Design Guidelines
Street Type | Right-of-Way Width (feet) | Cartway Width (feet) | |
|---|---|---|---|
Arterial | Pursuant to DelDOT requirements | ||
Collector | 60 | 34 | |
Local (cul-de-sac) | 50 | 24 |
H = 0.2 feet + 0.8 (D1 — D2) | ||||
|---|---|---|---|---|
Where: | ||||
D1 | = | Diameter of inlet pipe | ||
D2 | = | Diameter of outlet pipe | ||
If D1 is larger than D2, head loss = 0.2 feet | ||||
n | = | 0.015 for best concret-lined ditch | |
|---|---|---|---|
n | = | 0.025 for best unlined ditch | |
n | = | 0.03 to 0.15 for fair to poor natural streams and watercourses |
Excavation Material | Allowable Velocity (feet per second) | |
|---|---|---|
Fine sand and firm loam | 2.50 to 3.5 | |
Stiff clay and hardpan | 3.75 to 6.0 | |
Concrete-lined ditch | 15 |
Q = 3.087 x ((D^3)) ^0.5 x L | ||||
|---|---|---|---|---|
Where: | ||||
Q | = | Capacity in cubic feet per second | ||
D | = | Depth of spillway in feet | ||
L | = | Length of spillway in feet | ||
Rev = I * impervious area (square feet) ÷ 12 (inches) = cubic feet (cf) |
Rev = I * impervious area (square feet) ÷ 12 (inches) = cubic feet (cf) | ||||
|---|---|---|---|---|
An asterisk (*) in equations denotes multiplication. | ||||
Where: | ||||
I | = | The maximum equivalent infiltration amount (inches) that the site can physically accept or 0.50 inch, whichever is greater. | ||
Any decision to administratively approve or deny a permit application is subject to review by the Commissioners of the Town of Dewey Beach. |
Design Guidelines
Street Type | Right-of-Way Width (feet) | Cartway Width (feet) | |
|---|---|---|---|
Arterial | Pursuant to DelDOT requirements | ||
Collector | 60 | 34 | |
Local (cul-de-sac) | 50 | 24 |
H = 0.2 feet + 0.8 (D1 — D2) | ||||
|---|---|---|---|---|
Where: | ||||
D1 | = | Diameter of inlet pipe | ||
D2 | = | Diameter of outlet pipe | ||
If D1 is larger than D2, head loss = 0.2 feet | ||||
n | = | 0.015 for best concret-lined ditch | |
|---|---|---|---|
n | = | 0.025 for best unlined ditch | |
n | = | 0.03 to 0.15 for fair to poor natural streams and watercourses |
Excavation Material | Allowable Velocity (feet per second) | |
|---|---|---|
Fine sand and firm loam | 2.50 to 3.5 | |
Stiff clay and hardpan | 3.75 to 6.0 | |
Concrete-lined ditch | 15 |
Q = 3.087 x ((D^3)) ^0.5 x L | ||||
|---|---|---|---|---|
Where: | ||||
Q | = | Capacity in cubic feet per second | ||
D | = | Depth of spillway in feet | ||
L | = | Length of spillway in feet | ||
Rev = I * impervious area (square feet) ÷ 12 (inches) = cubic feet (cf) |
Rev = I * impervious area (square feet) ÷ 12 (inches) = cubic feet (cf) | ||||
|---|---|---|---|---|
An asterisk (*) in equations denotes multiplication. | ||||
Where: | ||||
I | = | The maximum equivalent infiltration amount (inches) that the site can physically accept or 0.50 inch, whichever is greater. | ||
Any decision to administratively approve or deny a permit application is subject to review by the Commissioners of the Town of Dewey Beach. |