2026 02 12 Crestmont CC and Eagle Rock Ave Stormwater Management Report

0 0 1000 2000 3000 4000 5000 6000 7000 Total Storage (cuft) 2-yr 10-yr 25-yr 100-yr Contours

Pond Report File: Eagle Rock Proposed (Future).hys Hydrology Studio v 3.0.0.39 10-21-2025 PAPS-1 Stage-Discharge Orifice Culvert / Orifices Cir Culvert Perforated Riser 1 (i) 2 (i) 3 Rise, in 3 3 Hole Diameter, in Span, in 3 3 No. holes No. Barrels 1 1 Invert Elevation, ft Invert Elevation, ft 553.00 554.80 Height, ft Orifice Coefficient, Co 0.60 0.60 Orifice Coefficient, Co Length, ft Barrel Slope, % N-Value, n Weir Weirs Riser Ancillary 1 2 3 Shape / Type Exfiltration, in/hr Crest Elevation, ft Crest Length, ft Angle, deg

Exfiltration, in/hr Crest Elevation, ft Crest Length, ft Angle, deg Weir Coefficient, Cw m = Flows through Culvert, i = Independent Stage-Discharge 556 3 555 2 554 1 553 0 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 0.55 0.6 0.65 0.7 0.75 0.8 0.85 0.9 0.95 1 Discharge (cfs) Top of Pond 2-yr 10-yr 25-yr 100-yr Pond Outflow

Hydrograph Report File: Eagle Rock Proposed (Future).hys Hydrology Studio v 3.0.0.39 10-21-2025 PR-2B Routing Hyd. No. 57 Hydrograph Type = Pond Route Peak Flow = 0.205 cfs Storm Frequency = 2-yr Time to Peak = 12.70 hrs Time Interval = 1 min Hydrograph Volume = 5,506 cuft Inflow Hydrograph = 56 - PR-2B Max. Elevation = 553.88 ft Pond Name = PAPS-1 Max. Storage = 2,314 cuft Pond Routing by Storage Indication Method Center of mass detention time = 2.69 hrs Qp = 0.205 cfs 2 1.9 1.8 1.7 1.6 1.5 1.4 1.3 1.2 1.1 1 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 Time (hrs) PR-2B PR-2B Routing

Hydrograph Report File: Eagle Rock Proposed (Future).hys Hydrology Studio v 3.0.0.39 10-21-2025 PR-2B Routing Hyd. No. 57 Hydrograph Type = Pond Route Peak Flow = 0.273 cfs Storm Frequency = 10-yr Time to Peak = 12.87 hrs Time Interval = 1 min Hydrograph Volume = 8,901 cuft Inflow Hydrograph = 56 - PR-2B Max. Elevation = 554.46 ft Pond Name = PAPS-1 Max. Storage = 3,854 cuft Pond Routing by Storage Indication Method Center of mass detention time = 2.99 hrs Qp = 0.273 cfs 3 2 1 0 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 Time (hrs) PR-2B PR-2B Routing

Hydrograph Report File: Eagle Rock Proposed (Future).hys Hydrology Studio v 3.0.0.39 10-21-2025 PR-2B Routing Hyd. No. 57 Hydrograph Type = Pond Route Peak Flow = 0.354 cfs Storm Frequency = 25-yr Time to Peak = 12.85 hrs Time Interval = 1 min Hydrograph Volume = 11,525 cuft Inflow Hydrograph = 56 - PR-2B Max. Elevation = 554.92 ft Pond Name = PAPS-1 Max. Storage = 5,060 cuft Pond Routing by Storage Indication Method Center of mass detention time = 3.22 hrs Qp = 0.354 cfs 4 3 2 1 0 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 Time (hrs) PR-2B PR-2B Routing

Hydrograph Report File: Eagle Rock Proposed (Future).hys Hydrology Studio v 3.0.0.39 10-21-2025 PR-2B Routing Hyd. No. 57 Hydrograph Type = Pond Route Peak Flow = 0.641 cfs Storm Frequency = 100-yr Time to Peak = 12.62 hrs Time Interval = 1 min Hydrograph Volume = 16,716 cuft Inflow Hydrograph = 56 - PR-2B Max. Elevation = 555.69 ft Pond Name = PAPS-1 Max. Storage = 7,083 cuft Pond Routing by Storage Indication Method Center of mass detention time = 3.07 hrs Qp = 0.641 cfs 5 4 3 2 1 0 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 Time (hrs) PR-2B PR-2B Routing

= = WATER QUALITY DESIGN STORM ROUTING CALCULATIONS FOR SETTING BOTTOM ORIFICE INVERT ELEVATIONS

SMALL-SCALE BIORETENTION BASIN 1

Hydrograph Report File: Eagle Rock Proposed (Future).hys Hydrology Studio v 3.0.0.39 10-21-2025 PR-1A Routing Hyd. No. 11 Hydrograph Type = Pond Route Peak Flow = 0.000 cfs Storm Frequency = 2-yr Time to Peak = 61 min Time Interval = 1 min Hydrograph Volume = 0.001 cuft Inflow Hydrograph = 10 - PR-1A Total Max. Elevation = 534.52 ft Pond Name = SSBB-1 Max. Storage = 2,487 cuft Pond Routing by Storage Indication Method Center of mass detention time = 2.59 hrs Qp = 0.000 cfs 3 2 1 0 -1 0 10 20 30 40 50 60 70 80 Time (min) Req'd Stor PR-1A Total PR-1A Routing