Save Hinkle Creek Update

Save Hinkle Creek Supporters       

We have remained very connected with the City of Folsom having just completed our fourth in person meeting this year with Marcus Yasutake, Environmental and Water Resources Director and his team.  After our June 13, 2017 City Council meeting, where many of you showed up to support Saving Hinkle Creek, we received a positive ruling from the State Water board stating that the City of Folsom was not required to access all manholes with a hydrovac truck.  After the positive ruling we received the September 1, 2017 letter from Evert Palmer, City Manager, outlining the path forward which is attached below.  The City Manager’s letter was in line with our recommended path forward.  Here is a summary of where we are today:

Update/Agreement – These are areas that we are in agreement.

Sewer Line Repairs
Approximately 2/3 of the sewer line will be replaced/realigned.  Approximate route of the new line is from the intersection of Blue Canyon way and Canyon Rim Drive to the center of Canyon Rim Court, then across the Hinkle Creek Nature Area to Oak Avenue.  The diameter of the pipe will be increased from 6 inches to 10 inches (with the exception detailed below).

To provide better flow, the upper portion of the sewer line will be re-routed which will result in abandoning the sewer manholes that are located in homeowners back yards.  The city will remove the steel lid and concrete cap and fill the manholes for those abandoned. 
Bidding Process Staff is preparing two separate bid alternatives which will be presented to City Council for approval. 

Conventional construction method:  This approach uses a conventional back hoe and requires a level temporary road to be constructed along the path of the new line which is 12 feet wide.  With the cuts and fills required to produce a level 12 foot wide surface on a steep slope this will have a significant negative impact on the trees and vegetation in Hinkle Creek.  If this method is necessary, the temporary road will be covered up and restored to as natural a condition as possible after construction.

All Terrain Excavation method:  While we believe it is financially prudent to get conventional bid for comparison, our strong recommendation has been to employ an all-terrain excavator which can dig the new sewer line without a level road. This approach should have benefits of causing much less damage to the trees and nature area since a 12 foot temporary road will not need to be constructed/de-constructed.  Here is a link to photos of an all-terrain excavators in action: https://www.google.com/search?q=all+terrain+excavator&client=firefox-b-1&tbm=isch&source=iu&ictx=1&fir=MlBioL3PQKOsnM%253A%252CGmdfgrQKvnFOnM%252C_&usg=AFrqEze51LPmspjF4xdLQXNx4mLoOOicTQ&sa=X&ved=2ahUKEwjt2PL9ncPdAhUNHzQIHQLdA_gQ9QEwAXoECAYQBg#imgrc=-_pRPC8tMci1IM:
Schedule

The current outlook is to get City Council approval in the June/July 2019 time frame and begin construction August/September 2019.
Open Items

Tree Impact – Quincy Engineering is to provide an estimate of the trees that will be impacted in three categories:
Trees impacted by the all-terrain excavator
Trees impacted by the non-mechanical dirt walking trail (should be zero)
Trees impacted if they build a temporary 12 foot wide construction road
The results of the analysis should be available in the next few weeks

Concerns/Disagreement

New Bridge Over Hinkle Creek

In the City Manager’s September 1, 2017 letter he states:
“Construct minor improvements that facilitate construction of the improvements and practical, non-mechanical response to SSO events

·       Single/double track dirt trail to support stable access by maintenance workers with shovels, rakes, buckets, and wheel barrows

·       Bridge over the creek near Oak Avenue at the base of the single/double track dirt trail in order to facilitate removal/hauling of contaminated material”

When we read this letter we believed that the bridge would be a narrow single/double track size bridge to accommodate the non-mechanical walking path and we encouraged them to use the current walking bridge just about 100 feet from the proposed bridge.  However in July 2018, the City Council approved an additional $205,000 contract that  authorizes Quincy engineering to design a permanent bridge that would accommodate heavy vehicles such as a back hoe. 
We know the all-terrain excavator can cross Hinkle Creek without any disruption, so a bridge is not required for construction of the new sewer line if the all-terrain construction method is employed.  So the issue is access to the manholes should there be an overflow after construction is completed.   Here is a summary of why we feel the bridge is not necessary:

There are about 18 manholes in the sewer line.  The bridge will provide mechanical equipment access to only two of the manholes as the topography is too steep for mechanical access without a permanent 12 foot wide road. 

The City Manager’s letter states manholes should be accessed with non-mechanical equipment via a single/double track dirt trail.  Why would we spend $205,000 to design (not build) a bridge if it is not required?

Since we had the sewer line completely cleaned and camera inspected in August 2016 we know that every inch of the line can be flushed without any mechanical machinery entering the nature area.  This is accomplished via long extremely high pressure hoses that are computer controlled and guided through the sewer line – the same process to used to clean the lines without access issues.
Marcus Yasutake shared that their SSO on site response time is 30 minutes.  Which applies to all of the manholes in the nature area.  We had proposed that he contract for emergency response from an all-terrain excavator contractor in the event a mechanical support was required to resolve a SSO.  On site response of the all-terrain vehicle would take more than 30 minutes, so conventional high pressure hoses and other procedures would be necessary to contain an overflow until the all-terrain excavator arrived on site.  The two manholes accessed via the bridge with mechanical equipment are the two closest to Hinkle Creek so SSO’s are most likely to allow waste overflow into the creek.

The City Manager’s letter states they will “Install electronic flow and level reporting inside manholes”  which provides early warning of any backups as most of these manholes are buried in the brush in the park unlike manholes in the center of the street.  This provides early warning of potential blockages.  Given the low volumn of liquids in this line it would take many hours of normal flows to generate a spill caused by a blockage in the line. 

It is very important to keep in mind that the sewer line has been in service for over 35 years and the city’s maintenance records are available for the past 14 years.  City records have recorded only two overflows in the last 14 years.  The point here is that combining annual flushing and camera inspection of the line along with replacing all questionable sections of the sewer line with almost double the capacity lines and installing an early warning overflow monitoring system should be way more than is necessary to minimize the probability of an overflow given it has happened only twice in 14 years.
6 Inch line under Hinkle Creek – for all sections of the pipe replaced except for one will be increased from a 6 inch diameter pipe to a 10 inch pipe.  That last section just before the sewer flow reaches Oak Avenue flows through a 6 inch line under Hinkle Creek.  The current proposal is to insert a liner in this line for better flow and not replace it with a 10 inch line because of environmental concerns of replacing the line under the creek.  Marcus Yasutake agreed to revisit this decision and get more details on the requirements to complete this construction with a 10 inch line under Hinkle Creek.  We believe it makes sense to upgrade the last ~50 feet to a 10 inch line vs. maintaining a 6 inch constriction at the critical point just before the overflow point into Hinkle Creek.   We will get an update in our next meeting on this issue.

We believe that combining: increasing the line to 10 inches under Hinkle Creek,  using non-mechanical access for SSO response (as agreed with the City), contracting all-terrain excavator for emergency response, annual flushing and camera inspection of the line and the fact that there have been so few SSO’s in this line results in an appropriate balance between maintaining the Hinkle Creek Nature Area and ensuring the sewer line is properly maintained. 

Since the June 13, 2017 City Council meeting we have made a lot of positive progress, however we still have some important open items to close.  We will keep you updated and will need your help when this issue is presented to the City Council for approval early next year.   

Given that there will be three City Council seats decided in the next election, we will be inviting all candidates to review our proposals and provide their opinions on how the city council should vote on this issue.  We will issue a summary of candidate responses to you before the end of October.

Thanks for your support – feel free to sent questions or comments to: SaveHinkleCreek@gmail.com 

Your Save Hinkle Creek Working Group

 Link to image of City Manager communication of 9/1/17: (https://drive.google.com/open?id=1XelK9I24N0kKQ__2_tYhDo72os8F3WQX