Environmental impact simulations

Shadow, Stormwater, Climate & Combined Impact Modeling

Proposed 3-Story Development (Case Z2023000505)  |  SE Corner SW 147th Ave & SW 28th St, Adjacent to Millennium Town Homes (SW 145th Ct)  |  Miami, FL 33175
Study conducted by Millennium Townhomes Association  |  March 2026
Simulation 1
Shadow projection across the community
This interactive map shows how the proposed 3-story building (38′8″ to roof, parapets reaching 48′4″) would cast shadows across the Millennium Town Homes community throughout the day and across seasons. Drag the time slider or press "Animate day" to watch the shadow sweep across the neighborhood.

Solar shadow projection

N
WE
S
4:00 PM
Alt: 25°
Full sun
Shadow
Residential
Commercial
Proposed
Trees
—
Lot in sun
—
Lot in shade
—
Sun elevation
—
Sun azimuth
Drag the time slider to see how shadows move throughout the day.
Methodology: Solar position calculated using NOAA algorithms for latitude 25.74°N. Shadow length = building height (38.67 ft to roof; parapets reach 48.33 ft) / tan(solar altitude). Property: 1.10 net acres (47,916 sq ft), SE corner SW 147th Ave & theoretical SW 28th St. Single 24-foot driveway access.
Simulation 2
Stormwater flooding simulation
This simulation visualizes how water accumulates during a storm event. The current vacant lot absorbs most rainfall. After development, the impervious building and parking shed water onto the surrounding community. Press "Run storm" to watch a rainfall event unfold.

Storm event — water accumulation model

Current Condition (Vacant Lot)
After Development (33-Unit Building)
Methodology: NRCS Curve Number method. Pre-development CN=74 (grass/brush, HSG B/C). Post-development CN=92 (~65% impervious). Lot area: 47,916 sq ft (1.10 net acres). Property lies within West Wellfield Interim Protection Area over the Biscayne Aquifer (Miami-Dade Code § 24-43).
What this means for homeowners: During a moderate 4-inch storm (common during Miami's May–October wet season), the developed site would shed approximately 3× more water than the current vacant lot. That excess water — thousands of additional gallons — flows directly onto the streets, yards, and foundations of the Millennium Town Homes community through a single 24-foot driveway on SW 147th Avenue, increasing standing water duration and flood risk for every adjacent property. The property sits within the West Wellfield Interim Protection Area over the Biscayne Aquifer — Miami-Dade's primary drinking water source.
Simulation 3
Stormwater runoff quantification
This chart quantifies the total runoff volume in gallons for various storm intensities, comparing the current vacant lot against the proposed development.

Rainfall-runoff model (NRCS CN method)

Current condition (vacant lot)

Pervious soil/grass CN ≈ 74 | ~85% pervious

After development (3-story + parking)

33-Unit Building 38'8" (parapets 48'4") Parking Green area Single 24-ft driveway & access
Formula: NRCS CN method: Q = (P - 0.2S)² / (P + 0.8S) where S = (1000/CN) - 10. Gallons = (Q inches / 12) × lot sq ft × 7.48052.
Simulation 4
Climate projections for SW Miami-Dade (2026–2100)
Official SE Florida Climate Compact projections show conditions will worsen dramatically over this building's lifespan — making every impact worse over time.

SE Florida Climate Compact — unified sea level rise projections

NOAA high curve (critical infrastructure)
USACE high curve
IPCC median
Source: SE Florida Regional Climate Change Compact, Unified Sea Level Rise Projection (2019 update). Miami-Dade County officially uses these projections.

Compound risk timeline

2026 (now)
Current: FEMA Zone AH/AE. Miami averages 67" annual rainfall, 72% humidity. Vacant lot (1.10 net acres) absorbs most rainfall on-site. Property lies within West Wellfield Interim Protection Area over the Biscayne Aquifer. Single 24-foot driveway access on SW 147th Ave.
2030
Sea level: +6–10 inches. Building ~4 years old. Reduced drainage capacity. Shadow-related mold effects compounding. Excess runoff strains already stressed drainage.
2040
Sea level: +10–17 inches. Days above 92.6°F increase toward 89/year. Higher heat + humidity + less sunlight = compounding mold crisis.
2060
Sea level: +14–26 inches (up to 34" for critical infrastructure). Flood risk increased 26%+ nationally. A building degrading drainage today will do so in a far more flood-prone future.
2080–2100
Sea level: +31–61 inches (up to 81" NOAA high). Nearly 2/3 of SW Miami-Dade post-Andrew lots at flood risk by 2080. Decisions about impervious surface today determine whether these homes survive.
Sources: SE Florida Climate Compact (2019), Miami-Dade County Sea Level Rise Strategy, ClimateCheck, NPR/NHC analysis (2022).
Simulation 5
Shadow-humidity compound mold risk
Combines the shadow analysis with Miami's humidity baseline to estimate mold risk increase for each unit in the community.

Mold risk index by season and unit

Winter peak risk increase
+68%
Western-row homes, Nov–Feb
Annual avg risk increase
+41%
All shadow-zone homes
Surface drying delay
+2.1 hrs
Avg additional wet time/day in winter
Mold threshold
55% RH
Miami baseline already 72%
Model: Risk index = (humidity × wetness duration × temperature) / UV exposure. Shadow reduces UV and increases wetness. Baseline = 100.
Simulation 6
Cumulative property value impact
Combines shadow value loss, flood risk discounting, insurance increases, and mold remediation costs over 30 years.

Community-wide financial impact projection

Sources: Shadow loss from Motu "Valuing Sunshine" (2.4%/hr). Flood discount from Cotality Miami study. Insurance: master policy increase ~$375/yr/unit + HO-6 increase ~$400/yr/unit + supplemental flood ~$1,000/yr/unit (per FEMA Risk Rating 2.0, WLRN/First Service Residential 2025, FL industry data). Mold remediation FL avg $2K–$8K per occurrence. NPV at 3% over 30 years.
Simulation 7
Insurance cost projection
Projects the annual and cumulative insurance cost increases for Millennium Town Homes residents resulting from the proposed development. Increased impervious surface raises flood risk; shadow-driven moisture accelerates mold claims; and Florida's hardening insurance market compounds these factors year over year. Costs include master HOA policy increases, individual HO-6 premium surcharges, and supplemental flood insurance.

Per-unit & community insurance cost forecast

Sources: FEMA Risk Rating 2.0 (April 2023). WLRN / First Service Residential (2025): South FL condo insurance rose 25% to $377/mo. Redfin/FL Surplus Lines Office: Miami HOA fees up 5.7–12.8%. Florida OIR: statewide property insurance increases averaging 7–12% annually (2020–2025). Master policy increase ~$375/yr/unit. HO-6 increase ~$400/yr/unit. Supplemental flood ~$1,000/yr/unit based on NFIP Risk Rating 2.0 for properties adjacent to increased impervious coverage.

Supplementary Documents

📄
Adverse Impact Analysis (PDF)
Full report with insurance projections & citations
⚖
Appeal Brief (PDF)
Opposition brief in support of appeal to BCC

Disclaimer: These simulations are approximations based on published methodologies, peer-reviewed research, and official government projections. They are supplementary evidence for a zoning appeal and do not constitute licensed engineering analyses.

Prepared by: Millennium Town Homes Association  |  Case Z2023000505 (Valemar Holdings LLC)  |  March 2026