2021.0170.PR0006 COY-Letter of Understanding_Stormwater Requirements_05-24-2016City of Yelm
Public Works Department
Physical Address: 901 Rhoton Road SE
Mailing Address: 105 Yelm Ave West
Yelm, WA 98597
(360)458-8406 Fax: (360) 458-8417
Web: www.ci.velm.wa.us
May 24, 2016
Tahoma Terra Holding, LLC
Attn: John Harkness
PO Box 73790
Puyallup, WA 98373
Subject: Letter of Understanding — Tahoma Terra Master Plan Community
Stormwater Requirements & Vesting
Dear Mr. Harkness,
The City of Yelm (COY) and Tahoma Terra Holding, LLC (Developer) have a mutual desire to come
to an understanding as it pertains to the stormwater management for the continued platting and
development of the Tahoma Terra Master Plan Community (MPC). A meeting was conducted
between the two parties on May 17, 2016 to coordinate the stormwater permitting requirements for
the MPC for Division 2, Phase 2's forthcoming application, as well as future requirements for the
MPC.
This letter is to memorialize the mutual understanding as it pertains to stormwater regulations and
requirements imposed by the COY for the MPC relating to existing stormwater infrastructure and
future development or modification of stormwater conveyance, treatment, and detention/infiltration
systems.
Both parties recognize the complexity of stormwater regulations, and agree that it is in their best
interest to develop continuity and engineering predictability for the MPC, and furthermore that the
development shall be vested to design all stormwater facilities utilizing the Department of Ecology
(DOE) 1992 Stormwater Manual for the Puget Sound Basin for any new or retrofit stormwater
facilities within the Tahoma Terra MPC. However, looking for ways to improve stormwater quality
discharge prior to infiltration utilizing latest practices shall be strongly considered.
Conditions to be met prior to final plat approval of Tahoma Terra Division 2 Phase 2
• Developer is required to conduct water quality monitoring at its existing regional wetpond
and infiltration pond to confirm that water quality standards are being achieved.
• Developer agrees to conduct a Winter Weather Stormwater Study in 2016-17 to determine
flows and depth to ground water and report those results to the City
• Developer shall install a minimum of one Ground Water Monitoring Well with the Winter
Weather Study as required per the 1992 DOE SWMM near the existing regional facility.
• The remaining development of the 198 -lots, which may be phased, will not require any
stormwater changes to the existing pond system, unless the as stated monitoring or study
of the facility determines it is not meeting the original designed performance requirements.
If modification is needed to the existing ponds, said modifications shall be completed prior
to the recording of the final plat of phases 5 and 6. City staff has already reviewed the
stormwater system for the current phase and has offered no comments that the regulations
in place are not being met.
Conditions for all future phases of the Tahoma Terra MPC
• If the Developer relocates his/her existing stormwater management pond system south of
Tahoma Blvd, any new facilities constructed as replacements will be designed to the most
current DOE design standards for water quality, however, maintaining the 1992 manual for
retention/detention.
This letter of understanding may be revised or revisited in the future if both parties agree that is
beneficial to the permitting, development or design of Tahoma Terra MPC.
Please feel free to contact me at (360) 458-8412 if you have any questions or require any further
clarification of these requirements.
Best Regards,
Chad A. Bedlington
Public Works Manager
Cc: Ryan Johnstone, PW Director
Grant Beck, P&CD Director
Tami Merriman, Associate Planner