Letting Creeks See The Light Of Day

New Storm Drainage Master Plan Revealed

Here is an excerpt from my October 2014 column, providing a description of a portion of the Mayfair neighborhood significantly shaped by the Park Hill Branch of Montclair Creek:

“The site is bounded on the north by Colfax Avenue, on the east by Leyden Street, and on the south by 13th Avenue. From 13th Avenue to 14th Avenue, the western boundary is Jasmine Street. At 14th Avenue, the boundary jogs one and a half blocks west from Jasmine to the alley halfway between Jersey and Ivy. It then turns north and extends along that alley from 14th Avenue back to Colfax.”

While you were reading that October column, I was attending two statewide conferences, one for floodplain and stormwater managers, and the other for watershed planners and managers. Colorado’s  massive floods of September, 2013 provided the backdrop for both conferences. I am very pleased to have observed a lot of the lessons the Mother Nature provided us during that dramatic week last year are truly being taken to heart by those in my profession and many of the citizens with whom we come into contact.

It was with great pleasure that I caught up with old friends and met new ones, and, among other things, had a chance to talk with peers about those lessons.

One of those old friends reminded me that the Denver City Council literally just adopted the September 2014 update Storm Drainage Master Plan. He told me that there was information in the new Master Plan that would address some concerns he knew that I have had for a long time.

As a result, I am taking a detour on my way to fulfilling my promise last month to show you “land use ‘bubbles’ that assume at least as much density as is currently permitted” and that rearrange that density  “substantially to interface logically with the “creek and pond” bubble and with the site’s perimeter.”

Instead, I will share some highlights from the new Master Plan (those of you who are not engineers or water planners hold your smirks about the word ‘highlights’!)

First Highlight: In German, “thalweg” means “valley course.” In waterspeak and in Denver’s new Master Plan, it means “… natural drainage paths, shown to identify the major overland flow paths that storm runoff would follow in storm events that produce runoff in excess of the existing storm drainage collection system capacities.” (In plain English, that means where stormwater flows after the pipes fill up).

Thalwegs are shown in the new Master Plan, so I have modified last month’s map to add the thalweg in the vicinity of 14th Avenue and Kearney Street.

Second Highlight: Denver Wastewater has coined the new term “Potential Inundation Areas” “… areas where stormwater has been report to collect in depths exceeding 12” during storm events and where various studies have identified the potential for water depths greater than 12” in a major storm event.”

“Property owners in PIAs are encouraged to implement floodproofing measures…” I will discuss and show some of the PIAs next month.

Third Highlight: Each major drainage basin discussed in the Master Plan is summarized in the Executive Summary. Here is the summary for the Montclair Creek watershed:

“The Montclair Drainage Basin … is the largest storm drainage basin in Denver which does not have a surface drainageway. A survey in 1861 shows two watercourses converging at present-day East Colfax and Colorado Boulevard, then continuing northwest through present-day City Park (Ferril Park) and onward to the South Platte River. A 1979 Geologic Map of Denver, prepared by the USGS, shows an identical pattern of alluvial soils … “

“The Capitol Hill Storm District Number 1 created in the early 1900’s financed construction of a large storm drainageway to convey storm flows to the South Platte River. In larger storms, runoff in excess of the drain capacity follows the original drainageway path and causes flooding at numerous locations and intersections.”

Sounds like a great watershed for some creek daylighting – a term that refers to the uncovering and restoration of creeks, streams, and rivers that were previously buried in underground pipes and culverts, covered by decks, or otherwise removed from view.

Most Important Highlight: At both conferences, I learned that others in my professional community share my interest in and desire to pursue the possibility of daylighting more creeks and rivers in Colorado. I am not, and never was, the Lone Ranger in terms of opening up undergrounded streams.

For evidence, join me in January 2015, when a daylighting and restoration project will begin at Montview Boulevard and Westerly Creek, between Boston and Clinton Streets, near the south end of Stapleton.

Brian Hyde is an expert in floodplain management and stream restoration. He wants your feedback at westerly_connect_brian@comcast.net or 720-939-6039.