The development of a drainage plan as described in this section is directed toward hard copy drawings and a non-electronic process of plan development and data supply. It is now common to utilize electronically gathered data supplied on terrain models, CADD drafting and automated design packages such as GEOPAK. Even with these advanced tools available to the engineer the basic drainage plan development concept is still applicable. The engineer is directed to consider this in applying the following procedure.

A copy of the project preliminary roadway plans with the proposed roadway section and construction limits noted is to be used as work plans to develop a pencil sketch type layout of the proposed drainage features. The sequence of development of these plans should be as follows:

(1) Confirm and add as necessary all existing drainage features (structure type, size, elevations).

(2) Note all existing drainage divides, flow directions, ditches, channels, etc.

(3) Confirm and add information addressing utilities that may affect drainage features.

(4) Plot any special ditches or other topographical features identified during field surveys and not included on the plans.

(5)Make notes of design controls identified during data collection and field survey stage.

(6) Determine and evaluate the patterns of surface flow as affected and developed by the project construction. (Note flow direction and concentrations as needed for clarity in red).

(7) Develop a scheme and layout of drainage features (bridges, box culverts, pipes, storm drainage systems, ditches, channels, etc.) to properly convey surface flow within and adjacent to the project. Note these features on the plans in red.

(8) Utilizing procedures presented in the following section of these guidelines, perform the design studies required to detail each drainage feature (type, size, location, material, etc.).

(9) Documentation of the design detail of each individual feature will be provided as directed in the related section of the guideline. A short summary of information relating to each feature shall be noted on these work plans and consist of the following as a minimum:

• location by station, skew or other descriptive detail
• type, size and material
• elevations (invert, grade, etc.)
• drainage area
• design discharge and elevation
• base discharge and elevation
• overtopping discharge and elevation

(10) Plot storm drainage system profiles including:

• pipe and inlet inverts
• utility crossings
• hydraulic grade line (water surface profile)

(11) Note all special channel and ditch detailing including special grades and permanent lining requirements.