.9 0.080 0.357 0.072 0.008 0.08 0.00
26 390 6.50 0.9 0.080 0.352 0.072 0.008 0.08 0.00
27 405 6.75 1.0 0.089 0.347 0.080 0.009 0.08 0.00
28 420 7.00 1.0 0.089 0.343 0.080 0.009 0.08 0.00
29 435 7.25 1.0 0.089 0.338 0.080 0.009 0.08 0.00
30 450 7.50 1.1 0.098 0.334 0.088 0.010 0.09 0.00
31 465 7.75 1.2 0.107 0.329 0.096 0.011 0.10 0.00
32 480 8.00 1.3 0.116 0.324 0.104 0.012 0.11 0.00
33 495 8.25 1.5 0.134 0.320 0.120 0.013 0.13 0.00
34 510 8.50 1.5 0.134 0.315 0.120 0.013 0.13 0.00
35 525 8.75 1.6 0.143 0.311 0.128 0.014 0.14 0.00
36 540 9.00 1.7 0.152 0.307 0.136 0.015 0.14 0.00
37 555 9.25 1.9 0.169 0.302 0.153 0.017 0.16 0.00
38 570 9.50 2.0 0.178 0.298 0.161 0.018 0.17 0.00
39 585 9.75 2.1 0.187 0.294 0.169 0.019 0.18 0.00
40 600 10.00 2.2 0.196 0.290 0.177 0.020 0.19 0.00
41 615 10.25 1.5 0.134 0.285 0.120 0.013 0.13 0.00
42 630 10.50 1.5 0.134 0.281 0.120 0.013 0.13 0.00
43 645 10.75 2.0 0.178 0.277 0.161 0.018 0.17 0.00
44 660 11.00 2.0 0.178 0.273 0.161 0.018 0.17 0.00
45 675 11.25 1.9 0.169 0.269 0.153 0.017 0.16 0.00
46 690 11.50 1.9 0.169 0.265 0.153 0.017 0.16 0.00
47 705 11.75 1.7 0.152 0.261 0.136 0.015 0.14 0.00
48 720 12.00 1.8 0.161 0.257 0.145 0.016 0.15 0.00
49 735 12.25 2.5 0.223 0.253 0.201 0.022 0.21 0.00
50 750 12.50 2.6 0.232 0.250 0.209 0.023 0.22 0.00
51 765 12.75 2.8 0.250 0.246 0.225 0.004 0.04 0.00
52 780 13.00 2.9 0.259 0.242 0.233 0.017 0.16 0.00
53 795 13.25 3.4 0.303 0.239 0.273 0.065 0.61 307.33
54 810 13.50 3.4 0.303 0.235 0.273 0.068 0.65 338.20
55 825 13.75 2.3 0.205 0.231 0.185 0.021 0.19 0.00
56 840 14.00 2.3 0.205 0.228 0.185 0.021 0.19 0.00
57 855 14.25 2.7 0.241 0.224 0.217 0.016 0.16 0.00
58 870 14.50 2.6 0.232 0.221 0.209 0.011 0.10 0.00
59 885 14.75 2.6 0.232 0.218 0.209 0.014 0.14 0.00
60 900 15.00 2.5 0.223 0.214 0.201 0.009 0.08 0.00
61 915 15.25 2.4 0.214 0.211 0.193 0.003 0.03 0.00
Time Loss Rate
in/hr

EFFECTIVE RAIN CALCULATION FORM
Plate E-2.2

Page 7 of 14 ends

Item 2.

EFFECTIVE RAIN CALCULATION FORM
62 930 15.50 2.3 0.205 0.208 0.185 0.021 0.19 0.00
63 945 15.75 1.9 0.169 0.205 0.153 0.017 0.16 0.00
64 960 16.00 1.9 0.169 0.201 0.153 0.017 0.16 0.00
65 975 16.25 0.4 0.036 0.198 0.032 0.004 0.03 0.00
66 990 16.50 0.4 0.036 0.195 0.032 0.004 0.03 0.00
67 1005 16.75 0.3 0.027 0.192 0.024 0.003 0.03 0.00
68 1020 17.00 0.3 0.027 0.189 0.024 0.003 0.03 0.00
69 1035 17.25 0.5 0.045 0.187 0.040 0.004 0.04 0.00
70 1050 17.50 0.5 0.045 0.184 0.040 0.004 0.04 0.00
71 1065 17.75 0.5 0.045 0.181 0.040 0.004 0.04 0.00
72 1080 18.00 0.4 0.036 0.178 0.032 0.004 0.03 0.00
73 1095 18.25 0.4 0.036 0.176 0.032 0.004 0.03 0.00
74 1110 18.50 0.4 0.036 0.173 0.032 0.004 0.03 0.00
75 1125 18.75 0.3 0.027 0.171 0.024 0.003 0.03 0.00
76 1140 19.00 0.2 0.018 0.168 0.016 0.002 0.02 0.00
77 1155 19.25 0.3 0.027 0.166 0.024 0.003 0.03 0.00
78 1170 19.50 0.4 0.036 0.164 0.032 0.004 0.03 0.00
79 1185 19.75 0.3 0.027 0.161 0.024 0.003 0.03 0.00
80 1200 20.00 0.2 0.018 0.159 0.016 0.002 0.02 0.00
81 1215 20.25 0.3 0.027 0.157 0.024 0.003 0.03 0.00
82 1230 20.50 0.3 0.027 0.155 0.024 0.003 0.03 0.00
83 1245 20.75 0.3 0.027 0.153 0.024 0.003 0.03 0.00
84 1260 21.00 0.2 0.018 0.151 0.016 0.002 0.02 0.00
85 1275 21.25 0.3 0.027 0.149 0.024 0.003 0.03 0.00
86 1290 21.50 0.2 0.018 0.148 0.016 0.002 0.02 0.00
87 1305 21.75 0.3 0.027 0.146 0.024 0.003 0.03 0.00
88 1320 22.00 0.2 0.018 0.145 0.016 0.002 0.02 0.00
89 1335 22.25 0.3 0.027 0.143 0.024 0.003 0.03 0.00
90 1350 22.50 0.2 0.018 0.142 0.016 0.002 0.02 0.00
91 1365 22.75 0.2 0.018 0.141 0.016 0.002 0.02 0.00
92 1380 23.00 0.2 0.018 0.139 0.016 0.002 0.02 0.00
93 1395 23.25 0.2 0.018 0.138 0.016 0.002 0.02 0.00
94 1410 23.50 0.2 0.018 0.138 0.016 0.002 0.02 0.00
95 1425 23.75 0.2 0.018 0.137 0.016 0.002 0.02 0.00
96 1440 24.00 0.2 0.018 0.137 0.016 0.002 0.02 0.00

EFFECTIVE RAIN & FLOOD VOLUMES SUMMARY
EFFECTIVE RAIN (in) 0.22
FLOOD VOLUME (acft) 0.17
FLOOD VOLUME (cuft) 7524.21
REQUIRED STORAGE (acft) 0.01
REQUIRED STORAGE (cuft) 645.53
PEAK FLOW (cfs) 0.65
Plate E-2.2

Page 8 of 14 ends

Item 2.

PROJECT: CALHOUN AT AVENUE 49 - 10 YEAR EVENT
JOB # 0
1 BASIN CHARACTERISTICS

CONTOUR DEPTH AREA VOLUME

INCR TOTAL INCR TOTAL INCR TOTAL
(ft) (ft) (sf) (sf) (cuft) (cuft) (acre-ft)
463.5 0 0 17610 0 0 0.00
464.5 1 1 1790 19400 18505 18505 0.42
465.5 1 2 1840 21240 20320 38825 0.89
466.5 1 3 1900 23140 22190 61015 1.40
467 0.5 3.5 970 24110 11813 72828 1.67

PERCOLATION CALCULATIONS
PERCOLATION RATE 0.67 in/hr 0.27 cfs

MAXWELL IV DRYWELLS
NUMBER USED 0
RATE/DRYWELL 0 cfs
TOTAL DISSIPATED 0 cfs
TOTAL PERCOLATION RATE 0.27 cfs
Basin Characteristics

Page 9 of 14 ends

Item 2.
1 JOB # 0
100 YEAR - 3 HOUR STORM EVENT

FLOW VOLUME TOTAL IN PERC TOTAL IN BASIN
UNIT (min) IN IN BASIN OUT BASIN DEPTH
PERIOD (cfs) (cuft) (cuft) (cuft) (cuft) (ft) (cuft) (acre-ft) 1 5 0.15 46 46 82 - 463.50 - 0.00
2 10 0.15 46 46 82 - 463.50 - 0.00
3 15 0.13 39 39 82 - 463.50 - 0.00
4 20 0.18 53 53 82 - 463.50 - 0.00
5 25 0.18 53 53 82 - 463.50 - 0.00
6 30 0.21 64 64 82 - 463.50 - 0.00
7 35 0.18 53 53 82 - 463.50 - 0.00
8 40 0.21 64 64 82 - 463.50 - 0.00
9 45 0.21 64 64 82 - 463.50 - 0.00
10 50 0.18 53 53 82 - 463.50 - 0.00
11 55 0.19 57 57 82 - 463.50 - 0.00
12 60 0.21 64 64 82 - 463.50 - 0.00
13 65 0.02 5 5 82 - 463.50 - 0.00
14 70 0.02 5 5 82 - 463.50 - 0.00
15 75 0.02 5 5 82 - 463.50 - 0.00
16 80 0.24 71 71 82 - 463.50 - 0.00
17 85 0.49 147 147 82 65 463.50 65 0.00
18 90 0.61 182 248 82 166 463.51 166 0.00
19 95 0.25 76 242 82 160 463.51 160 0.00
20 100 0.61 182 342 82 260 463.51 260 0.01
21 105 1.32 396 656 82 574 463.53 574 0.01
22 110 1.08 325 899 82 817 463.54 817 0.02
23 115 0.85 254 1,070 82 988 463.55 988 0.02
24 120 0.96 289 1,277 82 1,195 463.56 1,195 0.03
25 125 1.08 325 1,520 82 1,438 463.58 1,438 0.03
26 130 2.38 715 2,153 82 2,072 463.61 2,072 0.05
27 135 3.33 1,000 3,071 82 2,989 463.66 2,989 0.07
28 140 1.56 467 3,456 82 3,374 463.68 3,374 0.08
29 145 5.46 1,639 5,013 82 4,931 463.77 4,931 0.11
30 150 6.06 1,817 6,748 82 6,666 463.86 6,666 0.15
31 155 7.12 2,137 8,803 82 8,721 463.97 8,721 0.20
32 160 4.40 1,319 10,041 82 9,959 464.04 9,959 0.23
33 165 0.24 71 10,030 82 9,948 464.04 9,948 0.23
34 170 0.21 64 10,012 82 9,930 464.04 9,930 0.23
35 175 0.21 64 9,994 82 9,912 464.04 9,912 0.23
36 180 0.07 21 9,933 82 9,851 464.03 9,851 0.23

BALANCE IN
BASIN
TIME
Basin Depth Analysis

Page 10 of 14 ends

Item 2.
1 JOB # 0
100 YEAR - 6 HOUR STORM EVENT

FLOW VOLUME TOTAL IN PERC TOTAL IN BASIN
UNIT (min) IN IN BASIN OUT BASIN DEPTH
PERIOD (cfs) (cuft) (cuft) (cuft) (cuft) (ft) (cuft) (acre-ft) 1 5 0.08 23 23 82 - 463.50 - 0.00
2 10 0.09 28 28 82 - 463.50 - 0.00
3 15 0.09 28 28 82 - 463.50 - 0.00
4 20 0.09 28 28 82 - 463.50 - 0.00
5 25 0.09 28 28 82 - 463.50 - 0.00
6 30 0.11 33 33 82 - 463.50 - 0.00
7 35 0.11 33 33 82 - 463.50 - 0.00
8 40 0.11 33 33 82 - 463.50 - 0.00
9 45 0.11 33 33 82 - 463.50 - 0.00
10 50 0.11 33 33 82 - 463.50 - 0.00
11 55 0.11 33 33 82 - 463.50 - 0.00
12 60 0.12 37 37 82 - 463.50 - 0.00
13 65 0.12 37 37 82 - 463.50 - 0.00
14 70 0.12 37 37 82 - 463.50 - 0.00
15 75 0.12 37 37 82 - 463.50 - 0.00
16 80 0.12 37 37 82 - 463.50 - 0.00
17 85 0.12 37 37 82 - 463.50 - 0.00
18 90 0.12 37 37 82 - 463.50 - 0.00
19 95 0.12 37 37 82 - 463.50 - 0.00
20 100 0.12 37 37 82 - 463.50 - 0.00
21 105 0.12 37 37 82 - 463.50 - 0.00
22 110 0.12 37 37 82 - 463.50 - 0.00
23 115 0.12 37 37 82 - 463.50 - 0.00
24 120 0.14 42 42 82 - 463.50 - 0.00
25 125 0.12 37 37 82 - 463.50 - 0.00
26 130 0.14 42 42 82 - 463.50 - 0.00
27 135 0.14 42 42 82 - 463.50 - 0.00
28 140 0.14 42 42 82 - 463.50 - 0.00
29 145 0.14 42 42 82 - 463.50 - 0.00
30 150 0.14 42 42 82 - 463.50 - 0.00
31 155 0.14 42 42 82 - 463.50 - 0.00
32 160 0.14 42 42 82 - 463.50 - 0.00
33 165 0.15 46 46 82 - 463.50 - 0.00
34 170 0.15 46 46 82 - 463.50 - 0.00
35 175 0.15 46 46 82 - 463.50 - 0.00
36 180 0.15 46 46 82 - 463.50 - 0.00
37 185 0.15 46 46 82 - 463.50 - 0.00
38 190 0.17 51 51 82 - 463.50 - 0.00
39 195 0.17 51 51 82 - 463.50 - 0.00
40 200 0.17 51 51 82 - 463.50 - 0.00
41 205 0.19 56 56 82 - 463.50 - 0.00
42 210 0.20 60 60 82 - 463.50 - 0.00
43 215 0.22 65 65 82 - 463.50 - 0.00
44 220 0.22 65 65 82 - 463.50 - 0.00
45 225 0.23 70 70 82 - 463.50 - 0.00
46 230 0.23 70 70 82 - 463.50 - 0.00
47 235 0.25 74 74 82 - 463.50 - 0.00
48 240 0.25 74 74 82 - 463.50 - 0.00
49 245 0.04 13 13 82 - 463.50 - 0.00
50 250 0.20 60 60 82 - 463.50 - 0.00
51 255 0.35 106 106 82 24 463.50 24 0.00
52 260 0.51 152 176 82 95 463.51 95 0.00
53 265 0.66 199 293 82 211 463.51 211 0.00
54 270 0.66 199 410 82 328 463.52 328 0.01
55 275 0.82 245 574 82 492 463.53 492 0.01

TIME BALANCE IN
BASIN
Basin Depth Analysis

Page 11 of 14 ends

Item 2.
1 JOB # 0
100 YEAR - 6 HOUR STORM EVENT

FLOW VOLUME TOTAL IN PERC TOTAL IN BASIN
UNIT (min) IN IN BASIN OUT BASIN DEPTH
PERIOD (cfs) (cuft) (cuft) (cuft) (cuft) (ft) (cuft) (acre-ft)

TIME BALANCE IN
BASIN
56 280 0.97 292 784 82 702 463.54 702 0.02
57 285 1.13 338 1,040 82 958 463.55 958 0.02
58 290 1.13 338 1,296 82 1,214 463.57 1,214 0.03
59 295 1.28 385 1,599 82 1,517 463.58 1,517 0.03
60 300 1.44 431 1,949 82 1,867 463.60 1,867 0.04
61 305 2.21 664 2,530 82 2,448 463.63 2,448 0.06
62 310 2.99 896 3,344 82 3,262 463.68 3,262 0.07
63 315 3.45 1,035 4,297 82 4,215 463.73 4,215 0.10
64 320 3.92 1,175 5,390 82 5,308 463.79 5,308 0.12
65 325 4.69 1,407 6,715 82 6,633 463.86 6,633 0.15
66 330 6.08 1,825 8,458 82 8,376 463.95 8,376 0.19
67 335 0.35 106 8,482 82 8,400 463.95 8,400 0.19
68 340 0.14 42 8,442 82 8,360 463.95 8,360 0.19
69 345 0.09 28 8,388 82 8,306 463.95 8,306 0.19
70 350 0.08 23 8,329 82 8,247 463.95 8,247 0.19
71 355 0.05 14 8,261 82 8,179 463.94 8,179 0.19
72 360 0.03 9 8,189 82 8,107 463.94 8,107 0.19
Basin Depth Analysis

Page 12 of 14 ends

Item 2.
1 JOB # 0
100 YEAR - 24 HOUR STORM EVENT

FLOW VOLUME TOTAL IN PERC TOTAL IN BASIN
UNIT (min) IN IN BASIN OUT BASIN DEPTH
PERIOD (cfs) (cuft) (cuft) (cuft) (cuft) (ft) (cuft) (acre-ft) 1 15 0.02 15 15 246 - 463.50 - 0.00
2 30 0.03 23 23 246 - 463.50 - 0.00
3 45 0.03 23 23 246 - 463.50 - 0.00
4 60 0.03 30 30 246 - 463.50 - 0.00
5 75 0.03 23 23 246 - 463.50 - 0.00
6 90 0.03 23 23 246 - 463.50 - 0.00
7 105 0.03 23 23 246 - 463.50 - 0.00
8 120 0.03 30 30 246 - 463.50 - 0.00
9 135 0.03 30 30 246 - 463.50 - 0.00
10 150 0.03 30 30 246 - 463.50 - 0.00
11 165 0.04 38 38 246 - 463.50 - 0.00
12 180 0.04 38 38 246 - 463.50 - 0.00
13 195 0.04 38 38 246 - 463.50 - 0.00
14 210 0.04 38 38 246 - 463.50 - 0.00
15 225 0.04 38 38 246 - 463.50 - 0.00
16 240 0.05 46 46 246 - 463.50 - 0.00
17 255 0.05 46 46 246 - 463.50 - 0.00
18 270 0.06 53 53 246 - 463.50 - 0.00
19 285 0.06 53 53 246 - 463.50 - 0.00
20 300 0.07 61 61 246 - 463.50 - 0.00
21 315 0.05 46 46 246 - 463.50 - 0.00
22 330 0.06 53 53 246 - 463.50 - 0.00
23 345 0.07 61 61 246 - 463.50 - 0.00
24 360 0.07 61 61 246 - 463.50 - 0.00
25 375 0.08 69 69 246 - 463.50 - 0.00
26 390 0.08 69 69 246 - 463.50 - 0.00
27 405 0.08 76 76 246 - 463.50 - 0.00
28 420 0.08 76 76 246 - 463.50 - 0.00
29 435 0.08 76 76 246 - 463.50 - 0.00
30 450 0.09 84 84 246 - 463.50 - 0.00
31 465 0.10 91 91 246 - 463.50 - 0.00
32 480 0.11 99 99 246 - 463.50 - 0.00
33 495 0.13 114 114 246 - 463.50 - 0.00
34 510 0.13 114 114 246 - 463.50 - 0.00
35 525 0.14 122 122 246 - 463.50 - 0.00
36 540 0.14 130 130 246 - 463.50 - 0.00
37 555 0.16 145 145 246 - 463.50 - 0.00
38 570 0.17 152 152 246 - 463.50 - 0.00
39 585 0.18 160 160 246 - 463.50 - 0.00
40 600 0.19 168 168 246 - 463.50 - 0.00
41 615 0.13 114 114 246 - 463.50 - 0.00
42 630 0.13 114 114 246 - 463.50 - 0.00
43 645 0.17 152 152 246 - 463.50 - 0.00
44 660 0.17 152 152 246 - 463.50 - 0.00
45 675 0.16 145 145 246 - 463.50 - 0.00
46 690 0.16 145 145 246 - 463.50 - 0.00
47 705 0.14 130 130 246 - 463.50 - 0.00
48 720 0.15 137 137 246 - 463.50 - 0.00
49 735 0.21 190 190 246 - 463.50 - 0.00
50 750 0.22 198 198 246 - 463.50 - 0.00
51 765 0.04 33 33 246 - 463.50 - 0.00
52 780 0.16 141 141 246 - 463.50 - 0.00
53 795 0.61 553 553 246 307 463.52 307 0.01
54 810 0.65 584 891 246 646 463.53 646 0.01
55 825 0.19 175 821 246 575 463.53 575 0.01
56 840 0.19 175 750 246 504 463.53 504 0.01
57 855 0.16 141 645 246 399 463.52 399 0.01
58 870 0.10 94 493 246 248 463.51 248 0.01

TIME BALANCE IN
BASIN
Basin Depth Analysis

Page 13 of 14 ends

Item 2.
1 JOB # 0
100 YEAR - 24 HOUR STORM EVENT

FLOW VOLUME TOTAL IN PERC TOTAL IN BASIN
UNIT (min) IN IN BASIN OUT BASIN DEPTH
PERIOD (cfs) (cuft) (cuft) (cuft) (cuft) (ft) (cuft) (acre-ft)

TIME BALANCE IN
BASIN
59 885 0.14 123 371 246 125 463.51 125 0.00
60 900 0.08 75 200 246 - 463.50 - 0.00
61 915 0.03 27 27 246 - 463.50 - 0.00
62 930 0.19 175 175 246 - 463.50 - 0.00
63 945 0.16 145 145 246 - 463.50 - 0.00
64 960 0.16 145 145 246 - 463.50 - 0.00
65 975 0.03 30 30 246 - 463.50 - 0.00
66 990 0.03 30 30 246 - 463.50 - 0.00
67 1005 0.03 23 23 246 - 463.50 - 0.00
68 1020 0.03 23 23 246 - 463.50 - 0.00
69 1035 0.04 38 38 246 - 463.50 - 0.00
70 1050 0.04 38 38 246 - 463.50 - 0.00
71 1065 0.04 38 38 246 - 463.50 - 0.00
72 1080 0.03 30 30 246 - 463.50 - 0.00
73 1095 0.03 30 30 246 - 463.50 - 0.00
74 1110 0.03 30 30 246 - 463.50 - 0.00
75 1125 0.03 23 23 246 - 463.50 - 0.00
76 1140 0.02 15 15 246 - 463.50 - 0.00
77 1155 0.03 23 23 246 - 463.50 - 0.00
78 1170 0.03 30 30 246 - 463.50 - 0.00
79 1185 0.03 23 23 246 - 463.50 - 0.00
80 1200 0.02 15 15 246 - 463.50 - 0.00
81 1215 0.03 23 23 246 - 463.50 - 0.00
82 1230 0.03 23 23 246 - 463.50 - 0.00
83 1245 0.03 23 23 246 - 463.50 - 0.00
84 1260 0.02 15 15 246 - 463.50 - 0.00
85 1275 0.03 23 23 246 - 463.50 - 0.00
86 1290 0.02 15 15 246 - 463.50 - 0.00
87 1305 0.03 23 23 246 - 463.50 - 0.00
88 1320 0.02 15 15 246 - 463.50 - 0.00
89 1335 0.03 23 23 246 - 463.50 - 0.00
90 1350 0.02 15 15 246 - 463.50 - 0.00
91 1365 0.02 15 15 246 - 463.50 - 0.00
92 1380 0.02 15 15 246 - 463.50 - 0.00
93 1395 0.02 15 15 246 - 463.50 - 0.00
94 1410 0.02 15 15 246 - 463.50 - 0.00
95 1425 0.02 15 15 246 - 463.50 - 0.00
96 1440 0.02 15 15 246 - 463.50 - 0.00
Basin Depth Analysis

Page 14 of 14 ends

Item 2.
1 2
3 4
5 6
7 8
9 10
11 12
13 14
15 16
17 18
19 20
21 22
23 24
25 26
27 28
29 30
31 32
33 34
35 36
37 38
39 40
41 42
43 44
45 46
47 48
49 50
51 52
53 54
55 56
AB C D

RCFCD SYNTHETIC UNIT HYDROGRAPH

DATA INPUT SHEET
WORKSHEET PREPARED BY: JAMES R. BAZUA, P.E.

PROJECT NAME CALHOUN AT AVENUE 49 - 100 YEAR EVENT
JOB #
CONCENTRATION POINT DESIGNATION 1
AREA DESIGNATION SUBAREA 1

TRIBUTARY AREAS ACRES

COMMERCIAL
PAVING/HARDSCAPE 1.18
SF - 1 ACRE
SF - 1/2 ACRE
SF - 1/4 ACRE

MF - CONDOMINIUMS

MF - APARTMENTS

MOBILE HOME PARK
LANDSCAPING 0.83

RETENTION BASIN

GOLF COURSE

POINT RAIN
3-HOUR 2.12
6-HOUR 2.78
24-HOUR 4.47
BASIN CHARACTERISTICS: ELEVATION AREA
465 3025
466 3700
467 4430
468 5215
468.5 5630
PERCOLATION RATE (in/hr) 0.67

DRYWELL DATA

NUMBER USED
PERCOLATION RATE (cfs)
652
Item 2.

RCFCD SYNTHETIC UNIT HYDROGRAPH METHOD PROJECT: CALHOUN AT AVENUE 49 - 100 YEAR EVENT BASIC DATA CALCULATION FORM JOB # 0
SHORTCUT METHOD BY ES R. BAZUA, P.E. DATE 1/17/2025
[1] SOURCE
[2] FREQUENCY-YEARS 100
[3] DURATION:
[4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] [15]

POINT AREA AVERAGE POINT AREA AVERAGE POINT AREA AVERAGE

RAIN POINT RAIN POINT RAIN POINT

INCHES RAIN INCHES RAIN INCHES RAIN
(Plate E-5.2) INCHES (Plate E-5.4) INCHES (Plate E-5.6) INCHES

2.12 2.010 1.00 2.12 2.78 2.010 1.00 2.78 4.47 2.010 1.00 4.47

0.00 0.00 0.00 0.00 0.00 0.00

0.00 0.00 0.00 0.00 0.00 0.00
SUM [5] 2.01 SUM [7] 2.12 SUM [9] 2.01 SUM [11] 2.78 SUM [13] 2.01 SUM [15] 4.47 [16] AREA ADJ FACTOR 1.000 1.000 1.000
[17] ADJ AVG POINT RAIN 2.12 2.78 4.47
DURATION 3-HOUR 6-HOUR 24-HOUR
EFFECTIVE RAIN (in) 1.39 1.40 1.43
FLOOD VOLUME (cu-ft) 10,165 10,196 10,445
(acre-ft) 0.23 0.23 0.24
REQUIRED STORAGE (cu-ft) 9,580 9,148 8,100
(acre-ft) 0.22 0.21 0.19
PEAK FLOW (cfs) 3.70 3.26 0.80
MAXIMUM WSEL (ft) 467.45 467.36 467.13

0.189

15.00 0.000
[12] S^0.5
[13] L*LCA/S^0.5
[14] AVERAGE MANNINGS 'N'
[10] H-FEET 2.7
[11] S-FEET/MILE

PHYSICAL DATA

RAINFALL DATA
[1] CONCENTRATION POINT 1
SUBAREA 1

2.010
1000

0.003
471.5
468.8

0.02 1.0

1.0 2.0

14.3 3.78

0.05 STORM EVENT SUMMARY
[17] 100% OF LAG-MINUTES
[18] 200% OF LAG-MINUTES
[24] TOTAL PERCOLATION RATE (cfs)
[19] UNIT TIME-MINUTES (100%-200% OF LAG)
3-HOURS
Plate E-2.1

Page 2 of 14 ends

Item 2.

RCFCD SYNTHETIC UNIT HYDROGRAPH METHOD PROJECT CALHOUN AT AVENUE 49 - 100 YEAR EVENT CONCENTRATION POINT: 1BY MES R. BAZUA, P.E. DATE 1/17/2025

ADJUSTED LOSS RATE

SOIL RI PERVIOUS DECIMAL ADJUSTED AREA AVERAGE

GROUP NUMBER AREA PERCENT INFILTRATION ADJUSTED

INFILTRATION OF AREA RATE INFILTRATION

0.00 0.000 0.0000

LAND USE

COMMERCIAL

PAVING/HARDSCAPE
SF - 1 ACRE
SF - 1/2 ACRESF - 1/4 ACRE
MF - COND0MINIUMS

MF - APARTMENTS

MOBILE HOME PARKS

LANDSCAPING

RETENTION BASINS

GOLF COURSE

MOUNTAINOUS
Plate E-2.1

Page 3 of 14 ends

Item 2.

RCFCD SYNTHETIC UNIT HYDROGRAPH METHOD PROJECT: CALHOUN AT AVENUE 49 - 100 YEAR EVENT 100 YEAR - 3 HOUR STORM EVENT CONCENTRATION POINT: 1
BY: MES R. BAZUA, DATE 1/17/2025
DRAINAGE AREA-ACRES 2.01
UNIT TIME-MINUTES 5
LAG TIME - MINUTES 1.00
UNIT TIME-PERCENT OF LAG 502.5
TOTAL ADJUSTED STORM RAIN-INCHES 2.12
CONSTANT LOSS RATE-in/hr 0.25
LOW LOSS RATE - PERCENT 90% TOTAL PERCOLATION RATE (cfs) 0.05 cfs Unit Time Pattern Storm Effective Flood Required
Period Minutes Hours Percent Rain Rain Hydrograph Storage in/hr Flow
(Plate E-5.9) Max Low in/hr cfs cf
1 5 0.08 1.3 0.331 0.25 0.30 0.09 0.17 37.46
2 10 0.17 1.3 0.331 0.25 0.30 0.09 0.17 37.46
3 15 0.25 1.1 0.280 0.25 0.25 0.03 0.07 6.78
4 20 0.33 1.5 0.382 0.25 0.34 0.14 0.27 68.14
5 25 0.42 1.5 0.382 0.25 0.34 0.14 0.27 68.14
6 30 0.50 1.8 0.458 0.25 0.41 0.21 0.43 114.16
7 35 0.58 1.5 0.382 0.25 0.34 0.14 0.27 68.14
8 40 0.67 1.8 0.458 0.25 0.41 0.21 0.43 114.16
9 45 0.75 1.8 0.458 0.25 0.41 0.21 0.43 114.16
10 50 0.83 1.5 0.382 0.25 0.34 0.14 0.27 68.14
11 55 0.92 1.6 0.407 0.25 0.37 0.16 0.33 83.48
12 60 1.00 1.8 0.458 0.25 0.41 0.21 0.43 114.16
13 65 1.08 2.2 0.560 0.25 0.50 0.31 0.63 175.52
14 70 1.17 2.2 0.560 0.25 0.50 0.31 0.63 175.52
15 75 1.25 2.2 0.560 0.25 0.50 0.31 0.63 175.52
16 80 1.33 2.0 0.509 0.25 0.46 0.26 0.53 144.84
17 85 1.42 2.6 0.661 0.25 0.60 0.42 0.84 236.89
18 90 1.50 2.7 0.687 0.25 0.62 0.44 0.89 252.23
19 95 1.58 2.4 0.611 0.25 0.55 0.37 0.73 206.21
20 100 1.67 2.7 0.687 0.25 0.62 0.44 0.89 252.23
21 105 1.75 3.3 0.840 0.25 0.76 0.59 1.19 344.27
22 110 1.83 3.1 0.789 0.25 0.71 0.54 1.09 313.59
23 115 1.92 2.9 0.738 0.25 0.66 0.49 0.99 282.91
24 120 2.00 3.0 0.763 0.25 0.69 0.52 1.04 298.25
25 125 2.08 3.1 0.789 0.25 0.71 0.54 1.09 313.59
26 130 2.17 4.2 1.068 0.25 0.96 0.82 1.65 482.33
27 135 2.25 5.0 1.272 0.25 1.14 1.03 2.06 605.05
28 140 2.33 3.5 0.890 0.25 0.80 0.65 1.30 374.95
29 145 2.42 6.8 1.730 0.25 1.56 1.48 2.98 881.18
30 150 2.50 7.3 1.857 0.25 1.67 1.61 3.24 957.88
31 155 2.58 8.2 2.086 0.25 1.88 1.84 3.70 1095.94
32 160 2.67 5.9 1.501 0.25 1.35 1.26 2.52 743.12
33 165 2.75 2.0 0.509 0.25 0.46 0.26 0.53 144.84
34 170 2.83 1.8 0.458 0.25 0.41 0.21 0.43 114.16
35 175 2.92 1.8 0.458 0.25 0.41 0.21 0.43 114.16
36 180 3.00 0.6 0.153 0.25 0.14 0.02 0.03 0.00

EFFECTIVE RAIN & FLOOD VOLUMES SUMMARY
EFFECTIVE RAIN (in) 1.39
FLOOD VOLUME (acft) 0.23
FLOOD VOLUME (cuft) 10165.45
REQUIRED STORAGE (acft) 0.22
REQUIRED STORAGE (cuft) 9579.59
PEAK FLOW RATE (cfs) 3.70
Loss Rate
in/hr
Time

EFFECTIVE RAIN CALCULATION FORM
Plate E-2.2

Page 4 of 14 ends

Item 2.

RCFCD SYNTHETIC UNIT HYDROGRAPH METHOD PROJECT: CALHOUN AT AVENUE 49 - 100 YEAR EVENT 100 YEAR - 6 HOUR STORM EVENT CONCENTRATION POINT: 1
BY: JAMES R. BAZ DATE: 1/17/2025
DRAINAGE AREA-ACRES 2.01
UNIT TIME-MINUTES 5
LAG TIME - MINUTES 1.00
UNIT TIME-PERCENT OF LAG 502.5
TOTAL ADJUSTED STORM RAIN-INCHES 2.78
CONSTANT LOSS RATE-in/hr 0.245
LOW LOSS RATE - PERCENT 90% TOTAL PERCOLATION RATE (cfs) 0.05 cfs Unit Time Pattern Storm Effective Flood Required
Period Minutes Hours Percent Rain Rain Hydrograph Storage in/hr Flow
(Plate E-5.9) Max Low in/hr cfs cf
1 5 0.08 0.5 0.167 0.25 0.15 0.02 0.03 0.00
2 10 0.17 0.6 0.200 0.25 0.18 0.02 0.04 0.00
3 15 0.25 0.6 0.200 0.25 0.18 0.02 0.04 0.00
4 20 0.33 0.6 0.200 0.25 0.18 0.02 0.04 0.00
5 25 0.42 0.6 0.200 0.25 0.18 0.02 0.04 0.00
6 30 0.50 0.7 0.234 0.25 0.21 0.02 0.05 0.01
7 35 0.58 0.7 0.234 0.25 0.21 0.02 0.05 0.01
8 40 0.67 0.7 0.234 0.25 0.21 0.02 0.05 0.01
9 45 0.75 0.7 0.234 0.25 0.21 0.02 0.05 0.01
10 50 0.83 0.7 0.234 0.25 0.21 0.02 0.05 0.01
11 55 0.92 0.7 0.234 0.25 0.21 0.02 0.05 0.01
12 60 1.00 0.8 0.267 0.25 0.24 0.02 0.04 0.00
13 65 1.08 0.8 0.267 0.25 0.24 0.02 0.04 0.00
14 70 1.17 0.8 0.267 0.25 0.24 0.02 0.04 0.00
15 75 1.25 0.8 0.267 0.25 0.24 0.02 0.04 0.00
16 80 1.33 0.8 0.267 0.25 0.24 0.02 0.04 0.00
17 85 1.42 0.8 0.267 0.25 0.24 0.02 0.04 0.00
18 90 1.50 0.8 0.267 0.25 0.24 0.02 0.04 0.00
19 95 1.58 0.8 0.267 0.25 0.24 0.02 0.04 0.00
20 100 1.67 0.8 0.267 0.25 0.24 0.02 0.04 0.00
21 105 1.75 0.8 0.267 0.25 0.24 0.02 0.04 0.00
22 110 1.83 0.8 0.267 0.25 0.24 0.02 0.04 0.00
23 115 1.92 0.8 0.267 0.25 0.24 0.02 0.04 0.00
24 120 2.00 0.9 0.300 0.25 0.27 0.05 0.11 19.08
25 125 2.08 0.8 0.267 0.25 0.24 0.02 0.04 0.00
26 130 2.17 0.9 0.300 0.25 0.27 0.05 0.11 19.08
27 135 2.25 0.9 0.300 0.25 0.27 0.05 0.11 19.08
28 140 2.33 0.9 0.300 0.25 0.27 0.05 0.11 19.08
29 145 2.42 0.9 0.300 0.25 0.27 0.05 0.11 19.08
30 150 2.50 0.9 0.300 0.25 0.27 0.05 0.11 19.08
31 155 2.58 0.9 0.300 0.25 0.27 0.05 0.11 19.08
32 160 2.67 0.9 0.300 0.25 0.27 0.05 0.11 19.08
33 165 2.75 1.0 0.334 0.25 0.30 0.09 0.18 39.20
34 170 2.83 1.0 0.334 0.25 0.30 0.09 0.18 39.20
35 175 2.92 1.0 0.334 0.25 0.30 0.09 0.18 39.20
36 180 3.00 1.0 0.334 0.25 0.30 0.09 0.18 39.20
37 185 3.08 1.0 0.334 0.25 0.30 0.09 0.18 39.20
38 190 3.17 1.1 0.367 0.25 0.33 0.12 0.24 59.31
39 195 3.25 1.1 0.367 0.25 0.33 0.12 0.24 59.31
40 200 3.33 1.1 0.367 0.25 0.33 0.12 0.24 59.31
41 205 3.42 1.2 0.400 0.25 0.36 0.16 0.31 79.43
42 210 3.50 1.3 0.434 0.25 0.39 0.19 0.38 99.55
43 215 3.58 1.4 0.467 0.25 0.42 0.22 0.45 119.66
44 220 3.67 1.4 0.467 0.25 0.42 0.22 0.45 119.66
45 225 3.75 1.5 0.500 0.25 0.45 0.26 0.51 139.78
46 230 3.83 1.5 0.500 0.25 0.45 0.26 0.51 139.78
47 235 3.92 1.6 0.534 0.25 0.48 0.29 0.58 159.89
48 240 4.00 1.6 0.534 0.25 0.48 0.29 0.58 159.89
49 245 4.08 1.7 0.567 0.25 0.51 0.32 0.65 180.01
50 250 4.17 1.8 0.600 0.25 0.54 0.36 0.71 200.13
51 255 4.25 1.9 0.634 0.25 0.57 0.39 0.78 220.24
52 260 4.33 2.0 0.667 0.25 0.60 0.42 0.85 240.36
53 265 4.42 2.1 0.701 0.25 0.63 0.46 0.92 260.48
54 270 4.50 2.1 0.701 0.25 0.63 0.46 0.92 260.48
55 275 4.58 2.2 0.734 0.25 0.66 0.49 0.98 280.59
56 280 4.67 2.3 0.767 0.25 0.69 0.52 1.05 300.71

EFFECTIVE RAIN CALCULATION FORM
Time Loss Rate
in/hr
Plate E-2.2

Page 5 of 14 ends

Item 2.

EFFECTIVE RAIN CALCULATION FORM
Time Loss Rate
in/hr
57 285 4.75 2.4 0.801 0.25 0.72 0.56 1.12 320.82
58 290 4.83 2.4 0.801 0.25 0.72 0.56 1.12 320.82
59 295 4.92 2.5 0.834 0.25 0.75 0.59 1.18 340.94
60 300 5.00 2.6 0.867 0.25 0.78 0.62 1.25 361.06
61 305 5.08 3.1 1.034 0.25 0.93 0.79 1.59 461.64
62 310 5.17 3.6 1.201 0.25 1.08 0.96 1.92 562.22
63 315 5.25 3.9 1.301 0.25 1.17 1.06 2.12 622.56
64 320 5.33 4.2 1.401 0.25 1.26 1.16 2.32 682.91
65 325 5.42 4.7 1.568 0.25 1.41 1.32 2.66 783.49
66 330 5.50 5.6 1.868 0.25 1.68 1.62 3.26 964.54
67 335 5.58 1.9 0.634 0.25 0.57 0.39 0.78 220.24
68 340 5.67 0.9 0.300 0.25 0.27 0.05 0.11 19.08
69 345 5.75 0.6 0.200 0.25 0.18 0.02 0.04 0.00
70 350 5.83 0.5 0.167 0.25 0.15 0.02 0.03 0.00
71 355 5.92 0.3 0.100 0.25 0.09 0.01 0.02 0.00
72 360 6.00 0.2 0.067 0.25 0.06 0.01 0.01 0.00

EFFECTIVE RAIN & FLOOD VOLUMES SUMMARY
EFFECTIVE RAIN (in) 1.40
FLOOD VOLUME (acft) 0.23
FLOOD VOLUME (cuft) 10195.68
REQUIRED STORAGE (acft) 0.21
REQUIRED STORAGE (cuft) 9147.59
PEAK FLOW RATE (cfs) 3.26
Plate E-2.2

Page 6 of 14 ends

Item 2.

RCFCD SYNTHETIC UNIT HYDROGRAPH METHOD PROJECT: CALHOUN AT AVENUE 49 - 100 YEAR EVENT 100 YEAR - 24 HOUR STORM EVENT CONCENTRATION POINT: 1
BY: JAMES R. BAZ DATE: 1/17/2025
DRAINAGE AREA-ACRES 2.010 CONSTANT LOSS RATE-in/hr n/a
UNIT TIME-MINUTES 15 VARIABLE LOSS RATE (AVG) in/hr 0.2453 LAG TIME - MINUTES 1.00 MINIMUM LOSS RATE (for var. loss) - in/hr 0.123 UNIT TIME-PERCENT OF LAG 1507.5 LOW LOSS RATE - DECIMAL 0.90 TOTAL ADJUSTED STORM RAIN-INCHES 4.47 C 0.00227
PERCOLATION RATE (cfs) 0.05
Unit Time Pattern Storm Effective Flood Required
Period Minutes Hours Percent Rain Rain Hydrograph Storage in/hr Flow
(Plate E-5.9) Max Low in/hr cfs cf
1 15 0.25 0.2 0.036 0.433 0.032 0.004 0.01 0.00
2 30 0.50 0.3 0.054 0.428 0.048 0.005 0.01 0.00
3 45 0.75 0.3 0.054 0.423 0.048 0.005 0.01 0.00
4 60 1.00 0.4 0.072 0.418 0.064 0.007 0.01 0.00
5 75 1.25 0.3 0.054 0.413 0.048 0.005 0.01 0.00
6 90 1.50 0.3 0.054 0.408 0.048 0.005 0.01 0.00
7 105 1.75 0.3 0.054 0.403 0.048 0.005 0.01 0.00
8 120 2.00 0.4 0.072 0.399 0.064 0.007 0.01 0.00
9 135 2.25 0.4 0.072 0.394 0.064 0.007 0.01 0.00
10 150 2.50 0.4 0.072 0.389 0.064 0.007 0.01 0.00
11 165 2.75 0.5 0.089 0.384 0.080 0.009 0.02 0.00
12 180 3.00 0.5 0.089 0.379 0.080 0.009 0.02 0.00
13 195 3.25 0.5 0.089 0.375 0.080 0.009 0.02 0.00
14 210 3.50 0.5 0.089 0.370 0.080 0.009 0.02 0.00
15 225 3.75 0.5 0.089 0.365 0.080 0.009 0.02 0.00
16 240 4.00 0.6 0.107 0.361 0.097 0.011 0.02 0.00
17 255 4.25 0.6 0.107 0.356 0.097 0.011 0.02 0.00
18 270 4.50 0.7 0.125 0.352 0.113 0.013 0.03 0.00
19 285 4.75 0.7 0.125 0.347 0.113 0.013 0.03 0.00
20 300 5.00 0.8 0.143 0.343 0.129 0.014 0.03 0.00
21 315 5.25 0.6 0.107 0.338 0.097 0.011 0.02 0.00
22 330 5.50 0.7 0.125 0.334 0.113 0.013 0.03 0.00
23 345 5.75 0.8 0.143 0.330 0.129 0.014 0.03 0.00
24 360 6.00 0.8 0.143 0.325 0.129 0.014 0.03 0.00
25 375 6.25 0.9 0.161 0.321 0.145 0.016 0.03 0.00
26 390 6.50 0.9 0.161 0.317 0.145 0.016 0.03 0.00
27 405 6.75 1.0 0.179 0.312 0.161 0.018 0.04 0.00
28 420 7.00 1.0 0.179 0.308 0.161 0.018 0.04 0.00
29 435 7.25 1.0 0.179 0.304 0.161 0.018 0.04 0.00
30 450 7.50 1.1 0.197 0.300 0.177 0.020 0.04 0.00
31 465 7.75 1.2 0.215 0.296 0.193 0.021 0.04 0.00
32 480 8.00 1.3 0.232 0.292 0.209 0.023 0.05 0.00
33 495 8.25 1.5 0.268 0.288 0.241 0.027 0.05 6.29
34 510 8.50 1.5 0.268 0.284 0.241 0.027 0.05 6.29
35 525 8.75 1.6 0.286 0.280 0.257 0.007 0.01 0.00
36 540 9.00 1.7 0.304 0.276 0.274 0.028 0.06 9.01
37 555 9.25 1.9 0.340 0.272 0.306 0.068 0.14 80.76
38 570 9.50 2.0 0.358 0.268 0.322 0.090 0.18 120.10
39 585 9.75 2.1 0.375 0.264 0.338 0.111 0.22 159.37
40 600 10.00 2.2 0.393 0.260 0.354 0.133 0.27 198.58
41 615 10.25 1.5 0.268 0.256 0.241 0.012 0.02 0.00
42 630 10.50 1.5 0.268 0.253 0.241 0.015 0.03 0.00
43 645 10.75 2.0 0.358 0.249 0.322 0.109 0.22 154.08
44 660 11.00 2.0 0.358 0.245 0.322 0.112 0.23 160.67
45 675 11.25 1.9 0.340 0.242 0.306 0.098 0.20 134.85
46 690 11.50 1.9 0.340 0.238 0.306 0.101 0.20 141.31
47 705 11.75 1.7 0.304 0.235 0.274 0.069 0.14 83.00
48 720 12.00 1.8 0.322 0.231 0.290 0.091 0.18 121.66
49 735 12.25 2.5 0.447 0.228 0.402 0.219 0.44 354.32
50 750 12.50 2.6 0.465 0.224 0.418 0.240 0.48 392.84
51 765 12.75 2.8 0.501 0.221 0.451 0.280 0.56 463.63
52 780 13.00 2.9 0.519 0.218 0.467 0.301 0.60 502.00
53 795 13.25 3.4 0.608 0.214 0.547 0.394 0.79 669.68
54 810 13.50 3.4 0.608 0.211 0.547 0.397 0.80 675.55
55 825 13.75 2.3 0.411 0.208 0.370 0.203 0.41 325.56
56 840 14.00 2.3 0.411 0.205 0.370 0.206 0.42 331.29
57 855 14.25 2.7 0.483 0.202 0.434 0.281 0.57 466.31
58 870 14.50 2.6 0.465 0.199 0.418 0.266 0.54 439.54
59 885 14.75 2.6 0.465 0.196 0.418 0.269 0.54 445.03
60 900 15.00 2.5 0.447 0.193 0.402 0.254 0.51 418.10
61 915 15.25 2.4 0.429 0.190 0.386 0.240 0.48 391.08
62 930 15.50 2.3 0.411 0.187 0.370 0.225 0.45 363.98
63 945 15.75 1.9 0.340 0.184 0.306 0.156 0.31 239.77
64 960 16.00 1.9 0.340 0.181 0.306 0.159 0.32 244.85
65 975 16.25 0.4 0.072 0.178 0.064 0.007 0.01 0.00
66 990 16.50 0.4 0.072 0.176 0.064 0.007 0.01 0.00
67 1005 16.75 0.3 0.054 0.173 0.048 0.005 0.01 0.00
Time Loss Rate
in/hr

EFFECTIVE RAIN CALCULATION FORM
Plate E-2.2

Page 7 of 14 ends

Item 2.

EFFECTIVE RAIN CALCULATION FORM
68 1020 17.00 0.3 0.054 0.170 0.048 0.005 0.01 0.00
69 1035 17.25 0.5 0.089 0.168 0.080 0.009 0.02 0.00
70 1050 17.50 0.5 0.089 0.165 0.080 0.009 0.02 0.00
71 1065 17.75 0.5 0.089 0.163 0.080 0.009 0.02 0.00
72 1080 18.00 0.4 0.072 0.160 0.064 0.007 0.01 0.00
73 1095 18.25 0.4 0.072 0.158 0.064 0.007 0.01 0.00
74 1110 18.50 0.4 0.072 0.156 0.064 0.007 0.01 0.00
75 1125 18.75 0.3 0.054 0.153 0.048 0.005 0.01 0.00
76 1140 19.00 0.2 0.036 0.151 0.032 0.004 0.01 0.00
77 1155 19.25 0.3 0.054 0.149 0.048 0.005 0.01 0.00
78 1170 19.50 0.4 0.072 0.147 0.064 0.007 0.01 0.00
79 1185 19.75 0.3 0.054 0.145 0.048 0.005 0.01 0.00
80 1200 20.00 0.2 0.036 0.143 0.032 0.004 0.01 0.00
81 1215 20.25 0.3 0.054 0.141 0.048 0.005 0.01 0.00
82 1230 20.50 0.3 0.054 0.139 0.048 0.005 0.01 0.00
83 1245 20.75 0.3 0.054 0.138 0.048 0.005 0.01 0.00
84 1260 21.00 0.2 0.036 0.136 0.032 0.004 0.01 0.00
85 1275 21.25 0.3 0.054 0.134 0.048 0.005 0.01 0.00
86 1290 21.50 0.2 0.036 0.133 0.032 0.004 0.01 0.00
87 1305 21.75 0.3 0.054 0.131 0.048 0.005 0.01 0.00
88 1320 22.00 0.2 0.036 0.130 0.032 0.004 0.01 0.00
89 1335 22.25 0.3 0.054 0.129 0.048 0.005 0.01 0.00
90 1350 22.50 0.2 0.036 0.127 0.032 0.004 0.01 0.00
91 1365 22.75 0.2 0.036 0.126 0.032 0.004 0.01 0.00
92 1380 23.00 0.2 0.036 0.125 0.032 0.004 0.01 0.00
93 1395 23.25 0.2 0.036 0.124 0.032 0.004 0.01 0.00
94 1410 23.50 0.2 0.036 0.124 0.032 0.004 0.01 0.00
95 1425 23.75 0.2 0.036 0.123 0.032 0.004 0.01 0.00
96 1440 24.00 0.2 0.036 0.123 0.032 0.004 0.01 0.00

EFFECTIVE RAIN & FLOOD VOLUMES SUMMARY
EFFECTIVE RAIN (in) 1.43
FLOOD VOLUME (acft) 0.24
FLOOD VOLUME (cuft) 10444.84
REQUIRED STORAGE (acft) 0.19
REQUIRED STORAGE (cuft) 8099.53
PEAK FLOW (cfs) 0.80
Plate E-2.2

Page 8 of 14 ends

Item 2.

PROJECT: CALHOUN AT AVENUE 49 - 100 YEAR EVENT
JOB # 0
1 BASIN CHARACTERISTICS

CONTOUR DEPTH AREA VOLUME

PERCOLATION CALCULATIONS
PERCOLATION RATE 0.67 in/hr 0.05 cfs

MAXWELL IV DRYWELLS
NUMBER USED 0
RATE/DRYWELL 0 cfs
TOTAL DISSIPATED 0 cfs
TOTAL PERCOLATION RATE 0.05 cfs
Basin Characteristics

Page 9 of 14 ends

Item 2.
1 JOB # 0
100 YEAR - 3 HOUR STORM EVENT

FLOW VOLUME TOTAL IN PERC TOTAL IN BASIN
UNIT (min) IN IN BASIN OUT BASIN DEPTH
PERIOD (cfs) (cuft) (cuft) (cuft) (cuft) (ft) (cuft) (acre-ft) 1 5 0.17 52 52 14 37 465.01 37 0.00
2 10 0.17 52 89 14 75 465.02 75 0.00
3 15 0.07 21 96 14 82 465.02 82 0.00
4 20 0.27 82 164 14 150 465.04 150 0.00
5 25 0.27 82 232 14 218 465.06 218 0.01
6 30 0.43 128 346 14 332 465.10 332 0.01
7 35 0.27 82 414 14 400 465.12 400 0.01
8 40 0.43 128 529 14 514 465.15 514 0.01
9 45 0.43 128 643 14 629 465.19 629 0.01
10 50 0.27 82 711 14 697 465.21 697 0.02
11 55 0.33 98 794 14 780 465.23 780 0.02
12 60 0.43 128 908 14 894 465.27 894 0.02
13 65 0.63 190 1,084 14 1,070 465.32 1,070 0.02
14 70 0.63 190 1,260 14 1,245 465.37 1,245 0.03
15 75 0.63 190 1,435 14 1,421 465.42 1,421 0.03
16 80 0.53 159 1,580 14 1,566 465.47 1,566 0.04
17 85 0.84 251 1,817 14 1,803 465.54 1,803 0.04
18 90 0.89 266 2,069 14 2,055 465.61 2,055 0.05
19 95 0.73 220 2,275 14 2,261 465.67 2,261 0.05
20 100 0.89 266 2,527 14 2,513 465.75 2,513 0.06
21 105 1.19 358 2,872 14 2,858 465.85 2,858 0.07
22 110 1.09 328 3,185 14 3,171 465.94 3,171 0.07
23 115 0.99 297 3,468 14 3,454 466.02 3,454 0.08
24 120 1.04 312 3,766 14 3,752 466.10 3,752 0.09
25 125 1.09 328 4,080 14 4,066 466.17 4,066 0.09
26 130 1.65 496 4,562 14 4,548 466.29 4,548 0.10
27 135 2.06 619 5,167 14 5,153 466.44 5,153 0.12
28 140 1.30 389 5,542 14 5,528 466.53 5,528 0.13
29 145 2.98 895 6,424 14 6,409 466.75 6,409 0.15
30 150 3.24 972 7,381 14 7,367 466.99 7,367 0.17
31 155 3.70 1,110 8,477 14 8,463 467.21 8,463 0.19
32 160 2.52 757 9,220 14 9,206 467.37 9,206 0.21
33 165 0.53 159 9,365 14 9,351 467.40 9,351 0.21
34 170 0.43 128 9,479 14 9,465 467.42 9,465 0.22
35 175 0.43 128 9,594 14 9,580 467.45 9,580 0.22
36 180 0.03 9 9,589 14 9,575 467.45 9,575 0.22

BALANCE IN
BASIN
TIME
Basin Depth Analysis

Page 10 of 14 ends

Item 2.
1 JOB # 0
100 YEAR - 6 HOUR STORM EVENT

FLOW VOLUME TOTAL IN PERC TOTAL IN BASIN
UNIT (min) IN IN BASIN OUT BASIN DEPTH
PERIOD (cfs) (cuft) (cuft) (cuft) (cuft) (ft) (cuft) (acre-ft) 1 5 0.03 10 10 14 - 465.00 - 0.00
2 10 0.04 12 12 14 - 465.00 - 0.00
3 15 0.04 12 12 14 - 465.00 - 0.00
4 20 0.04 12 12 14 - 465.00 - 0.00
5 25 0.04 12 12 14 - 465.00 - 0.00
6 30 0.05 14 14 14 0 465.00 0.00 0
7 35 0.05 14 14 14 0 465.00 0.00 0
8 40 0.05 14 14 14 0 465.00 0.00 0
9 45 0.05 14 14 14 0 465.00 0.00 0
10 50 0.05 14 14 14 0 465.00 0.00 0
11 55 0.05 14 14 14 0 465.00 0.00 0
12 60 0.04 13 13 14 - 465.00 - 0.00
13 65 0.04 13 13 14 - 465.00 - 0.00
14 70 0.04 13 13 14 - 465.00 - 0.00
15 75 0.04 13 13 14 - 465.00 - 0.00
16 80 0.04 13 13 14 - 465.00 - 0.00
17 85 0.04 13 13 14 - 465.00 - 0.00
18 90 0.04 13 13 14 - 465.00 - 0.00
19 95 0.04 13 13 14 - 465.00 - 0.00
20 100 0.04 13 13 14 - 465.00 - 0.00
21 105 0.04 13 13 14 - 465.00 - 0.00
22 110 0.04 13 13 14 - 465.00 - 0.00
23 115 0.04 13 13 14 - 465.00 - 0.00
24 120 0.11 33 33 14 19 465.01 19 0.00
25 125 0.04 13 32 14 18 465.01 18 0.00
26 130 0.11 33 51 14 37 465.01 37 0.00
27 135 0.11 33 70 14 56 465.02 56 0.00
28 140 0.11 33 89 14 75 465.02 75 0.00
29 145 0.11 33 108 14 94 465.03 94 0.00
30 150 0.11 33 128 14 113 465.03 113 0.00
31 155 0.11 33 147 14 133 465.04 133 0.00
32 160 0.11 33 166 14 152 465.05 152 0.00
33 165 0.18 53 205 14 191 465.06 191 0.00
34 170 0.18 53 244 14 230 465.07 230 0.01
35 175 0.18 53 283 14 269 465.08 269 0.01
36 180 0.18 53 322 14 308 465.09 308 0.01
37 185 0.18 53 362 14 348 465.10 348 0.01
38 190 0.24 73 421 14 407 465.12 407 0.01
39 195 0.24 73 480 14 466 465.14 466 0.01
40 200 0.24 73 540 14 526 465.16 526 0.01
41 205 0.31 94 619 14 605 465.18 605 0.01
42 210 0.38 114 719 14 705 465.21 705 0.02
43 215 0.45 134 838 14 824 465.25 824 0.02
44 220 0.45 134 958 14 944 465.28 944 0.02
45 225 0.51 154 1,098 14 1,084 465.32 1,084 0.02
46 230 0.51 154 1,237 14 1,223 465.36 1,223 0.03
47 235 0.58 174 1,397 14 1,383 465.41 1,383 0.03
48 240 0.58 174 1,557 14 1,543 465.46 1,543 0.04
49 245 0.65 194 1,737 14 1,723 465.51 1,723 0.04
50 250 0.71 214 1,937 14 1,923 465.57 1,923 0.04
51 255 0.78 234 2,158 14 2,144 465.64 2,144 0.05
52 260 0.85 254 2,398 14 2,384 465.71 2,384 0.05
53 265 0.92 275 2,658 14 2,644 465.79 2,644 0.06
54 270 0.92 275 2,919 14 2,905 465.86 2,905 0.07
55 275 0.98 295 3,200 14 3,185 465.95 3,185 0.07

TIME BALANCE IN
BASIN
Basin Depth Analysis

Page 11 of 14 ends

Item 2.
1 JOB # 0
100 YEAR - 6 HOUR STORM EVENT

FLOW VOLUME TOTAL IN PERC TOTAL IN BASIN
UNIT (min) IN IN BASIN OUT BASIN DEPTH
PERIOD (cfs) (cuft) (cuft) (cuft) (cuft) (ft) (cuft) (acre-ft)

TIME BALANCE IN
BASIN
56 280 1.05 315 3,500 14 3,486 466.03 3,486 0.08
57 285 1.12 335 3,821 14 3,807 466.11 3,807 0.09
58 290 1.12 335 4,142 14 4,128 466.19 4,128 0.09
59 295 1.18 355 4,483 14 4,469 466.27 4,469 0.10
60 300 1.25 375 4,844 14 4,830 466.36 4,830 0.11
61 305 1.59 476 5,306 14 5,291 466.47 5,291 0.12
62 310 1.92 576 5,868 14 5,854 466.61 5,854 0.13
63 315 2.12 637 6,490 14 6,476 466.77 6,476 0.15
64 320 2.32 697 7,173 14 7,159 466.93 7,159 0.16
65 325 2.66 798 7,957 14 7,943 467.11 7,943 0.18
66 330 3.26 979 8,921 14 8,907 467.31 8,907 0.20
67 335 0.78 234 9,142 14 9,127 467.35 9,127 0.21
68 340 0.11 33 9,161 14 9,147 467.36 9,147 0.21
69 345 0.04 12 9,159 14 9,145 467.36 9,145 0.21
70 350 0.03 10 9,155 14 9,140 467.36 9,140 0.21
71 355 0.02 6 9,147 14 9,132 467.35 9,132 0.21
72 360 0.01 4 9,136 14 9,122 467.35 9,122 0.21
Basin Depth Analysis

Page 12 of 14 ends

Item 2.
1 JOB # 0
100 YEAR - 24 HOUR STORM EVENT

FLOW VOLUME TOTAL IN PERC TOTAL IN BASIN
UNIT (min) IN IN BASIN OUT BASIN DEPTH
PERIOD (cfs) (cuft) (cuft) (cuft) (cuft) (ft) (cuft) (acre-ft) 1 15 0.01 6 6 42 - 465.00 - 0.00
2 30 0.01 10 10 42 - 465.00 - 0.00
3 45 0.01 10 10 42 - 465.00 - 0.00
4 60 0.01 13 13 42 - 465.00 - 0.00
5 75 0.01 10 10 42 - 465.00 - 0.00
6 90 0.01 10 10 42 - 465.00 - 0.00
7 105 0.01 10 10 42 - 465.00 - 0.00
8 120 0.01 13 13 42 - 465.00 - 0.00
9 135 0.01 13 13 42 - 465.00 - 0.00
10 150 0.01 13 13 42 - 465.00 - 0.00
11 165 0.02 16 16 42 - 465.00 - 0.00
12 180 0.02 16 16 42 - 465.00 - 0.00
13 195 0.02 16 16 42 - 465.00 - 0.00
14 210 0.02 16 16 42 - 465.00 - 0.00
15 225 0.02 16 16 42 - 465.00 - 0.00
16 240 0.02 19 19 42 - 465.00 - 0.00
17 255 0.02 19 19 42 - 465.00 - 0.00
18 270 0.03 23 23 42 - 465.00 - 0.00
19 285 0.03 23 23 42 - 465.00 - 0.00
20 300 0.03 26 26 42 - 465.00 - 0.00
21 315 0.02 19 19 42 - 465.00 - 0.00
22 330 0.03 23 23 42 - 465.00 - 0.00
23 345 0.03 26 26 42 - 465.00 - 0.00
24 360 0.03 26 26 42 - 465.00 - 0.00
25 375 0.03 29 29 42 - 465.00 - 0.00
26 390 0.03 29 29 42 - 465.00 - 0.00
27 405 0.04 32 32 42 - 465.00 - 0.00
28 420 0.04 32 32 42 - 465.00 - 0.00
29 435 0.04 32 32 42 - 465.00 - 0.00
30 450 0.04 36 36 42 - 465.00 - 0.00
31 465 0.04 39 39 42 - 465.00 - 0.00
32 480 0.05 42 42 42 - 465.00 - 0.00
33 495 0.05 49 49 42 6 465.00 6 0.00
34 510 0.05 49 55 42 13 465.00 13 0.00
35 525 0.01 12 24 42 - 465.00 - 0.00
36 540 0.06 51 51 42 9 465.00 9 0.00
37 555 0.14 123 132 42 90 465.03 90 0.00
38 570 0.18 162 252 42 210 465.06 210 0.00
39 585 0.22 202 411 42 369 465.11 369 0.01
40 600 0.27 241 610 42 568 465.17 568 0.01
41 615 0.02 21 589 42 547 465.16 547 0.01
42 630 0.03 28 575 42 532 465.16 532 0.01
43 645 0.22 196 729 42 687 465.20 687 0.02
44 660 0.23 203 889 42 847 465.25 847 0.02
45 675 0.20 177 1,024 42 982 465.29 982 0.02
46 690 0.20 184 1,166 42 1,123 465.33 1,123 0.03
47 705 0.14 125 1,249 42 1,206 465.36 1,206 0.03
48 720 0.18 164 1,370 42 1,328 465.39 1,328 0.03
49 735 0.44 397 1,725 42 1,682 465.50 1,682 0.04
50 750 0.48 435 2,117 42 2,075 465.62 2,075 0.05
51 765 0.56 506 2,581 42 2,539 465.76 2,539 0.06
52 780 0.60 544 3,083 42 3,041 465.90 3,041 0.07
53 795 0.79 712 3,753 42 3,711 466.09 3,711 0.09
54 810 0.80 718 4,428 42 4,386 466.25 4,386 0.10
55 825 0.41 368 4,754 42 4,712 466.33 4,712 0.11
56 840 0.42 374 5,085 42 5,043 466.41 5,043 0.12
57 855 0.57 509 5,551 42 5,509 466.53 5,509 0.13
58 870 0.54 482 5,991 42 5,949 466.64 5,949 0.14

TIME BALANCE IN
BASIN
Basin Depth Analysis

Page 13 of 14 ends

Item 2.
1 JOB # 0
100 YEAR - 24 HOUR STORM EVENT

FLOW VOLUME TOTAL IN PERC TOTAL IN BASIN
UNIT (min) IN IN BASIN OUT BASIN DEPTH
PERIOD (cfs) (cuft) (cuft) (cuft) (cuft) (ft) (cuft) (acre-ft)

TIME BALANCE IN
BASIN
59 885 0.54 487 6,436 42 6,394 466.75 6,394 0.15
60 900 0.51 460 6,854 42 6,812 466.85 6,812 0.16
61 915 0.48 433 7,245 42 7,203 466.94 7,203 0.17
62 930 0.45 406 7,609 42 7,567 467.03 7,567 0.17
63 945 0.31 282 7,849 42 7,807 467.08 7,807 0.18
64 960 0.32 287 8,094 42 8,052 467.13 8,052 0.18
65 975 0.01 13 8,065 42 8,022 467.12 8,022 0.18
66 990 0.01 13 8,035 42 7,993 467.12 7,993 0.18
67 1005 0.01 10 8,003 42 7,961 467.11 7,961 0.18
68 1020 0.01 10 7,970 42 7,928 467.10 7,928 0.18
69 1035 0.02 16 7,944 42 7,902 467.10 7,902 0.18
70 1050 0.02 16 7,918 42 7,876 467.09 7,876 0.18
71 1065 0.02 16 7,892 42 7,850 467.09 7,850 0.18
72 1080 0.01 13 7,863 42 7,821 467.08 7,821 0.18
73 1095 0.01 13 7,833 42 7,791 467.08 7,791 0.18
74 1110 0.01 13 7,804 42 7,762 467.07 7,762 0.18
75 1125 0.01 10 7,772 42 7,729 467.06 7,729 0.18
76 1140 0.01 7,736 6 42 7,694 467.06 7,694 0.18
77 1155 0.01 10 7,703 42 7,661 467.05 7,661 0.18
78 1170 0.01 13 7,674 42 7,632 467.04 7,632 0.18
79 1185 0.01 10 7,642 42 7,599 467.04 7,599 0.17
80 1200 0.01 6 7,606 42 7,564 467.03 7,564 0.17
81 1215 0.01 10 7,573 42 7,531 467.02 7,531 0.17
82 1230 0.01 10 7,541 42 7,499 467.01 7,499 0.17
83 1245 0.01 10 7,508 42 7,466 467.01 7,466 0.17
84 1260 0.01 6 7,473 42 7,430 467.00 7,430 0.17
85 1275 0.01 10 7,440 42 7,398 466.99 7,398 0.17
86 1290 0.01 6 7,404 42 7,362 466.98 7,362 0.17
87 1305 0.01 10 7,372 42 7,330 466.98 7,330 0.17
88 1320 0.01 6 7,336 42 7,294 466.97 7,294 0.17
89 1335 0.01 10 7,303 42 7,261 466.96 7,261 0.17
90 1350 0.01 6 7,268 42 7,225 466.95 7,225 0.17
91 1365 0.01 6 7,232 42 7,190 466.94 7,190 0.17
92 1380 0.01 6 7,196 42 7,154 466.93 7,154 0.16
93 1395 0.01 6 7,160 42 7,118 466.92 7,118 0.16
94 1410 0.01 6 7,125 42 7,082 466.92 7,082 0.16
95 1425 0.01 6 7,089 42 7,047 466.91 7,047 0.16
96 1440 0.01 6 7,053 42 7,011 466.90 7,011 0.16
Basin Depth Analysis

Page 14 of 14 ends

Item 2.
1 2
3 4
5 6
7 8
9 10
11 12
13 14
15 16
17 18
19 20
21 22
23 24
25 26
27 28
29 30
31 32
33 34
35 36
37 38
39 40
41 42
43 44
45 46
47 48
49 50
51 52
53 54
55 56
AB C D

RCFCD SYNTHETIC UNIT HYDROGRAPH

DATA INPUT SHEET
WORKSHEET PREPARED BY: JAMES R. BAZUA, P.E.

PROJECT NAME CALHOUN AT AVENUE 49 - 100 YEAR EVENT
JOB #
CONCENTRATION POINT DESIGNATION 1
AREA DESIGNATION SUBAREA 2

TRIBUTARY AREAS ACRES

COMMERCIAL
PAVING/HARDSCAPE 2.51
SF - 1 ACRE
SF - 1/2 ACRE
SF - 1/4 ACRE
MF - CONDOMINIUMS 7.46

MF - APARTMENTS

MOBILE HOME PARK
LANDSCAPING 0.6

RETENTION BASIN

GOLF COURSE

POINT RAIN
3-HOUR 2.12
6-HOUR 2.78
24-HOUR 4.47
BASIN CHARACTERISTICS: ELEVATION AREA
465 15600
466 17120
467 18710
468 20350
468.5 21200
PERCOLATION RATE (in/hr) 0.67

DRYWELL DATA

NUMBER USED
PERCOLATION RATE (cfs)
666
Item 2.

POINT AREA AVERAGE POINT AREA AVERAGE POINT AREA AVERAGE

RAIN POINT RAIN POINT RAIN POINT

INCHES RAIN INCHES RAIN INCHES RAIN
(Plate E-5.2) INCHES (Plate E-5.4) INCHES (Plate E-5.6) INCHES

2.12 10.570 1.00 2.12 2.78 10.570 1.00 2.78 4.47 10.570 1.00 4.47

0.00 0.00 0.00 0.00 0.00 0.00

0.00 0.00 0.00 0.00 0.00 0.00
SUM [5] 10.57 SUM [7] 2.12 SUM [9] 10.57 SUM [11] 2.78 SUM [13] 10.57 SUM [15] 4.47 [16] AREA ADJ FACTOR 1.000 1.000 1.000
[17] ADJ AVG POINT RAIN 2.12 2.78 4.47
DURATION 3-HOUR 6-HOUR 24-HOUR
EFFECTIVE RAIN (in) 1.54 1.64 1.79
FLOOD VOLUME (cu-ft) 59,174 63,009 68,653
(acre-ft) 1.36 1.45 1.58
REQUIRED STORAGE (cu-ft) 56,096 57,661 56,204
(acre-ft) 1.29 1.32 1.29
PEAK FLOW (cfs) 20.00 17.69 4.66
MAXIMUM WSEL (ft) 468.11 468.19 468.12
24-HOURS
[15] LAG TIME-HOURS
[16] LAG TIME-MINUTES

1.6 1.6

3.2 25.5

5.05 0.02

PHYSICAL DATA

RAINFALL DATA
[1] CONCENTRATION POINT 1
SUBAREA 2

10.570
724

0.019
472
468.5

0.137
100.00

0.001
[12] S^0.5
[13] L*LCA/S^0.5
[14] AVERAGE MANNINGS 'N'
[10] H-FEET 3.5
[11] S-FEET/MILE
Plate E-2.1

Page 2 of 14 ends

Item 2.

RCFCD SYNTHETIC UNIT HYDROGRAPH METHOD PROJECT CALHOUN AT AVENUE 49 - 100 YEAR EVENT CONCENTRATION POINT: 1BY MES R. BAZUA, P.E. DATE 1/17/2025

ADJUSTED LOSS RATE

SOIL RI PERVIOUS DECIMAL ADJUSTED AREA AVERAGE

GROUP NUMBER AREA PERCENT INFILTRATION ADJUSTED

INFILTRATION OF AREA RATE INFILTRATION

0.00 0.000 0.0000

LANDSCAPING

RETENTION BASINS

GOLF COURSE

MOUNTAINOUS
SF - 1 ACRE
SF - 1/2 ACRESF - 1/4 ACRE
MF - COND0MINIUMS

MF - APARTMENTS

MOBILE HOME PARKS
(24-(T/60))^1.55 +

LAND USE

COMMERCIAL

PAVING/HARDSCAPE
Plate E-2.1

Page 3 of 14 ends

Item 2.

RCFCD SYNTHETIC UNIT HYDROGRAPH METHOD PROJECT: CALHOUN AT AVENUE 49 - 100 YEAR EVENT 100 YEAR - 3 HOUR STORM EVENT CONCENTRATION POINT: 1
BY: MES R. BAZUA, DATE 1/17/2025
DRAINAGE AREA-ACRES 10.57
UNIT TIME-MINUTES 5
LAG TIME - MINUTES 1.62
UNIT TIME-PERCENT OF LAG 308.6
TOTAL ADJUSTED STORM RAIN-INCHES 2.12
CONSTANT LOSS RATE-in/hr 0.19
LOW LOSS RATE - PERCENT 90% TOTAL PERCOLATION RATE (cfs) 0.24 cfs Unit Time Pattern Storm Effective Flood Required
Period Minutes Hours Percent Rain Rain Hydrograph Storage in/hr Flow
(Plate E-5.9) Max Low in/hr cfs cf
1 5 0.08 1.3 0.331 0.19 0.30 0.14 1.44 360.41
2 10 0.17 1.3 0.331 0.19 0.30 0.14 1.44 360.41
3 15 0.25 1.1 0.280 0.19 0.25 0.09 0.91 199.07
4 20 0.33 1.5 0.382 0.19 0.34 0.19 1.98 521.75
5 25 0.42 1.5 0.382 0.19 0.34 0.19 1.98 521.75
6 30 0.50 1.8 0.458 0.19 0.41 0.26 2.79 763.76
7 35 0.58 1.5 0.382 0.19 0.34 0.19 1.98 521.75
8 40 0.67 1.8 0.458 0.19 0.41 0.26 2.79 763.76
9 45 0.75 1.8 0.458 0.19 0.41 0.26 2.79 763.76
10 50 0.83 1.5 0.382 0.19 0.34 0.19 1.98 521.75
11 55 0.92 1.6 0.407 0.19 0.37 0.21 2.25 602.42
12 60 1.00 1.8 0.458 0.19 0.41 0.26 2.79 763.76
13 65 1.08 2.2 0.560 0.19 0.50 0.37 3.86 1086.45
14 70 1.17 2.2 0.560 0.19 0.50 0.37 3.86 1086.45
15 75 1.25 2.2 0.560 0.19 0.50 0.37 3.86 1086.45
16 80 1.33 2.0 0.509 0.19 0.46 0.31 3.33 925.11
17 85 1.42 2.6 0.661 0.19 0.60 0.47 4.94 1409.13
18 90 1.50 2.7 0.687 0.19 0.62 0.49 5.21 1489.80
19 95 1.58 2.4 0.611 0.19 0.55 0.42 4.40 1247.79
20 100 1.67 2.7 0.687 0.19 0.62 0.49 5.21 1489.80
21 105 1.75 3.3 0.840 0.19 0.76 0.65 6.82 1973.82
22 110 1.83 3.1 0.789 0.19 0.71 0.59 6.28 1812.48
23 115 1.92 2.9 0.738 0.19 0.66 0.54 5.75 1651.14
24 120 2.00 3.0 0.763 0.19 0.69 0.57 6.01 1731.81
25 125 2.08 3.1 0.789 0.19 0.71 0.59 6.28 1812.48
26 130 2.17 4.2 1.068 0.19 0.96 0.87 9.24 2699.85
27 135 2.25 5.0 1.272 0.19 1.14 1.08 11.39 3345.21
28 140 2.33 3.5 0.890 0.19 0.80 0.70 7.36 2135.16
29 145 2.42 6.8 1.730 0.19 1.56 1.54 16.23 4797.28
30 150 2.50 7.3 1.857 0.19 1.67 1.66 17.58 5200.63
31 155 2.58 8.2 2.086 0.19 1.88 1.89 20.00 5926.66
32 160 2.67 5.9 1.501 0.19 1.35 1.31 13.81 4071.24
33 165 2.75 2.0 0.509 0.19 0.46 0.31 3.33 925.11
34 170 2.83 1.8 0.458 0.19 0.41 0.26 2.79 763.76
35 175 2.92 1.8 0.458 0.19 0.41 0.26 2.79 763.76
36 180 3.00 0.6 0.153 0.19 0.14 0.02 0.16 0.00

EFFECTIVE RAIN & FLOOD VOLUMES SUMMARY
EFFECTIVE RAIN (in) 1.54
FLOOD VOLUME (acft) 1.36
FLOOD VOLUME (cuft) 59173.82
REQUIRED STORAGE (acft) 1.29
REQUIRED STORAGE (cuft) 56095.73
PEAK FLOW RATE (cfs) 20.00
Loss Rate
in/hr
Time

EFFECTIVE RAIN CALCULATION FORM
Plate E-2.2

Page 4 of 14 ends

Item 2.

RCFCD SYNTHETIC UNIT HYDROGRAPH METHOD PROJECT: CALHOUN AT AVENUE 49 - 100 YEAR EVENT 100 YEAR - 6 HOUR STORM EVENT CONCENTRATION POINT: 1
BY: JAMES R. BAZ DATE: 1/17/2025
DRAINAGE AREA-ACRES 10.57
UNIT TIME-MINUTES 5
LAG TIME - MINUTES 1.62
UNIT TIME-PERCENT OF LAG 308.6
TOTAL ADJUSTED STORM RAIN-INCHES 2.78
CONSTANT LOSS RATE-in/hr 0.194
LOW LOSS RATE - PERCENT 90% TOTAL PERCOLATION RATE (cfs) 0.24 cfs Unit Time Pattern Storm Effective Flood Required
Period Minutes Hours Percent Rain Rain Hydrograph Storage in/hr Flow
(Plate E-5.9) Max Low in/hr cfs cf
1 5 0.08 0.5 0.167 0.19 0.15 0.02 0.18 0.00
2 10 0.17 0.6 0.200 0.19 0.18 0.01 0.06 0.00
3 15 0.25 0.6 0.200 0.19 0.18 0.01 0.06 0.00
4 20 0.33 0.6 0.200 0.19 0.18 0.01 0.06 0.00
5 25 0.42 0.6 0.200 0.19 0.18 0.01 0.06 0.00
6 30 0.50 0.7 0.234 0.19 0.21 0.04 0.42 52.19
7 35 0.58 0.7 0.234 0.19 0.21 0.04 0.42 52.19
8 40 0.67 0.7 0.234 0.19 0.21 0.04 0.42 52.19
9 45 0.75 0.7 0.234 0.19 0.21 0.04 0.42 52.19
10 50 0.83 0.7 0.234 0.19 0.21 0.04 0.42 52.19
11 55 0.92 0.7 0.234 0.19 0.21 0.04 0.42 52.19
12 60 1.00 0.8 0.267 0.19 0.24 0.07 0.77 157.98
13 65 1.08 0.8 0.267 0.19 0.24 0.07 0.77 157.98
14 70 1.17 0.8 0.267 0.19 0.24 0.07 0.77 157.98
15 75 1.25 0.8 0.267 0.19 0.24 0.07 0.77 157.98
16 80 1.33 0.8 0.267 0.19 0.24 0.07 0.77 157.98
17 85 1.42 0.8 0.267 0.19 0.24 0.07 0.77 157.98
18 90 1.50 0.8 0.267 0.19 0.24 0.07 0.77 157.98
19 95 1.58 0.8 0.267 0.19 0.24 0.07 0.77 157.98
20 100 1.67 0.8 0.267 0.19 0.24 0.07 0.77 157.98
21 105 1.75 0.8 0.267 0.19 0.24 0.07 0.77 157.98
22 110 1.83 0.8 0.267 0.19 0.24 0.07 0.77 157.98
23 115 1.92 0.8 0.267 0.19 0.24 0.07 0.77 157.98
24 120 2.00 0.9 0.300 0.19 0.27 0.11 1.12 263.76
25 125 2.08 0.8 0.267 0.19 0.24 0.07 0.77 157.98
26 130 2.17 0.9 0.300 0.19 0.27 0.11 1.12 263.76
27 135 2.25 0.9 0.300 0.19 0.27 0.11 1.12 263.76
28 140 2.33 0.9 0.300 0.19 0.27 0.11 1.12 263.76
29 145 2.42 0.9 0.300 0.19 0.27 0.11 1.12 263.76
30 150 2.50 0.9 0.300 0.19 0.27 0.11 1.12 263.76
31 155 2.58 0.9 0.300 0.19 0.27 0.11 1.12 263.76
32 160 2.67 0.9 0.300 0.19 0.27 0.11 1.12 263.76
33 165 2.75 1.0 0.334 0.19 0.30 0.14 1.47 369.55
34 170 2.83 1.0 0.334 0.19 0.30 0.14 1.47 369.55
35 175 2.92 1.0 0.334 0.19 0.30 0.14 1.47 369.55
36 180 3.00 1.0 0.334 0.19 0.30 0.14 1.47 369.55
37 185 3.08 1.0 0.334 0.19 0.30 0.14 1.47 369.55
38 190 3.17 1.1 0.367 0.19 0.33 0.17 1.83 475.33
39 195 3.25 1.1 0.367 0.19 0.33 0.17 1.83 475.33
40 200 3.33 1.1 0.367 0.19 0.33 0.17 1.83 475.33
41 205 3.42 1.2 0.400 0.19 0.36 0.21 2.18 581.11
42 210 3.50 1.3 0.434 0.19 0.39 0.24 2.53 686.90
43 215 3.58 1.4 0.467 0.19 0.42 0.27 2.88 792.68
44 220 3.67 1.4 0.467 0.19 0.42 0.27 2.88 792.68
45 225 3.75 1.5 0.500 0.19 0.45 0.31 3.24 898.47
46 230 3.83 1.5 0.500 0.19 0.45 0.31 3.24 898.47
47 235 3.92 1.6 0.534 0.19 0.48 0.34 3.59 1004.25
48 240 4.00 1.6 0.534 0.19 0.48 0.34 3.59 1004.25
49 245 4.08 1.7 0.567 0.19 0.51 0.37 3.94 1110.04
50 250 4.17 1.8 0.600 0.19 0.54 0.41 4.29 1215.82
51 255 4.25 1.9 0.634 0.19 0.57 0.44 4.65 1321.61
52 260 4.33 2.0 0.667 0.19 0.60 0.47 5.00 1427.39
53 265 4.42 2.1 0.701 0.19 0.63 0.51 5.35 1533.18
54 270 4.50 2.1 0.701 0.19 0.63 0.51 5.35 1533.18
55 275 4.58 2.2 0.734 0.19 0.66 0.54 5.71 1638.96
56 280 4.67 2.3 0.767 0.19 0.69 0.57 6.06 1744.75

EFFECTIVE RAIN CALCULATION FORM
Time Loss Rate
in/hr
Plate E-2.2

Page 5 of 14 ends

Coachella City CouncilDecember 17, 2025

Coachella City Council
December 17, 2025