Recent content by watershedc

Hi: Does anyone have a good reference for an appropriate curve number representing disturbed soil with temporary stabilzation consisting of hay mulch or an RECP? Thanks.

Peter, I'm having some difficulty visualizing your recommendation. Just to make sure I provided a clear description of the configuration- the grate is 30" diameter, round. One side will be tipped up from horizontal to match the 3:1 slope of the basin. The result will be a round grate that is...

So, using a vee/trap weir outlet, the invert should set to the elevation of the spillway, the notch left blank, and the width set to 2.5'- the diameter of the riser. Is this the configuration you would recommend for modeling this scenario? thanks for clarifying.

Hello, I am modeling a concrete riser and grate in a detention pond. The 30 inch diameter grate on top of the riser will be angled to match the 3:1 slope it is embeded in. I am not sure the best way to model this angled outlet.

OK. Given the approach of considering total seasonal rainfall vs individual storm events, hydrocad could not be utilized, is that correct?

Thanks for the reply. The ultimate purpose of the H&H study is related to runoff management, although the management facilites being modeled may double as snowmaking water reserves. We expect that other sources (baseflow) would be used in conjunction with stored runoff for the snowmaking. I...

I have set up a runoff model in support of a snowmaking feasibility study. I am trying to determine what specific rainfall events would be most appropriate to model to best evaluate available surface runoff volumes for snowmaking. I also wonder if it would be appropriate to include...

Hello, Does anyone have a suggestion on appropriate CN to use for multiple wetland areas, which are included in a large scale modeling analysis? The wetland areas appear to hold permanent pools of water based on orthophotography, although I'm hesitant to assign a high CN such as 98 or even 100...

Thanks everyone. This is helpful information. The roof I am trying to model is existing, and I am interested in possible detention effects to determine permit compliance. It sound like the bottom line is I need better data to really determine what is happening.

Peter, the storm event I'm evaluating creates a ponding dpeth of 0.11' on the roof. I just received better data on the drain system. It consists of 16, 6" orfices flush to roof. The peak discharge was reduced from 16 to 3 cfs. I was suprised to see so much detention.

Thanks. I followed the guidance recommended for modeling a roof. Made the roof area a subwatershed routed into a pond with outlet. Even though I do not have specific numbers for the drains coming of the roof, I entered 30 X 30" horizontal orifices as the roof outlet, and defined the roof...

Hello, I am trying to model a large roof (3.5 acres) and the roof drain pipe receiving the runoff. I do not have data on the size and exact number of vertical pipes draining the roof, but suspect they are not the controlling factor in the model because there are so many of them. I do have...

Hi group, I'm trying to model an open channel as a pond structure, since I would like to account for exfiltration via an under drain along the swale, and a raised outlet structure at the discharge point of the channel. I notice that it is possible to model a horizontal cylinder with a sloped...

I'm trying to model the effects of both an inlet grate at the surface and an outflow pipe in a catch basin. I understand that catch basins are typically modeled as zero storage pond structures, however, I'm unsure about how to set up the routing to evaluate both of these controls. Thanks in...