I am reviewing an engineer's drainage report, showing both current and proposed conditions for a housing addition. In the proposed design, a detention pond is designed, with an outlet structure. The details are shown in the accompanying file. To figure the discharge at the elevations, would I...
Say I have a pre-construction site which has a total area of 3.8 acres. In this 3.8 acres lies two homes (about 1400 sf - one floor), two separate garages (not connected to the homes and about 450 sf each) and a small shed. The rest of the acreage is grass, in good condition. When the runoff...
Hello,
I am struggling with HEC-HMS, particularly with Control Specifications and Time Series Data. I don't understand what they are and how to configure them so I don't keep getting errors after errors. [banghead]
As far as the time series data goes, my predecessor told me to use the Type II...
Hello,
I am reviewing drainage which has a detention pond with the outlet structure as shown on the accompanying file.
The outlet structure is a 4' x 4' Riser Box. The top elevation of this box is 1300, while the bottom elevation is 1295.30. There are two circular openings on one side of the...
hello all,
I am reviewing a proposed construction site's drainage report. Included in it is a detention basin to capture the water after construction, slow it down and then take it to the ditch of the adjoining state highway. The parking lot area of the proposed construction site has a storm...
Hello,
In reviewing a detention basin with a single outlet structure being that of a 18" pipe with no riser attached, how do I analyze the pipe? I'm wanting to use this analysis to put together a table with elevations and discharges of the pipe. Would I analyze it using HY8 or using Orifice...
Hello everyone,
The detention basin has an outlet structure of a 3' x 3' box, with a V-notch weir on the entrance side and a 12" RCP stubbed into the opposite wall. I work with HEC-HMS. The pipe has a very flat slope (0.26%); it has tailwater. How would I figure the discharge going through the...
hello,
I've only been using HMS for a little over a year now, so I may not have come across this in the program yet. I have a drainage area flowing through a double 24" RCP. Can I analyze the RCP as a reach in HMS? Once the water flows this double pipe, it combines with water which has flowed...
Hello,
I use HEC-HMS to route water through a detention pond. To find the elevation - discharge curve, I use Excel to find the discharge relating to its relevant elevation - using the Weir or Orifice Equations as appropriate. I'm working on a detention pond that has a 4' wide by 45' long...
I'm fairly new to the Dam / Reservoir hydraulic modeling, so I'm sure there a million questions zooming around in my head, but, for now, I have just a couple.
I'm working on a Dam that was built in 1967. Before the previous drainage engineer retired, he told me to use the sediment pool...
hello everyone,
I'm fairly new to the detention pond hydraulics concept but am understanding it so far. A question or two....I've read in some manuals (don't recall specific ones)or books that the user should calculate the weir and orifice equations. Is this for a riser pipe (or box) or is this...
I'm fairly new to this much in-depth study of hydrology and hydraulics; so forgive me if I sound ignorant. I used to use mainly the Rational Method; now I'm using TR-55 and HEC-HMS. Most of the drainage areas I come across are less than one square mile or 640 acres.
My question is this: when...
