Paradise Valley readies new guidelines to corral local water flow

Paradise Valley officials gathered at Town Hall to discuss potential storm water mitigation efforts. (Independent Newsmedia/Terrance Thornton)

An effort fueled by a desire to preserve natural washes and a systematic approach to address where the water flows in, down and around the topography of the Town of Paradise Valley is afoot at Town Hall.

Paradise Valley Town Council is in the midst of a storm drainage design manual update more than 30 years in the making, and embedded within the municipal planning tool are potential parameters on how and what lots home builders and resort developers can and cannot build.

While town officials appear adamant to ensure flexibility within the manual update, the municipality is expected to host a community charrette in the coming weeks giving both residents and local builders a chance to provide feedback on proposed changes.

Paradise Valley Town Council hosted a March 8 work study discussion on the drainage manual update, which served as a first blush look at how town staff are developing design parameters.

The discussion revolved around five key questions, which was presented by Jeremy Knapp, Paradise Valley engineering services analyst. They are:

  • Does town council favor requiring a retention easement?
  • Does town council favor adding a first-flush requirement?
  • Does town council prefer a proactive or reactive approach to maintenance of stormwater facilities?
  • Does town council prefer to leave the preservation of natural wash language unchanged?
  • Does town council want to allow parking lot storage or not?

The Town of Paradise Valley has been in the process of updating its 1987 Storm Drain Design Manual, which is now coined the “Storm Drainage Design Manual,” and many of those revisions speak directly to water retention requirements and how those rules effect natural water flow.

On Sept. 8, 2014, the Town of Paradise Valley experienced a level of rain exceeding what is known as a 100-year storm event that left an estimated 80 homes flooded in what town officials have coined the Cheney and Cherokee watersheds.

That flood and one that occurred in 2013 of a similar magnitude spurred an interest in where water flows within town limits, town leaders agree.

A flood level, or flood stage, is the level at which water is risen to a sufficient level — typically measured at 100-year events — to flood areas not normally covered by water, causing a threat to life or property.

Home building is a big part of market activity in the Town of Paradise Valley and how those projects impact natural water flow plays a role in storm water mitigation, officials say. (File photo)

Preservation of the natural wash

Paradise Valley Town Manger Kevin Burke says within the pending update to the storm drainage manual is a proposal for a tiered system to address natural wash preservation and sets in place formal waterflow guidelines.

Kevin Burke

“What is the goal of the council?” Mr. Burke asked.

“What is more important to you as a community? To preserve the natural wash or is it to allow the developer to use the property as they want and just make sure the water flows. Because right now the policy piece that has been codified says you have to leave that open and we are trying to find where is that middle ground?”

Mr. Knapp explains the town is proposing to develop a three-tier system for evaluating the parameters of modifying both “minor” and “natural” washes on private property.

“Property owners sometimes don’t know that it is their responsibility to maintain washes or basins and culverts,” Mr. Knapp explained.

“Maybe not even being able to recognize what is on their property and maintaining it properly. More recently, staff had been proactively providing this information and approving more dry wells and underground retention facilities that the owners may not have known they were there.”

At the core of the issue, Mr. Knapp says, was to what degree does water flow modification need to be regulated?

“The issue was do we allow private property owners to modify washes on their private property or require them to be protected?” he said of the key policy question. “It is a town value to protect the natural character of washes, but recognize private property development rights.”

Mr. Knapp contends a tiered approach to the modification of natural waterflow could be a middle ground between storm water management and property value.

Engineering Analysis Jeremy Knapp talking to town council. (file photo)

“There is nothing in the code that eliminates access to a property because there is a wash in the way — that is one of baseline parameters for this section of the document,” he said.

“All washes have to maintain their existing entry and exit points no matter what happens between that entry and exit point with that development. I know there is some concern —- and we have talked about specific lots about how this would effect the marketability of that lot and or what can be built on either side of the wash for example —- there is some concern about the application.”

But Mr. Knapp explains further the manual modification proposal is merely a formality to already adopted practices.

“I think this is codifying some (things) we have been doing in practice,” he said. “This, in terms of text, is more lenient than what the code says. There are lots where this will effect what can be built on that lot if there is a wash.”

A formal approach

Paradise Valley Vice Mayor Jerry Bien-Willner points out the document being discussed is only as good as the person who enforces it.

Jerry Bien-Willner

“This is more permissive than what is allowed under the current manual; however, I have heard that this document is only as good as the town engineer,” he said during the public discussion. “This is an attempt to systematize an approach where you had certain tiers of handling it. I like predictability in knowing what people are doing.”

Vice Mayor Bien-Willner says he thinks, at the onset, this is a good step toward striking a balance.

“I think there is some merit to having some natural features. It’s no different than hillside,” he said. “I think this tries to strike a balance.”

But how new stormwater guidelines evolve — and the calculations that could determine those parameters — may have financial ramifications, Vice Mayor Bien-Willner points out.

“There is a property value issue as well if you change the parameters wildly,” he said the manual update.
Paradise Valley Councilman Scott Moore says he sees a workable plan forming.

Scott Moore

“I think what we are looking at tonight does give more flexibility to what is currently in place,” he said of the staff presentation.

“This is going to be done through a drainage report and evaluated by an engineer. It isn’t just somebody who decides whether or not it meets the criteria —- it’s done by an engineer.”

But Councilman Moore, and his colleagues, agree the building community ought to have a say in how these rules are developed.

“I certainly want to hear from our building community and if you are getting those comments, I want to see those as well,” he said of town staff communication with local developers and home builders.

Retention and first-flush

Mr. Knapp presented to council a typical challenge with enforcing water retention requirements that, until now, has gone undocumented.

A view of boulders that sometimes fall down residential areas at the base of Camelback Mountain due to flooding exacerbated by drainage issues. (Submitted photo)

“This is a challenge we have had in the past,” he said of retention basin easement requirements. “The idea of using a recordable document for those storm drainage facilities was discussed with the town attorney. As the property changes hands from one property owner to the next they will be aware that these facilities exist on the property and they need to be maintained.”

Mr. Knapp says as proposed, a retention requirement would be a document that would run with the land, but would not carry an easement on the property.

Town officials are also proposing a new requirement regarding the first-flush of water flow — the first half-inch of rain carrying sediment and contaminants into the storm drainage system — for certain hillside properties.

“The first flush is that first half-inch of rain we have been discussing on a property that often collects and transports oil, grease, gas and other pollutants such as sediment that eventually make its way into the storm drain system,” Mr. Knapp said, noting staff was originally asked to explore requiring first-flush requirements on commercial property within town limits.

“But staff is recommending we require the first-flush only for the hillside lots with a slope of greater than 30 percent. Anything less than 30 percent will have on-site retention, which would address the first flush anyways.”

Northeast Valley Managing Editor Terrance Thornton can be contacted at tthornton@newszap.com

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