From:	Michael Behrendt
Sent:	Wednesday, June 27, 2018 12:43 PM
Subject:	Riverwoods - tree protection - email from John Parry
Attachments:	Managing Trees Consttuction 2edn ISA.pdf

To the Planning Board,
Please see the email below and attachment from John Parry.

Michael Behrendt
Durham Town Planner
Town of Durham
8 Newmarket Road
Durham, NH  03824
(603) 868-8064
www.ci.durham.nh.us



From: John Parry [mailto:jeparry3@comcast.net]  
Sent: Sunday, June 24, 2018 10:00 PM 
To: Michael Behrendt 
Cc: Todd Selig; Michael Lynch 
Subject: Tree Protection at River Woods

Hi Michael – I hope you are well. I am writing to provide comment on the River 
Woods project. Can you please pass this on to the Planning Board prior to their 
meeting next week. Thanks - John


Dear Planning Board:

I am writing to comment on the River Woods Project (also applies to the 
Mill  Plaza Project).  I work as an urban forester in the New England States and 
New York, and provide states and municipalities with technical assistance on a 
variety of urban forestry topics - protecting trees during construction is a concern 
that comes up often. I want to encourage you to require that steps be taken to 1) 
assess trees on the sites, 2) identify trees that should be saved and 3) require 
specific steps be taken to protect trees during construction.


Background on tree damage during construction
In some past projects in Durham, developers have “saved” some trees from 
removal, but not taken steps to protect then during construction. Damage occurs 
in various ways, and over time the trees decline and die.

Certain types of disturbance and tree damage are commonly seen in construction 
areas; roots are severed by trenching and grading, soil is compacted by use of 
heavy equipment & storage of supplies,  stems & branches are sometimes 
wounded, etc.

Some tree species are more susceptible to damage than others. Older, over 
mature trees are also more at risk. When damage is excessive, some trees may 
recover, but others will decline, sometimes over a period of 5 to 10 years.

Tree root systems are more shallow (most of the roots are in the top 18 inches of 
soil) and more wide spreading (can extend well past the crown spread) than most 
people realize.  This means that tree roots are easily damaged during 
construction.


Suggestions for tree protection
There are many techniques that can be used to provide protection, and avoid the 
types of damage described above. Three general steps to consider are;

1.        Develop a tree protection plan. This starts with an assessment of the trees, 
and associated natural resources, identifies trees to be protected.

2.        Protect trees during construction.
Recommend specific protection techniques to be used. Some 
techniques are fairly simple and low cost (Acceptable Practices), 
others are more sophisticated and more expensive (Best 
Management Practices - BMPs). BMPs should be used as much as 
possible, but for some municipalities cost may be a consideration. 

The best and most effective protection is to protect the tree root 
system. Identify the Critical Protection  Zone (CRZ) which is basically a 
circle of a certain radius around the tree. The CRZ  identifies an area 
of the root system that must be protected to avoid extensive 
damage. There are different methods to define the CPZ, and it may 
vary depending on the tree species, age, condition, soil type and 
other factors. One common formulae is to save a circle with a radius 
equal to 1 foot for every inch of tree diameter. Fencing or barriers 
are erected to keep construction activity away from the tree and root 
system.

There are many other protection techniques that can be used. They 
are too numerous to mention here, but some references are 
provided below that provide detailed specifications. 

“Managing Trees During Construction: Best management 
Practices -  International Society of Arboriculture”.  I have 
attached examples from the publication, and sent a copy of it 
to Michael for your use.

“Trees and Development: A Technical Guide to Preservation of 
Trees During Land development” – Matheny and Clark. 


3.        After construction, when tree damage has occurred, there are some 
techniques that should be used to help trees recover, from damage (irrigation, 
wound repair, pruning, etc.). 


The above outline provides a only a brief summary of this issue. The Town and 
developer could work with a Forester, Certified Arborist, Landscape architect or 
other professional to provide profession advice and help develop a plan for tree 
preservation.  


If I can provide more detailed information or follow up on specific questions 
please let me know.  

John Parry
5 Denbow Rd
Durham, NH