To: Honorable Mayor and Members of Town Council
Through: David L. Corliss, Town Manager
From: Mark Marlowe, P.E., Director of Castle Rock Water
Roy Gallea, Engineering Manager
Matthew Hayes, Technical Engineering Manager
Title
Ordinance Amending Castle Rock Municipal Code Section 15.10.030 to Permit the Use of the IAPMO Water Demand Calculator for Residential Water Calculations Only (Second Reading - Approved on First Reading on September 3, 2024 by a vote 7-0) [Castle Rock Water Service Area]
Body
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Executive Summary
The purpose of this memorandum is to request Town Council approval of an Ordinance revising the Town Code to require the use of the International Association of Plumbing and Mechanical Officials (IAPMO) Water Demand Calculator for service line sizing for residential development. Castle Rock Water is seeking to adopt code that requires Ultra High Efficiency Toilets (0.8 gallons per flush (gpf)) in new residential construction in accordance with our Strategic Plan for meeting the goal of 100 gallons per capita per day water conservation. Through the public outreach process, the Plumbing Manufacturers International (PMI) expressed concerns about the impact on water quality and solids removal due to the reduced water use of these toilets.
The Town contracted Dewberry Engineers to evaluate the use of the Water Demand Calculator to more accurately size the internal plumbing to reduce the possible water age within the internal plumbing. Dewberry also evaluated the potential for water quality and solids removal with the 0.8 gpf toilets. The conclusion of this analysis determined that based on typical residential water demands, water quality and solids removal are not a concern for single family residential homes and that incorporation of the new Water Demand Calculator to size the supply and drainage lines improves the engineering of these homes. This change will provide additional support for proceeding forward with the requirement for Ultra High Efficiency toilets in single family residential homes and multifamily residential development. Therefore, CR Water is recommending revising the Town Code to require the use of the IAPMO Water Demand Calculator for sizing of water supply lines.
Budget Impact
There are no costs to the Town associated with this code revision. Based on our analysis of the 10 representative homes, the builder will see a cost savings of approximately $875 per home. This is based on the smaller pipe sizes within the home. The code revision will make future residential development more water efficient by decreasing the size of the supply side plumbing resulting in hot water getting to showers and sinks more quickly with less waste. The code revision will also support moving to 0.8 gpf toilet requirements for residential development which will provide additional water conservation, saving the Town capital investments for additional future renewable water rights and infrastructure.
Staff Recommendation
Staff recommends approval of the Municipal Code revision for the required use of the IAPMO Water Demand Calculator for residential service line and water supply line sizing inside the building.
Proposed Motion
“I move to approve the Ordinance as introduced by title.”
Alternative Motions
“I move to approve the Ordinance as introduced by title, with the following conditions: (list conditions).
“I move to continue this item to the Town Council meeting on _____ date to allow additional time to (list information needed).”
Attachments
Staff Report
Attachment A: Ordinance